Apatite fission track evidence for Miocene extensional faulting east-central Nevada, northern Basin and Range province

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

OSTI ID:5022518

Miller, E L; Dumitru, T A ^[1]; Gans, P B ^[2]; Brown, R W ^[3]

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1. Stanford Univ., CA (United States). Geology Dept.
2. Univ. of California, Santa Barbara, CA (United States). Geological Sciences Dept.
3. La Trobe Univ., Bundoora (Australia). Geology Dept.

Apatite fission track ages indicates that a large component of motion along many of the present range-bounding faults occurred in the Early to Middle Miocene, tilting and uplifting rocks through the apatite annealing zone (120--60 C) between 18--13 Ma (n = 20, Deep Creeks), 18--15 Ma (northern Snake Range, n = 20), 25--17 Ma (n = 7, southern Snake Range), 24--15 Ma (Egan Range, n = 6), 23--18 Ma (Kern Mts., n = 2) and 28--16 ma (Schell Creek Range, n = 2). Long track length distributions indicate rapid cooling through the 120--60 C interval followed by residence at low, near surface temperatures. The data set also indicates that the combined Deep Creek-Kern Mountains-northern and southern Snake Range constitutes a single coherent footwall crustal block beneath a > 150 km-long system of east-dipping Miocene faults which includes at least the eastern portions of faults that have been mapped as the Snake Range decollement (NSRD). Conglomerates deposited in hanging wall basins along this fault system contain metamorphic and granitic boulders whose FT ages are coeval with footwall unroofing. The deposits themselves are now known to be younger than previously reported (Oligocene) as ages from boulders are Miocene. The thick (> 2 km) sequences of synorogenic conglomerate indicates rapid unroofing; large slide blocks attest to generation of steep, fault-controlled topography. Faults that cut this sequence are now known to be younger than 15 Ma. Thus, protracted extensional faulting affected the region, beginning in the Early Oligocene and continuing to the Recent, but a significant part of this extension, including a large component of the slip on the NSRD, was accomplished in the Early to Middle Miocene. Data from this region is compatible with a growing base of apatite fission track data from elsewhere in the northern Basin and Range, which, together with geologic relationships, suggest an important episode of Miocene extension and Basin and Range development.

• OSTI ID: 5022518
• 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
APATITES
CENOZOIC ERA
DEVELOPED COUNTRIES
FISSION TRACKS
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
MINERALS
MIOCENE EPOCH
NEVADA
NORTH AMERICA
PARTICLE TRACKS
PHOSPHATE MINERALS
STRATA MOVEMENT
TERTIARY PERIOD
USA