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Title: Sedimentologic evidence for structural and topographic evolution following the onset of strike slip, E San Francisco Bay area, CA

Abstract

Mid- to Upper Miocene continental (Orinda and Mulholland Fms.) and shallow marine (Neroly Fm.) strata in the Upper San Leandro Reservoir watershed (SLR) area east of San Francisco Bay preserve important information on structural and landscape evolution during the early phases of strike slip along the Pacific-North American plate boundary. The SLR area lies between the Hayward and Calaveras Faults, major strands of the San Andreas Fault system, and is bisected by the NW-striking Cull Creek Fault (CCF). Geologic mapping delineates five completely intercalated lithofacies in the Mulholland Fm. at SLR. The conglomerate-dominated, sandstone-dominated, and interbedded conglomerate, sandstone, and siltstone facies represent fluvial channel and floodplain deposits; the sandstone + mudstone facies represent lacustrine-deltaic and shallow lacustrine deposits; the shale facies records open lacustrine deposition. Sparse unidirectional paleocurrent indicators show southerly and easterly transport west of the CCF and both westerly and easterly transport east of the CCF. Conglomerate-rich and sand-rich facies tracts are juxtaposed along the CCF. Clast assemblages in Mulholland conglomerates include abundant chart, graywacke, blueschist, and vein quartz, suggesting derivation from a Franciscan-dominated source terrane. Clast assemblages in the gradationally underlying and interfingering Neroly Fm. suggest that it shared the same source terrane; this is atypical formore » the primarily andesitic (Sierra-derived) Neroly. Fluvial deposits are volumetrically dominant in the Mulholland Fm. at SLR; open-lacustrine shales occur in stratigraphically isolated lenses ranging from > 1 km to < 100 m along strike. This suggests numerous small lakes on a broad drainage plain rather than the single large lake envisioned by previous workers.« less

Authors:
 [1]
  1. CSUH, Hayward, CA (United States)
Publication Date:
OSTI Identifier:
5589543
Report Number(s):
CONF-921058-
Journal ID: ISSN 0016-7592; CODEN: GAAPBC
Resource Type:
Conference
Journal Name:
Geological Society of America, Abstracts with Programs; (United States)
Additional Journal Information:
Journal Volume: 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; Journal ID: ISSN 0016-7592
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; CALIFORNIA; WATERSHEDS; GEOMORPHOLOGY; DRAINAGE; GEOLOGIC FAULTS; LAKES; MINERALOGY; STRATIGRAPHY; DEVELOPED COUNTRIES; GEOLOGIC FRACTURES; GEOLOGIC STRUCTURES; GEOLOGY; NORTH AMERICA; SURFACE WATERS; USA; 580000* - Geosciences

Citation Formats

Buising, A V. Sedimentologic evidence for structural and topographic evolution following the onset of strike slip, E San Francisco Bay area, CA. United States: N. p., 1992. Web.
Buising, A V. Sedimentologic evidence for structural and topographic evolution following the onset of strike slip, E San Francisco Bay area, CA. United States.
Buising, A V. 1992. "Sedimentologic evidence for structural and topographic evolution following the onset of strike slip, E San Francisco Bay area, CA". United States.
@article{osti_5589543,
title = {Sedimentologic evidence for structural and topographic evolution following the onset of strike slip, E San Francisco Bay area, CA},
author = {Buising, A V},
abstractNote = {Mid- to Upper Miocene continental (Orinda and Mulholland Fms.) and shallow marine (Neroly Fm.) strata in the Upper San Leandro Reservoir watershed (SLR) area east of San Francisco Bay preserve important information on structural and landscape evolution during the early phases of strike slip along the Pacific-North American plate boundary. The SLR area lies between the Hayward and Calaveras Faults, major strands of the San Andreas Fault system, and is bisected by the NW-striking Cull Creek Fault (CCF). Geologic mapping delineates five completely intercalated lithofacies in the Mulholland Fm. at SLR. The conglomerate-dominated, sandstone-dominated, and interbedded conglomerate, sandstone, and siltstone facies represent fluvial channel and floodplain deposits; the sandstone + mudstone facies represent lacustrine-deltaic and shallow lacustrine deposits; the shale facies records open lacustrine deposition. Sparse unidirectional paleocurrent indicators show southerly and easterly transport west of the CCF and both westerly and easterly transport east of the CCF. Conglomerate-rich and sand-rich facies tracts are juxtaposed along the CCF. Clast assemblages in Mulholland conglomerates include abundant chart, graywacke, blueschist, and vein quartz, suggesting derivation from a Franciscan-dominated source terrane. Clast assemblages in the gradationally underlying and interfingering Neroly Fm. suggest that it shared the same source terrane; this is atypical for the primarily andesitic (Sierra-derived) Neroly. Fluvial deposits are volumetrically dominant in the Mulholland Fm. at SLR; open-lacustrine shales occur in stratigraphically isolated lenses ranging from > 1 km to < 100 m along strike. This suggests numerous small lakes on a broad drainage plain rather than the single large lake envisioned by previous workers.},
doi = {},
url = {https://www.osti.gov/biblio/5589543}, journal = {Geological Society of America, Abstracts with Programs; (United States)},
issn = {0016-7592},
number = ,
volume = 24:7,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 1992},
month = {Wed Jan 01 00:00:00 EST 1992}
}

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