摘要
对2023年跨唐山断裂带北段沿北西-南东向实施的一条长约30 km的深反射剖面的初至波走时进行反演,获得唐山市北部的浅层精细速度结构剖面。速度结构剖面揭示出,测线坐标2.5~8.5 km新生代沉积厚约150 m,较为均匀;丰台-野鸡坨断裂隐伏于测线坐标3.5 km处,倾向北西,F2-1断裂隐伏于测线坐标8.5 km处,倾向南东;这2条断裂之间存在一个北西低南东高的隐伏凸起。测线坐标8.5~15.2 km,自北西向南东新生代沉积逐渐加厚,最大厚度约250 m,显示出荆各庄凹陷为箕状新生代断陷。陡河断裂出露于15.2 km处,倾向北西。测线坐标15.2~24 km为唐山凸起,仅局部区域有很薄的新生代沉积,同等深度上,P波速度远高于两侧;巍山下方有一近直立的低速带,向下延伸至少600 m,推测为唐山-巍山-长山南坡断裂带的破碎带。测线坐标24 km至测线端部为开平凹陷的西北部,表现为一规整的盆地边缘形态,新生代沉积约130 m。陡河断裂、唐山-巍山-长山断裂为第四纪活动断裂。
The first arrival travel times of a deep reflection profile,approximately 30 km long,implemented along the northwest-southeast direction across the northern segment of the Tangshan fault in 2023 were inverted to obtain a detailed shallow velocity structure profile in the northern part of Tangshan.The velocity structure profile reveals that from 2.5 to 8.5 km along the survey line,the Cenozoic Era sediments are about 150 m thick and relatively uniform.The Fengtai-Yejituo fault is hidden at the survey line coordinate of 3.5 km,trending northwest,and F 2-1 fault is hidden at 8.5 km,trending southeast;there is a hidden bulge between these two faults that is low in the northwest and high in the southeast.From 8.5 to 15.2 km along the survey line,the Cenozoic Era sediments gradually thicken from northwest to southeast,with a maximum thickness of about 250 m,indicating that the Jinggezhuang depression is a gull-shaped Cenozoic fault depression.The Douhe fault is exposed at 15.2 km,trending northwest.From 15.2 to 24 km along the survey line,it is the Tangshan uplift,with only local areas having very thin Cenozoic Era sediments,and the P-wave velocity at the same depth is much higher than on both sides;there is a nearly vertical low-velocity zone under Weishan,extending at least 600 m downward,which is speculated to be the fault zone of the Tangshan-Weishan-Changshan south slope fault belt.From the survey line coordinate of 24 km to the end of the survey line,it is the northwestern part of the Kaiping depression,showing a regular basin edge morphology,with Cenozoic Era sediments of about 130 m.The Douhe fault and the Tangshan-Weishan-Changshan fault are active faults of the Quaternary.
作者
贾佳
王夫运
刘巧霞
段永红
范振宇
王宏伟
高占永
JIA Jia;WANG Fuyun;LIU Qiaoxia;DUAN Yonghong;FAN Zhenyu;WANG Hongwei;GAO Zhanyong(Geophysical Exploration Center,CEA,75 Wenhua Road,Zhengzhou 450002,China)
出处
《大地测量与地球动力学》
北大核心
2025年第8期834-839,共6页
Journal of Geodesy and Geodynamics
基金
国家自然科学基金(42074070,42374073)
中国地震局地球物理勘探中心青年基金(YFGEC2022005)
国家重点研发计划(2017YFC1500202)。
关键词
唐山市北部
初至波走时成像
浅部速度结构
断裂活动性
地质构造
northern Tangshan
first arrival travel time tomography
shallow velocity structure
fault activity
geological structure
