基于地震横波速度结构研究鲁西地区金刚石成矿深部过程OA

The western Shandong area represents one of China's most prospective regions for diamond exploration:the Mengyin area hosts the first primary diamond mine with industrial value,while the Tancheng area has yielded the Jinji and Changlin diamonds,the two largest by weight ever found in China,and was the site of one of the largest earthquakes in Chinese history.Whether these occurrences represent a coincidence or reflect an inherent geodynamic connectionwarrants in-depth investigation.Diamonds originate from kimberlite,which is the deepest known magmatic source,yet their deep mineralization processes remain poorly constrained.Using regional earthquake and travel-time data from China Earthquake Science Data Center spanning 2009 to 2020,this paper employs double-difference seismic tomography to reconstruct the three-dimensional crustal velocity structure beneath the Shandong section of the Tanlu fault zone,derives the three-dimensional crustal shear-wave velocity structure of western Shandong,and integrates these results with C-O isotope data from carbonate rocksto examine the deep structural controls on diamond mineralization.Our analysis suggests the existence of a deep-seated carbon reservoir in the southern Shandong section of the Tanlu fault zone.Under high-temperature,high-pressure,and reducing conditions,magma emplacement formed carbonate rocks or graphitized marble,creating conditions suitable for the formation of primary diamond ore.Comparing the Mengyin kimberlites with the Tancheng diamond placers reveals that the Tanlu fault zone,as a lithospheric-scale structure transecting the eastern part of the North China Craton,plays a pivotal role in the coupling system of plate subduction,magmatic response,and the deep carbon cycle.