scholarly journals Hyposaline to hypoxic foraminiferal facies and stratigraphy of Middle Jurassic to basal Cretaceous deposits of the Trøndelag Platform, mid-Norwegian shelf

Author(s):  
Jenő Nagy ◽  
Randi Marie Støkken Hendrickson
2013 ◽  
Vol 151 (1) ◽  
pp. 41-48 ◽  
Author(s):  
PATRICK S. DRUCKENMILLER ◽  
ERIN E. MAXWELL

AbstractOphthalmosauridae is a clade of derived thunniform ichthyosaurs that are best known from Callovian (late Middle Jurassic) to Cenomanian-aged (Late Cretaceous) deposits in both the Northern and Southern Hemispheres. Ophthalmosaurids arose prior to the Early–Middle Jurassic boundary, however, very little is known about their diversity and distribution in the earliest phase of their evolutionary history during the Aalenian–Bathonian (Middle Jurassic) interval. Here we describe new diagnostic ophthalmosaurid material from the Early Bajocian (Middle Jurassic) of Alaska. The specimen, UAMES 3411, is a partial disarticulated skull that was discovered in the Middle Jurassic Tuxedni Formation, which was deposited in shallow marine settings outboard of the then-accreting Wrangellia composite terrane. The new material is significant in that it is the first Jurassic ichthyosaur described from Alaska, one of the oldest ophthalmosaurids known and the only Middle Jurassic ophthalmosaurid described from the Northern Hemisphere. The new material adds to a rapidly growing data set on ophthalmosaurid diversity and suggests that the clade was geographically widespread by the Early Bajocian, very early in its evolutionary history.


2003 ◽  
Vol 1 ◽  
pp. 611-630
Author(s):  
Henrik I. Petersen ◽  
Lars H. Nielsen ◽  
Torben Bidstrup ◽  
Erik Thomsen

The burial depth and the magnitude of Late Cretaceous – Early Cenozoic and Neogene–Pleistocene uplift of Lower–Middle Jurassic strata in the Fennoscandian Border Zone are estimated from measurements of huminite reflectance and comparison with a regional coalification gradient. The regional coalification curve is constructed by plotting uplift-corrected sample depths against more than 300 huminite/vitrinite reflectance values from Upper Triassic – Lower Cretaceous deposits in the Danish Basin and the Fennoscandian Border Zone. The present sample depths are corrected for Late Cretaceous inversion in the Sorgenfrei–Tornquist Zone and for Neogene–Pleistocene regional uplift. A coalification curve is erected; it cuts the abscissa at 0.2 %Ro corresponding to the reflectance of peat. This curve is considered to approximate to a reliable coalification profile over much of the study area. The Jurassic coals from the Fennoscandian Border Zone are of low rank and, based on the regional coalification curve, they have been buried to c. 625–2450 m. In the eastern part of the Rønne Graben, in the Kolobrzeg Graben and in the Arnager–Sose Fault Block, the Jurassic strata were subsequently uplifted c. 290–1400 m, corresponding to the amount of Late Cretaceous – Early Cenozoic inversion observed on seismic sections. Thus, it appears that Neogene–Pleistocene uplift did not influence the Bornholm area significantly. The data from the Höganäs Basin and Fyledal indicate a total uplift of c. 1450–2450 m, corresponding to estimates from the inversion zone in the Kattegat. The data from Anholt, on the eastern margin of the inversion zone, indicate c. 975 m of uplift.


Stratigraphy ◽  
2018 ◽  
Vol 15 (1) ◽  
pp. 37-46 ◽  
Author(s):  
Michael A. Kaminski ◽  
Septriandi A. Chan ◽  
Ramona Balc ◽  
Hafiz Mehtab Gull ◽  
Abduljamiu O. Amao ◽  
...  

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