佳木斯地块一那丹哈达地体近地表速度结构

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关键词：佳木斯地块;那丹哈达地体;初至波走时层析成像;速度结构;敦化—密山断裂;跃进山断裂doi：10.13278/j.cnki.jjuese.20250343 中图分类号：P631.4 文献标志码：A

Abstract：To reveal the near-surface structural characteristics of the Jiamusi block-Nadanhada terrane，this study applies the first-arrival traveltime tomography method based on deep seismicreflection profile data to invert and obtain the near-surface P-wave velocity structure model of the study area，and further depicted the spatial distribution characteristics of the fault zones. The inversion results show that the thickness of the sedimentary cover generally exhibits a regional distribution pattern of being thicker in the west and thinner in the east.There is significant lateral heterogeneity in the vicinity of the main fault zones. Specifically，the thickness of the sedimentary cover within the Jiamusi block is relatively thin （0.5-0.7km） ），which increases rapidly when crossing the Dunhua-Mishan fault zone and the Yuejinshan fault zone，with the maximum local thickness exceeding 2km . In contrast，the thickness of the sedimentary cover within the Nadanhada terrane is generally less than 0.5km . The Yuejinshan fault zone is manifested as a significant lithospheric-scale velocity gradient zone，which further reveals its nature as a boundary fault separating different tectonic units. Meanwhile，the Dunhua-Mishan fault zone is characterized by a nearly vertical low-velocity anomaly zone，indicating that the physical properties of the rocks wihtin the fault zone have been weakened due to fragmentation caused by tectonic activities.

Key words： Jiamusi block； Nadanhada terrane； first-arrival traveltime tomography； velocitystructure;Dunhua-Mishan fault;Yuejinshan fault

0 引言

佳木斯地块一那丹哈达地体位于中国东北部，该区域构造位置独特，是探讨古太平洋板块与欧亚大陆相互作用的关键区域，在东亚大陆边缘的地体拼贴与增生演化中具有重要的构造意义[1]。（剩余16079字）