When did movement begin on the Furnace Creek fault zone
- Geological Survey, Denver, CO (United States)
About 50 km of post-Jurassic right-lateral slip has occurred on the northern part of the Furnace Creek fault zone (FCFZ). The sedimentology, stratigraphy, and structure of Tertiary rocks suggest that movement on the fault began no earlier than 12--8 Ma and possibly as late as 5--4 Ma. Large remnants of erosion surfaces occur on both sides of the FCFZ in the southern White Mountains and Fish Lake Valley and are buried by rhyolite and basalt, mostly 12--10 Ma; the ash flows and welded tuffs were likely erupted from sources at least 40 km to the east. Thus, the area probably had gentle topography, suggesting a lengthy period of pre-late Miocene tectonic stability. On the west side of the FCFZ, Cambrian sedimentary rocks are buried by a fanglomerate with an [sup [minus]]8.4-Ma rhyolite flow near its base. The lithology of the fanglomerate depends chiefly on proximity to different bedrock units and locally is monolithologic adjacent to single formations. Based on its sedimentology and lithologic association with adjacent faulted bedrock, the fanglomerate is interpreted to have formed as a result of movement on these faults. On the west side of the FCFZ, sedimentary rocks dated by tephrochronology rest on 15( )-10-Ma volcanic rocks overlying the erosion surface. Miocene and later movement on the FCFZ likely postdates mid-Miocene tectonic stability. If the fanglomerate formed due to movement on the FCFZ, then the fault was active at 8.4 Ma. However, the faults that influenced fraglomerate deposition are not connected to the FCFZ and may predate it. If so, then the FCFZ may not have begun to move until after 5.3 Ma, the age of the basalt that caps sandstone interpreted to reflect inactivity of the faults. The unconformity-bounded landslide unit on the east side of the FCFZ probably reflects a tectonic event between about 5 and 4 Ma, coincident with either the onset of motion or renewed activity on the FCFZ.
- OSTI ID:
- 5022899
- Report Number(s):
- CONF-9305259-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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