Folds--Offshore Santa Cruz, California

This part of DS 781 presents data for the folds for the geologic and geomorphic map of the Offshore Santa Cruz map area, California. The vector data file is included in "Folds_OffshoreSantaCruz.zip," which is accessible from http://dx.doi.org/10.5066/F7TM785G. The offshore Santa Cruz 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 Santa Cruz Fault zone, a prominent structure west of the San Andreas Fault in the broader San Andreas Fault system. The Santa Cruz 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 Santa Cruz 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 Santa Cruz 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 Santa Cruz Fault zone (i.e., Frijoles Fault) forms the eastern boundary of the Santa Cruz high. Folds 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 Santa Cruz-Hosgri fault zone, coastal California: Geologic evidence and tectonic implications: Geological Society of America Special Paper 391, 43 p.本数据集（DS 781）的该部分提供了加利福尼亚州近海圣克鲁兹（Offshore Santa Cruz）制图区域的地质与地貌图褶皱相关数据。矢量数据文件封装于"Folds_OffshoreSantaCruz.zip"中，可通过链接http://dx.doi.org/10.5066/F7TM785G获取。 近海圣克鲁兹制图区域位于北美板块（North American Plate）与太平洋板块（Pacific Plate）之间离散转换边界的主控构造——圣安德烈亚斯断层（San Andreas Fault）西南约15至25千米处。该制图区域横跨右行走滑的圣克鲁兹断裂带（Santa Cruz Fault zone），这是更广范围圣安德烈亚斯断裂系统中，圣安德烈亚斯断层西侧的显著构造。圣克鲁兹断裂带主体分布于近海海域，南起康塞普申角（Point Conception），北至博利纳斯（Bolinas）与雷耶斯角（Point Reyes），延伸长度达400千米（Dickinson等，2005），并在制图区域内的佩斯卡德罗角（Pescadero Point）以及半月湾以北数千米的柱石角（Pillar Point）等海岸岬角处出露陆地。 在近海区域，圣克鲁兹断裂系统形成宽度约2至4千米的离散剪切带，包含两条主要的分支断裂。西支断裂（又称弗里霍莱斯断裂（Frijoles Fault））从佩斯卡德罗角向近海延伸。东支断裂（又称海岸大道断裂（Coastways Fault）或海豹湾断裂（Seal Cove Fault））在本制图区域内主体分布于陆上。据测算，该区域圣克鲁兹断裂带的累积侧向滑移速率介于4至10毫米/年（美国地质调查局（U.S. Geological Survey），2010）。圣克鲁兹断裂带的西支断裂（即弗里霍莱斯断裂）构成了圣克鲁兹高地的东部边界。 褶皱构造主要通过地震反射剖面（seismic reflection profile）数据解译完成（详见OFR 2013-1071），相关地震反射剖面采集于2007年至2010年间。 引用文献 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. 及 Brabb, E.E., 2005, 《加利福尼亚海岸新近纪圣克鲁兹-霍斯格里断裂带的右旋净滑移：地质证据与构造意义》：美国地质学会专题论文（Geological Society of America Special Paper）391，共43页。