Dinoflagellate and organic facies stratigraphy of the Twin Creek Limestone (Jurassic) in western Wyoming and northeastern Utah, USA.
Item
-
Title
-
Dinoflagellate and organic facies stratigraphy of the Twin Creek Limestone (Jurassic) in western Wyoming and northeastern Utah, USA.
-
Identifier
-
AAI9108186
-
identifier
-
9108186
-
Creator
-
Van Pelt, Robert Scott.
-
Contributor
-
Adviser: Daniel Habib
-
Date
-
1990
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Palynology
-
Abstract
-
Palynological study of six sections of the Twin Creek Limestone (Jurassic) in the surface and subsurface of western Wyoming and northeastern Utah yielded 59 species and 32 genera of dinoflagellate cysts, many of which are biostratigraphically significant. In addition, 12 species and 7 genera of pollen and spores were recognized.;The dinoflagellate stratigraphy is dated by ammonite and pelecypod taxa, which in turn have been calibrated against ammonite assemblages from Arctic and western Canada, southern Alaska, and against European stratotype sections. However, where there is lack of resolution, ages (Late Bathonian-Callovian) assigned to dinoflagellate species from European stratotype and Arctic Canadian sections have been utilized. One new dinoflagellate species, Medicodinium scrobiculatum sp. nov. is described from Late Bajocian sediments. The last appearance of this species appears to coincide with the Bajocian/Bathonian boundary.;Three regional palynozones were established for the formation. They are from oldest to youngest: (I) Mendicodinium scrobiculatum Taxon Range Zone (Late Bajocian), (II) Atopodinium prostatum Interval Zone (late Middle/early Late Bathonian to Late Bathonian), (III) Gonyaulacysta centriconnata Interval Zone (Early Callovian).;The similarity of these zones with those published for Europe and Arctic Canada suggests that the Late Bajocian, Late Bathonian, and Early Callovian were times of cosmopolitan assemblages. Increase in the number of dinoflagellate species and the occurrence of abundant amorphous debris suggest an expanding marine environment. A decrease in the number of dinoflagellate species, coincident with an increase in terrigenous material (tracheal and cuticular tissue, pollen grains and spores), correlates with a change towards marine regression.;Two parasequences have been defined for the Twin Creek Limestone (Camp Davis section). A correlation exists between shallowing conditions, as evidenced by lithologic interpretations, and decreases in marine microplankton. Conversely, initial deepening coincides with an increase in the number of marine microplankton taxa.;The studied sections (Twin Creek Limestone) lie within the oil window. The sediments in the Camp Davis section (northernmost section) lie within the early stage of maturation, with the remaining sections exhibiting a greater degrees of maturation.;The kerogen content consists of amorphous debris, marine microplankton, tracheal and cuticular tissue, pollen grains, spores, and inertinite.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
