山东胶东矿集区燕山期构造热事件与金矿成矿耦合探讨

Study on Coupling between Yanshannian Tectonic Thermal Events and Gold Mineralization in Jiaodong Ore Concentrating Area in Shandong Province

中生代胶东地区有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,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2次伸展。本文基于汇集的71个SHRIMP锆石U-Pb同位素年龄,并参考前人已有划分方案,提出胶东地区燕山期花岗岩年代格架:160～150Ma玲珑-昆嵛山花岗岩侵位,130～126Ma郭家岭花岗闪长岩形成,120～110Ma伟德山花岗闪长岩-花岗岩侵位,110～100Ma崂山A型晶洞过碱性碱长花岗岩侵位,代表燕山运动的结束;区内3期金矿成矿事件(150Ma、120～110Ma和100Ma～90Ma)则与玲珑、郭家岭和伟德山岩体的构造-岩浆热事件相耦合。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3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。

There were twice major collision orogenic events in Jiaodong area in Mesozoic period. One event was Indo-china orogeny. It was mainly showed as the subduction of Yangtze plate to the North China Plate, and formed Sulu high pressure-ultra-high pressure metamorphic belt, syn-orogenic granite and post- orogenic high alkali syenite. The other event was Yanshan orogeny; Its continental dynamics environment was originated from the transformation of central Asia-Tethyan structural domain to Pacific tectonic domain, and the subduction of Pacific plate. It showed as three times of magmatic activities and stretching in Jiaodong area. In this paper, based on collecting 71 groups of SHRIMP U-Ph zircon age datas, referring to the previous classification scheme, a chronological frame pattern of Yanshanian granites had been put forward： Linglong-Kunyushan granite emplacement was in in 160~150Ma; the formation of Guojialing granodiorite was in 130 ~ 126Ma; Weideshan granodiorite-granite emplacement was in 120 ~ 110Ma; Laoshan A-type miarolitic cavity parlkaline alkali feldspar granite emplacement was in ll0~100Ma and represented the end of Yanshan movement. Gold mineralization in three periods in this area （150Ma, 120 ~ll0Ma, 100~90Ma） had coupled relation with Linglong-Kunyushan granite, Guojialing granodiorite and Weideshan granodiorite-granite. Jiaodong tectonic-magmatic events and gold mineralization were controlled by the interactions among Tethyan tectonic domain, Paleo-ocean tectonic domain and the Pacific tectonic domain. The dynamics background of gold ore-forming was the transition of Mesozoic tectonic system and the lithosphere thinning, which was formed by the suhduction of the Pacific plate toward the North China Plate.