山东焦家金成矿带地球物理特征及找矿预测

Geophyisical characteristics and prospecting prediction of Jiaojia gold metallogenic belt,Shandong province

本文以焦家断裂带为研究目标,综合利用地质、重力、磁法、大地电磁等资料,总结了区域物性、重磁场特征,并选择典型剖面,利用实测MT数据,开展了2.5D重磁电联合精细反演,推断了控矿断裂构造的深部变化特征.A-A′剖面重磁电特征显示,焦家断裂带上盘呈现低阻-中磁特征,而下盘呈现高阻-高磁特征,焦家断裂带和三山岛断裂带的视电阻率异常梯度带在4 km以浅非常清晰,分界线走势基本沿焦家断裂带深部延伸,呈现"漏斗"形状.本文根据建立的地质-地球物理找矿预测模型推断,焦家断裂带剖面上低磁异常向高磁异常的过渡带、布格重力异常梯级带的转弯部位和视电阻率等值线同步向下弯曲、间距变大及由陡变缓部位都是成矿的有利部位,为今后该地区金矿勘查提供重要技术指导.

This study takes Jiaojia fault zone as the target,comprehensively analyzes and utilizes geological,gravity,magnetic,magnetotelluric and other data,summarizes the regional physical properties,gravity and magnetic field characteristics,selects typical profiles,carries out 2.5D gravity,magnetoelectric joint fine inversion applying MT data by V8 measurement,and deduces the deep change characteristics of ore-controlling fault structures.The gravity,magnetic and electric characteristics of the A-A'section show that the upper wall of Jiaojia fault zone shows low resistance-medium magnetic characteristics,while the lower wall shows high resistance-high magnetic characteristics.The dividing line basically extends along the deep part of Jiaojia fault zone,illustrating a“funnel”shape.According to the results of gravity,magnetic and electric joint inversion,Jiaojia fault and western Sanshandao fault zone show apparent resistivity anomalous gradient zone at the depth of less than 4 km.Based on a geological-geophysical prospecting prediction model,this study infers that the transition zone from low magnetic anomaly to high magnetic anomaly on the section of Jiaojia fault zone,the turning position of Bouguer gravity anomaly step zone and the apparent resistivity contour curve simultaneously bend downward,the spacing becomes larger and the position from steep to slow are all favorable for mineralization.This study provides guidance for gold exploration in this area in future.