【作者】 肖凡；

【导师】 赵鹏大； 陈建国； Frits Agterberg；

【作者基本信息】 中国地质大学 ， 矿产普查与勘探， 2013， 博士

【副题名】以东天山戈壁沙漠区“土屋式”斑岩铜（钼）矿为例

【摘要】 本文以东天山戈壁沙漠覆盖区“土屋式”斑岩型铜(钼)矿为例,研究覆盖区矿产资源评价方法。首先,系统的收集了研究区区域地质、矿产、航磁、重力、化探、遥感、数字高程及地质勘探报告等数据资料并进行分类、整理及数据录入工作(如坐标配准、矢量化、属性表赋值等),建立多源综合信息预测空间数据库；其次,通过对东天山地区区域地质背景以及土屋-延东典型矿床(区)地质、地球物理、地球化学和遥感地质特征的综合分析,逐步理清了东天山“土屋式”斑岩型铜(钼)矿床所产出的地质构造环境及其主要成矿地质特征与找矿标志,建立了“土屋式”斑岩型铜(钼)矿床找矿地质概念模型；在此基础上,利用多种数据处理方法分别对研究区区域重磁、化探、遥感数据进行处理和地质解释：①应用地球物理位场边缘信息增强的方法(斜导数及其水平导数和欧拉反褶积反演方法)对重磁数据边界信息进行增强处理,运用向上延拓的方法分离重磁区域异常和局部异常,建立重磁解译标志,推断和解译覆盖区隐伏构造和岩体；②根据岩石建造类型划分地质单元,利用富集系数法对不同地质单元内地球化学元素的富集规律进行探索分析,揭示戈壁沙漠覆盖层物质组成与基岩区可能的内在成因联系,查明不同地球化学元素的“活动性”,以确定合理的、与“土屋式”斑岩型铜(铝)矿化密切相关的化探指示元素组合并在此基础上利用分形局部奇异性分析的方法增强覆盖层内弱缓异常信息,利归一化指数叠加法计算多元素化探综合异常；③建立遥感影像(ETM+)线环构造目视解译标志,对研究区遥感影像进行目视解译。与此同时,对遥感影像进行辐射定标、大气校正、干扰信息剔除(盐碱地、植被、云、阴影等)等预处理,运用基于特征导向的主成分分析方法(Crosta技术)分别提取铁染和羟基蚀变异常;最后,以综合预测准则为指导,逐个提取与“土屋式”斑岩型铜(钼)成矿有利的要素图层并利用证据权法进行信息综合计算成矿后验概率图,圈定成矿远景区并进行评价。据此,得出如下主要结论与认识：(1)东天山及其邻区具有多板块、多构造单元的复杂地质结构,其主要由塔里木、伊犁、哈萨克斯坦-准噶尔等几个古板快或微板片及其增生边缘先后经历了一系列的裂解、增生、拼合过程后形成的。自太古宙-古元古代原始陆核形成以来,其地壳大致先后经历了五个重要的构造演化阶段：前震旦纪基底演化阶段、震旦纪-中志留世古天山洋形成与早期演化阶段、晚志留世-早石炭世古天山洋演化与大陆初始主碰撞阶段、晚石炭世-三叠纪后碰撞构造与壳幔相互作用阶段以及侏罗纪-第四纪陆内发展演化阶段。其中,以第四阶段(晚石炭世-三叠纪后碰撞构造与壳幔相互作用阶段)壳幔相互作用最为强烈,伴随有大规模岩浆作用,特别是中-酸性花岗质类岩浆活动,有利于区内金属成矿元素大量迁移和富集,在时间上与东天山地区成矿作用高峰期相对应,与包括“土屋式”斑岩型铜(铝)矿床在内的铁、铜、镍、钼、金等多金属矿化关系密切。目前,学界对东天山及其邻区板块构造单元划分方案及其相应的构造属性尚存在很多争议。当前一种新的认识为：以大草滩-大南湖断裂(那拉提-红柳河缝合带东段)为界,东天山及其邻区可划归为两大板块构造单元,以南为哈萨克斯坦-准格尔板块,以北属塔里木板块。研究区所涉及的大地构造环境有哈萨克斯坦-准格尔板块东南缘吐-哈中间地块、哈尔里克-大南湖古生代复合岛弧带及塔里木板块北缘觉罗塔格晚古生代裂陷槽、中天山地块、艾尔宾晚古生代残留洋盆、北山早古生代裂谷带。其中,与“土屋式”斑岩型(铝)矿床产出关系密切的构造环境可能为觉罗塔格晚古生代裂陷槽及哈尔里克-大南湖古生代代复合岛弧带；(2)“土屋式”斑岩型铜(钼)矿床主要产于石炭纪碎屑岩-火山(凝灰)岩建造岩系中,如千敦组(C1gd)、脐山组(C2qs)、梧桐窝子组(C2w)等,与石炭纪-二叠纪中-酸性浅成侵入斑岩体,如斜长花岗斑岩和闪长玢岩等有关。矿化围岩蚀变发育,分带明显,围绕矿体呈“中心式”对称面型分布,自内向外大体上依次为强石英-黑云母-绢云母-硬石膏化带、石英-绢云母化带(绢云岩化带)和青磐岩化带。与Cu、Mo、Au、Ag、As、Sb、 Pb、Zn、W、Bi、Cd等地球化学元素及其组合异常有关。斑岩(矿化)体通常表现为高极化率、中-低电阻率、局部高磁和低重力异常特征,并伴随有有铁染和羟基遥感蚀变异常。(3)覆盖区区域物探数据处理与综合地质解释应遵循以下基本原则：①以地质先验知识为前提,密切结合地质资料进行物探数据的处理及综合分析。一方面,要全面认识和理解研究区区域地质演化过程、成矿地质背景(地层、构造、岩浆岩等)、区域成矿规律等重大基础地质问题,为合理解译区域构造格架(包括断裂及构造单元等)提供正确的地质指导；另一方面,要充分考虑和系统收集区域内不同岩矿石建造的物性资料,如磁化率、密度、电阻率等,为定量或定性解释物探异常的性质做准备;②严格遵循地球物理的基本原理和工作方法,以地质为依据,岩矿石物性特征为基础,循序渐进,逐步深化；③充分运用GIS和信息提取技术,利用GIS综合分析重磁异常与地质、构造、遥感以及化探等资料及其异常之间的对应关系,各类信息相互验证补充,以提高推断解译的可靠性。利用GIS空间分析,如缓冲区分析、叠加分析等,可以定量分析各地质要素,如岩体、构造等,与已知矿化之间的关联关系；④定性与定量相结合。定量数据处理或定量解释工作包括异常的分离、边界信息的增强、定量或半定量反演等,在一定程度上能给覆盖区重磁解译工作增加很多辅助信息,如通过导数换算或欧拉反演,可以提取或者更清晰反映某类地质体或地质构造的形态特征等。但是,在实际工作中,决不能忽略定性解译工作的重要性,通常不能单靠某种或某几种数学模型的组合进行计算分析就可以得到满意的结果,因为地质现象往往是极其复杂的,很多地质现象并不具有明显的数学统计规律性,唯有在仔细分析地质事实的前提下,通过解译人员的综合定性对比分析,才有可能认识到更为复杂的地质规律;(4)东天山地处大陆性气候环境,为典型的内陆干旱荒漠地球化学景观区,其基岩风化程度高,风沙大,风成沙、风成黄土覆盖严重。一方面,覆盖层对下伏岩矿石地球化学元素的垂向迁移有屏蔽作用；另一方面,地球化学元素侧向迁移作用普遍存在,不同地质单元内地球化学元素的组成发生了很大的变化,覆盖层中地球化学元素的富集程度与基岩区有密切的成因联系：在风化、剥蚀以及风沙搬运过程,基岩中“活动性”较强的地球化学元素会大量迁移至覆盖层中富集形成外源次生异常。它们叠加于覆盖层内源次生富集异常之上,对识别和提取覆盖层以下与隐伏岩矿石建造有关的化探异常产生很大的干扰。因此,在戈壁沙漠覆盖区,区域化探资料的应用,无论是数据处理还是地质解释都面临极大挑战：其一,提取弱缓信息,受覆盖层的影响,勘查地球化学技术所获取的直接或间接找矿信息往往为弱缓信息；其二,识别和分解复合叠加信息,在风化、剥蚀、风沙搬运等表生地质作用过程中,覆盖层通常会大量接受和堆积来基岩区的风化物,所获取的地球化学信息多为内源次生异常与外源次生异常信息的混合叠加。为了尽可能的减小戈壁沙漠覆盖区区域化探数据的使用风险,本文以识别和提取与“土屋式”斑岩型铜(铝)矿化有关的地球化学异常为例,探索和总结了一套针对戈壁沙漠覆盖区区域化探数据处理的一般技术流程,取得了良好的应用效果,初步认识了东天山地区区域地球化学元素迁移及其在各地质单元内的分布特征：(5)覆盖层物质组成明显的受基岩区影响,二者中不同元素的富集系数呈现很强的线性关系,指示其物质组成很可能存在成因上的联系。依据地球化学元素在基岩区和覆盖层中的相对富集程度,可将研究区区域地球化学数据中39种元素(氧化物)大致分为三组：①Au、U、K、Ag、Sr、As等在覆盖层中相对富集的元素,其有两种可能的来源：其一,为覆盖层本身相对富集的组分,由覆盖层下伏富含这类元素的地质体中垂向迁移至覆盖层内次生富集；其二,为覆盖层以外的基岩区侧向迁移组分(如风成土、风成沙等)中富集的元素；②Si、B、Li、La、Th等在全区分布相对均匀的元素,其也有两种可能的来源：其一,为地球化学性质相对较稳定的一类元素,在表生地质作用过程中没有或仅轻微发生“原岩”和迁移组分之间的“分异”,主要以被动迁移的方式进入到覆盖层中；其二,为覆盖层以外的基岩区中相对富集的元素发生“原岩”和迁移组分之间有限程度的“分异”和侧向迁移至覆盖层中富集,重新调整了它们在“原岩”和覆盖层中元素的富集程度,最终呈现“均匀”分布的状态；③Mg、Co、Cr、Cu、Ni等基岩区中相对富集的元素,其在基岩区中的含量可能本身就相对比较高,而且在发生“原岩”和迁移组分之间成分的“分异”作用时,往往更趋向于留在“原岩”中。覆盖层中元素的次生富集可能很大程度上依赖于基岩区不同岩性及其组分的“分异”和侧向迁移作用,其中Au、As、Sb、Cd等元素的最重要来源可能为火山-火山碎屑沉积岩,K、Bi、Ba等的主要来源可能为侵入岩,Ca的主要来源可能为沉积-变质岩地层。(6)研究区区域化探元素组合与分布规律大致呈现以下特征：①火山-沉积岩中普遍相对富集Cu、Au、As、Cr、Co、Ni、Sb、 Cd、Fe、Ti、V、Zn、Mg、Mo、Ag等多种金属元素,与区内Fe、Cu、Au、Ag等多金属矿化关系密切；②中-酸性侵入岩中一般相对富集A、K、Na、Si、Be、Bi、Ba等与长英质侵入岩或稀有金属矿化有关的元素；③区内沉积岩-变质岩地层相对富Ca、Mg等与碳酸盐岩建造有关的元素。与“土屋式”斑岩型铜(钼)矿化有关的化探指示元素可以为Cu、Mo、Au、Ag、As、Sb、Pb、Zn、W、Bi、Cd等,但Au、Ag、As、Sb、Cd、W、Bi的“活动性”较强,易迁移至覆盖层中富集形成假异常,给化探数据的处理、异常筛选和解释带来不便。因此,选择Cu、Mo、Pb、Zn四种元素作为与“土屋式”斑岩型铜(钼)矿化有关的区域化探指示元素可能更具合理性,其不仅考虑了“土屋式”斑岩型铜(铝)矿化本身的地球化学特征,同时也考虑了东天山戈壁荒漠地球化学景观区元素地球化学行为对次生异常的影响。(7)戈壁沙漠覆盖区基岩裸露区线环构造解译相对简单,但在覆盖层内能解译出的信息非常有限。遥感蚀变信息提取的关键是各类干扰因素的剔出,如盐碱地、植被、阴影和云等,在此基础上,利用基于特征导向的主成分分析方法(Cr6sta技术)提取铁染和羟基蚀变异常效果较好。(8)“土屋式”斑岩型铜(钼)矿床综合预测准则为：①构造环境：觉罗塔格晚古生代裂陷槽、哈尔里克-大南湖古生代复合岛弧带；②围岩地层：石炭统拉班玄武岩-安山岩及中-酸性火山角砾岩-玄武岩建造岩系；③岩浆岩：石炭纪-二叠纪闪长岩、闪长玢岩、石英闪长岩、花岗闪长岩等；④重磁异常：上延20-30km剩余异常高值区内或梯度带上,局部中-高重磁异常；⑤化探异常：Cu、Mo、Pb、Zn指示元素组合异常;⑥遥感蚀变：铁染和羟基蚀变异常；(9)依据后验概率图,研究区共划分出四个一级远景区(A1、A2、A3、A4)和两个二级远景区(B1和B2)。其中,Al、A2、A3、A4远景区,处于有利的成矿构造环境(位于觉罗塔格晚古生代裂陷槽和哈尔里克-大南湖古生代复合岛弧带内)、具备良好的成矿地质条件和明显的物化探及遥感异常,A1、A2、A3远景区构成呈近东西向延伸的斑岩铜(钼)矿带,中部A1远景区已发现有土屋-延东超大型斑岩型铜(钼)矿床,东部A2远景区也发现有三岔口、三岔口东等中小型斑岩型铜(钼)矿床,而西部(A3远景区)尚未有发现,因此,寻找“土屋式”斑岩铜(钼)矿的潜力可能很大;A4远景区,位于土屋-延东斑岩型铜矿矿集区北侧,处于覆盖层中,成矿环境好,位于哈尔里克-大南湖古生代复合岛弧内,目前尚未有发现斑岩型铜(钼)矿床产出,因此,找矿潜力可能很大,是寻找中-酸性岩浆活动有关的热液型铜(钼)多金属矿床的重要远景区,建议进一步开展大比例尺预测和找矿工作；B1和B2远景区位于斑岩型铜(钼)矿带北侧,已发现有土墩南东小型铜矿、东戈壁大型铝矿,因此,也可能具有较好的找矿前景。更多还原

【Abstract】 In order to illustrate the general and efficient procedures for mineral resource assessment in covered area,"Tuwu-type" porphyry Cu-Mo deposit in Gobi desert covered landscape of Eastern Tianshan, China, was taken to as an example and well studied. Firstly, on the basis of Geographic Information System (GIS), the mufti-source information spatial database that was consist of geological maps, deposits or occurrences, aeromagnetic, bouguer gravity, geochemical, remote sensing images, digital elevation and exploration and/or mining tables or reports as well as other mineral resources associated data of the studied area was established by means of data inputting works such as coordinate registration, vectorization and attribute table assignment etc.; Secondly, the exploration conceptual model for "Tuwu-type" porphyry Cu-Mo deposit was proposed on the basis of the studies in both geology of region and Tuwu-Yandong deposit, such as the comprehensive analysis of geological, geophysical, geochemical and remote sensing characteristics. Then, based on the conceptual model, various of data processing methods were applied to bouger gravity, aeromagnetic, geochemical and remote sensing data for identifying and extracting mineralization associated anomalies:(a) in the geophysical data processing, the enhancement approaches for boundary information of potential field such as tilt derivation, the total horizontal derivation of tilt derivation and eular deconvolution methods were applied to enhance edge characteristics of bouger gravity and aeromagnetic anomalies and upward continuation was applied to isolate localized and regional anomalies of the bouger gravity and aeromagnetic data. On the basis of the processing results of the bouger gravity and aeromagnetic data, concealed tectonics and intrusions both in the covered and uncovered areas were interpreted by means of the establishment of bouger gravity and aeromagnetic interpretation criteria from outcrops district of the studied area;(b) in the geochemical data processing, firstly, geological units were divided according to the characteristics of lithological construction or combination. Next, elements behavior was analyzed by the way that accumulation coefficient analysis of elements in different geological units so as to investigate possible mobility of the elements for determining a set of proper indicator elements including Cu, Mo, Pb and Zn for porphyry Cu-Mo mineralization and Al2O3, Na2O, Be, and MgO for felsic intrusions, respectively. Then, singularity mapping technique was employed to enhance and recognize weak geochemical anomaly signals of Cu, Mo, Pb and Zn, and Al2O3, Na20, Be, and MgO in the Gobi desert covered district. Finally, the normalized index overly method was applied for integrating single element geochemical anomalies of Cu, Mo, Pb and Zn and principal component analysis method was utilized to Al2O3, Na2O, Be, and MgO derived by singularity mapping in order to delineate integrated geochemical anomaly information associated with porphyry Cu-Mo mineralization and felsic intrusions, respectively; and (c) in the remote sensing data processing, firstly, linear and circler structures both in the covered and uncovered areas were interpreted by means of the establishment of remote sensing interpretation criteria from outcrops district of the studied area. Then, the remote sensing images were preprocessed by means of radiometric calibration, atmospheric correction, and interference (saline-alkali soil, vegetation, shadow, etc.) removed. On the basis of results of the preprocessing, feature-oriented principal component analysis method (Crosta approach) was further used to extract alteration anomalies of iron and hydroxy; In the end, the integrated prediction criteria for "Tuwu-type" porphyry Cu-Mo deposit was drawn on the basis of the exploration conceptual model and the comprehensively processing results of geophysical, geochemical and remote sensing image data. Based on the prediction criteria, weights-of-evidence method was employed to integrate the evidence themes that the favorable geological, geochemical, geophysical and remote sensing anomalies including tectonics, strata, intrusions, bouger gravity anomaly, aeromagnetic anomaly, and the alteration anomalies of iron and hydroxy to calculate posterior probability map for delineating prospects for future’s porphyry Cu-Mo deposits exploration. According to the above study works, the following main conclusions could be drowned:(1) The East Tianshan involves several tectonic units that Tarim, Ili, Kazakhstan-Junggar, and several other micro-plates, which have undergone a series of geological evolutional events such cracking, hyperplasia and collision. Since the original continental crust of East Tianshan in Archean-Proterozoic was formed, it has gone through five important tectonic evolution stages: The evolution stage of Precambrian basement, the formation and early evolution stage of Ancient Tianshan ocean from Sinian to middle Silurian, the stage of Tianshan oceanic evolution and primary collision of ancient continents from late Silurian to early Carboniferous, the stage of post-collision and crust-mantle interaction from late Carboniferous to Triassic and the evolution stage of continent from Jurassic to Quaternary. Among these five stages, the fourth stage that the stage of post-collision and crust-mantle interaction from late Carboniferous to Triassic has undergone many intensive crust-mantle interaction activities, which accompanied with strong magmatism, particularly for the acidic granitoids or igneous that were usually considered to be in favor of migration and enrichment for metal mineralization associated elements, which was generally corresponding with the metallogenic peak periods of various of metals in the Eastern Tianshan such as iron, copper, nickel, molybdenum, gold, silver and other metal mineralizations including "Tuwu-type" porphyry Cu-Mo deposits. However, there are still many disputes for researchers on the issues that the tectonic properties of the East Tianshan and its adjacent region until now. In currently, a new perspective is that taking Dacaotan-Dnanhu fault as the boundary of plates, the East Tianshan can be divided into two main tectonic units that Kazakhstan-Junggar plate in the south and Tarim plate in the north. The tectonic units of the studied area involved in Turban-Hami massif and Ha’erlike-Dananhu Paleozoic island-arc that belong to the southeastern margin of Kazakhstan-Junggar plate, and Jueluotage late Paleozoic rift, central Tianshan block, Ai’erbin late Paleozoic ocean basin, and north Tianshan early Paleozoic rift that belong to the north Tarim Plate. Among these tectonic units, the "Tuwu-type" porphyry Cu-Mo deposits would like to produce in Jueluotage late Paleozoic rift and Ha’erlike-Dananhu Paleozoic island-arc.(2)"Tuwu-type" porphyry Cu-Mo deposits are mainly hosted in the Carboniferous strata that are dominantly composed by clastic or/and volcanic rocks, such as Gandun Formation (C1gd), Qishan Formation (C2qs), Wutongwozi Formation (C2w), etc., and the Carboniferous-Permian acidic porphyry intrusions, such as plagioclase porphyries and diorites. The alterations are well developed and symmetrically around the ore bodies, from the inside to outside, which were the quartz-biotite-sericite-anhydrite, quartz-sericite and propylitic alteration, respectively."Tuwu-type" porphyry Cu-Mo deposits are associated with geochemical anomalies of Cu, Mo, Au, Ag, Bi, Zn, Ni, Pb, W, As, Sb and Cd. Porphyries (mineralized intrusions) usually have high chargeability, medium to low resistivity, high local magnetic anomaly, low bouger gravity anomaly and iron and hydroxy alteration anomalies.(3) The integrated processing and geological interpretation for geophysical data in covered area should follow several important principles:(a) the prior knowledge of geology in the studied area should be one of the most important prerequisites in geophysical data processing and comprehensive geological interpretation. On the one hand, well understanding the geological evolution events and backgrounds such as strata, tectonics, and magmatic rocks, as well as other metallogenic regularities of the studied area could provide a reasonable geological guidance for interpretation of regional structural framework including the concealed faults and intrusions; On the other hand, the physical properties of different rocks or/and minerals such as magnetic susceptibility, density, resistivity should be collected to be assistant for quantitative or qualitative explanations of the proper geological significance for geophysical anomalies;(b) the basic principles and interpretation procedures for geophysical data that bouguer gravity and aeromagnetic anomaly should be strictly followed;(c) application of GIS and geoinformation technologies, which could be employed to analyze the spatial correlation among bouguer gravity and magnetic anomalies with other geoinformations including geological, tectonic, mineralization, remote sensing and geochemical data for improvement of the reliability of the interpreted results by means of spatial analysis approaches such as such as overlay and buffer; and (d) application of both qualitative and quantitative approaches in geophysical data processing and interpretation. Processing bouguer gravity and areomagnetic data with quantitative methods such as the localized and regional anomalies separation, boundary information enhancement, and quantitative or semi-quantitative inversion could provide many important aided information for interpretation of them in covered area, e.g. it could identify and extract the morphological characteristics of some structures or geobodies much more easily from the geophysical data being processed by derivative or/and euler deconvolution methods. However, in practically, the significance for qualitative interpretation could never be ignored because the complicated geological phenomena could not easy to be totally described by several mathematical models or their combination so as the results of statistical analysis for geophysical data usually have no full geological significance and qualitative interpretation guided by the geological regularities have to be done for identifying the possible and more complicated geological information;(4) The geochemical landscape of Eastern Tianshan in which the study area is located is inner continental arid desert. Physical and chemical weathering in these areas is well developed and resulted in decomposition of exposed rocks (bedrock). The wind is so strong that weathered bedrock could easily be blown far away to accumulate in relatively low terrain (basins). Some areas are completely covered by regolith sediments such as windblown sand or soil, alluvial gravel, sandstone and calichehorizons. On the one hand, the geochemical anomaly formed by vertical migration of elements from deep would be weaked due to the Gobi desert coverage; On the other hand, the lateral migration of geochemical elements has commonly existed so as the geochemical composition of different geological units usually have been changed. There is a strong genetic relationship of elements enrichment between Gobi desert covered layer and bedrock:the mobile geochemical elements enriched in bedrock would like to migrate to be accumulated in the covered layer to form pseudo geochemical anomaly in the process of weathering and wind transportation. The pseudo anomaly that is usually considered to be strong noisy signal in geochemical anomaly identification would overprint on the possible mineralization associated geochemical anomaly that the weak anomaly produced by vertical migration of elements from various of concealed geobodies including mineral deposits covered by Gobi desert. Therefore, in Gobi desert covered geochemical landscape, the application that both data processing and geological interpretation of regional geochemical data would be a challenge task in both extraction of the weak and decomposition of the overprinted geochemical anomaly duo to the Gobi desert coverage. In this paper, to reduce the risk for application of regional geochemical data in the Gobi desert covered area as much as possible, the identification and delineation of "Tuwu-type" porphyry Cu-Mo mineralization associated geochemical anomalies has been taken as an example to explore and summarize a general procedure for regional geochemical data processing in the Gobi desert covered landscape of the Eastern Tianshan.(5) The geochemical composition in Gobi desert covered layer probably depends on the composition of bedrock. There is a strong linear relastionship between the elements accoumulation coefficient of Gobi desert covered layer and bedrock outcrops area, which possiblely indicate a genertic relationship in geochemical composition between them. The39geochemical elements (oxides) can be divided into three groups based on their relative enrichment in the bedrock and the Gobi desert coverd layer:(a) the elements that are more enriched in the Gobi desert covered layer, e.g. Au, As, W, Cd, Ag, Hg, Sb, Bi, K, and Ca etc. There are two possible sources for this group of elements. The first one is vertical migration from buried mineralization or bedrock covered by Gobi dersrt covered layer and the second one is lateral migration from bedrock by wind and streams. In the second situation, these elements may have been originally enriched in some lithological units, but their mobility (away from host rocks) was so strong that they readily fractionalized from their host rocks in bedrock because of their unstable geochemical properties, then moved to and accumulated in Gobi desert covered layer. This group of elements were likely to form high concentration geochemical anomalies (secondary enrichment) but without mineralization associated significance in Gobi desert covered layer;(b) the elements that are generally equally enriched in both Gobi desert covered layer and bedrock outcrops area, e.g. Zr, Y, Nb, Ba, B, Si, Sr and Li, etc. These elements can be considered to be stable in geochemical behavior in that they were not limited to be formation by fractionalization from their host rock in bedrock but mainly moved to and accumulated in Gobi desert covered layer with fragments of host rocks by physical processes such as wind or stream transformation; and (c) the elements that are much more enriched in bedrock outcrops area, e.g. Mg, Co, Cr, Ni, Cu, Be, Mn, Fe, Pb and Zn, etc. These elements may have been originally enriched in some lithological environments and their immobility (retention in host rocks) was so strong that, during geochemical fractionation between mobile (e.g. fragments of host rocks that would be moved to and accumulated in Gobi desert covered layer) and immobile (remains of host rocks) status, they would probably remain in the host rocks of bedrock rather than become enriched in fragments of weathered rocks accumulated in Gobi desert covered layer. Thus, the geochemical anomalies formed by this group of elements usually are of possible mineralization associated significance in the study area. There is a source genetic relationship between the geochemical composition of Gobi desert covered layer and bedroak outcrops area due to the strong lateral migriation of the mobile elements from bedrock to be accumulated in Gobi desert covered layer, which coud be generally sumerized to be that the elements such as Au, As, Sb, and Cd could be the most probably come from igneous-volcanic associated sedimentary rocks, the elements such as K, Bi, and Ba could be the most probably come from intermediate-acid intrusions, and Ca could be the most probably come from sedimentary-metamorphic rocks.(6) On the basis of the accumulation coefficient analysis of elements in various of geological units in the studied area, there is a gernal conclusion for the enrichment regular of elements in these geological units could be drowend:(a) the elements such as Cu, Au, As, Cr, Co, Ni, Sb, Cd, Fe, Ti, V, Zn, Mg, Mo, and Ag are more relatively enrichment in igneous-volcanic associated sedimentary rocks, which are usually considered to be generiticaly associated with Fe, Cu, Ni, Au, and Ag polymetallic mineralization in the Eastern Tianshan;(b) the elements such as Al, K, Na, Si, Be, Bi, and Ba are relatively enrichment in intemadiate-acid intrusions, which are generally considered to be closely related with rare elemets metal mineralization including Li and Be; and (c) the elements such as Ca and Mg are more enrichment in sedimentary-metamorphic strata that are mainly composed by carbonate rocks. Though the candidate geochemical indicator elements for "Tuwu-type" porphyry Cu-Mo mineralization could be Cu, Mo, Au, Ag, As, Sb, Pb, Zn, W, Bi and Cd, in which Au, Ag, As, Sb, Bi and W are strongly mobile elements that can be easily moved over large distances, accumulated as secondary enrichment in Gobi desert covered layer to form non-mineralization associated geochemical anomalies, which are usually considered to be pseudo geochemical anomalies providing relatively strong noise signals in mineralization-associated geochemical anomaly identification. Therefore, Au, Ag, As, Sb, Bi and W probably should exclude from the candidate indicator elements and only the remain elements that Cu, Mo, Pb and Zn would be the most appropriate indicator elements for porphyry Cu-Mo mineralization associated geochemical identification in the study area.(7) In Gobi desert covered landscape of the Eastern Tianshan, interpretation of linear and circler structures using remote sensing images in bedrock outcrops area is relatively easy, but it is very difficult for Gobi desert covered area. The most important issue for the extraction of ateration information using remote sensing data is to remove interferences such as saline-alkali soil, vegetation, shadow and clouds. On the basis of the preprocessing of remote sensing data including the references removed, feature-oriented principal component analysis method (Crosta approach) method has proved to be a useful approach for the extraction of iron and hydroxyl alteration anomalies.(8) The integrated prediction criteria for "Tuwu-type" porphyry Cu-Mo deposits could be sumerized as follows:(a) tectonic units:Jueluotage late Paleozoic rift and Ha’erlike-Dananhu Paleozoic island arc;(b) favorable strata:Carboniferous tholeiite-andesite and intermediate-acid volcanic breccia-basalts;(c) intrusions:Carboniferous-Permian diorites, quartz diorites, granodiorites and plagioclase granite porphyries, etc.;(d) bouguer gravity and magnetic anomalies:the reginal anomaly is that the high or/and gradient zone of bouguer gravity and magnetic at the extension of20-30km and the local anomaly is that the medium-high loacalized bouguer gravity and magnetic anomalies;(f) geochemical anomalies:the geochemical anomalies of Cu, Mo, Pb and Zn; and (g) alteration for remote sensing information:iron and hydroxy anomalies;(9) On the basis of postprobality map for "Tuwu-type" porphyry Cu-Mo mineralization in the studied area, there are four high potential prospective areas that A1, A2, A3and A4and two moderate potential prospective areas that B1and B2have been delineated. The A1, A2, A3, and A4prospects are located in the favorable tectonic environments that Jueluotage late Paleozoic rift and Ha’erlike-Dananhu Paleozoic island-arc. They have faverable geological conditions, geophysical, geochemical and remote sensing anomalies. A1, A2, and A3prospects constitute a EW trend porphyry Cu-Mo mineralization zone, in which the Tuwu-Yandong superlarge porphyry Cu-Mo deposit have been found in the middle of the mineralization zone that the prospect A1, Sanchakou, Eastern Sanchakou and other small size porphyry Cu-Mo deposits have been discovered in the eastern of the of the mineralization zone that the prospect A2and there is no discovered in the western of of the mineralization zone that the A3prospect. Therefore, maybe the prospecting potential in the prospect A3would be large. Both the prospects B1and B2are located in north of the porphyry Cu-Mo mineralization zone. There has been found eastern Tudun small size Cu depost and East Gobi large Mo deposit. Thus, it also probably has high potential for prospecting porphyry Cu-Mo deposites.更多还原