Abstract The crustal structure between different subregions of the North China craton (NCC) plays an important role in improving our understanding on the craton evolution. Here we present a flexural Moho map and isostatic residual gravity field of the NCC derived from the GO_CONS_GCF_2_TIM_R3 model. We first investigate the influence of additional sources on the forward flexure calculation, especially the distinct thinning of the lithospheric thickness from west to east. After removing the gravity effects of the LAB undulations, the flexural Moho and isostatic residual gravity field of the NCC are calculated using the Vening-Meinesz regional isostasy models. There are high to medium positive residual anomalies beneath the Eastern block and Trans-North China Orogen, while negative residual anomalies delineate the Yinshan block, Ordos plateau and Khondalite belt. This obvious disparity is consistent well with the decreasing depth of the flexural Moho from west to the east. A profile across the Eastern block, Trans-North China orogen and the Western block was employed to construct a density structure of the crust and uppermost mantle. By comparing the surface topography, Bouguer gravity, isostatic Moho and seismological Moho undulations, we find that the flexural Moho is much shallower than the seismic Moho beneath the northern margin of the Ordos block, possibly indicating the over-compensated isostatic state caused by the dominant NW–SE oriented compressional deformation in the lithospheric processes. Density modeling results further predicted that a high density body may exist in the lower crust beneath the northern margin of the Ordos block, which could be a westward-dipping upper-middle crust remnant stagnating in the lower crust beneath the Western block. Medium to high pressure metamorphism of granulite facies or eclogite facies, resulting from subsequent continental thickening during the continental collision may be responsible for modifying the remaining subduction remnant.

中文翻译：

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GOCE重力资料推导的华北克拉通等静压状态及地壳结构

摘要 华北克拉通（NCC）不同亚区之间的地壳结构对提高我们对克拉通演化的认识具有重要作用。在这里，我们展示了从 GO_CONS_GCF_2_TIM_R3 模型导出的 NCC 的弯曲莫霍面图和等静压残余重力场。我们首先研究了额外来源对前向弯曲计算的影响，特别是岩石圈厚度自西向东明显变薄。在去除 LAB 波动的重力影响后，使用 Vening-Meinesz 区域均衡模型计算 NCC 的弯曲莫霍面和等静压残余重力场。东部地块和横贯华北造山带下存在高到中等的正残余异常，而阴山地块则存在负残余异常，鄂尔多斯高原和孔达石带。这种明显的差异与弯曲莫霍面自西向东递减的深度一致。使用横跨东部地块、横贯华北造山带和西部地块的剖面来构建地壳和最上地幔的密度结构。通过对比地表地形、布格重力、等静压莫霍面和地震莫霍面起伏，我们发现鄂尔多斯地块北缘下弯曲莫霍面比地震莫霍面浅得多，这可能表明由主导作用引起的过度补偿等静压状态。岩石圈过程中 NW-SE 取向的压缩变形。密度模拟结果进一步预测鄂尔多斯地块北缘下地壳可能存在高密度体。这可能是一个向西倾斜的中上地壳残余物，滞留在西部地块下方的下地壳中。由大陆碰撞期间随后的大陆增厚引起的麻粒岩相或榴辉岩相的中高压变质作用可能是改变剩余俯冲残余物的原因。