Faults--Offshore Pigeon Point, California

This part of DS 781 presents data for the faults for the geologic and geomorphic map of the Offshore Pigeon Point map area, California. The vector data file is included in "Faults_OffshorePigeonPoint.zip," which is accessible from http://dx.doi.org/10.5066/F7513W80 The offshore Pigeon Point map area lies about 15 to 25 km southwest of the San Andreas Fault, the dominant structure in the distributed transform boundary between the North American and Pacific plates. The map area straddles the right-lateral Pigeon Point Fault zone, a prominent structure west of the San Andreas Fault in the broader San Andreas Fault system. The Pigeon Point Fault zone occurs predominantly in the offshore and extends 400 km from Point Conception on the south to Bolinas and Point Reyes on the north (Dickinson and others, 2005), coming onland at coastal promontories such as Pescadero Point in the map area and Pillar Point, a few km north of Half Moon Bay. In the offshore, the Pigeon Point Fault system forms a distributed shear zone about 2 to 4 km wide that includes two main diverging fault strands. The western strand (also known as the Frijoles Fault) extends offshore from Pescadero Point. The eastern strand (also known as the Coastways Fault or Seal Cove Fault), is mostly onshore in this map area. Cumulative lateral slip on the Pigeon Point Fault zone is thought to range from 4 to 10 mm/yr in this region (U.S. Geological Survey, 2010). The western strand of the Pigeon Point Fault zone (i.e., Frijoles Fault) forms the eastern boundary of the Pigeon Point high. Faults were primarily mapped by interpretation of seismic reflection profile data (see OFR 2013-1071). The seismic reflection profiles were collected between 2007 and 2010. References Cited Dickinson, W.R., Ducea, M., Rosenberg, L.I., Greene, H.G., Graham, S.A., Clark, J.C., Weber, G.E., Kidder, S., Ernst, W.G., and Brabb, E.E., 2005, Net dextral slip, Neogene Pigeon Point-Hosgri fault zone, coastal California: Geologic evidence and tectonic implications: Geological Society of America Special Paper 391, 43 p.本DS 781数据集的本部分提供了加利福尼亚州近海鸽子点制图区（Offshore Pigeon Point map area）地质地貌图相关的断层数据。矢量数据文件收录于"Faults_OffshorePigeonPoint.zip"压缩包，可通过http://dx.doi.org/10.5066/F7513W80获取。 近海鸽子点制图区位于圣安德烈亚斯断层（San Andreas Fault，北美板块与太平洋板块之间弥散型转换边界的主控构造）西南约15至25公里处。该制图区横跨右旋鸽子点断层带（right-lateral Pigeon Point Fault zone），该断层带是广义圣安德烈亚斯断层系统中圣安德烈亚斯断层西侧的重要构造。鸽子点断层带主体分布于近海区域，整体延伸400公里，南起康塞普西翁角（Point Conception），北至博利纳斯与雷耶斯角（Point Reyes）（Dickinson等，2005），在制图区内的佩斯卡德罗角（Pescadero Point）以及半月湾以北数公里处的皮拉尔角（Pillar Point）等海岸岬角处出露陆地。 在近海区域，鸽子点断层系统形成了宽度约2至4公里的弥散剪切带，包含两条主要分支断层段。西支断层（又称弗里霍莱斯断层（Frijoles Fault））从佩斯卡德罗角向近海延伸。东支断层（又称海岸断层（Coastways Fault）或海豹湾断层（Seal Cove Fault））在本制图区内主体出露于陆地。该区域内鸽子点断层带的累计侧向滑移量据估算为4至10毫米/年（美国地质调查局（U.S. Geological Survey），2010）。鸽子点断层带的西支（即弗里霍莱斯断层）构成了鸽子点高地的东部边界。 本次断层制图主要基于地震反射剖面数据解译完成（详见OFR 2013-1071）。地震反射剖面数据采集于2007年至2010年间。 参考文献 Dickinson, W.R.、Ducea, M.、Rosenberg, L.I.、Greene, H.G.、Graham, S.A.、Clark, J.C.、Weber, G.E.、Kidder, S.、Ernst, W.G. 与 Brabb, E.E.，2005，加利福尼亚海岸新近纪鸽子点-霍斯格里断层带的净右旋滑移：地质证据与构造意义：美国地质学会特刊391号（Geological Society of America Special Paper 391），共43页。