招平断裂郭家埠地区蚀变岩特征及找矿意义

郭家埠地区位于招平断裂中段,该地区围岩蚀变发育,蚀变分带明显。选取切穿该区蚀变带的1012剖面,分析其围岩蚀变特征,自断裂中心向两侧蚀变岩依次为:黄铁绢英岩、绢英岩和钾化花岗岩,蚀变强度依次减弱。蚀变岩地球化学分析显示:随着蚀变的增强,Si、K、Fe增加,Na减少,说明蚀变是一种硅化、钾化、而去Na的过程;稀土元素总量整体呈降低的趋势。钾化花岗岩轻重稀土元素分异程度较强,轻稀土相对富集,而绢英岩重稀土富集;Rb、Ba含量总体随着矿化强度的增强而增加,高场强元素含量在钾化蚀变阶段和黄铁绢英岩化阶段减少,在绢英岩化阶段增加。通过探讨蚀变岩与找矿的关系,认为黄铁矿化、绢云母化、钾长石化等蚀变是找矿的直接标志。郭家埠地区蚀变岩带规模大,蚀变强,钻孔资料表明深部蚀变岩Au含量已达边界品位,加之周边地区成矿条件较好,初步推测郭家埠地区成矿前景良好。

Altered rock characteristics and their prospecting significance in Guojiabu District of Zhao-Ping fracture

GuoJiabu District is located in the middle of Zhao - Ping fracture, where wall rock alteration develops well and the alteration zone is obvious. In this paper, Section 1012 cutting through the alteration zone is selected to analyze the rock alteration characteristics. From the center of the fracture to the two sides, the altered rock belt follows： pyrite sericite quartzite, sericite quartzite and K -feldspathized granite and the intensity of the alteration decreases in turn. The geochemical analysis of the altered rocks indicates that with the intensity of the alteration strengthening, Si, K, Fe increase and Na reduces, showing it is a Si, K alteration process while Na is removed; ∑ REE increases. The differentiation degree of heavy and light REE is stronger in K-feldspathized granite, light REE relatively enriched, and sericite quartzite enriching the heavy REE ;with the mineralization intensity strengthening, the contents of Rb, Ba element rise. The content of the high field strength elements decreases in the K-feldspathized granite phase and pyrite sericite quartzite alteration phase and increases in the sericite quartzite phase. After studying the relationship between altered rock band and prospecting, it is found that pyritization, sericitization, silicification are direct signals of the prospecting. From the large scale, strongly altered rocks of Guojiabu District, the drilling data show that the content of Au reaches the cut-off grade and the good mineralization conditions in surrounding areas, it is speculated there are good metallogenic prospects in Guojiabu District.