Three−Dimensional Metallogenic Prediction with Integration of Structural Reconstruction at the Dayingezhuang Gold Deposit, Northwestern Jiaodong Peninsula
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摘要:
矿床在形成后常被构造改造,但现有三维成矿预测中对其关注较少。笔者选择胶东半岛大尹格庄构造蚀变岩型金矿为研究对象,采用基于不规则三角网(TIN)的构造复原方法还原被断裂错断的矿体与控矿断裂的三维结构,开展复原前后的矿化空间/控矿因素对比分析并实现深边部三维成矿预测。结果表明,构造复原方法消除了断裂和矿体被错断产生的空间距离及倾角变化;复原后的矿化分布具有更强的空间自相关性,被错断区域的矿化分布由分散变为连续。此外,相同参数下,复原后的预测模型比复原前模型具有更高的性能,说明对复原后的矿化分布和控矿指标之间的关联关系表达更加显著。因此,顾及构造改造的三维成矿预测有利于预测结果的准确性,可为大尹格庄矿床深部找矿工作提供可靠参考。
Abstract:Mineral deposits are often deformed after mineralization, which is, however, less concerned in the current three−dimensional (3D) prospectivity modeling. This paper selected the Dayingezhuang structural altered rock type gold deposit as a case study and used a structural restoration method based on triangular irregular network (TIN) to reconstruct 3D orebody and ore−controlling fault, analyzed and compared the mineralization structure and ore−controlling factors before and after restoration and finally completed the 3D mineral prospectivity at depth. The results show that the structural restoration method can eliminate the variation of spatial distance and dip angle of fault and orebody caused by deformation. The reconstructed mineralization distribution has a stronger spatial autocorrelation feature that is shown as the change of scattered mineralization distribution to spatially continuous at the offset parts. In addition, the reconstructed prediction model has higher performance than that without restoration under the same parameters, indicating that the correlation between the mineralization distribution and ore control factors is more significant. Therefore, the three−dimensional metallogenic prediction modeling with integration of structural reconstruction has improved the propectivity accuracy and can provide a reliable reference for deep prospecting in the Dayingezhuang deposit.
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Key words:
- TIN /
- structural reconstruction /
- 3D prospectivity modeling /
- Dayingezhuang gold deposit
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图 1 胶东半岛区域地质图(修改自杨立强等,2014)
Figure 1.
图 2 大尹格庄矿床地质简图(Yang et al.,2016)
Figure 2.
表 1 大尹格庄金矿矿体预测概念模型表
Table 1. Conceptual model for gold prediction of the Dayingezhuang gold deposit
地质体 控矿地质因素 地质意义 表达形式 矿化分布 自身空间分布(IOre) 反映金的品位(Au)和金属量(AuMet)的空间结构。 建模:克立格法等
表达:栅格模型
指标:IOre招平主断裂面 距离场(dF) 反映成矿流体从断裂面向两侧的流动程度。 建模:距离分析
表达:栅格模型
指标:dF形态起伏
(waF、wbF)反映断裂面形态起伏变化对矿化的控制作用。 建模:形态分析
表达:栅格模型
指标:waF、wbF坡度分析(gF) 反映断裂面对含矿流体的圈闭和矿质沉淀的控制作用。 建模:形态分析
表达:栅格模型
指标:gF陡缓变化(cF) 反映断裂面由陡变缓/由缓变陡部位对矿化的控制作用 建模:形态分析
表达:栅格模型
指标:cF表 2 复原前后变异函数拟合参数表
Table 2. Parameters for fitting the variance functionbefore/after the reconstruction
成矿空间 块金值C0 基台值C 空间相关度
C0/ C0+C变程a(m) 复原前 0.38 0.63 0.38 113.82 复原后 0.28 0.75 0.27 122.86 表 3 复原前后各向异性椭球体参数表
Table 3. Anisotropic ellipsoidal parameters before/after the reconstruction
成矿
空间方位
(°)倾伏角
(°)倾角
(°)主轴/
次主轴主轴/
次轴复原前 209.64 –5.93 39.67 1.47 3.26 复原后 201.02 –3.22 35.03 1.37 3.07 -
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