Collaborative Research: Mesozoic to Present-Day Tectonics of Northeast Russia: A Cooperative Research Program with the Yakut Science Center and NEISRI

该奖项为阿拉斯加费尔班克斯大学、密歇根州立大学、雅库特科学中心（YSC，雅库茨克，俄罗斯）和东北跨学科科学研究所（NEISRI，马加丹，俄罗斯）于1990年发起的合作研究项目提供支持。该研究项目是跨学科的，利用古地磁、地质年代学、地球化学、地震学和构造地质学研究俄罗斯东北部从西伯利亚地台边缘到鄂霍次克-楚科奇火山带（OCVB）的中生代至新生代构造史。研究区包括中生代北极和太平洋起源地体增生带和现今北美洲和欧亚大陆的板块边界。到目前为止，该合作项目已经探测到了中生代花岗岩的年龄递进，在Kolyma构造环（KSL）西北部发现了广泛的古地磁叠印，并获得了该地区已有的古地磁资料。基于区域和远震资料的地震震源机制显示，该地区由北冰洋开放驱动的地壳缩短被鄂霍次克（OK）板块向东南的挤压所缓解。为了扩大对KSL的了解，该项目将重点关注它的东南端，那里的地层与在环的东北部研究的地层相似，从东南走向转向东北走向。该地区也位于NA-OK板块边界，在低分辨率卫星图像中可以看到断层痕迹和地震产生的特征。下一阶段的工作将涉及NEISRI和YSC沿科利马河和印迪吉尔卡河进行两次横断面，并分析收集的样本。这些样带穿过Kular-Nera板岩带、Omulevka复合地层、Il'in-Tas地层或它们的沿走向等效地层。根据一个模型，这些单元代表了位于Kolyma-Omolon超地体（K-OS）边缘或附近的Uyandina-Yasachnaya岛弧的晚侏罗世弧前、弧后和弧后矿床；然而，这一模式仍有相当大的争议，特别是与俯冲的极性有关。本文的主要目的是确定乌伊丁纳弧的年龄和极性，K-OS与Viliga陆架地体的关系，古地磁叠印的范围，是否发生过斜向弯曲，晚白垩世OCVB的年龄和古纬度，NA-OK板块边界的详细构造和位置，以及该地区的地壳结构。这些问题的解决将有助于限制俄罗斯东北部的构造演化，这将对北太平洋和北冰洋的构造产生影响。特别是，这项工作将有助于确定对古气候学有影响的北极盆地隔离的时间和方法。地震研究将有助于限制由压缩引起的地壳增厚量，并有助于波传播研究和禁止核试验监测。

Abstract This award provides supports to continue a cooperative research program between the University of Alaska Fairbanks, Michigan State University, the Yakut Science Center (YSC, Yakutsk, Russia), and the Northeast Interdisciplinary Scientific Research Institute (NEISRI, Magadan, Russia) which was initiated in 1990. The research program is interdisciplinary, using paleomagnetism, geochronology, geochemistry, seismology and structural geology to study the Mesozoic to Cenozoic tectonic history of noptheastern Russia from the edge of the Siberian platform up to, and including, the Okhotsk-Chukotka volcanic belt (OCVB). The study area includes the zone of Mesozoic accretion of terranes of both Arctic and Pacific origins and the present-day plate boundary between North America (NA) and Eurasia (EU). So far, this cooperative project has detected an age progression among Mesozoic granites, identified a widespread paleomagnetic overprint in the northwestern Kolyma Structural Loop (KSL), and obtained previously published paleomagnetic data for the region. Earthquake focal mechanisms, based on regional and teleseismic data, reveal that crustal shortening in the region, driven by the opening of the Arctic Ocean is being relieved by the extrusion of the Okhotsk (OK) plate to the southeast. To expand understanding of the KSL, this project will focus on its southeastern end, where formations similar to those studied in the northeastern part of the loop turn from a southeasterly strike to a northeasterly one. This region also lies along the NA-OK plate boundary and fault traces and seismically generated features are visible in low resolution satellite images. The next phase of work will involve two transects by NEISRI and the YSC along the Kolyma and Indigirka Rivers, and analysis the samples collected. These transects cross the Kular-Nera slate belt, the Omulevka composite terrane, the Il'in-Tas formation, or their along-strike equivalents. These units represent, according to one model, the Late Jurassic forearc, arc, and back-arc deposits of the Uyandina-Yasachnaya island arc which was located on or near the edge of the Kolyma-Omolon superterrane (K-OS); this model, however, is still open to considerable debate, especially relating to the polarity of subduction. The primary objectives here are to determine the age and polarity of the Uyandina arc, the relationship between the K-OS and the Viliga shelf terrane, the extent of the paleomagnetic overprint, whether oroclinal bending occurs, the age and paleolatitude of the Late Cretaceous OCVB, the detailed tectonics and location of the NA-OK plate boundary, and the crustal structure of the region. Resolution of these problems will aid in constraining the tectonic evolution of northeast Russia, which has implications for the tectonics of the North Pacific and the Arctic Ocean. In particular, this work will aid in determining the timing and methodology of the isolation of the Arctic basin which has impact on paleoclimatology. The seismic studies will help in constraining the amount of crustal thickening resulting from compression and aid in wave propagation studies and nuclear test- ban monitoring.