First record ofOphthalmosaurus(Reptilia: Ichthyosauria) from the Tithonian (Upper Jurassic) of Mexico

2010 ◽  
Vol 84 (1) ◽  
pp. 149-155 ◽  
Author(s):  
Marie-Céline Buchy
Keyword(s):  
Middle Jurassic ◽  
Late Jurassic ◽  
Field Work ◽  
First Record ◽  
Upper Jurassic ◽  
Marine Transgression ◽  
North East ◽  
The Pacific ◽  
Invertebrate Assemblages ◽  
Marine Reptile

From the Middle Jurassic on, the Tethys basin opened westward; the existence of a Carribean corridor linking the European and Pacific realms now appears well supported by comparison of marine reptile assemblages (e.g., Gasparini and Fernández, 1997, 2005; Gasparini et al., 2000; Fernández and Iturralde-Vinent, 2000; Gasparini and Iturralde-Vinent, 2001, 2006; Gasparini et al., 2002). Marine transgression in Mexico began during the Callovian, as evidenced by the evaporites of the Minas Viejas Fm. However, microfossils and invertebrate assemblages indicate that the Mexican Gulf remained isolated from both the European Archipelago and the Pacific, at least temporarily, until the middle Berriasian; the Florida uplift and southward movement of Yucatan were proposed as possibly forming a barrier (Salvador et al., 1993; Adatte et al., 1994, 1996; Goldhammer, 1999; Goldhammer and Johnston, 2001; Gasparini and Iturralde-Vinent, 2006). After almost a decade of field work and examination of collections, the Late Jurassic marine reptile assemblage of north-east Mexico confirms the conclusions drawn from microfossils and invertebrates. Poorly diagnostic ichthyosaur remains, with various thalattosuchians, numerically dominate the assemblage. Sauropterygians are rare, mainly represented by large pliosaurids of unclear affinities, a few vertebrae attributed to elasmosaurids, and a unique cryptoclidid. Turtles are yet to be reported (Frey et al., 2002; Buchy et al., 2003, 2005b, 2006a–d; Buchy, 2007, 2008a, b; material currently under study).

scholarly journals A Balto-Scandian Middle Cambrian fauna from Peary Land, North Greenland

1988 ◽  
Vol 137 ◽  
pp. 118-118
Author(s):  
T.P Fletcher ◽  
A.K Higgins ◽  
J.S Peel
Keyword(s):  
North America ◽  
Field Work ◽  
First Record ◽  
Geological Survey ◽  
Northern Coast ◽  
Middle Cambrian ◽  
The Pacific ◽  
Cambrian Trilobite ◽  
Inland Ice ◽  
North Greenland

The first record of Middle Cambrian faunas of 'Atlantic' affinity from the Franklinian basin sequence of North Greenland was made by Poulsen (1969) who noted that previously described Greenland faunas were of 'Pacific' type. Field work by the Geological Survey of Greenland during the last decade has established that 'Atlantic' faunas are widespread in more outer shelfsequences along the northern coast of North Greenland while the 'Pacific' faunas occur within inner shelfsequences more to the south, near the margin of the Inland Ice. North Greenland preserves both faunas in dose geographical juxtaposition in only slightly tectonised geological settings. Thus, alatest Middle Cambrian trilobite fauna described by Robison (in press) from the Holm Dal Formation in an area some 40 km south of the presently discussed locality (and more inner shelf) includes a mixture of polymeroids characteristic of the Cedaria Zone of North America and agnostoids characteristic of the Lejopyge laevigata Zone of the Swedish standard zonation.

scholarly journals Jurassic dinoflagellate cyst stratigraphy of Store Koldewey, North-East Greenland

2004 ◽  
Vol 5 ◽  
pp. 99-112 ◽  
Author(s):  
Stefan Piasecki ◽  
John H. Callomon ◽  
Lars Stemmerik
Keyword(s):  
Middle Jurassic ◽  
Upper Jurassic ◽  
Dinoflagellate Cysts ◽  
The South ◽  
Important Species ◽  
East Greenland ◽  
Sequence Stratigraphic ◽  
Fine Grained ◽  
North East ◽  
The North

The Jurassic of Store Koldewey comprises a Middle Jurassic succession towards the south and an Upper Jurassic succession towards the north. Both successions onlap crystalline basement and coarse sediments dominate. Three main lithostratigraphical units are recognised: the Pelion Formation, including the Spath Plateau Member, the Payer Dal Formation and the Bernbjerg Formation. Rich marine macrofaunas include Boreal ammonites and the successions are dated as Late Bathonian – Early Callovian and Late Oxfordian – Early Kimmeridgian on the basis of new collections combined with material in earlier collections. Fine-grained horizons and units have been analysed for dinoflagellate cysts and the stratigraphy of the diverse and well-preserved flora has been integrated with the Boreal ammonite stratigraphy. The dinoflagellate floras correlate with contemporaneous floras from Milne Land, Jameson Land and Hold with Hope farther to the south in East Greenland, and with Peary Land in North Greenland and Svalbard towards the north. The Middle Jurassic flora shows local variations in East Greenland whereas the Upper Jurassic flora gradually changes northwards in East Greenland. A Boreal flora occurs in Peary Land and Svalbard. The characteristic and stratigraphically important species Perisseiasphaeridium pannosum and Oligosphaeridium patulum have their northernmost occurrence on Store Koldewey, whereas Taeniophora iunctispina and Adnatosphaeridium sp. extend as far north as Peary Land. Assemblages of dinoflagellate cysts are used to characterise significant regional flooding events and extensive sequence stratigraphic units.

Exploration in the southwest Malita Graben: initial results and remaining potential

2013 ◽  
Vol 53 (2) ◽  
pp. 428
Author(s):  
Kelsey Jewett ◽  
Anne-Claire Lorage ◽  
Said Amiribesheli ◽  
Han Kee Tan
Keyword(s):  
Middle Jurassic ◽  
Late Jurassic ◽  
Upper Jurassic ◽  
Reservoir Quality ◽  
High Co2 ◽  
Fault Block ◽  
Fault Leakage ◽  
Net To Gross ◽  
Hydrocarbon Charge ◽  
Initial Results

In 2011, Total E&P Australia and Petronas Carigali drilled two exploration wells in permit WA-403-P in the northern Bonaparte Basin. Both wells targeted the Middle-Jurassic play of the Elang/Plover formations that have yielded all commercial discoveries in the area. Notably, the wells were drilled in a less-explored area near the axis of the basin, targeting reservoirs at or more than 4,000 m. Pre-drill, the critical risks were recognised as burial-related reservoir degradation and cross-fault leakage into Upper Jurassic to Lower Cretaceous sands. The first well, Durville-1, was drilled on a poorly imaged three-way dip closure to the south of the Flamingo High. A gas column with high CO2 content was encountered in thick, high net-to-gross sands of lowermost Berriasian age. Drilling was terminated before the Elang Formation was reached. The second well, Laperouse-1, was drilled on a well-imaged fault block near the southern margin of the Malita Graben. The structure was formed in the Late Jurassic and lacks recent fault activation; thus, it was anticipated that early hydrocarbon charge might protect the reservoir from severe diagenesis. Laperouse-1 encountered a thick succession of Tithonian to Berriasian water-bearing sand packages; it reached total depth in the Elang Formation. The WA-403-P drilling campaign has confirmed the presence of thick Cretaceous sandstone in the area, although significant discrepancies in reservoir quality are observed between Durville-1 and Laperouse-1.

Calosargus talbragarensisnew species: the first brachyceran fly from the Jurassic of Australia (Diptera, Archisargidae)

2012 ◽  
Vol 86 (4) ◽  
pp. 641-645 ◽  
Author(s):  
Stefanie K. Oberprieler ◽  
David K. Yeates
Keyword(s):  
New Species ◽  
Southern Hemisphere ◽  
Middle Jurassic ◽  
First Record ◽  
Upper Jurassic ◽  
Wing Morphology ◽  
Single Well ◽  
Early Upper

The first fly fossil discovered from the Upper Jurassic Talbragar Fish Bed in Australia is described and illustrated. Based on a single, well preserved wing,Calosargus (Calosargus) talbragarensisnew species is assigned to the extinct brachyceran family Archisargidae. Wing morphology suggests a relationship between this extinct family and Stratiomyidae. The Archisargidae have so far only been found in China, Kazakhstan and Mongolia.CalosargusMostovski, 1997 currently comprises seven species from the Callovian (late Middle Jurassic) of China and three species from the Oxfordian (early Upper Jurassic) of Kazakhstan. This oldest brachyceran fossil from Australia and first record of the Archisargidae in the southern hemisphere presents evidence that higher flies were present in this region in the Jurassic, when this group is thought to have commenced its diversification.

scholarly journals Depositional environments of Lower Cretaceous (Ryazanian– Barremian) sediments from Wollaston Forland and Kuhn Ø, North-East Greenland

2013 ◽  
Vol 61 ◽  
pp. 19-36 ◽  
Author(s):  
Sebastian Pauly ◽  
Jørg Mutterlose ◽  
Peter Alsen
Keyword(s):  
Lower Cretaceous ◽  
Late Jurassic ◽  
Stable Carbon Isotopes ◽  
Short Interval ◽  
First Record ◽  
Depositional Environments ◽  
Heavy Minerals ◽  
Mineral Contents ◽  
East Greenland ◽  
North East

Lower Cretaceous sediments from the Wollaston Forland–Kuhn Ø area in North-East Greenland have been analyzed for stable carbon isotopes, total organic carbon (TOC) content, and major and trace elements, aiming at a lithological characterization and reconstruction of the depositional environments. The marine sediments of Ryazanian–Barremian age were deposited in North-East Greenland directly after a major Late Jurassic – earliest Cretaceous rifting event. The Lower Cretaceous post-rift sediments are composed of fossiliferous calcareous mud- and marlstones assigned to the Albrechts Bugt (upper Ryazanian – Valanginian) and Rødryggen (Hauterivian) Members. The calcareous sediments are commonly sandwiched between black mudstones of Late Jurassic – earliest Cretaceous (Bernbjerg Formation) and mid Cretaceous (unnamed formation) age. The carbon isotope curves present the first record for the Lower Cretaceous (upper Ryazanian – Barremian) of North-East Greenland. The Ryazanian – Hauterivian sediments are characterized by a mixture of terrigenous detrital matter (quartz, clay minerals, heavy minerals) similar to average shale, with varying CaCO3 concentrations. The Barremian black mudstones on the contrary have lower CaCO3 and higher clay mineral contents. The deposition of the Bernbjerg Formation took place under anoxic bottom water conditions. The depositional environment of the Albrechts Bugt and Rødryggen Members is characterized by well-oxygenated sea-floor conditions, hemipelagic sedimentation of fine-grained terrigeneous detrital matter, and biogenic carbonate settling. After this relatively short interval of carbonate sedimentation under oxic conditions, bottom waters were affected by dysoxic conditions, responsible for the burial of organic matter in the Barremian.

scholarly journals Maximum Middle Jurassic transgression in East Greenland: evidence from new ammonite finds, Bjørnedal, Traill Ø

2004 ◽  
Vol 5 ◽  
pp. 31-49 ◽  
Author(s):  
Peter Alsen ◽  
Finn Surlyk
Keyword(s):  
New Species ◽  
Middle Jurassic ◽  
Upper Jurassic ◽  
Middle Part ◽  
The South ◽  
East Greenland ◽  
Lower Upper ◽  
North East ◽  
A New Species ◽  
Lower Callovian

A Middle – lower Upper Jurassic sandstone-dominated succession, more than 550 m thick, with mudstone intercalations in the middle part is exposed in Bjørnedal on Traill Ø, North-East Greenland. A number of ammonite assemblages have been found, mainly in the mudstones. They indicate the presence of the Lower Callovian Cadoceras apertum and C. nordenskjoeldi Chronozones. The mudstones represent northern wedges of the Fossilbjerget Formation hitherto known only from Jameson Land to the south. In Bjørnedal they interfinger with sandstones of the Pelion and Olympen Formations. The presence of the Fossilbjerget Formation in this region indicates complete drowning of the Middle Jurassic sandstone-dominated Pelion Formation during maximum Middle Jurassic transgression. A new species, Kepplerites tenuifasciculatus, is described in the appendix by J.H. Callomon. The holotype and paratype are from Jameson Land, East Greenland, but the species is also found in Bjørnedal, Traill Ø, North-East Greenland.

scholarly journals The Jurassic of North-East Greenland

2004 ◽  
Vol 5 ◽  
pp. 1-7 ◽  
Author(s):  
Lars Stemmerik
Keyword(s):  
Middle Jurassic ◽  
Upper Jurassic ◽  
East Greenland ◽  
Dinoflagellate Cyst ◽  
Fluvial Deposits ◽  
South Eastern ◽  
North East

The Jurassic rift succession of East Greenland has been intensely studied over the last 25 years, particularly within the main outcrop areas of Jameson Land and Wollaston Forland. The more isolated and poorly known outcrops on Traill Ø, Hold with Hope, Hochstetter Forland and Store Koldewey were investigated in the late 1980s and mid-1990s in order to develop a better regional understanding of the Jurassic in eastern Greenland.This collection of seven papers focuses on stratigraphic and depositional aspects of the Jurassic at these localities. Comprehensive descriptions of the Jurassic on Hold with Hope and south-eastern Traill Ø are accompanied by papers covering fluvial deposits and new ammonite collections from the Middle Jurassic of Traill Ø. The bulletin is concluded by studies of the dinoflagellate cyst stratigraphy of the Middle and Upper Jurassic of Hold with Hope, Hochstetter Forland and Store Koldewey.

scholarly journals The Jurassic of Kuhn Ø, North-East Greenland

2003 ◽  
Vol 1 ◽  
pp. 865-892 ◽  
Author(s):  
Per C. Alsgaard ◽  
Vince L. Felt ◽  
Henrik Vosgerau ◽  
Finn Surlyk
Keyword(s):  
Source Rock ◽  
Middle Jurassic ◽  
Barents Sea ◽  
Upper Jurassic ◽  
Shallow Marine ◽  
East Greenland ◽  
Base Level ◽  
North East ◽  
The Barents Sea ◽  
Lower Unit

The Middle–Upper Jurassic succession of Kuhn Ø, North-East Greenland accumulated in a major half-graben and is an excellent analogue for the subsurface of the mid-Norwegian shelf. On Kuhn Ø, peneplaned crystalline basement was incised by a drainage system during a major base-level lowstand, probably in late Early or early Middle Jurassic times. It was filled with fluvial conglomerates of the newly defined Middle Jurassic Bastians Dal Formation during subsequent base-level rise. As sea level continued to rise, precursor-peat of the coals of the Muslingebjerg Formation formed in swamps which covered the conglomerates and filled the remaining space of the incised valley system. The valley and interfluve areas were flooded in Late Bathonian – Callovian times and tidally-dominated, shallow marine sandstones of the Pelion Formation were deposited on top of the valley fill and over the adjacent basement peneplain. These sandstones are overlain by the newly defined shallow marine Oxfordian Payer Dal Formation which is subdivided into a lower unit and an upper unit, separated by a major drowning surface. The Payer Dal Formation sands were flooded in the Late Jurassic and organic-rich, offshore mudstones of the Bernbjerg Formation were deposited. The Jurassic succession of Kuhn Ø can thus be subdivided into large-scale sedimentary units separated by major drowning surfaces. They are of regional extent, and in combination with biostratigraphic and 87Sr/86Sr isotope data they allow the correlation of the sedimentary units on Kuhn Ø with more offshore deposits to the south in Wollaston Forland and more landwards successions to the north in Hochstetter Forland. Petrographically, the trough cross-bedded sandstones of the Pelion Formation and the lower unit of the Payer Dal Formation include both calcite-cemented and poorly cemented quartz sandstones. The calcite cement was derived from dissolution of abundant calcareous fossils and forms concretionary horizons. The upper unit of the Payer Dal Formation mainly consists of weaklycemented quartz sandstones with porosities around 30%. The sandstones of the Pelion and Payer Dal Formations on Kuhn Ø are petrographically very similar to Jurassic sandstones from the mid- Norwegian shelf and the Barents Sea with regard to original mineralogical composition, sorting and grain size. The Bernbjerg Formation mudstones are comparable to the Upper Jurassic source rock of the mid-Norwegian shelf and the Barents Sea, but have lower hydrogen index (HI) values due to terrigenous input in a relatively proximal setting. Coals of the Muslingebjerg Formation have significant source rock potential with measured HI values up to 700, kerogen types II–III and total organic carbon (TOC) values above 50%.

scholarly journals Triassic and Jurassic transtension along part of the Sorgenfrei–Tornquist Zone in the Danish Kattegat

2003 ◽  
Vol 1 ◽  
pp. 437-458 ◽  
Author(s):  
Tommy Egebjerg Mogensen ◽  
John A. Korstgård
Keyword(s):  
Early Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Strike Slip ◽  
Early Permian ◽  
North East ◽  
The North ◽  
Tectonic Events ◽  
Weakness Zone ◽  
Surrounding Areas

In the Kattegat area, Denmark, the Sorgenfrei–Tornquist Zone, an old crustal weakness zone, was repeatedly reactivated during Triassic, Jurassic and Early Cretaceous times with dextral transtensional movements along the major boundary faults. These tectonic events were minor compared to the tectonic events of the Late Carboniferous – Early Permian and the Late Cretaceous – Early Tertiary, although a dynamic structural and stratigraphic analysis indicates that the Sorgenfrei–Tornquist Zone was active compared to the surrounding areas. At the end of the Palaeozoic, the area was a peneplain. Regional Triassic subsidence caused onlap towards the north-east, where the youngest Triassic sediments overlie Precambrian crystalline basement. During the Early Triassic, several of the major Early Permian faults were reactivated, probably with dextral strike-slip along the Børglum Fault. Jurassic – Early Cretaceous subsidence was restricted primarily to the area between the two main faults in the Sorgenfrei–Tornquist Zone, the Grenå–Helsingborg Fault and the Børglum Fault. This restriction of basin development indicates a change in the regional stress field at the Triassic–Jurassic transition. Middle Jurassic and Late Jurassic – Early Cretaceous subsidence followed the Early Jurassic pattern with local subsidence in the Sorgenfrei–Tornquist Zone, but now even more restricted to within the zone. The subsidence showed a decrease in the Middle Jurassic, and increased again during Late Jurassic – Early Cretaceous times. Small faults were generated internally in the Sorgenfrei–Tornquist Zone during the Mesozoic with a pattern that indicates a broad transfer of strike-slip/oblique-slip motion from the Grenå–Helsingborg Fault to the Børglum Fault.

scholarly journals Refining the marine reptile turnover at the Early–Middle Jurassic transition

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10647
Author(s):  
Valentin Fischer ◽  
Robert Weis ◽  
Ben Thuy
Keyword(s):  
Middle Jurassic ◽  
Fossil Record ◽  
Late Jurassic ◽  
Western Europe ◽  
Marine Ecosystems ◽  
Taxonomic Composition ◽  
Restricted Area ◽  
Marine Reptile ◽  
Geological Formations ◽  
Geological Period

Even though a handful of long-lived reptilian clades dominated Mesozoic marine ecosystems, several biotic turnovers drastically changed the taxonomic composition of these communities. A seemingly slow paced, within-geological period turnover took place across the Early–Middle Jurassic transition. This turnover saw the demise of early neoichthyosaurians, rhomaleosaurid plesiosaurians and early plesiosauroids in favour of ophthalmosaurid ichthyosaurians and cryptoclidid and pliosaurid plesiosaurians, clades that will dominate the Late Jurassic and, for two of them, the entire Early Cretaceous as well. The fossil record of this turnover is however extremely poor and this change of dominance appears to be spread across the entire middle Toarcian–Bathonian interval. We describe a series of ichthyosaurian and plesiosaurian specimens from successive geological formations in Luxembourg and Belgium that detail the evolution of marine reptile assemblages across the Early–Middle Jurassic transition within a single area, the Belgo–Luxembourgian sub-basin. These fossils reveal the continuing dominance of large rhomaleosaurid plesiosaurians, microcleidid plesiosaurians and Temnodontosaurus-like ichthyosaurians up to the latest Toarcian, indicating that the structuration of the upper tier of Western Europe marine ecosystems remained essentially constant up to the very end of the Early Jurassic. These fossils also suddenly record ophthalmosaurid ichthyosaurians and cryptoclidid plesiosaurians by the early Bajocian. These results from a geographically-restricted area provide a clearer picture of the shape of the marine reptile turnover occurring at the early–Middle Jurassic transition. This event appears restricted to the sole Aalenian stage, reducing the uncertainty of its duration, at least for ichthyosaurians and plesiosaurians, to 4 instead of 14 million years.

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