Biochronology and magnetostratigraphy of the Pliocene Panaca Formation, southeast Nevada

Persistent Link:
http://hdl.handle.net/10150/284594
Title:
Biochronology and magnetostratigraphy of the Pliocene Panaca Formation, southeast Nevada
Author:
Mou, Yun
Issue Date:
1999
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
About 2,500 specimens of small mammal fossils were collected from 10 localities in the Pliocene Panaca Formation in Meadow Valley, southeast Nevada. The most common taxa are cricetid and heteromyid rodents, and lagomorphs. Twenty-seven species, including five new species, were recognized from the fauna. A new genus of microtine rodent, Nevadomys, including three new species, N. fejfari, N. lindsayi, and N. downsi, is recognized. Nevadomys was probably derived from the Hemphillian Paramicrotoscoptes. Repomys minor n. sp. is another new species of high-crowned cricetid that was detected in the Panaca local fauna. With abundant upper and lower third molars of Repomys, it was possible to amend the diagnoses of genus Repomys. The fifth new species recognized from the fauna is a shrew, Paranotiosorex panacaensis n. gen. and sp. Enamel microstructure of molars of the microtine rodents Mimomys panacaensis and Nevadomys n. gen. from the fauna were examined under the scanning electronic microscope. Mimomys panacaensis shows the same schmelzmuster among different populations. Nevadomys has a more primitive schmelzmuster compared to Mimomys panacaensis. Both its leading and trailing edges are entirely composed of radial enamel. The assemblage of small mammal fossils suggests that the Panaca local fauna represents the early Blancan land mammal age. The first appearance datum of Mimomys panacaensis is suggested as the beginning of Blancan land mammal age, and the absolute age of the lowest stratigraphic datum of M. panacaensis in the Panaca Formation is interpolated from magnetostratigraphy and is considered as the age of the Hemphillian-Blancan boundary. The magnetostratigraphy of the Panaca Formation in Meadow Valley is established based on four sections in the basin. The ash in the Rodent Hill section was dated at 4.64 +/- 0.03 Ma, which constrains the correlation of the reversed polarity magnetozone in the Rodent Hill section to the C3n.2r in the Geomagnetic Polarity Time Scale (GPTS). The other three sections are correlated to the Rodent Hill section based on the ashes. The Panaca Formation in Meadow Valley was deposited from 4.50--5.30 Ma, and the Hemphillian-Blancan boundary is around 4.95 Ma, close to the termination of Thvera Subchron in the GPTS.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Geology.; Paleontology.; Paleozoology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Earth Sciences
Degree Grantor:
University of Arizona
Advisor:
Lindsay, Everett H.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleBiochronology and magnetostratigraphy of the Pliocene Panaca Formation, southeast Nevadaen_US
dc.creatorMou, Yunen_US
dc.contributor.authorMou, Yunen_US
dc.date.issued1999en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractAbout 2,500 specimens of small mammal fossils were collected from 10 localities in the Pliocene Panaca Formation in Meadow Valley, southeast Nevada. The most common taxa are cricetid and heteromyid rodents, and lagomorphs. Twenty-seven species, including five new species, were recognized from the fauna. A new genus of microtine rodent, Nevadomys, including three new species, N. fejfari, N. lindsayi, and N. downsi, is recognized. Nevadomys was probably derived from the Hemphillian Paramicrotoscoptes. Repomys minor n. sp. is another new species of high-crowned cricetid that was detected in the Panaca local fauna. With abundant upper and lower third molars of Repomys, it was possible to amend the diagnoses of genus Repomys. The fifth new species recognized from the fauna is a shrew, Paranotiosorex panacaensis n. gen. and sp. Enamel microstructure of molars of the microtine rodents Mimomys panacaensis and Nevadomys n. gen. from the fauna were examined under the scanning electronic microscope. Mimomys panacaensis shows the same schmelzmuster among different populations. Nevadomys has a more primitive schmelzmuster compared to Mimomys panacaensis. Both its leading and trailing edges are entirely composed of radial enamel. The assemblage of small mammal fossils suggests that the Panaca local fauna represents the early Blancan land mammal age. The first appearance datum of Mimomys panacaensis is suggested as the beginning of Blancan land mammal age, and the absolute age of the lowest stratigraphic datum of M. panacaensis in the Panaca Formation is interpolated from magnetostratigraphy and is considered as the age of the Hemphillian-Blancan boundary. The magnetostratigraphy of the Panaca Formation in Meadow Valley is established based on four sections in the basin. The ash in the Rodent Hill section was dated at 4.64 +/- 0.03 Ma, which constrains the correlation of the reversed polarity magnetozone in the Rodent Hill section to the C3n.2r in the Geomagnetic Polarity Time Scale (GPTS). The other three sections are correlated to the Rodent Hill section based on the ashes. The Panaca Formation in Meadow Valley was deposited from 4.50--5.30 Ma, and the Hemphillian-Blancan boundary is around 4.95 Ma, close to the termination of Thvera Subchron in the GPTS.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectGeology.en_US
dc.subjectPaleontology.en_US
dc.subjectPaleozoology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineEarth Sciencesen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorLindsay, Everett H.en_US
dc.identifier.proquest9934864en_US
dc.identifier.bibrecord.b39684921en_US
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