矾山岩浆型磷(铁)矿床地质、地球物理、遥感影象特征及其找矿模型

GEOLOGICAL, GEOPHYSICAL AND REMOTE SENSING CHARACTERS OF FANSHAN MAGMATIC PHOSPHORUS (IRON) DEPOSIT AND ITS ORE HUNTING MODEL

矾山磷 (铁 )矿床为一隐伏矿床 ,赋存在印支期碱性 超基性杂岩体中。矿床地处中朝准地台燕山台褶带 ,该处莫霍面深 39～ 40km ,并由陡变缓 ,矿床还处于张宣幔枝外围拆离滑脱带上。不同方向的深大断裂在矿床附近交叉通过 ,区域褶皱是印支期开阔宽缓的复式背向斜。赋矿的碱性 超基性杂岩体生成于 2 0 3～ 2 48Ma ,产状为岩盆 ,由三期侵入岩和一期脉岩组成 ,具层状岩系特征和韵律结构。矿体产于第一期岩石辉石岩带中。杂岩体航磁异常最高达36 0 0nT ,形态规则 ,地表剖面磁异常最高达 45 0 0nT ,剩余重力异常达 0 .2× 10 -4 m/s2 。在遥感影象图中 ,杂岩体与深部相连的同期岩体共同组成复合环状构造 ,并受北东向断裂和更大的环形断裂控制。据此建立了找矿模型。

The Fanshan phosphorus (iron) deposit, a hidden deposit, occurs within a Indo Sinian alkali ultrabasic complex in the Yanshan folded belt of the Sino Korean paraplatform. The Moho is 39～40km deep beneath the Yanshan folded belt, changing from steep to gentle and penetrated by the Zhang Jiakou Xuan Hua mantle branch whose decollement structure hosts the Fanshan deposit. Differently striking deep faults meet close to the deposit and regional folds organize the Indo Sinian rolling composite anticlines or synclines. The alkali-ultrabasic complex, occurring as a lopolith and aged 203～248Ma, includes three phases of intrusive rocks and one phase of dike rock, characteristic of bedding and rhythm. The ore bodies are associated with the first phase of intrusive rock or pyroxenite. The complex is measured by aerial magnetic survey, reaching 3600nT and shaping regularly, by surface magnetic survey, reaching 4500nT, and by gravity survey, reaching 0.2x10 -4 m/s 2(20g·μ). The remote sensing images reveal that the complex and the deeply interconnected contemporaneous rock bodies compose jointly a composite ring structure controlled by NE trending deep bigger faults. Such a analysis allows establishment of a model for exploring deposits of its kind.