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

9707189公园这项研究是哥伦比亚大学和耶鲁大学合作的，涉及在美国东北部稳定的克拉通环境中调查不同类型的地幔不均一性。在这个地质古老的地区，强烈的不均一性是意想不到的，因为横向温度梯度--活动构造区的不均一性的主要原因--可能非常弱。走时异常与横波分裂变化相关，因此至少部分非均质性可能是由于地幔组构方向的横向变化所致。这项研究将检验这样一种假设，即“各向异性域”，即与过去的构造活动有关的应变地幔岩石的相干体积，是旅行时非均质性的主要来源。这些数据将来自美国东北部最近高密度的固定和便携式台站记录的地震图，以形成体波旅行时间和横波分裂测量的数据集。***

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. ***