山东省临沂凸起东北缘重力场特征及大地构造单元边界讨论  

Gravity field characteristics and boundaries of geotectonic units on the northeastern margin of the Linyi uplift,Shandong Province

作　　者：王润生 武斌 张海瑞 于嘉宾 董彦龙 郭国强 康一鸣 WANG Run-Sheng;WU Bin;ZHANG Hai-Rui;YU Jia-Bin;DONG Yan-Long;GUO Guo-Qiang;KANG Yi-Ming(Shandong Geophysical and Geochemical Exploration Institute,Jinan 250013,China;Shandong Geological Exploration Engineering Technology Research Center,Jinan 250013,China;No.4 Exploration Institute of Geology and Mineral Resources of Shandong Province,Weifang 261021,China;School of Earth Sciences,China University of Geosciences(Wuhan),Wuhan 430074,China;State Key Laboratory of Geological Processes and Mineral Resources,China Univesity of Geosciences(Wuhan),Wuhan 430074,China)

机构地区：[1]山东省物化探勘查院,山东济南250013 [2]山东省地质勘查工程技术研究中心,山东济南250013 [3]山东省第四地质矿产勘查院,山东潍坊261021 [4]中国地质大学(武汉)地球科学学院,湖北武汉430074 [5]中国地质大学(武汉)地质过程与矿产资源国家重点实验室,湖北武汉430074

出　　处：《物探与化探》2023年第2期279-289,共11页Geophysical and Geochemical Exploration

基　　金：山东省级地质勘查项目(鲁勘字(2018)36号);山东省重大科技创新工程项目(2018CXGC1601);山东省地矿局科技攻关项目(KY202226)。

摘　　要：临沂凸起东北缘位于鲁西地块东端,东侧紧邻沂沭大断裂,NE向鄌郚—葛沟断裂与NW向蒙山断裂控制了研究区内主要构造格架。受新生界覆盖影响,区内主要构造单元边界几乎处于隐伏状态,蒙山断裂东端走向变化及临沂凸起北界角度不整合界线的展布均有待深入研究。本文利用最新1∶5万高精度重力资料,基于重力场定性分析及多元化重力位场转换解释,同时结合山东省大地构造单元划分方案,对区内构造单元边界位置及其交切关系进行了重点研究和讨论。分析认为:蒙山凸起、平邑凹陷交界的蒙山断裂在半程镇以东由NW走向转为近EW走向,并明显切割NE向鄌郚—葛沟断裂,且向东再次呈现NW向转折趋势;临沂凸起、平邑凹陷交界的角度不整合界线既非向北终止于蒙山断裂,也非向南转折,而是向东延伸至鄌郚—葛沟断裂,该不整合界线也控制了平邑凹陷南界,使其NW向条带状重力异常向东转折,在区内呈现出“靴形”重力低值异常特征。本研究基于高精度重力边界识别,精细厘定了临沂凸起东北缘地段的断裂体系及构造区划,为该区基础地质研究工作提供了高精度重力数据支撑,同时为下步矿产地质调查工作奠定了良好的基础。The northeastern margin of the Linyi uplift is located at the eastern end of the Luxi Block and immediately adjacent to the Yishu fault in the east.The main structural framework of the study area is controlled by the NE-trending Tangwu-Gegou fault and the NW-trending Mengshan fault.Covered by the Cenozoic sediments,the boundaries of main tectonic units in the study area are almost all concealed,and it is necessary to further investigate the change in the strike of the eastern end of the Mengshan fault as well as the distribution of the angular unconformity along the northern boundary of the Linyi uplift.Using the latest 1∶50,000 high-precision gravity data,this study mainly investigated the positions and intersection relationships of the boundaries of tectonic units based on the qualitative analysis of gravity field,the interpretation of multiple gravity potential field conversion,and the division scheme of geotectonic units in Shandong Province.The analysis results are as follows.The Mengshan fault at the junction of the Mengshan uplift and the Pingyi sag transitions from the NW trending to nearly-EW trending in the east of Bancheng Town,significantly cuts the NE-trending Tangwu-Gegou fault,and shows a NW-trending turn to the east again.The angular unconformity at the junction of the Linyi uplift and the Pingyi sag neither ends in the Mengshan fault in the north nor turns southward but extends to the Tangwu-Gegou fault in the east.This unconformity also controls the southern boundary of the Pingyi sag,making the NW-trending banded gravity anomalies of the sag turn eastward.Consequently,the boot-shaped low-value gravity anomalies were formed in the study area.Based on the high-precision gravity boundary identification,this study determined the fault system and tectonic division of the northeastern margin of the Linyi uplift,providing high-precision gravity data for the basic geological study in the study area and laying a good foundation for further mineral geological survey.

关 键 词：临沂凸起 重力异常 位场转换 大地构造单元 边界识别 

分 类 号：P631[天文地球—地质矿产勘探]