Shexian County, Hebei Province

The tectonic position of kimberlite area in Shexian County is located in Wu 'an sag at the southern end of Taihang Mountain uplift belt at the front edge of Shanxi platform anticline, kimberlite area is located at the edge of mantle uplift area (according to the data of Shijiazhuang Comprehensive Geological Brigade of Hebei Bureau of Geology and Mineral Resources, 1986), and Zanhuang uplift is on the north side. The regional basement structural line is NE-trending, and the main regional faults are NE-trending. Zanhuang uplift and depression strike NNE, and produce obliquely with Taihang Mountain uplift belt at a small angle.

Kimberlite intrudes into the Cambrian-Ordovician limestone stratum, and there are 7 kimberlite veins (1, 2, 3, 4, 8, 9, 10) and 3 small-scale kimberlite pipes (5, 6, 7) in the rock area, forming a long 15km back door. The strike of kimberlite veins in the rock area is controlled by structural joints or structures, and there are signs of multi-stage and multi-stage kimberlite magmatism in the field (Ikebana et al., 1996).

Kimberlite in Shexian County is a typical transitional phase of root facies or volcanic facies, and its lithology is dominated by kimberlite or phlogopite kimberlite and breccia, with occasional primary homologous breccia (Zhang Andi et al., 199 1). At present, due to the lack of isotopic age data and other geological evidence, it is difficult to determine its age (Dong Zhenxin,1994; Zhang Peiyuan, 200 1). There is no G 10 garnet in kimberlite, but more eclogite inclusions are found. Zhang Andi and others (199 1) think that these kimberlites are rich in chromite with low titanium, high aluminum and magnesium, and low titanium, magnesium, aluminum and chromium spinel, indicating that the kimberlites near the Taihang fault only capture some deep prisoners and are kimberlites without diamonds.