鲁西白彦组砾岩中重矿物组合特征及其物源指示意义

白彦砾岩主要分布在剥蚀低山、丘陵斜坡地带和山麓地带寒武—奥陶纪碳酸盐岩中的岩溶地貌的溶蚀沟、溶蚀槽及洞穴等负地形中,以燧石角砾为主,砾岩中的重矿物主要为金刚石、黄铁矿、赤铁矿、磁铁矿、褐铁矿、锆石、金红石、绿帘石、磷灰石、电气石;其中重矿物的种类和重量在区域砾岩点上分布差距较大,其中赤铁矿、磁铁矿、褐铁矿分布范围最大,含量最多。重矿物组合ZTR指数分析一般在0.2～0.8之间,最低为0.00,局部达到1.0～2.0;最高值在费县南西为15.95。金刚石含量最高可达64.61mg/m~3,低者只有0.164mg/m~3,北部金刚石矿物的含量自中段向两端逐渐降低;南带则呈自中心向四周环形扩散。从重矿物相对含量和重矿物组合ZTR指数来判断金刚石矿物的物源供应来源应在泗水县和白彦镇一带。

Characteristics of Heavy Mineral Assemblage and Significance of Provenance Indication of Baiyan Formation Conglomerate in Western Shandong Province

Baiyan conglomerate is mainly distributed in the karst landform of the dissolution ditch, dissolution groove and cave and other negative terrain of the Cambrian Ordovician carbonate in the eroded low mountains, hills and slopes, and the foothills. Cchert breccia is main rock. Heavy minerals in the conglomerate are mainly diamond, pyrite, hematite, magnetite, limonite, zircon, rutile, epidote, apatite and tourmaline. There is a big difference in the distribution of heavy mineral types and weight in the regional conglomerate points. Among them, hematite, magnetite and limonite are distributed in the largest range with the most content. ZTR index of heavy mineral assemblage is generally 0.2~0.8, the lowest is 0.00, the local index is 1.0~2.0, and the highest value is 15.95 in the southwest of Feixian county. The highest content of diamond is 64.61mg/m3, and the lowest is 0.164mg/m3. The content of diamond minerals in the north decreases gradually from the middle to the two sides, while in the south, it diffuses from the center to the surrounding area. According to relative content of heavy minerals and ZTR index of heavy mineral assemblage, the source supply of diamond minerals should be in the area of Sishui county and Baiyanzhen town.