应用二维经验模分解(BEMD)法提取滇东Pt、Pd元素地球化学异常

The application of bidimensional empirical mode decomposition(BEMD) to the extraction of Pt and Pd anomalies in eastern Yunnan Province

应用二维经验模分解(BEMD)法从滇东Pt-Pd含量数据中提取2类Pt-Pd异常,即由二维内蕴模函数3(BIMF3)表征的区域Pt-Pd异常和由二维内蕴模函数2(BIMF2)表征的局部Pt-Pd异常。根据异常产出的地质特征,区域Pt-Pd异常可进一步划分为2个亚类:其一是位于受SN向小江断裂和NE向寻甸-宣威深大断裂控制的二叠纪峨眉山玄武岩分布区的异常,其特征是具有明显的浓集中心,异常强度大;其二是分布于研究区中南部的黑色岩系中的异常,异常强度弱。其中前者是滇东Pt-Pd找矿的有利地段。局部Pt-Pd异常可进一步划分为3个亚类:①分布于玄武岩区,受SN-NE向深大断裂与其次级断裂交会域控制的异常;②分布于不同地质时期黑色岩系中的异常;③哀牢山断裂北侧与基性、超基性侵入岩有关的异常。其中,分布于玄武岩区的Pt-Pd局部异常强度高、规模大,是进一步找寻Pt-Pd资源的远景地段。

The bidimensional empirical mode decomposition（BEMD）was applied to analyze non-stationary Pt-Pd concentration data in eastern Yunnan Province.Two kinds of Pt-Pd anomalies were obtained.One is the regional Pt-Pd anomalies shown in the BIMF3,and the other is the local Pt-Pd anomalies shown in the BIMF2.The regional Pt-Pd anomalies can be subdivided into two subtypes based on geological features of the anomalies.One includes anomalies with obvious concentrated centers and high anomalous intensity located in Emeishan basalt areas controlled by the SN-trending Xiaojiang fault and the NE-trending Xundian-Xuanwei fault,whereas the other includes the weak anomalies distributed in black rock series within central and southern parts of the study area.The former constitutes the favorable areas in search for Pt-Pd deposits.The local Pt-Pd anomalies can also be subdivided into three subtypes： the first one include anomalies located in the Emeishan basalts controlled by the intersecting areas of the SN-and the NE-trending deep-seated faults and their secondary faults;the second one include those located in black rock series with different geological epochs;the third one include those located on the northeastern side of the Ailaoshan fault and associated with basic,ultra-basic intrusive rocks.Among them,the Pt-Pd anomalies with high strength of the first subtype are prospective areas in search for Pt-Pd deposits.