Collaborative Research: Complex Upper Mantle Structure Beneath Northeast US Investigated Through Shear Wave Tomography

这项研究是哥伦比亚大学和耶鲁大学的合作，涉及对美国东北部稳定克拉通环境中不同类型的地幔非均质性的研究。这个地质古老地区的强烈非均质性是出乎意料的，因为横向温度梯度——活动构造地区非均质性的主要原因——可能非常微弱。行时异常与剪切波分裂变化相关，因此至少部分非均质性可能是由于地幔结构方向的横向变化。这项研究将验证“各向异性域”的假设，即与过去构造活动相关的应变地幔岩石的相干体积，是走时非均质性的主要来源。这些数据将来自最近在美国东北部高密度的固定和便携式台站记录的地震图，以形成一个体波传播时间和横波分裂测量数据集。＊＊＊

9707189 Park This research is a collaboration between Columbia University and Yale University involving the investigation of different types of mantle heterogeneity in the stable cratonic environment of the northeastern U.S. The strong heterogeneity in this geologically old region is unexpected since lateral temperature gradients - the main cause of heterogeneity in areas of active tectonics - are probably very subdued. Travel-time anomalies correlate with shear-wave splitting variations, so at least some of the heterogeneity is probably due to lateral changes in the orientation of mantle fabrics. This research will test the hypothesis that "anisotropic domains," coherent volumes of strained mantle rock related to past tectonic activity, are the primary source of traveltime heterogeneity. The data are to come from seismograms recorded by the recent high density of fixed and portable stations in the northeastern U.S. to form a dataset of body wave traveltimes and shear wave splitting measurements. ***