Faults--Offshore of Tomales Point Map Area, California

This part of DS 781 presents data for faults for the geologic and geomorphic map of the Offshore of Tomales Point map area, California. The vector data file is included in "Faults_OffshoreTomalesPoint.zip," which is accessible from http://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/data_catalog_OffshoreTomalesPoint.html.

The Point Reyes Peninsula is bounded to the south and west in the offshore by the north- and east-dipping Point Reyes Thrust Fault (McCulloch, 1987; Heck and others, 1990), which lies about 20 km west of Tomales Point. Granitic basement rocks are offset about 1.4 km on this thrust fault offshore of Point Reyes (McCulloch, 1987), and this uplift combined with west-side-up offset on the San Andreas Fault (Grove and Niemi, 2005) resulted in uplift of the Point Reyes Peninsula, including Tomales Point and the adjacent continental shelf. Grove and others (2010) reported uplift rates of as much as 1 mm/yr for the south flank of the Point Reyes Peninsula based on marine terraces, but reported no datable terrace surfaces that could constrain uplift for the flight of 4-5 terraces exposed farther north along Tomales Point.

Faults were primarily mapped by interpretation of seismic reflection profile data (see field activity S-15-10-NC). The seismic reflection profiles were collected between 2007 and 2010.

References Cited

Grove, K., and Niemi, T.M., 2005, Late Quaternary deformation and slip rates in the northern San Andreas fault zone at Olema Valley, Marin County, California: Tectonophysics, v. 401, p. 231-250.

Grove, K, Sklar, L.S., Scherer, A.M., Lee, G., and Davis, J., 2010, Accelerating and spatially-varying crustal uplift and its geomorphic expression, San Andreas fault zone north of San Francisco, California: Tectonophysics, v. 495, p. 256-268.

Heck, R.G., Edwards, E.B., Kronen, J.D., Jr., and Willingham, C.R., 1990, Petroleum potential of the offshore outer Santa Cruz and Bodega basins, California, in Garrison, R.E., Greene, H.G., Hicks, K.R., Weber, G.E., and Wright, T.L., eds. Geology and tectonics of the central California coastal region, San Francisco to Monterey: Pacific Section, American Association of Petroleum Geologists Bulletin GB67, p. 143-164.

McCulloch, D.S., 1987, Regional geology and hydrocarbon potential of offshore central California, in Scholl, D.W., Grantz, A., and Vedder, J.G., eds., Geology and Resource Potential of the Continental Margin of Western North America and Adjacent Oceans Beaufort Sea to Baja California: Houston, Texas, Circum-Pacific Council for Energy and Mineral Resources, Earth Science Series, v. 6., p. 353-401.

本数据集DS 781的本章节提供了加利福尼亚州托马莱斯角近海区域地质与地貌图相关的断层数据。矢量数据文件收录于"Faults_OffshoreTomalesPoint.zip"，可通过http://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/data_catalog_OffshoreTomalesPoint.html 获取。

雷斯岬半岛（Point Reyes Peninsula）的南侧与西侧近海区域被北倾及东倾的雷斯岬逆冲断层（Point Reyes Thrust Fault）所围限，该断层距托马莱斯角以西约20千米（McCulloch, 1987; Heck et al., 1990）。在雷斯岬近海的该逆冲断层上，花岗岩基底岩体被错断约1.4千米（McCulloch, 1987）；结合圣安德烈亚斯断层（San Andreas Fault）的西盘上升错动（Grove and Niemi, 2005），最终导致包括托马莱斯角及邻近大陆架在内的雷斯岬半岛抬升。Grove等人（2010）根据海蚀阶地数据，报道了雷斯岬半岛南翼最高达1毫米/年的抬升速率，但未提及可用于约束托马莱斯角以北更远处出露的4至5阶地群抬升过程的可定年阶地面。

断层数据主要通过解读地震反射剖面（seismic reflection profile）数据完成（详见野外活动编号S-15-10-NC），这些地震反射剖面采集于2007年至2010年期间。

引用文献
1. Grove, K. 与 Niemi, T.M.，2005，加利福尼亚州马林县奥莱马谷北圣安德烈亚斯断层带的晚第四纪变形与滑动速率：《构造物理学》，第401卷，第231-250页。
2. Grove, K.、Sklar, L.S.、Scherer, A.M.、Lee, G. 与 Davis, J.，2010，加利福尼亚州旧金山以北圣安德烈亚斯断层带的加速且空间异质性地壳抬升及其地貌表现：《构造物理学》，第495卷，第256-268页。
3. Heck, R.G.、Edwards, E.B.、Kronen, J.D. Jr. 与 Willingham, C.R.，1990，加利福尼亚州近海圣克鲁斯外海与博德加盆地的石油潜力，收录于Garrison, R.E.、Greene, H.G.、Hicks, K.R.、Weber, G.E. 与 Wright, T.L. 主编的《加利福尼亚中部海岸区域地质与构造：旧金山至蒙特雷》：美国石油地质学家协会太平洋分会GB67通报，第143-164页。
4. McCulloch, D.S.，1987，加利福尼亚中部近海区域地质与油气潜力，收录于Scholl, D.W.、Grantz, A. 与 Vedder, J.G. 主编的《北美西部大陆边缘及邻近海洋地质与资源潜力：波弗特海至下加利福尼亚》：得克萨斯州休斯顿，环太平洋能源与矿产资源委员会地球科学系列，第6卷，第353-401页。