摘要
依兰陨石坑是我国发现并证实的第二个陨石坑,其直径约为1.85 km。前人在依兰陨石坑区域开展了冲击变质诊断性证据的相关研究,钻孔资料揭示了依兰陨石坑撞击构造的实际深度。然而,依兰陨石坑撞击构造的地下结构三维特征仍需通过地球物理探测加以约束。本研究在依兰陨石坑布设了220台节点式地震仪,并基于一个月的连续观测数据和背景噪声的谱比方法(HVSR),计算并提取研究区的峰值频率,随后利用蒙特卡洛反演获得研究区的浅层速度结构和沉积层厚度。结果显示,依兰陨石坑区域的峰值频率范围为0.3~10 Hz,从中心向周缘呈现逐渐升高的趋势;依兰陨石坑中心区域的沉积层厚度约为100 m,与附近钻孔资料结果一致,沉积层厚度由中心向坑缘逐渐减少至约20 m;在地表以下200 m深度处存在另一界面,可能对应于钻孔揭示的中粗粒花岗岩与细粒花岗岩的界面。本研究揭示依兰陨石坑区域的场地特征及撞击构造的浅层速度结构,为区域科学研究与科普工作提供重要的基础资料。
The Yilan crater represents the second confirmed meteorite impact crater discovered in China,with an estimated diameter of about 1850 meters.Previous research in the Yilan crater region focused primarily on evidence associated with impact metamorphism.Drill core data revealed the true depth of the crater’s impact structure.Nevertheless,the three-dimensional characteristics of this structure require further constraint through geophysical exploration techniques.In this study,a total of 220 nodal seismographs were deployed across the Yilan crater area,collecting continuous data over a one-month period.Applying the Horizontal to Vertical Spectral Ratio(HVSR)method based on ambient noise,the peak frequency of the study area was determined.Subsequently,Monte Carlo inversion was utilized to derive the shallow velocity structure and sediment layer thickness within the study area.The findings show that the peak frequency in the Yilan crater region increased radially from the center toward the periphery,ranging between 0.3 Hz and 10 Hz.The sediment layer thickness of the Yilan crater gradually decreases from approximately 100 m at the center to about 20 m near the rim.The sediment layer thickness adjacent to the drill hole aligns with the drill core data,confirming a depth of 100 m.An additional interface was identified at 200 m below the surface,potentially corresponding to the boundary between medium-coarse-grained granite and fine-grained granite near the drill hole.This study provides crucial foundational data regarding the site effects and the three-dimensional shallow velocity structure of the impact structure beneath the Yilan crater,which are essential for advancing scientific research and promoting regional educational initiatives.
作者
罗恒
邓阳凡
张周
朱晟
熊成
马骥骁
胡仲发
黄润青
LUO Heng;DENG Yangfan;ZHANG Zhou;ZHU Sheng;XIONG Cheng;MA Jixiao;HU Zhongfa;HUANG Runqing(State Key Laboratory of Deep Earth Processes and Resources,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Guangdong Earthquake Agency,Guangzhou 510070,Guangdong,China)
出处
《大地构造与成矿学》
北大核心
2025年第4期900-911,共12页
Geotectonica et Metallogenia
基金
国家自然科学基金项目(42322401)
广州市科技计划资助项目(202201010453)联合资助。
