胶东金矿成矿构造背景探讨

在编制1∶50万山东省大地构造相图基础上,通过对大地构造相研究显示：胶东微地块是经多期增生和碰撞而形成的,其漫长的板块构造演化明显具有阶段性。侏罗纪是该区板块构造演化史上的一个重要转换期,构造演化由原来的南、北分异转变为东、西分异,胶东地区NE向新生构造起了主要作用。胶东地区中生代有2次重要的碰撞造山事件,印支造山作用主要表现为扬子板块向华北板块俯冲,形成苏鲁高压-超高压变质带及同造山花岗岩及后造山高碱正长岩;燕山造山作用的大陆动力学环境起源于中亚-特提斯构造域向滨太平洋构造域转化和太平洋板块的俯冲,在胶东地区表现为3次造山和3次伸展。晚侏罗世造山早期玲珑片麻状花岗岩组合是区域构造挤压导致地壳增厚引起地壳重熔的产物,代表了大陆弧花岗岩特征;早白垩世造山中期郭家岭花岗闪长岩-花岗岩组合代表了造山期大陆弧花岗岩的特点;造山晚期伟德山闪长岩-花岗闪长岩-花岗岩组合表现为大陆弧花岗岩,后造山A型崂山晶洞过碱性碱长花岗岩-正长花岗岩组合为大陆造陆隆升花岗岩与后造山花岗岩,代表燕山构造的结束。胶东地区构造-岩浆事件和金矿成矿作用受控于特提斯、古亚洲洋和太平洋三大构造域的相互作用,金矿形成的动力学背景是中生代构造体制转折和岩石圈减薄,起因与太平洋板块向华北板块的俯冲机制有关。

Study on Tectonic Background of Gold Mineralization in Jiaodong Area

On the basis of making ＂Shandong tectonic phase diagram with the scale of 1 ∶ 500000＂,through study on tectonic phase,it is showed that Jiaodong block was formed by multi-phase proliferation and collision.Its long plate tectonic evolution had obvious stages.Jurassic plate tectonic evolution in the history in this area was an important transition period.Tectonic evolution changed from north and south differentiation to east and west differentiation.New construction with the trend of NE in Jiaodong area played a major role.There were two important collisional events in Mesozoic period in Jiaodong area.Indosinian orogeny mainly represented in the subduction from Yangtze plate to the North China plate,and formed Sulu high-pressure-ultrahigh-pressure metamorphic belt and syn-orogenic granite and post-orogenic high-alkali syenite rock.Yanshan orogenic continental origin in the dynamic environment was formed in the transformation of Central Asia-Tethyan tectonic domain to the Pacific tectonic domain and the Pacific subduction,which perfomed as three orogenics and three times extensions in Jiaodong region.Linglong gneissic granite combination in early orogenic period of late Jurassic were the production of regional tectonic compression which led to crustal thickening caused by the product of crustal melting,and represented characteristics of continental arc granites.Peralkaline alkali-feldspar and granite-syenite granite combination in Post-orogenic A type Laoshan miarolitic were continental epeirogenic uplift granitoids and post-orogenic granites,which represented the end of Yanshan orogenic movement.Tectonic-magmatic events and gold mineralization were controlled by the interaction of Tethys,Paleo-Asian ocean and the Pacific ocean.Dynamic background of gold mineralizaiton was the formation of Mesozoic tectonic regime and rock lithospheric thinning.Its origin had close relation with the subduction mechanism of the Pacific plate to North China plate.