山东郗山-龙宝山地区与碱性岩有关的稀土矿床地质特征及成因

郗山和龙宝山稀土矿具有相似的成矿地质背景、控矿岩体特征及矿床地质特征。燕山早期碱性侵入岩与稀土矿关系密切,稀土矿体主要赋存于杂岩体内及其附近围岩中;稀土元素和同位素研究表明,含矿质的富碱岩浆可能属壳幔混源型,碱性岩浆及成矿物质最初可能都来源于上地幔同一部位,而在岩浆上侵过程中同化混染了地壳物质。郗山稀土矿为单一富轻稀土矿床,矿脉类型以含稀土石英重晶石碳酸盐脉为主,含稀土矿物以氟碳铈矿和氟碳钙铈矿为主,碳酸铈钠矿和菱钙锶铈矿属国内首次发现。龙宝山稀土矿为稀土、金共生矿,矿脉类型主要为石英脉和硅化角砾岩;含稀土矿物主要有氟碳铈矿、氟碳铈镧矿、氟碳钙铈矿;金矿物有自然金、银金矿等。成矿时代稍晚于岩浆岩形成时代,属中生代燕山晚期;矿床成因类型为碱性岩浆期后中-低温热液稀土矿床。

Geological Characteristics and Origin ofRare Earth Deposits Related with Alkaline Rockin Chishan-Longbaoshan Area in Shandong Province

Rare earth deposits in Chishan and Longbaoshan area have similar geological mineralization background, rock-controlling characteristics and geological characteristics of deposits. Alkaline intrusive rock in early Yanshan period has close relation with rare earth deposit. Rare earth ore bodies mainly occurred in complex and country rocks in surrounding areas. As showed by the study on rare earth elements and isotope results, it is regarded that ore-bearing alkaline concentrated magma probably belongs to crust-mantle magma source mixed type, and alkaline magma and ore-forming materials may be derived from the same parts of the mantle, while crust materials were mixed and assimilated in the process of magma intrusion. Chishan rare earth deposit is a single light rare earth deposit. Rare earth bearing carbonate quartz barite veins are its main vein types. Rare earth bearing minerals are mainly composed of harmartite and parisite deposits, while carbonate calcium cerium deposit and diamond calcium strontium bastnasite deposit were first found in China. Longbaoshan rare earth deposit is a symbiotic deposit of rare earth ores and gold ores. Quartz veins and silicified breccia veins are its major vein types; rare-earth bearing minerals are mainly composed of harmartite deposit, harmartite lanthanum deposit and harmartite calcium deposit; gold minerals are native gold and silver gold. Its ore-forming period is later than the formation of igneous rocks and belongs to late Mesozoic Yanshan period; It is alkaline magmatic low-temperature hydrothermal rare earth deposit.