upper callovian
Recently Published Documents


TOTAL DOCUMENTS

30
(FIVE YEARS 4)

H-INDEX

7
(FIVE YEARS 0)

2020 ◽  
Vol 56 (2) ◽  
pp. 159-174
Author(s):  
Finn Surlyk ◽  
Rikke Bruhn

Sandstones of the Middle–Upper Jurassic Brora Arenaceous Formation of the Inner Moray Firth, NE Scotland have hitherto been interpreted as representing coastal, tidally-influenced bars. The formation is exposed close to the northern basin-bounding Helmsdale Fault, and the middle member of the formation, the Clynelish Quarry Sandstone, consists of thick, mainly structureless sandstone beds with wavy, commonly amalgamated boundaries. It also includes sandstone bodies with sigmoidal clinothems, erosional surfaces and backset beds. Rich marine faunas dominated by bivalves and ammonites occur at a few levels, whereas trace fossils are rare or absent. The Clynelish Quarry Sandstone is here reinterpreted as reflecting deposition by hyperpycnal sandy density flows in flood-generated marine, subaqueous, delta-scale clinoforms and lobes in front of local mountain streams. The reinterpretation of these sandstones implies the presence of a tectonically controlled, relatively steep basin margin along the line of the Helmsdale Fault. The Brora Arenaceous Formation thus dates the onset of Jurassic rifting in the Inner Moray Firth to the latest Callovian rather than the late Oxfordian as previously interpreted from seismic data.


Author(s):  
A. A. Mironenko ◽  
V. N. Komarov

Until now thefindingsof rhyncholites from the Jurassic marine sediments of Crimea were very scarce. In both the Oxfordian and Kimmeridgian of Crimea, rhyncholites were never found despite the fact that in Western and Central Europe they are very numerous in Middle and Upper Jurassic marine sediments. We have described five new findings of rhyncholites from Crimea whose age ranges from the Upper Callovian to the Kimmeridgian. They belong to the five different species (including three new ones) of the genus Gonatocheilus Till, 1907, which was never previously described in Crimea. We also discuss the taxonomy of rhyncholites and argue that the genus Palaeotheutis Till, 1906 is unavailable according to article 33 of International code of zoological nomenclature and the genus Gonatocheilus Till, 1907 should be used instead of it.


2016 ◽  
Author(s):  
Hassan Eltom ◽  
◽  
Luis A. Gonzalez ◽  
Eugene C. Rankey ◽  
Stephen T. Hasiotis ◽  
...  

2014 ◽  
Vol 88 (6) ◽  
pp. 1212-1221 ◽  
Author(s):  
Mark A. Wilson ◽  
Elizabeth A. Reinthal ◽  
William I. Ausich

A new species of Apiocrinites is described from the Matmor Formation (Middle Jurassic, upper Callovian) of Hamakhtesh Hagadol, southern Israel. Apiocrinites feldmani n. sp. is a small species associated with the larger A. negevensis in a calcareous sponge and coral patch reef community. During life the columns of A. feldmani were commonly and preferentially infested with a soft-bodied parasite that grew with the crinoid and became embedded in its skeleton. These parasites embedded at the articulation between columnals, forcing the columnals to grow around them and producing with time a conical pit surrounded by swollen stereom. If the parasite died while the crinoid was still growing, the conical pit was roofed over by continued growth of columnals, resulting in a swelling with no external opening. Because the crinoids invested energy in forming extra skeleton around these parasites and because the crinoid stems were consequently deformed and likely lost flexibility, we consider these parasites to have caused significant harm. Curiously, these parasites apparently did not infect the larger and more common contemporaneous A. negevensis that lived in the same community.


Sign in / Sign up

Export Citation Format

Share Document