豫西熊耳山地区槐树坪金矿岩石-土壤找矿指示元素的确定及其应用

槐树坪金矿床位于河南省洛阳市嵩县境内,是豫西熊耳山地区近年来新发现的大型金矿床。本次研究对槐树坪金矿区地表及井下不同类型的较新鲜围岩、蚀变岩和矿石以及地表1∶20000面积性土壤采样,分析29项微量元素,从岩石和土壤两种采样介质来确定槐树坪金矿床的地球化学找矿指示元素。一方面基于较新鲜围岩的元素含量特征确定每个微量元素在该区岩石中的异常下限,进而分别计算了蚀变岩和矿石中微量元素平均含量与异常下限的比值,即异常衬度。按照异常衬度大于1.4的标尺确定了蚀变岩与矿石中明显富集的微量元素组合。另一方面,基于Au与28项微量元素在较新鲜围岩、蚀变岩、矿石三种介质中含量关系散点图直观确定了指示金成矿的微量元素组合。综合二者确定出槐树坪金矿区岩石地球化学找矿的指示元素组合为Au、Ag、As、Sb、Hg、Sn、Mo、Bi、Cu、Pb、Zn、Cd、Nb计13项。针对地表1∶20000面积性土壤调查,采用上述岩石中异常衬度为1.4作为土壤异常下限绘制了槐树坪金矿区微量元素的地球化学异常剖析图,以槐树坪金矿区已探明鸡公山一带的主成矿段为模型确定了土壤地球化学找矿的指示元素组合为Au、Ag、As、Sb、Hg、Bi、Cu、Pb、Zn、Cd、B计11项。综合上述结果认为在找矿指示元素组合方面土壤对岩石具有明显的继承性。基于岩石与土壤介质中共同的10项找矿指示元素,构建了归一化的综合异常指标,以鸡公山矿段为标准对整个槐树坪矿区进行了综合评价,发现槐树坪矿区内马蹄沟、秦佛爷沟、姜疙瘩和天坪西4处具有类似鸡公山矿段的找矿潜力。

Determination indicator elements for geochemical exploration on rock and soil survey in Huaishuping gold deposit in western Henan Province, China

Huaishuping gold deposit is a large-scale gold deposit discovered recently in Xiong''ershan district in western Henan Province, China. Different types of fresh host rocks, alteration rocks and ores are collected on the surface and under the pit in Huaishuping deposit area and soil geochemical survey is fulfilled with a scale of 1:20000. 29 trace elements including Au are analyzed in rock and soil samples. Lower anomaly limit of each trace element is determined on fresh host rocks. Average of each trace element in alteration rocks and ores is derived respectively to calculate its anomaly contrast which is the ratio of its average in alteration rocks or ores to its lower anomaly limit in fresh host rocks. The element, which anomaly contrast is larger than 1.4, is selected as the indicator element for gold mineralization in the first step. On the other hand, the scatter plots of Au to the other 28 trace elements in fresh host rocks, alteration rocks and ores are illustrated to determine indicator elements for gold mineralization. The results of the two methods indicate that indicator elements of rock geochemical prospecting are Au, Ag, As, Sb, Hg, Sn, Mo, Bi, Cu, Pb, Zn, Cd, and Nb (13 items) in Huaishuping gold deposit. Geochemical anomaly maps are drawn on the soil survey results in Huaishuping district using 1.4 anomaly contrasts in rock samples as lower anomaly limits in soil samples. Jigongshan ore section, which is the main ore section in Huaishuping gold deposit, is selected as a model area to determine the indicator elements and the results show that indicator elements of soil geochemical prospecting are Au, Ag, As, Sb, Hg, Bi, Cu, Pb, Zn, Cd, and B (11 items). Comparing the indicator elements between rock and soil survey samples, inheritance on indicator elements is inferred from rocks to soils during weathering. 10 common indicator elements in rock and soil samples are selected to construct a comprehensive anomaly index. The whole area of Huaishuping gold deposit is evaluated on the comprehensive anomaly index. The evaluation results show that 4 other sections, Matigou, Qinfoyegou, Jianggeda, and Tianpingxi, have similar mineral potential to that of Jigongshan ore section in Huaishuping area.