【作者】 黄学光； 贺玉贞； 王亚烈； 臧广才； 蒋汶田；

【Author】 Huang Xueguang;He Yuzhen;Wang Yalie;Zang Guangcai;Jiang Wentian;Tianjing Institute of Geology and Mineral Resources,CAGS;

【机构】 天津地质矿产研究所；

【摘要】 华北中元古代沉积海泡石产于燕山裂陷槽内,赋存于蓟县系雾迷山组韵律的底层,呈多层产出,并集中成组出现。矿层延伸稳定,海泡石古量随与山海关古陆的距离加大而减少。与国内外同类型矿床相比,本矿床具有成矿时代的古老性、成矿作甩的特殊性和保存条件的优越性3个突出特点。更多还原

【Abstract】 The Northern China Middle Proterozoic sedimentary sepiolite is distributed 60-180 km to the east of Beijing.The ore-bearing Wumishan Formation of Jixian System(1310-1207 Ma by Ar-Ar method) has thickness from 2000 m to more than 3000 m with well developed sedimentary rhythm,consisting mainly of dolostone and delostone with silica band.At the base of rhythm is the sandy clayish dolostone,sedimentary characteristics of which represent a still water low energy environment.The texture of platty pebble of chrysanthemum type,widely developed in rhythm,is a quasi-synchronous texture by synchronous fracture.The development to a large lextent of this and other sliding textures indicates the frequent activity of synchronous fracture,resulting in alteration of depth of sea water in basin and cyclic introduction of landsource sand and clay,finally the extremely thick rhythmic sedimentation of Wumishan Formation.According to our study sepiolite was formed at the late stage of transition period from Yanliao rift to platform.The mineralization area is located in lagune near the Shanhaiguan paleocontinent side.The basal layer of rhythm in Wumishan Formation is clay-bearing layer,in which sepiolite montmorillonite and illite are the main clay mineral.The thickness of ore body,the content of sepiolite and landsource(silty) sand are decreasing as the distance from paleocontinent is increasing.Although after sedimentation the sepiolite has evolved a long 1200 Ma year geological history,the ore body is preserved perfectly,not changed into talc in great amount.Compared with other deposits at home and abroad Northern China Middle Proterozoic sepiolite deposit is distinguished by its ancient age of ore-forming process,speciality of mineralization and perfect preservation and is the world oldest particular sedimentary sepiolite deposit.更多还原