WIDESPREAD, SHALLOW-MARINE, STORM-GENERATED SANDSTONE UNITS IN THE UPPER CRETACEOUS MOSBY SANDSTONE, CENTRAL MONTANA

1984 ◽  
pp. 143-161 ◽  
Author(s):  
DUDLEY D. RICE
Keyword(s):  
Upper Cretaceous ◽  
Shallow Marine ◽  
Central Montana

Isotaphonomy in concept and practice: an exploration of vertebrate microfossil bonebeds in the Upper Cretaceous (Campanian) Judith River Formation, north-central Montana

Paleobiology ◽  
2017 ◽  
Vol 43 (2) ◽  
pp. 248-273 ◽  
Author(s):  
Raymond R. Rogers ◽  
Matthew T. Carrano ◽  
Kristina A. Curry Rogers ◽  
Magaly Perez ◽  
Anik K. Regan
Keyword(s):  
Upper Cretaceous ◽  
Statistical Tests ◽  
Sampling Strategies ◽  
North Central ◽  
Wetland Ecosystems ◽  
Future Studies ◽  
Size And Shape ◽  
Definition Of ◽  
Central Montana ◽  
Judith River Formation

AbstractVertebrate microfossil bonebeds (VMBs)—localized concentrations of small resilient vertebrate hard parts—are commonly studied to recover otherwise rarely found small-bodied taxa, and to document relative taxonomic abundance and species richness in ancient vertebrate communities. Analyses of taphonomic comparability among VMBs have often found significant differences in size and shape distributions, and thus considered them to be non-isotaphonomic. Such outcomes of “strict” statistical tests of isotaphonomy suggest discouraging limits on the potential for broad, comparative paleoecological reconstruction using VMBs. Yet it is not surprising that sensitive statistical tests highlight variations among VMB sites, especially given the general lack of clarity with regard to the definition of “strict” isotaphonomic comparability. We rigorously sampled and compared six VMB localities representing two distinct paleoenvironments (channel and pond/lake) of the Upper Cretaceous Judith River Formation to evaluate biases related to sampling strategies and depositional context. Few defining distinctions in bioclast size and shape are evident in surface collections, and most site-to-site comparisons of sieved collections are indistinguishable (p≤0.003). These results provide a strong case for taphonomic equivalence among the majority of Judith River VMBs, and bode well for future studies of paleoecology, particularly in relation to investigations of faunal membership and community structure in Late Cretaceous wetland ecosystems. The taphonomic comparability of pond/lake and channel-hosted VMBs in the Judith River Formation is also consistent with a formative model that contends that channel-hosted VMBs were reworked from pre-existing pond/lake assemblages, and thus share taphonomic history.

Northeast Pacific Cretaceous record ofPyropsis(Neogastropoda: Pyropsidae) and paleobiogeography of the genus

2011 ◽  
Vol 85 (6) ◽  
pp. 1199-1215 ◽  
Author(s):  
Richard L. Squires
Keyword(s):  
Southern California ◽  
Upper Cretaceous ◽  
New World ◽  
Vancouver Island ◽  
Northern California ◽  
Shallow Marine ◽  
Northeast Pacific ◽  
Siliciclastic Rocks ◽  
First Time ◽  
Warm Temperate

The neogastropod genusPyropsisConrad, 1860 (family Pyropsidae Stephenson, 1941) is recognized for the first time from Upper Cretaceous shallow-marine siliciclastic rocks in the region extending from Vancouver Island, British Columbia southward to southern California. Four new species were detected:Pyropsis aldersoni(earliest Coniacian, southern California),Pyropsis californica(early Coniacian, northern California),Pyropsis louellae(late Coniacian or early Santonian, northern California), andPyropsis grahami(late early Campanian, Vancouver Island).A critical review of the global reports ofPyropsis, a genus that has been commonly confused with other genera (especiallyTudiclaRöding, 1798), establishes thatPyropsishad an amphitropical distribution and lived in warm-temperate waters adjacent to a broad tropical realm. It is rare to uncommon wherever found, and its geologic range is middle Cenomanian to an age near the Cretaceous/Paleogene boundary (probably earliest Paleocene). It was moderately widespread before the Maastrichtian but was predominantly restricted to the New World during the Maastrichtian.

Late Cretaceous – Tertiary sediments offshore central West Greenland: lithostratigraphy, sedimentary evolution, and petroleum potential

1985 ◽  
Vol 22 (7) ◽  
pp. 1001-1019 ◽  
Author(s):  
Flemming Rolle
Keyword(s):  
Upper Cretaceous ◽  
Source Rocks ◽  
Petroleum Potential ◽  
Shallow Marine ◽  
West Greenland ◽  
Reservoir Rocks ◽  
Sedimentary Sequences ◽  
Sedimentary Evolution ◽  
Petroleum Generation ◽  
Exploratory Wells

Five dry exploratory wells were drilled through Upper Cretaceous and Tertiary sediments on the West Greenland shelf in 1976 and 1977. Two of these entered Precambrian basement, two bottomed in Paleocene or Upper Cretaceous basalt, and one in Campanian mudstone. On the basis of samples and logs supplied to the Geological Survey of Greenland the sedimentary sequence has been divided into seven new formations: the Campanian Narssarmiut Formation, consisting of coarse basement wash and black mudstone; the Campanian to Eocene Ikermiut Formation, consisting of marine organic-rich mudstone; the Upper Paleocene to Eocene Hellefisk Formation, comprising shallow-marine to paralic sandstone and mudstone; the Eocene Nukik Formation, consisting of turbiditic sandstone and mudstone; the Eocene to Oligocene Kangâmiut Formation of shelf to shallow-marine clean and argillaceous sandstone; the Oligocene to Neogene Manîtsoq Formation, consisting of coarse paralic to fan delta sandstone; and the Neogene Ataneq Formation, consisting of protected shallow-marine mudstone.The sedimentary evolution of the area fits well with earlier proposed models for the tectonic evolution of the Baffin Bay–Labrador Sea region.Potential petroleum source rocks are present in the Upper Cretaceous to Paleocene mudstone, and, even though they are largely immature in the drilled sections, they are expected to have entered the petroleum generation zone in the deeper parts of the basin. Their potential is mainly for gas, but some oil potential is also present. No reservoir rocks were encountered in the deeper parts of the sedimentary sequences, and the porous sandstones that occur higher in the sequence lack seals.

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