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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Rayleigh and S wave tomography constraints on subduction termination and lithospheric foundering in central California
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Rayleigh and S wave tomography constraints on subduction termination and lithospheric foundering in central California

机译：瑞利和S波断层摄影限制在加利福尼亚州中部的俯卧终止和岩石层

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摘要

The crust and upper mantle structure of central California have been modified by subduction termination, growth of the San Andreas plate boundary fault system, and small-scale upper mantle convection since the early Miocene. Here we investigate the contributions of these processes to the creation of the Isabella Anomaly, which is a high seismic velocity volume in the upper mantle. There are two types of hypotheses for its origin. One is that it is the foundered mafic lower crust and mantle lithosphere of the southern Sierra Nevada batholith. The alternative suggests that it is a fossil slab connected to the Monterey microplate. A dense broadband seismic transect was deployed from the coast to the western Sierra Nevada to fill in the least sampled areas above the Isabella Anomaly, and regional-scale Rayleigh and S wave tomography are used to evaluate the two hypotheses. New shear velocity (Vs) tomography images a high-velocity anomaly beneath coastal California that is sub-horizontal at depths of similar to 40-80 km. East of the San Andreas Fault a continuous extension of the high-velocity anomaly dips east and is located beneath the Sierra Nevada at similar to 150-200 km depth. The western position of the Isabella Anomaly in the uppermost mantle is inconsistent with earlier interpretations that the Isabella Anomaly is connected to actively foundering foothills lower crust. Based on the new Vs images, we interpret that the Isabella Anomaly is not the dense destabilized root of the Sierra Nevada, but rather a remnant of Miocene subduction termination that is translating north beneath the central San Andreas Fault. Our results support the occurrence of localized lithospheric foundering beneath the high elevation eastern Sierra Nevada, where we find a lower crustal low Vs layer consistent with a small amount of partial melt. The high elevations relative to crust thickness and lower crustal low Vs zone are consistent with geological inferences that lithospheric founderin
机译：加州中部的地壳和上部地幔结构已经通过俯冲终止，San Andreas板边界故障系统的生长进行了修改，自早期内科以来的小规模上部地幔对流。在这里，我们调查这些过程对Isabella异常的创建的贡献，这是上部地幔中的高地震速度体积。它的起源有两种类型的假设。其中一个是，它是南部塞拉尼达斯托莱斯南部塞罗斯南部的制造机迈克克下地壳和地幔。替代方案表明它是一个连接到蒙特利微孔板的化石板。宽宽带地震横断面从海岸部署到西部塞拉尼达西部，以填补伊莎贝拉异常上方的最低排样区域，以及区域规模的瑞利和S波断层扫描用于评估两个假设。新的剪切速度（VS）断层扫描图像在沿海加利福尼亚州的高速异常是船水平，深度与40-80 km相似。 San Andreas Fault的东部连续延伸高速异常倾斜的倾斜倾斜，位于塞拉尼达达的塞拉尼达达，与150-200公里深度相近。 Isabella异常的西方地位在最上面的地幔中与早期的解释不一致，即Isabella异常与伊莎贝拉异常相连，以积极的创造山麓底部地壳。基于新的VS图像，我们解释了伊莎贝拉异常不是塞拉尼达达的密集稳定的根，而是一个内蒙古郊区的残余，即在圣安德烈亚斯的错误中北面翻译。我们的结果支持在高海拔东部塞拉涅达山脉下方的局部岩石术中的发生，在那里我们发现较低的地壳低VS层与少量的部分熔体一致。相对于结壳厚度和降低地壳低Vs的区域中的高海拔与地质推断该岩石圈founderin一致

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