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  • 1.
    Andersson, U.B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Högdahl, K.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Sjöström, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Bergman, S.
    Multistage growth and reworking of the  Palaeoproterozoic crust in the Bergslagen area, southern Sweden: evidence from U-Pb  geochronology2006In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 143, no 5, p. 679-697Article in journal (Refereed)
  • 2.
    Aswad, Khalid J. A.
    et al.
    Department of Geology, College of Science, Mosul University, Iraq.
    Aziz, Nabaz R. H.
    Department of Geology, College of Science, Sulaimani University, Kurdistan Region, Iraq.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Cr-spinel compositions in serpentinites, and their implications for the petrotectonic history of the Zagros Suture Zone, Kurdistan Region, Iraq2011In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 148, no 5-6, p. 802-818Article in journal (Refereed)
    Abstract [en]

    Accessory chrome spinels are scattered throughout the serpentinite masses in two allochthonous thrust sheets belonging to the Penjween–Walash sub-zone of the northwestern Zagros Suture Zone in Kurdistan. Based on field evidence, the serpentinites are divided into two groups: (1) highly sheared serpentinites (110–80 Ma), which occupy the lower contact of the ophiolitic massifs of the Upper Allochthonous sheet (Albian–Cenomanian age), and (2) ophiolitic mélange serpentinites of mixed ages (150 and 200 Ma) occurring along thrust faults on the base of the volcano-sedimentary segment (42–32 Ma) of the Lower Allochthonous sheet. The Cr-spinels of both groups show a wide range of YCr (Cr/(Cr + Al) atomic ratio) from 0.37 to 1.0, while the XMg (Mg/(Mg + Fe2+) atomic ratio) ranges from 0.0 to 0.75. Based on the Cr-spinel compositions of the entire dataset and in conjunction with back-scattered electron imaging, from core to rim, three spinel stages have been recognized: the residual mantle stage, a Cr-rich stage and a third stage showing a very narrow magnetite rim. These three stages are represented by primary Cr-spinel, pre-serpentinization metamorphosed spinel and syn- or post-serpentinization spinel, respectively. The chemical characteristics of primary (first-stage) Cr-spinels of both serpentinite groups indicate a tectonic affinity within a fore-arc setting of peridotite protoliths. The second stage indicates that Cr-spinels have undergone subsolidus re-equilibration as a result of solid–solid reaction during pre-serpentinization cooling of the host rock. Here the primary Cr-spinel compositions have been partly or completely obscured by metamorphism. During the third stage, the Cr-spinels have undergone solid–fluid re-equilibration during syn- or post-serpentinization processes. Both the second and third stages point to diachronous metamorphic paths resulting from continuous tectonic evolution influenced by either slow or fast uplift of mantle protoliths. In the fast metamorphic paths, the primary chrome spinels are flanked by a very narrow magnetite rim. The presence of two groups of distally separated serpentinites with different emplacement ages and fore-arc tectonic affinity could indicate that the closure of the Tethys Ocean culminated in two fortuitous subduction processes.

  • 3. Aziz, Nabaz R. H.
    et al.
    Aswad, Khalid J. A.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Contrasting Settings of Serpentinite Bodies in Northwestern Zagros Suture Zone, Kurdistan Region, Iraq2011In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 148, no 5-6, p. 819-837Article in journal (Refereed)
    Abstract [en]

    Protrusions and lenses of serpentinite–matrix mélanges occur at several places along the thrust faults of the Zagros Suture Zone. They separate the lower allochthonous thrust sheet, the ‘Lower Allochthon’ (i.e. Walash–Naopurdan nappe), of Paleocene–Eocene age from sediments of the Arabian platform and the upper thrust sheet of Mesozoic, ophiolite-bearing terranes termed the ‘Upper Allochthon’ (i.e. Gemo–Qandil nappe). The serpentinite–matrix mélanges occur mostly as stretched bodies (slices) on both sides of the Lower Allochthon (Hero, Halsho and Pushtashan (HHP) and Galalah, Qalander and Rayat (GQR)). Their overall chondrite-normalized rare earth element (REE) patterns form two main groups. Group One exhibits enrichment in the total REEs (> 1 × chondrite) whereas the Group Two pattern shows depletion (i.e. < 1 × chondrite). Bulk-rock MORB-normalized profiles of Group Two are almost flat in the MREE–HREE region with flattening profiles in the Gd–Lu range (> 3 times the MORB composition). In comparison with Group One, Group Two has extremely high REE content and displays variable depletions in the moderately incompatible high-field-strength elements (HFSEs) (Zr, Hf, Y) relative to their adjacent REEs. The REEs in the GQR serpentinite–matrix mélanges have a noticeably high LREE content, and a positive Eu anomaly, and their HREE content never reaches more than 1 × chondrite (i.e. < 0.01 to 1 × chondrite). The latter indicates that the hemipelagic sedimentary, melt-like components (i.e. high LREE, U/La, La/Sm and low Ba/Th) control the geochemical peculiarities of this type of serpentinite. The HHP serpentinite–matrix mélanges, however, are either equally divided between the two REE pattern groups (e.g. Hero, Halsho) or inclined towards Group One (e.g. Pushtashan). Contrary to GQR serpentinites, the variation in HHP serpentinite–matrix mélanges spans a compositional spectrum from U/La-rich to more Ba/Th-rich. Such ratio variations reflect the large variation in these two subducted sedimentary components (i.e. carbonate and hemipelagic sediment mix). The obvious differences in the trace element signatures of the GQR and HHP serpentinite–matrix mélanges might be related to plate tectonic parameters such as convergence rate, subduction age and thickness and type of subducted slab. It is more likely that the influx of subducted components to the mantle wedge relied heavily on the composition of the sedimentary inputs. These vary considerably with time from the relatively deepwater hemipelagic sediments (Qulqula Radiolarite Formation) to platform carbonate sediments (Balambo limestone). The trace element signatures of the GQR and HHP serpentinite–matrix mélanges might suggest multi-staging of the allochthonous sheet emplacement on the Arabian platform sediments.

  • 4.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology.
    Recent Advances in the Origin and Early Radiation of Vertebrates. Arratia, G., Wilson, M. V. H. & Cloutier, R. (eds)2005In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 142, no 6, p. 823-823Article, book review (Other (popular science, discussion, etc.))
  • 5.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology.
    Silurian and Lower Devonian thelodonts and putative chondrichthyans from the Canadian Artic Archipelago. Märss, T., Wilson M. V. H. & Thorsteinsson, R.2007In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 144, no 6, p. 1032-1032Article, book review (Other academic)
  • 6.
    Bremer, Oskar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Niedzwiedzki, Grzegorz
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Blom, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Dec, Marek
    Polish Acad Sci, Inst Paleobiol, Twarda 51-55, PL-00818 Warsaw, Poland.
    Kozłowski, Wojciech
    Univ Warsaw, Inst Geol, Zwirki & Wigury 93, PL-02089 Warsaw, Poland.
    Vertebrate microremains from the upper Silurian Winnica Formation of the Holy Cross Mountains, Poland2018In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 155, no 7, p. 1523-1541Article in journal (Refereed)
    Abstract [en]

    Vertebrate microremains from the upper Silurian Winnica Formation in the Holy Cross Mountains, Poland are described from the Winnica and Rzepin sections. Both sites record the uppermost part of the Supianka Member, but represent different depositional environments. The Winnica samples come from a low-energy environment, while the Rzepin sample was taken from a high-energy, oolitic facies. Both sites contain thelodonts Thelodus parvidens, Thelodus trilobatus, an anaspid cf. Liivilepis and a number of acanthodian scales of 'nostolepid', poracanthodid and 'gomphonchid' types. Notable differences between the sites are the addition of the osteostracan Tahulaspis cf. ordinata, the thelodont Paralogania ludlowiensis and acanthodian scales identified as Nostolepis gracilis in the Rzepin section. Placing the vertebrate faunas within the vertebrate biozonation established for the Silurian proved difficult. The suggested late Ludlow age for the Supianka Member based on sequence stratigraphical and chemostratigraphical correlations cannot be definitely confirmed or refuted, but a late Ludfordian age seems the most plausible based on invertebrate and vertebrate faunas. The much lower abundance of poracanthodid acanthodians in the Rzepin sample supports the notion of Poracanthodes porosus Zone as a deep-water equivalent to a number of vertebrate biozones. The presence of P. ludlowiensis only in the oolitic sample confirms a long temporal range, but restricted environmental distribution for this taxon.

  • 7. Brusatte, Stephen L.
    et al.
    Butler, Richard J.
    Niedzwiedzki, Grzegorz
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Sulej, Tomasz
    Bronowicz, Robert
    Satkunas, Jonas
    First record of Mesozoic terrestrial vertebrates from Lithuania: phytosaurs (Diapsida: Archosauriformes) of probable Late Triassic age, with a review of phytosaur biogeography2013In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 150, no 1, p. 110-122Article in journal (Refereed)
    Abstract [en]

    Fossils of Mesozoic terrestrial vertebrates from Lithuania and the wider East Baltic region of Europe have previously been unknown. We here report the first Mesozoic terrestrial vertebrate fossils from Lithuania: two premaxillary specimens and three teeth that belong to Phytosauria, a common clade of semiaquatic Triassic archosauriforms. These specimens represent an uncrested phytosaur, similar to several species within the genera Paleorhinus, Parasuchus, Rutiodon and Nicrosaurus. Because phytosaurs are currently only known from the Upper Triassic, their discovery in northwestern Lithuania (the Saltiskiai clay-pit) suggests that at least part of the Triassic succession in this region is Late Triassic in age, and is not solely Early Triassic as has been previously considered. The new specimens are among the most northerly occurrences of phytosaurs in the Late Triassic, as Lithuania was approximately 7-10. further north than classic phytosaur-bearing localities in nearby Germany and Poland, and as much as 40. further north than the best-sampled phytosaur localities in North America. The far northerly occurrence of the Lithuanian fossils prompts a review of phytosaur biogeography and distribution, which suggests that these predators were widely distributed in the Triassic monsoonal belt but rarer in more arid regions.

  • 8.
    Cooper, Mark R.
    et al.
    Geol Survey Northern Ireland, Dundonald House,Upper Newtownards Rd, Belfast BT4 3SB, Antrim, North Ireland.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Lemon, Kirstin
    Geol Survey Northern Ireland, Dundonald House,Upper Newtownards Rd, Belfast BT4 3SB, Antrim, North Ireland.
    The "Clay-with-Flints' deposit in Northern Ireland: reassessment of the evidence for an early Paleocene ignimbrite2018In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 155, no 8, p. 1811-1820Article in journal (Refereed)
    Abstract [en]

    Reassessment of key geological sections, field relationships and petrographical characteristics of the Northern Ireland Clay-with-Flints' and Donald's Hill Ignimbrite Formation' show they formed dominantly by sedimentary processes. The involvement of a previously postulated pyroclastic flow during early Paleocene time is not recognized and, as such, the Donald's Hill Ignimbrite Formation stratigraphic term is discounted. Instead a multistage model of formation by sedimentary accumulation and remobilization is presented and the term Clay-with-Flints is retained. Regionally, two dominant facies are recognized in most Clay-with-Flints sections. Facies 1 was formed by an initial accumulation of flints on a chalk landscape undergoing karstification, and involved deposition of a clay matrix derived predominantly from contemporaneous erosion of subtropical soil horizons formed mainly on basalt. In Facies 2, evidence is observed for widespread remobilization of Facies 1 deposits by high-density mudflows driven by the advancement of the Antrim Lava Group, which caused the blockage of subsurface and marginalization of surface drainage. A stratigraphical constraint imposed by the presence of a supposed ignimbrite in this part of the North Atlantic Igneous Province has been problematic, but this is resolved by its identification as a diachronous, sedimentary deposit that formed until buried by either the lower or upper formations of the Antrim Lava Group.

  • 9.
    Dahlin, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Johansson, Åke
    Andersson, Ulf B.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Source character, mixing, fractionation and alkali metasomatismin in Palaeoproterozoic greenstone dykes, Dannemora area, NE Bergslagen region, Sweden2013In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 151, no 04, p. 573-590Article in journal (Refereed)
    Abstract [en]

    The geochemical and isotopic characteristics of metamorphosed Svecofennian maficdykes from the Dannemora area in the NE part of the Bergslagen region in central Sweden wereinvestigated and compared to mafic intrusive rocks in their vicinity. The dykes, with an inferred ageof c. 1860–1870 Ma, are calc-alkaline, sub-alkaline and basaltic in composition and have a mixedsubduction and within-plate geochemical affinity. They are the result of mixing of at least three mantlesource components with similar basaltic major element composition, but different concentrations ofincompatible trace elements. Magma M1 is strongly enriched both in Rare Earth Elements (REE)and High-Field-Strength Elements (HFSE); magma M2 is highly enriched in Large-Ion LithophileElements (LILE, except Sr) with only moderate enrichment in HFSE and REE (particularly low inHeavy Rare Earth Elements); and magma M3 is enriched in Sr and has a flat REE profile. MagmaM3 also has a somewhat more positive (depleted) initial εNd value of +1.8, compared to +0.4 to +0.5 for magmas M1 and M2. The magma evolution was controlled by a mixture of fractionation (mainlyaffecting the compatible elements) and mixing, best seen in the incompatible element concentrationsand the Nd isotope data. The basaltic overall composition indicates little or no wholesale contaminationby upper continental crust, but the dykes have undergone later metasomatic changes mainly affectingthe alkali elements.

  • 10. Donoghue, E.
    et al.
    Troll, V.R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Schwarzkopf, L.M.
    Goodhue, R.
    Clayton, G.
    Organic block coatings in block and ash flow deposits at Merapi volcano, Java, Indonesia2009In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 146, p. 113-120Article in journal (Refereed)
  • 11. Eriksson, Mats E.
    et al.
    Frisk, Åsa M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Polychaete palaeoecology in an early Late Ordovician marine astrobleme of Sweden2011In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 148, no 2, p. 269-287Article in journal (Refereed)
    Abstract [en]

    The post-impact Dalby Limestone (Kulcruse; Upper Ordovician) of the Tvaren crater, southeastern Sweden, has been analysed with regards to polychaetes, as represented by scolecodonts. A palaeoecological succession is observed in the Tvaren-2 drill core sequence, as the vacant ecospace was successively filled by a range of benthonic, nektonic and planktonic organisms. Scolecodonts belong to the first non-planktonic groups to appear and constitute one of the most abundant fossil elements. The polychacte assemblage recorded has an overall composition characteristic of that of the Upper Ordovician of Baltoscandia. Oenonites, Vistulella, Mochtyella and the enigmatic 'Xanioprion' represent the most common genera, whereas Pteropelta, Protarabellites?, Atraktoprion and Xanioprion are considerably more rare. The assemblage differs from coeval ones particularly in its poorly represented ramphoprionid fauna and the relatively high frequency of 'Xanioprion'. A taxonomic succession and changes in abundance and relative frequency of different taxa is observed from the deepest part of the crater and upwards towards more shallow water environments. The initial post-impact assemblage does not, however, necessarily represent a benthonic colonization of the crater floor. Instead it seems to be a taphocoenosis, as indicated by its taxonomic correspondence to the rim facies fauna recovered from Dalby Limestone erratics of the Ringson island. The Tvaren succession has yielded considerably richer scolecodont assemblages than hitherto recorded from the approximately coeval Lockne crater, possibly as a consequence of shallower water settings in the former area.

  • 12. Holohan, E.P.
    et al.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Errington, M.
    Donaldson, C.H.
    Nicoll G.R., G.R.
    Emeleus, C.H.
    The Southern Mountains Zone, Isle of Rum, Scotland: volcanic and sedimentary processes upon an uplifted and subsided magma chamber roof2009In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 146, no 3, p. 400-418Article in journal (Refereed)
  • 13. Jerram, D.A.
    et al.
    Goodenough, K.
    Troll, V.R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Introduction: from the British Tertiary into the future – modern perspectives on the British Palaeogene and North Atlantic Igneous provinces2009In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 146, no 3, p. 305-308Article in journal (Refereed)
    Abstract [en]

    The study of volcanic rocks and igneous centres has long been a classic part of geological research. Despite the lack of active volcanism, the British Isles have been a key centre for the study of igneous rocks ever since ancient lava flows and excavated igneous centres were recognized there in the 18th century (Hutton, 1788). This led to some of the earliest detailed studies of petrology. The starting point for many of these studies was the British Palaeogene Igneous Province (BPIP; formerly known as the ‘British Tertiary’ (Judd, 1889), and still recognized by this name by many geologists around the globe). This collection of lavas, volcanic centres and sill/dyke swarms covers much of the west of Scotland and the Antrim plateau of Northern Ireland, and together with similar rocks in the Faroe Islands, Iceland and Greenland forms a world-class Large Igneous Province. This North Atlantic Igneous Province (NAIP) began to form through continental rifting above a mantle plume at c. 60 Ma, and subsequently evolved as North America separated from Europe, creating the North Atlantic Ocean.

  • 14.
    Jerram, Dougal A.
    et al.
    Department of Earth Sciences, University of Durham, South Road, Durham DH1 3LE, UK.
    Goodenough, Kathryn M.
    British Geological Survey, Murchison House, West Mains Road, Edinburgh EH9 3LA, UK.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Introduction: from the British Tertiary into the future – modern perspectives on the British Palaeogene and North Atlantic Igneous provinces2009In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 146, no 3, p. 305-308Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    The study of volcanic rocks and igneous centres has long been a classic part of geological research. Despite the lack of active volcanism, the British Isles have been a key centre for the study of igneous rocks ever since ancient lava flows and excavated igneous centres were recognized there in the 18th century (Hutton, 1788). This led to some of the earliest detailed studies of petrology. The starting point for many of these studies was the British Palaeogene Igneous Province (BPIP; formerly known as the ‘British Tertiary’ (Judd, 1889), and still recognized by this name by many geologists around the globe). This collection of lavas, volcanic centres and sill/dyke swarms covers much of the west of Scotland and the Antrim plateau of Northern Ireland, and together with similar rocks in the Faroe Islands, Iceland and Greenland forms a world-class Large Igneous Province. This North Atlantic Igneous Province (NAIP) began to form through continental rifting above a mantle plume at c. 60 Ma, and subsequently evolved as North America separated from Europe, creating the North Atlantic Ocean.

  • 15. Karim, K.H.
    et al.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Mushir, K
    Hessami, K.
    Significance of angular unconformities between Cretaceous and Tertiary strata in the Northwestern Segment of the Zagros Fold-Thrust Belt, Kurdistan Region, Iraq2011In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 148, no 5-6, p. 925-939Article in journal (Refereed)
    Abstract [en]

    In this study, two angular unconformities are found and analysed for the first time in the Mesozoic–Cenozoic succession in the northwestern segment of the Zagros fold–thrust belt (ZFTB) in the Kurdistan Region. The first unconformity exists between Lower Cretaceous and Paleocene–Eocene rocks and the second between the Campanian Shiranish Formation and the Maastrichtian Tanjero Formation. Each of these unconformities is found in two different localities in the Zagros Imbricate Zone (i.e. the highly deformed zone immediately SW of the Zagros Suture) of the ZFTB of the Kurdistan Region near the border with Iran. The study uses recent geological mapping, structural and stratigraphic analyses in addition to using previous biozonation of the stratigraphic units that bound the two unconformities. The first unconformity was initiated with obduction of the ophiolite and Lower Cretaceous radiolarite onto the passive margin of the Arabian plate. This unconformity formed during an early phase of the Zagros orogeny, which is associated with the developing of a foreland basin, and resulted in the folding of the radiolarites and their uplift to form high-relief land. The erosion of this high-relief land resulted in the formation of the Paleocene–Eocene Red Bed Series and their deposition on the folded radiolarite. The timing of the deformation that caused this unconformity is hard to determine; however, its stratigraphic position may suggest that it possibly is related to post-Cenomanian movements. The second unconformity is between the tilted Campanian Shiranish Formation (hemipelagite) and Tanjero Formation (500 m of conglomerate in the more proximal area). These unconformities indicate that deformation and uplift of the sedimentary units was variable during ophiolite obduction in this part of the ZFTB. We argue that deformation, ophiolite obduction and collision are likely to have varied in space and time along the c. 2000 km long ZFTB.

  • 16.
    Kear, Benjamin P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Budd, Graham E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    New perspectives on ancient marine reptiles2014In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 151, no 1, p. 5-6Article in journal (Other academic)
    Abstract [en]

    Amniotes first invaded saline lagoons and coastal seaways towards the end of the Palaeozoic (Early Permian, similar to 280 Ma: Pineiro et al. 2012), but by the dawn of the Mesozoic (Early-Middle Triassic, similar to 250-235 Ma: Rieppel, 2002; McGowan & Motani, 2003) they had achieved a diversity of specialized body-forms requisite for an obligate oceanic lifestyle. Such an explosive ecomorphological radiation paved the way for amniote dominance of large-bodied aquatic carnivore/omnivore niches over the next 185 Ma, with some lineages (e.g. dyrosaurid crocodylomorphs and bothremydid turtles: Gaffney, Tong & Meylan, 2006; Barbosa, Kellner & Sales Viana, 2008) even persisting on into the Palaeogene (until similar to 50 Ma), and diversifying (i.e. chelonioid sea turtles: Hirayama, 1997) alongside emergent marine mammals through the Neogene (from similar to 23 Ma) and up until today.

  • 17.
    Kear, Benjamin P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Ekrt, Boris
    Prokop, Josef
    Georgalis, Georgios L.
    Turonian marine amniotes from the Bohemian Cretaceous Basin, Czech Republic2014In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 151, no 1, p. 183-198Article, review/survey (Refereed)
    Abstract [en]

    Despite being known for over 155 years, the Late Cretaceous marine amniotes of the Bohemian Cretaceous Basin in the Czech Republic have received little recent attention. These fossils are however significant because they record a diverse range of taxa from an incompletely known geological interval: the Turonian. The presently identifiable remains include isolated bones and teeth, together with a few disarticulated skeletons. The most productive stratigraphical unit is the Lower-Middle Turonian Bila Hora Formation, which has yielded small dermochelyoid sea turtles, a possible polycotylid plesiosaur and elements compatible with the giant predatory pliosauromorph Polyptychodon. A huge protostegid, together with an enigmatic cheloniid-like turtle, Polyptychodon-like dentigerous components, an elasmosaurid and a tethysaurine mosasauroid have also been found in strata corresponding to the Middle-Upper Turonian Jizera Formation and Upper Turonian - Coniacian Teplice Formation. The compositional character of the Bohemian Cretaceous Basin fauna is compatible with coeval assemblages from elsewhere along the peri-Tethyan shelf of Europe, and incorporates the globally terminal Middle-Upper Turonian occurrence of pliosauromorph megacarnivores, which were seemingly replaced by mosasauroids later in the Cretaceous.

  • 18.
    Kear, Benjamin P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Zammit, Maria
    In utero foetal remains of the Cretaceous ichthyosaurian Platypterygius: ontogenetic implications for character state efficacy2014In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 151, no 1, p. 71-86Article in journal (Refereed)
    Abstract [en]

    Ichthyosaurians provide some of the most famous examples of live birth' in the amniote fossil record based on spectacular complete skeletons of gravid females. Such remains facilitate direct comparisons between adult and foetal life stages, and thus have significant impact on phylogenetic hypotheses that require discrete character states to be ontogenetically uncoupled. This is especially true for Cretaceous ichthyosaurian taxa, the majority of which have been established using single specimens of assumed osteological maturity. Our assessment of in utero ichthyosaurian remains from the late Albian of Australia was therefore aimed at testing ontogenetic stability amongst key traits defining the most ubiquitous Cretaceous taxon: Platypterygius. Surprisingly, almost all of the salient features were identifiable in our sample of undoubtedly immature individuals. Indeed, only the proportions of the sclerotic ring, relative ossification and fusion of various basicranial elements, development of the axial skeleton, prominence of the deltopectoral crest and dorsal trochanter, and formation (but seemingly not number) of distal articular facets on the humerus were found to vary from larger-bodied members of the same species (P. australis). Ontogenetic continuity amongst the majority of other phylogenetically pertinent skeletal structures advocates their application for cladistic analyses, and suggests that many classic characters used to differentiate Platypterygius remain diagnostic irrespective of growth stage.

  • 19.
    Koyi, Hemin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Univ Gavle, Dept Ind Dev IT & Land Management, Gavle, Sweden.
    Hessami, Khaled
    IIEES, Tehran, Iran.
    Modelling role of basement block rotation and strike-slip faulting on structural pattern in cover units of fold-and-thrust belts2016In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 153, no 5-6, p. 827-844Article in journal (Refereed)
    Abstract [en]

    A series of scaled analogue models are used to study (de)coupling between basement and cover deformation. Rigid basal blocks were rotated about a vertical axis in a bookshelf' fashion, which caused strike-slip faulting along the blocks and in the overlying cover units of loose sand. Three different combinations of cover-basement deformations are modelled: (i) cover shortening before basement fault movement; (ii) basement fault movement before cover shortening; and (iii) simultaneous cover shortening with basement fault movement. Results show that the effect of the basement faults depends on the timing of their reactivation. Pre- and syn-orogenic basement fault movements have a significant impact on the structural pattern of the cover units, whereas post-orogenic basement fault movement has less influence on the thickened hinterland of the overlying belt. The interaction of basement faulting and cover shortening results in the formation of rhombic structures. In models with pre- and syn-orogenic basement strike-slip faults, rhombic blocks develop as a result of shortening of the overlying cover during basement faulting. These rhombic blocks are similar in appearance to flower structures, but are different in kinematics, genesis and structural extent. We compare these model results to both the Zagros fold-and-thrust belt in southwestern Iran and the Alborz Mountains in northern Iran. Based on the model results, we conclude that the traces of basement faults in cover units rotate and migrate towards the foreland during regional shortening. As such, these traces do not necessarily indicate the actual location or orientation of the basement faults which created them.

  • 20. Landing, Ed
    et al.
    Geyer, Gerd
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Buchwaldt, Robert
    Bowring, Samuel A.
    Geochronology of the Cambrian: a precise Middle Cambrian U-Pb zircon date from the German margin of West Gondwana2015In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 152, no 1, p. 28-40Article in journal (Refereed)
    Abstract [en]

    A volcanic tuff 1.0 m above the base of the Triebenreuth Formation in the Franconian Forest provides the first precise and biostratigraphically bracketed date within the traditional Middle Cambrian. The first illustration of fossils from the Triebenreuth Formation in this report and their discussion allow a more highly refined correlation within the Middle Cambrian. A weighted mean Pb-206-U-238 date of 503.14 +/- 0.13/0.25/0.59 Ma on zircons from this subaerial pyroclastic tuff was determined by U-Pb chemical abrasion isotope dilution mass spectrometry (CA-TIMS) techniques. At c. 6.0-7.0 Ma younger than the base of the traditional Middle Cambrian in Avalonia, the new West Gondwanan date from east-central Germany suggests that estimates of 500 Ma for the base of the traditional Upper Cambrian and 497 Ma on the base of the Furongian Series may prove to be too old'. Biostratigraphically well-bracketed dates through most of the Middle Cambrian/Series 3 and below the upper Upper Cambrian/upper Furongian Series do not exist. An earlier determined 494.4 +/- 3.8 Ma date from the Southwell Group of Tasmania may actually prove to be a reasonable estimate for the age of the base of the traditional Upper Cambrian. Until high precision dates are determined on the base of the traditional Upper Cambrian and base of the Furongian Series, the rates of biotic replacements and geological developments and the durations of biotic zones in the Middle/Series 3 and Upper Cambrian/Furongian Series remain as best guesses'.

  • 21.
    Lorenz, Henning
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Gee, David G.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Larionov, Alexander N.
    Majka, Jaroslaw
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    The Grenville-Sveconorwegian orogen in the high Arctic2012In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 149, no 5, p. 875-891Article in journal (Refereed)
    Abstract [en]

    Throughout the high Arctic, from northern Canada (Pearya) to eastern Greenland, Svalbard, Franz Josef Land, Novaya Zemlya, Taimyr and Severnaya Zemlya and, at lower Arctic latitudes, in the Urals and the Scandinavian Caledonides, there is evidence of the Grenville-Sveconorwegian Orogen. The latest orogenic phase (c. 950 Ma) is well exposed in the Arctic, but only minor Mesoproterozoic fragments of this orogen occur on land. However, detrital zircons in Neoproterozoic and Palaeozoic successions provide unambiguous Mesoproterozoic to earliest Neoproterozoic (c. 950 Ma) signatures. This evidence strongly suggests that the Grenville-Sveconorwegian Orogen continues northwards from type areas in southeastern Canada and southwestern Scandinavia, via the North Atlantic margins to the high Arctic continental shelves. The widespread distribution of late Mesoproterozoic detrital zircons far to the north of the Grenville-Sveconorwegian type areas is usually explained in terms of long-distance transport (thousands of kilometres) of either sediments by river systems from source to sink, or of slices of lithosphere (terranes) moved on major transcurrent faults. Both of these interpretations involve much greater complexity than the hypothesis favoured here, the former involving recycling of the zircons from the strata of initial deposition into those of their final residence and the latter requiring a diversity of microcontinents. Neither explains either the fragmentary evidence for the presence of Grenville-Sveconorwegian terranes in the high Arctic, or the composition of the basement of the continental shelves. The presence of the Grenville-Sveconorwegian Orogen in the Arctic, mainly within the hinterland and margins of the Caledonides and Timanides, has profound implications not only for the reconstructions of the Rodinia supercontinent in early Neoproterozoic time, but also the origin of these Neoproterozoic and Palaeozoic mountain belts.

  • 22.
    Lorenz, Henning
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Gee, David G.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Whitehouse, Martin J.
    New geochronological data on Palaeozoic igneous activity and deformation in the Severnaya Zemlya Archipelago, Russia, and implications for the development of the Eurasian Arctic margin2007In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 144, no 1, p. 105-125Article in journal (Refereed)
    Abstract [en]

    The Severnaya Zemlya Archipelago, located close to the continental edge of the Kara Shelf in the Russian high Arctic, represents, together with northern Tajmyr, the exposed Neoproterozoic and Palaeozoic part of the North Kara Terrane. This terrane has been interpreted as an independent microcontinent or part of a larger entity, such as Arctida or Baltica, prior to collision with Siberia in Late Carboniferous time. A major stratigraphic break, the Kan'on (canyon) River Unconformity, separates folded Late Cambrian from Early Ordovician successions in one area, October Revolution Island. New geochronological U–Th–Pb ion-microprobe data on volcanic and intrusive rocks from this island constrain the age of an important magmatic episode in the earliest Ordovician. A tuff, in association with Tremadocian fossils, overlying the Kan'on River Unconformity, has been dated to 489.5 ± 2.7 Ma. The youngest rocks beneath the unconformity are of the Peltura minor Zone, and the latter has been dated previously, in western Avalonia, to 490.1+1.7−0.9 Ma. Thus, little time is available for the tectonic episode recorded by the unconformity, and the similarities in radiometric dates may indicate problems with the correlation of faunal markers for the Cambrian–Ordovician boundary across palaeo-continents. The other extrusive and intrusive rocks which have been related to Early Ordovician rifting in the Severnaya Zemlya area yield ages from 489 Ma to 475 Ma. An undeformed granite, cutting folded Neoproterozoic successions on neighbouring Bol'shevik Island has been dated to 342 ± 3.6 Ma and 343.5 ± 4.1 Ma (Early Carboniferous), in accord with evidence elsewhere of Carboniferous strata unconformably overlying the folded older successions. This evidence conflicts with the common interpretation that the structure of the Severnaya Zemlya Archipelago originated during the collision of the North Kara Terrane with Siberia in Late Carboniferous time. An alternative interpretation is that Severnaya Zemlya was located in the Baltica foreland of the Caledonide Orogen and that the eastward-migrating deformation of the foreland basin reached the area of the archipelago in latest Devonian to Early Carboniferous time. This affinity of the North Kara Terrane to Baltica is further supported by 540–560 Ma xenocrysts in Ordovician intrusions on October Revolution Island, an age which is characteristic of the Timanide margin of Baltica.

  • 23.
    Majka, Jaroslaw
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Be'eri-Shlevin, Yaron
    Gee, David G.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Czerny, Jerzy
    Frei, Dirk
    Ladenberger, Anna
    Torellian (c. 640 Ma) metamorphic overprint of Tonian (c. 950 Ma) basement in the Caledonides of southwestern Svalbard2014In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 151, no 4, p. 732-748Article in journal (Refereed)
    Abstract [en]

    Ion microprobe dating in Wedel Jarlsberg Land, southwestern Spitsbergen, provides new evidence of early Neoproterozoic (c. 950 Ma) meta-igneous rocks, the Berzeliuseggene Igneous Suite, and late Neoproterozoic (c. 640 Ma) amphibolite-facies metamorphism. The older ages are similar to those obtained previously in northwestern Spitsbergen and Nordaustlandet where they are related to the Tonian age Nordaustlandet Orogeny. The younger ages complement those obtained recently from elsewhere in Wedel Jarlsberg Land of Torellian deformation and metamorphism at 640 Ma. The Berzeliuseggene Igneous Suite occurs in gently N-dipping, top-to-the-S-directed thrust sheets on the eastern and western sides of Antoniabreen where it is tectonically intercalated with younger Neoproterozoic sedimentary formations, suggesting that it provided a lower Tonian basement on which upper Tonian to Cryogenian sediments (Deilegga Group) were deposited. They were deformed together during the Torellian Orogeny, prior to deposition of Ediacaran successions (Sofiebogen Group) and overlying Cambro-Ordovician shelf carbonates, and subsequent Caledonian and Cenozoic deformation. The regional importance of the late Neoproterozoic Torellian Orogeny in Svalbard's Southwestern Province and its correlation in time with the Timanian Orogeny in the northern Urals as well as tectonostratigraphic similarities between the Timanides and Pearya (northwestern Ellesmere Island) favour connection of these terranes prior to the opening of the Iapetus Ocean and Caledonian Orogeny.

  • 24. Masrouhi, Amara
    et al.
    Bellier, Olivier
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Vila, Jean-Marie
    Ghanmi, Mohamed
    The evolution of the Lansarine-Baouala salt canopy in the North African Cretaceous passive margin in Tunisia2013In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 150, no 5, p. 835-861Article in journal (Refereed)
    Abstract [en]

    Detailed geological mapping, dating, and gravimetric and seismic data are used to interpret the Lansarine-Baouala salt structure (North Tunisia) as a salt canopy emplaced during the Cretaceous Period. The extensional tectonic regime related to the Cretaceous continental margin offered at least two factors that encouraged buried Triassic salt to extrude onto the sea floor and flow downslope: (i) extension induced normal faults that provided routes to the surface, and led to the formation of submarine slopes along which salt could flow; (ii) this structural setting led to differential sedimentation and consequently differential loading as a mechanism for salt movement. The present 40-km-long Lansarine-Baouala salt structure with its unique mass of allochthonous Triassic salt at surface was fed from at least four stems. The salt structure is recognized as one of the few examples worldwide of a subaerial salt canopy due to the coalescence of submarine sheets of Triassic salt extruded in Cretaceous times.

  • 25. Meyer, R.
    et al.
    Nicoll, G.R.
    Hertogen, J.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Ellam, R.
    Emeleus, H.
    Trace element and isotope constraints on crustal anatexis byupwelling mantle melts in the North Atlantic Igneous Province: anexample from the Isle of Rum, NW Scotland2009In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 146, no 3, p. 382-399Article in journal (Refereed)
    Abstract [en]

    Sr and Nd isotope ratios, together with lithophile trace elements, have been measured in arepresentative set of igneous rocks and Lewisian gneisses from the Isle of Rum in order to unravel thepetrogenesis of the felsic rocks that erupted in the early stages of Palaeogene magmatism in the NorthAtlantic Igneous Province (NAIP). The Rum rhyodacites appear to be the products of large amountsof melting of Lewisian amphibolite gneiss. The Sr and Nd isotopic composition of the magmas canbe explained without invoking an additional granulitic crustal component. Concentrations of the traceelement Cs in the rhyodacites strongly suggests that the gneiss parent rock had experienced Cs and Rbloss prior to Palaeogene times, possibly during a Caledonian event. This depletion caused heterogeneitywith respect to 87Sr/86Sr in the crustal source of silicic melts. Other igneous rock types on Rum (dacites,early gabbros) are mixtures of crustalmelts and and primarymantle melts. Forward Rare Earth Elementmodelling shows that late stage picritic melts on Rum are close analogues for the parent melts of theRum Layered Suite, and for the mantle melts that caused crustal anatexis of the Lewisian gneiss.These primary mantle melts have close affinities to Mid-Oceanic Ridge Basalts (MORB), whose traceelement content varies from slightly depleted to slightly enriched. Crustal anatexis is a common processin the rift-to-drift evolution during continental break-up and the formation of Volcanic Rifted Marginssystems. The ‘early felsic–later mafic’ volcanic rock associations from Rum are compared to similarassociations recovered from the now-drowned seaward-dipping wedges on the shelf of SE Greenlandand on the Vøring Plateau (Norwegian Sea). These three regions show geochemical differences thatresult from variations in the regional crustal composition and the depth at which crustal anatexis took place.

  • 26.
    Moczydlowska, Malgorzata
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Pease, Victoria
    Willman, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Wickström, Linda
    Agić, Heda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    A Tonian age for the Visingsö Group in Sweden constrained by detrital zircon dating and biochronology: implications for evolutionary events2018In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 155, no 5, p. 1175-1189Article in journal (Refereed)
  • 27.
    Moczydłowska, Małgorzata
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Budd, Graham
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Agić, Heda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Ecdysozoan-like sclerites among Ediacaran microfossils2015In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 152, no 6, p. 1145-1148Article in journal (Refereed)
    Abstract [en]

    We report the occurrence of organically preserved microfossils from the subsurface Ediacaran strata overlying the East European Platform in Poland, in the form of sclerites and cuticle fragments of larger organisms. They are morphologically similar to those known from Cambrian strata and associated with various metazoan fossils of recognized phyla. The Ediacaran age of the microfossils is evident from the stratigraphic position below the base of the Cambrian System and above the isotopically dated tuff layers at c. 551±4Ma. Within this strata interval, other characteristic Ediacaran microorganisms co-occur such as cyanobacteria, vendotaenids, microalgae, Ceratophyton,Valkyria and macroscopic annelidan Sabellidites. The recent contributions of organic sclerites in revealing the scope of the Cambrian explosion are therefore also potentially extendable back to the Ediacaran Period when animals first appear in the fossil record.

  • 28. Mukherjee, S.
    et al.
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Flanking Microstructures2009In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 146, no 4, p. 517-526Article in journal (Refereed)
    Abstract [en]

    Ductile sheared rocks of the Higher Himalayan Crystalline unit (HHC) in micro-scale reveal flanking microstructures defined by nucleated   minerals (the cross-cutting elements, CEs), and deflected cleavages and   grain margins (the host Fabric elements, HEs) of other minerals.Depending on different or the same senses of drag across the   cross-cutting elements, the flanking microstructures are grouped into   Type 1 or Type 2 varieties, respectively. Cross-cutting elements of Type 2 flanking microstructures connote post-tectonic directional growth. The cross-cutting elements of the Type I flanking   microstructures consistently demonstrate top-to-SW non-coaxial shearing   in the Higher Himalayan Crystalline unit. Here the external host fabric elements bounding the cross-cutting elements act as the C-planes. These   cross-cutting element minerals are usually parallelogram-shaped,   underwent crystal-plastic deformation and their nucleations are pre- or   syntectonic. The facts that the host fabric elements are dragged even in absence of rheological softening at the boundaries of the   cross-cutting elements, and that the cross-cutting elements are non-rigid, indicate strong bonds between the host fabric elements and   the cross-cutting elements. Salient morphological variations in the   flanking microstructures are: (1) variable intensity and senses of drag   along the single and the opposite crosscutting element margins; (2) host fabric elements defined only at one side of the cross-cutting   elements; and (3) presence of a thin hazy zone at the HE-CE contacts.   The observed cross-cutting element minerals are either of nearly the same or of greater competency than the mineral grains which host them.

  • 29. Mukherjee, S.
    et al.
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Viscosity estimates of salt in the Hormuz and Namakdan salt diapirs, Persian Gulf2010In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 147, no 4, p. 497-507Article in journal (Refereed)
    Abstract [en]

    The parabolic surface profiles of the Hormuz and Namakdan salt diapirs in the Persian Gulf suggest that they have been extruding with Newtonian viscous rheologies for the last 104 years. We derive velocity profiles for these diapirs, neglecting gravitational spreading and erosion/dissolution while assuming incompressible Newtonian rheology of the salt. Fitting known rates of extrusion at specific points in its elliptical cross-section, the dynamic viscosity of the salt of the Hormuz diapir is found to range between 1018 and 1021 Pa s. Approximating its sub-circular cross-section to a perfect circle, the range of viscosity of the salt of the Namakdan diapir is obtained as 1017–1021 Pa s. These calculated viscosities fall within the range for naturally flowing salts elsewhere and for other salt diapirs but are broader than those for salts with Newtonian rheology deforming at room temperatures. The salts of the Hormuz and Namakdan diapirs are expected to exhibit a broader range of grain size, which matches the limited existing data.

  • 30. Nicoll, Graeme R.
    et al.
    Holness, Marian B.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Donaldson, Colin H.
    Holohan, Eoghan P.
    Emeleus, C. Henry
    Chew, David
    Early mafic magmatism and crustal anatexis on the Isle of Rum: evidence from the Am Mam intrusion breccia2009In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 146, no 3, p. 368-381Article in journal (Refereed)
    Abstract [en]

    The Rum Igneous Centre comprises two early marginal felsic complexes (the Northern Marginal Zone and the Southern Mountains Zone), along with the later central ultrabasic-basic layered intrusions. These marginal complexes represent the remnants of near-surface to eruptive felsic magmatism associated with caldera collapse, examples of which are rare in the North Atlantic Igneous Province. Rock units include intra-caldera collapse breccias, rhyolitic ignimbrite deposits and shallow-level felsic intrusions, as well the enigmatic 'Am Mam intrusion breccia'. The latter comprises a dacitic matrix enclosing lobate basaltic inclusions (similar to 1-15 cm) and a variety of clasts, ranging from millimetres to tens of metres in diameter. These clasts comprise Lewisian gneiss, Torridonian sandstone and coarse gabbro. Detailed re-mapping of the Am Mam intrusion breccia has shown its timing of emplacement as syn-caldera, rather than pre-caldera as previously thought. Textural analysis of entrained clasts and adjacent, uplifted country rocks has revealed their thermal metamorphism by early mafic intrusions at greater depth than their present structural position. These findings provide a window into the evolution of the early mafic magmas responsible for driving felsic magmatism on Rum. Our data help constrain some of the physical parameters of this early magma-crust interaction and place it within the geochemical evolution of the Rum Centre.

  • 31. Petronis, M.
    et al.
    ODriscoll, B.
    Troll, V.R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Geissman, J.W.
    Emeleus, C.H.
    Palaeomagnetic and Anisotropy of Magnetic Susceptibility data bearing on the emplacement of the Western Granite, Isle of Rum, NW Scotland2009In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 146, p. 419-436Article in journal (Refereed)
  • 32. Sachs, Sven
    et al.
    Kear, Benjamin P.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Postcranium of the paradigm elasmosaurid plesiosaurian Libonectes morgani (Welles, 1949)2015In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 152, no 4, p. 694-710Article in journal (Refereed)
    Abstract [en]

    Elasmosauridae constitutes one of the most immediately recognizable plesiosaurian radiations. Their distinctive body plan represents the popular model for Plesiosauria, and is typified by an osteological morphology especially adapted for hyper-elongation of the neck. Nevertheless, many archetypal elasmosaurids are known only from incomplete and/or inadequately documented material, a problem that has contributed to their uncertain intra-clade relationships. A prime example of this is Libonectes morgani from the Upper Cretaceous of Texas, USA, which is frequently presented as an elasmosaurid structural proxy because of its three-dimensionally preserved holotype skull. Perplexingly though, both the taxonomic diagnosis and phylogenetic placement of L. morgani rely primarily upon the cervical vertebrae, together with the pectoral girdle and forelimb, yet most of these elements are now lost and figured only as line drawings. We therefore reviewed the remnant postcranial skeleton of L. morgani first-hand with the objective of clarifying its defining character states. Our observations showed that the existing diagnosis of L. morgani is indeed inadequate. Moreover, the only identifiable autapomorphies occurred within the axial skeleton. This concurred with an examination of character scores used in published plesiosaurian phylogenies, and highlights the persistent significance of postcranial elements for discriminating elasmosaurid taxa.

  • 33.
    Sachs, Sven
    et al.
    Nat Kundemuseum Bielefeld, Abt Geowissensch, Adenauerpl 2, D-33602 Bielefeld, Germany.;Hof 9, D-51766 Engelskirchen, Germany..
    Wilmsen, Markus
    Senckenberg Nat Hist Sammlungen Dresden, Museum Mineral & Geol, Sekt Palaozool, Konigsbrucker Landstr 156, D-01109 Dresden, Germany..
    Knueppe, Joschua
    Idastr 13, D-49479 Ibbenburen, Germany..
    Hornung, Jahn J.
    Fuhlsbuttler Str 611, D-22337 Hamburg, Germany..
    Kear, Benjamin P.
    Uppsala University, Music and Museums, Museum of Evolution.
    Cenomanian-Turonian marine amniote remains from the Saxonian Cretaceous Basin of Germany2017In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 154, no 2, p. 237-246Article in journal (Refereed)
    Abstract [en]

    The Saxonian Cretaceous Basin constitutes an important source of rare Late Cretaceous marine amniote fossils from Germany. It is also historically famous, having been documented in a series of monographic works published by the distinguished German palaeontologist Hanns Bruno Geinitz in the nineteenth century. The most productive rock units include the upper Cenomanian Dolzschen Formation and upper Turonian Strehlen and Weinbohla limestones (lower Strehlen Formation). A survey of curated specimens recovered from these deposits has now identified isolated teeth of probable polycotylid and elasmosaurid plesiosaurians, as well as several humeri that are referred to protostegid marine turtles. The Saxonian Cretaceous Basin formed a continuous epeiric seaway with the Bohemian Cretaceous Basin during late Cenomanian - Turonian time. A western connection to the North Sea Basin also existed via the North German and Munsterland Cretaceous basins. The Mesozoic marine amniote remains from these regions therefore record a coeval northern European fauna that was probably homogeneous across the northern peri-Tethyan margin during Late Cretaceous time.

  • 34.
    Sturesson, U.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Popov, L.E.
    Holmer, L.E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Bassett, M.G.
    Felitsyn, S.
    Belyatsky, B.
    Neodymium isotopic composition of Cambrian-Ordovician biogenic apatite in the Baltoscandian Basin: implications for palaeogeographical evolution and patterns of biodiversity2005In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 142, no 4, p. 419-439Article in journal (Refereed)
    Abstract [en]

    Biogenic apatite preserved in 148 samples of conodonts and organophosphatic-shelled brachiopods from Cambrian through Ordovician successions of the Baltoscandian Basin (Baltica Plate) preserves a sensitive record of early Palaeozoic sea-water chemistry interpreted via neodymium isotope ratios. Consistent Nd(t) values of 9.6 to 8.3 for Lower to Middle Cambrian samples suggest no significant lateral or temporal variation across the region. Average Upper Cambrian values are 7.2 to 7.7. Sedimentary analysis suggests that the influence of continental weathering from Baltica as a major source of radiogenic Nd was negligible. Ordovician samples show a rise to 5 to 6 in the early Arenig, early–mid Llanvirn and late Caradoc. Sea-water mixing from the southeast Iapetus Ocean was a constant factor throughout Cambrian–Ordovician times. The rise reflects erosion of obducted volcanic arc complexes along the Caledonian margin, and probably also relates to pollution of the Baltica sector of Iapetus from the approaching Avalonia Plate. Patterns of evolutionary biodiversity and palaeobiogeographical linkages support the geochemical signatures in interpreting the tectonic history of the region. Extinction of lingulate brachiopod faunas in the Tremadoc, followed by subsequent recovery and emergence of benthic assemblages typical of the Ordovician Evolutionary Fauna in the Billingen–early Volkhov regional stages coincide with significant changes in geochemical characteristics of water masses across the Baltoscandian basin. The early and mid Ordovician (Arenig to Llandeilo) brachiopod faunas of the North Estonian Confacies Belt are characterized by high endemism and low turnover rates, whereas increased immigration resulted in the extinction of a number of local lineages in the late Llanvirn. From the mid Caradoc to mid Ashgill, when Baltica was drifting on a course to collide eventually with Avalonia and gradually approach Laurentia, brachiopod assemblages were characterized by higher turnover rates. At the same time they gradually became more cosmopolitan and less influenced by the invasion of new faunas.

  • 35. Suan, Guillaume
    et al.
    Rulleau, Louis
    Mattioli, Emanuela
    Sucheras-Marx, Baptiste
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Rousselle, Bruno
    Pittet, Bernard
    Vincent, Peggy
    Martin, Jeremy E.
    Lena, Alex
    Spangenberg, Jorge E.
    Foellmi, Karl B.
    Palaeoenvironmental significance of Toarcian black shales and event deposits from southern Beaujolais, France2013In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 150, no 4, p. 728-742Article in journal (Refereed)
    Abstract [en]

    New sedimentological, biostratigraphical and geochemical data recording the Toarcian Oceanic Anoxic Event (T-OAE) are reported from a marginal marine succession in southern Beaujolais, France. The serpentinum and bifrons ammonite zones record black shales with high (1-10 wt %) total organic carbon contents (TOC) and dysoxia-tolerant benthic fauna typical of the 'Schistes Carton' facies well documented in contemporaneous nearby basins. The base of the serpentinum ammonite zone, however, differs from coeval strata of most adjacent basinal series in that it presents several massive storm beds particularly enriched in juvenile ammonites and the dysoxia-tolerant, miniaturized gastropod Coelodiscus. This storm-dominated interval records a marked negative 5 parts per thousand carbonate and organic carbon isotope excursion being time-equivalent with that recording storm-and mass flow-deposits in sections of the Lusitanian Basin, Portugal, pointing to the existence of a major tempestite/turbidite event over tropical areas during the T-OAE. Although several explanations remain possible at present, we favour climatically induced changes in platform morphology and storm activity as the main drivers of these sedimentological features. In addition, we show that recent weathering, most probably due to infiltration of O-2-rich meteoric water, resulted in the preferential removal of C-12-enriched organic carbon, dramatic TOC loss and total destruction of the lamination of the black shale sequence over most of the studied exposure. These latter observations imply that extreme caution should be applied when interpreting the palaeoenvironmental significance of sediments lacking TOC enrichment and lamination from outcrops with limited surface exposures.

  • 36.
    Tolmacheva, Tatiana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Popov, Leonid E.
    Gogin, Ivan
    Conodont biostratigraphy and faunal assemblages in radiolarian ribbon-banded cherts of the Burubaital Formation, West Balkhash Region, Kazakhstan2004In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 141, no 6, p. 699-715Article in journal (Refereed)
    Abstract [en]

    Biostratigraphical study of the early to mid-Ordovician conodont fauna from ribbon-banded radiolarian cherts of the middle Burubaital Formation in Central Kazakhstan reveals an almost complete succession of conodont biozones from the late Tremadocian to the early Darriwilian. During this interval, biosiliceous sediments were deposited in basinal environments, inhabited by lingulate brachiopods, sponges, pterobranchs and caryocaridids in conditions of high fertility and primary productivity of surface water. The community structure of taxonomically diverse conodont assemblages typifying open oceanic environments is not significantly different from that of epicratonic basins of the North Atlantic conodont province. The regional increase of oxygenated bottom waters at the base of the Oepikodus evae Biozone is possibly related to considerable changes in palaeo-oceanographical circulation patterns. The finds of three natural clusters of Prioniodus oepiki (McTavish) enable us to propose an emended diagnosis of this species.

  • 37. Topper, Timothy P.
    et al.
    Brock, Glenn A.
    Skovsted, Christian B.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Paterson, John R.
    Palaeoscolecid scleritome fragments with Hadimopanella plates from the early Cambrian of South Australia2010In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 147, no 1, p. 86-97Article in journal (Refereed)
    Abstract [en]

    Phosphatized articulated palaeoscolecid scleritome fragments with attached Hadimopanella Gedik, 1977 plates are described from the lower Cambrian Mernmerna Formation of South Australia. Hadimopanella is principally known from single, isolated, button-shaped, phosphatic sclerites. The new articulated material from South Australia reveals for the first time the configuration of plates referable to Hadimopanella within the scleritome. The scleritome fragments represent the main trunk sections of the cuticle with anterior and posterior terminations lacking. Each annulus on the trunk is ornamented by rows of irregularly alternating Hadimopanella plates. The large majority of plates display a single, centrally located, conical node referable to the form species H. apicata Wrona, 1982. However, individual plates display considerable morphological variation with plates situated along the flattened trunk margin identical to the form species H. antarctica Wrona, 1987. The South Australian material displays the detailed scleritome configuration of cuticular plates and platelets and demonstrates irrefutably that plates of the form species H. apicata and H. antarctica occur as mineralized cuticular elements on the same palaeoscolecid scleritome.

  • 38. Vincent, Peggy
    et al.
    Martin, Jeremy E.
    Fischer, Valentin
    Suan, Guillaume
    Khalloufi, Bouziane
    Sucheras-Marx, Baptiste
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Lena, Alex
    Janneau, Kevin
    Rousselle, Bruno
    Rulleau, Louis
    Marine vertebrate remains from the Toarcian-Aalenian succession of southern Beaujolais, Rhone, France2013In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 150, no 5, p. 822-834Article in journal (Refereed)
    Abstract [en]

    A previously undocumented marine vertebrate fauna comprising ichthyosaur, plesiosaur, marine crocodilian and fish remains from the Toarcian-Aalenian succession at Lafarge quarry, southern Beaujolais (Rhone, France) is described on the basis of both historical collections and new discoveries. The taxonomic composition of the Lafarge quarry marine vertebrate assemblage highlights its cosmopolitan nature and strong relationships with taxa known from elsewhere in Europe. Several groups are recorded for the first time in the Toarcian-Aalenian succession of France, implying new palaeobiogeographic interpretations and prompting discussion of marine amniote diversity during this interval.

  • 39.
    Yu, Fusheng
    et al.
    China Univ Petr, State Key Lab Petr Resources & Prospecting, Beijing 102249, Peoples R China.;China Univ Petr, Dept Earth Sci, Fuxue Rd, Beijing 102249, Peoples R China..
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Cenozoic tectonic model of the Bohai Bay Basin in China2016In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 153, no 5-6, p. 866-886Article in journal (Refereed)
    Abstract [en]

    Modelling results and seismic interpretation illustrate that the Cenozoic evolution of the Bohai Bay Basin (BBB) can be divided into different stages. A transtensional phase during Paleocene - early Oligocene time created NE-trending strike-slip faults and E-W-trending normal faults which were driven roughly by N-S-extension, making an angle of 25 degrees with the strike-slip faults. Seismic data interpretation yields evidence that inversion phases occurred within the NE Xialiaohe Depression of the greater Bohai Bay Basin. This inversion phase is attributed to rotation and partial inversion that occurred during late Oligocene time, leading to formation of inversion structures along the NE part of Tanlu Fault. This episode is attributed to an anticlockwise rotation of the eastern part of the BBB driven by the convergence between the Pacific and Eurasian plates. The tectonic scenario described was simulated in scaled analogue models, which were extended by pulling two basement plates away from each other. Partial inversion was simulated by rotation of one of the plates relative to the other. Model results show many of the features observed in the BBB. Our model results are used to argue that, unlike the two-episode extension and whole-basin inversion models previously proposed for the BBB, a single N-S-aligned extension followed by anticlockwise rotation accounts for the Cenozoic evolution of the BBB and produces some of the structural complexities observed in the basin.

  • 40. Zammit, Maria
    et al.
    Kear, Benjamin P.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Norris, Rachel M.
    Locomotory capabilities in the Early Cretaceous ichthyosaur Platypterygius australis based on osteological comparisons with extant marine mammals2014In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 151, no 1, p. 87-99Article in journal (Refereed)
    Abstract [en]

    Reconstructing the swimming capabilities of extinct marine tetrapods is critical for unravelling broader questions about their palaeobiology, palaeoecology and palaeobiogeography. Ichthyosaurs have long been the subject of such investigations because, alongside cetaceans, they are one of the few tetrapod lineages to achieve a highly specialized fish-like body plan. The dominant locomotory mode for the majority of derived, post-Triassic ichthyosaurs is hypothesized to have been caudal fin-driven propulsion. Limb-based swimming has however been suggested for some highly autapomorphic forms, such as the Cretaceous genus Platypterygius, which has a remarkably robust humeral morphology and exceptionally broad paddle-like limbs. To evaluate this atypical lifestyle model, we conducted a comprehensive comparative osteological assessment of Platypterygius in relation to extant marine mammals, whose analogous skeletal frameworks provide a structurally compatible selection of alternate propulsive strategies. Based on a proxy exemplar of the most completely known species, P.australis from the Early Cretaceous of Australia, the propodial shape, absence of functional elbow/knee joints, tightly interlocking carpals, hyperphalangy and extreme reduction of the pelvic girdle are most similar to cetaceans as opposed to pinnipeds or dugongs. There is no obvious structural consistency with aquatic mammals that use sustained forelimb-driven swimming. The exceptionally broad fore-paddle (a product of hyperdactyly) and extensive humeral muscle insertions might therefore have had a cetacean-like role in enhancing manoeuvrability and acceleration performance. We conclude that, despite its atypical features, P. australis was most likely similar to other ichthyosaurs in using lateral sweeps of the tailfin to generate primary propulsive thrust.

  • 41. Zarei, M.
    et al.
    Raeisi, E.
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Karst development on a mobile substrate: Konarsiah salt extrusion, Iran2012In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 149, no 3, p. 412-422Article in journal (Refereed)
    Abstract [en]

    Most karst terranes develop slowly on static limestone substrates as part of the global hydrological cycle. Here we introduce the novel concept of a karst morphology developing very rapidly on a more soluble substrate of salt (NaCl) that is moving through its own global cycle. We open with a reminder of karst features and processes in limestone. We then illustrate the global salt cycle using the 180 or so extrusions of Hormoz salt in the Zagros Mountains of Iran. After describing the geology of an example, we consider how it fits into the evolution of salt extrusions. This example, Konarsiah, was chosen for its simple hydrology. Konarsiah is covered by residual soils of the insoluble components that remain in place as the Hormoz salt is dissolved. Dolines in the surface of these soils enlarge and the soils thicken as the moving salt dissolves. The long-term rate of salt dissolution and soil production on Konarsiah are estimated using traditional methods. The calculated age of the thickest, most distal soil is used to constrain the average rate at which the underlying salt flows downslope after extruding from two vents. The average velocities constrained for salt flow are lower than rates of displacement of markers near the summit of Konarsiah measured at irregular intervals over five years. Salt extruding from recently truncated diapirs near the arid south coast of Iran exhibit all the features seen in classical karst terranes. In the more humid mountains inland, vegetated soils protect salt extrusions like Konarsiah from erosion and limit their salt karst features. Soil covers also probably even out salt flow velocities. Salt extrusions advance when such protective covers grow and thicken in humid conditions. They retreat when such protection is lost to erosion in drier conditions. These external signs complement internal recumbent folds in extruded salt that signal intervals of faster salt flow when wet than dry. They also add to the features that render salt extrusions records of climate change.

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