Prospectivity mapping for porphyry Cu-Mo mineralization in the eastern Tianshan, Xinjiang, northwestern China
Prospectivity mapping for porphyry Cu-Mo mineralization in the eastern Tianshan, Xinjiang, northwestern China
复制标题
新疆东天山斑岩铜钼矿化远景图
DOI：
10.1007/s11053-019-09486-5
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发表时间：
2020
影响因子：
5.4
通讯作者：
Yongzhang Zhou
中科院分区：
文献类型：
--
作者：
Fan Xiao;Kaiqi Wang;Weisheng Hou;Zhenghai Wang;Yongzhang Zhou
为了综合利用区域尺度的地质、地球化学和地球物理数据，在东天山地区寻找斑岩型铜钼多金属矿床（PCMPDs），采用普通证据权（WofE）、模糊证据权（FWofE）和逻辑回归（LR）3种数据驱动的矿产远景图（MPM）方法，整合这些数据集，以绘制未发现的PCMPD的前景。首先，对东天山地区PCMPDs的成矿地质背景和成矿作用进行了综述。然后介绍了以地质图、水系沉积物地球化学数据、布格重磁数据为基础的空间数据集，并在PCMPDs找矿模型的基础上，利用GIS技术，利用空间数据集构建了构造、岩性、地球物理和地球化学证据层。最后，这些证据层集成使用WofE，FWofE和LR方法，获得后验概率图的PCMPD和结果进行了严格的比较。主要结论如下：（1）东天山斑岩型铜钼成矿作用产于康古尔塔格-黄山深断裂带晚古生代大南湖-大草滩弧系俯冲边界。这种地质推断得到所有数据驱动的MPM方法的支持;（2）WofE和FWofE的条件独立性假设在实际应用中很容易被违反。由于证据层的地质相关性，这个问题似乎很难规避;（3）LR建模方法的不确定性，特别是对于使用多类响应变量的模型，主要来自于（ln变换）线性关系;以及（4）如果不需要估计未发现的PCMPD的数量，可以推荐通过WofE或FWofE建模而有偏差地估计的远景图，以通过对潜在的未发现的PCMPD进行更详细的勘测来瞄准新的勘探区域。否则，通过LR建模和二进制证据建模方法无偏估计的前景图可以优先使用。
In order to comprehensively utilize regional-scale geological, geochemical and geophysical datasets for future exploration of undiscovered porphyry Cu–Mo polymetallic deposits (PCMPDs) in the Chinese Eastern Tianshan orogenic belt, three data-driven mineral prospectivity mapping (MPM) methods, namely ordinary weights of evidence (WofE), fuzzy weights of evidence (FWofE) and logistic regression (LR), were employed to integrate these datasets for mapping prospectivity of undiscovered PCMPDs. Firstly, the geological setting and mineralization of PCMPDs in the Eastern Tianshan district are reviewed. Then, spatial datasets based on geological maps, stream sediment geochemical data, and Bouguer gravity and aeromagnetic data are introduced, and on the basis of the prospecting model for PCMPDs, layers of structural, lithological, geophysical and geochemical evidences are constructed using the spatial datasets by means of GIS-based techniques. Finally, these evidential layers were integrated by using the WofE, FWofE and LR methods to obtain posterior probability maps of PCMPDs and the results are critically compared. The main conclusions are that: (1) the porphyry Cu–Mo mineralization in the Eastern Tianshan was occurred in the subduction boundary of the Late Paleozoic Dananhu-Dacaotan arc system of Kanguertag-Huangshan deep fault belt. This geological inference is supported by all the data-driven MPM methods; (2) the conditional independence assumption for both WofE and FWofE can be easily violated in practical applications. This issue seems very difficult to be circumvented due to geological correlations of evidence layers; (3) the uncertainty of the LR modeling approach particularly with respect to models using multiclass response variables mainly arises from over-fitting of the (ln-transformed) linear relationship; and (4) if there is no need for estimation of the number of undiscovered PCMPDs, the prospectivity map biasedly estimated by either WofE or FWofE modeling can be recommended for targeting new exploration areas with more detailed reconnaissance of potential undiscovered PCMPDs. Otherwise, the prospectivity map unbiasedly estimated by LR modeling with binary evidence modeling approach can be priority of use.