Graduation Semester and Year
Summer 2020
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Earth and Environmental Science
Department
Earth and Environmental Sciences
First Advisor
Galina P. Nestell
Second Advisor
Merlynd K. Nestell
Abstract
The upper Albian - lower Cenomanian (Cretaceous) Washita Group in North Central Texas records the fluctuating shallow-marine depositional setting of the transgressive Skull Creek Seaway. The Washita Group consists of nine formations (in ascending order: Kiamichi, Duck Creek, Fort Worth, Denton, Weno, Paw Paw, Main Street, Grayson, and Buda. The Buda Formation was excluded from the present study because it is absent in the region. The foraminifers of the Washita Group are well known for their diversity and were heavily studied for several decades in the mid-1900’s, although recently they have been largely ignored. The present study has identified 102 species of foraminifers from the Washita Group. Of those 102 species, 19 are planktonic, 24 species are agglutinated and 59 are calcareous benthonic forms. From the distribution of planktonic foraminiferal species identified, five local planktonic foraminiferal zones are proposed for North-Central Texas (in ascending order): Favusella washitensis Zone, Ticinella primula Zone, Muricohedbergella delrioensis Zone, Planomalina buxtorfi Zone, and Thalmanninella appenninica Zone. Several species of planktonic foraminifers not previously documented from North-Central Texas aid in correlation with other regions, such as Muricohedbergella praelibyca and Paracostellagerina libyca. Two new species of planktonic foraminifers, Ticinella sp. A and Thalmanninella sp. A, are described. The 24 species of agglutinated foraminifers identified, including the new species Textulariopsis sp. A, were analyzed to determine the composition of the cements and grains in the test wall. Thirteen species, including Glomospirella gaultina, Reophax deckeri, Scherochorella minuta, Ammobaculites dentonensis, A. fragmentarius, A. subcretaceus, A. testacea, Simobaculites cuyleri, Flabellammina alexanderi, Triplasia acutocarinata, Aaptotoichus clavellatus, Trochammina depressa, and Cribratina texana, were determined to be strictly organic-cemented and eleven species, including Sculptobaculites goodlandensis, Acruliammina longa, Quasispiroplectammina longa, Q. nuda, Haimasiella wintoni, Textulariopsis rioensis, T. washitensis, T. sp. A, Gaudryina cushmani, Gaudryinella delrioensis, and Verneuilina sp., are calcareous cemented. Of the 59 species of calcareous benthonic foraminifers identified from the Washita Group, five species are newly described, including Pygmaeoseistron sp. A, Lagena sp. A, Lenticulina sp. A. Marginulina sp. A, and Lingulogavelinella sp. A, and the five species Pyramidulina? striatifera, Lenticulina washitensis, Citharina perstriata, Pseudosaracenaria striatolipa, and Lingulogavelinella asterigerinoides are emended. Two taxa originally described as varieties have been elevated to the species level: C. perstriata and P. striatolipa. Four assemblages of calcareous benthonic foraminifers are described: Assemblage 1 (Kiamichi Formation), Assemblage 2 (Duck Creek Formation - middle part of the Weno Formation), Assemblage 3 (middle part of the Weno Formation - upper part of the Main Street Formation), and Assemblage 4 (upper part of the Main Street Formation and the Grayson Formation).
License
This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.
Recommended Citation
Rashall, Jenny, "FORAMINIFERS OF THE ALBIAN-CENOMANIAN (CRETACEOUS) WASHITA GROUP IN NORTH-CENTRAL TEXAS, U.S.A." (2020). Earth & Environmental Sciences Dissertations. 93.
https://mavmatrix.uta.edu/ees_dissertations/93
