Reconstructing normal fault systems with synextensional lacustrine sediments: Examples from northeast Nevada

Conference · Thu Apr 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5126691

Mueller, K J ^[1]

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1. Univ. of Montana, Missoula, MT (United States). Dept. of Geology

The Tertiary history of the Windermere Hills, NE Nevada includes the development of five overprinted extensional fault systems which range from late Eocene to middle Miocene in age. Definition of the age, stratigraphic architecture and sedimentary facies in synextensional half-grabens permits reconstruction of the complex extensional chronology of this area. The earliest Tertiary strata exposed in the region consist of late Eocene calc-alkaline volcanic deposits whose thickness does not change significantly within the study area. This, and recognition that these strata are tilted similar amounts as younger synextensional sediments suggest they are not directly associated with normal faulting. Conglomerate interbedded in the calc-alkaline volcanic sequence is associated with steep-sided volcanic landforms suggesting that late Eocene (39-41 Ma) relief was produced by volcanic processes and not extensional faulting. Early Oligocene and middle Miocene synextensional deposits are differentiated by their wedge-shaped stratigraphic architecture, fault bounded margins, and abrupt thickness and facies variations. Sedimentary facies in these basins are dominated by aggraded lacustrine fan delta deposits which fine abruptly basinward. Age dating of these strata suggest that 1-3 kilometers of sediment were deposited in 2-4 Ma in rapidly subsiding half-grabens. Synextensional sediments are also associated with similarly aged unconformities and paleovalleys in adjacent uplifted blocks. Definition of the timing of basin margin faults hinges on their correct correlation with coarse-grained marginal facies associated with a particular episode of extension. Problems are illustrated in fault bounded half-grabens which contain fine-grained lacustrine sediments in marginal settings.

• OSTI ID: 5126691
• Report Number(s): CONF-9305259--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
CENOZOIC ERA
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC MODELS
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOLOGY
LAKES
NEVADA
NORTH AMERICA
SEDIMENTARY BASINS
SEDIMENTS
STRATIGRAPHY
SURFACE WATERS
TECTONICS
TERTIARY PERIOD
USA