摘要
金属资源勘查工作的一个关键环节是发现与物化探异常相应的地质异常,并由此不断深化,逐步逼近主矿体。为了阐明这种深化过程,本文以青海拉陵灶火中游勘查区为例,提出成矿地质异常序列的概念,并将其划分为理论序列和勘查序列两种类型。理论序列是成矿系统演化过程中一系列时空有序的成矿作用相关地质过程的记录,可以从成矿系统理论进行推导;勘查序列遵循异常显著性和找矿有效性原则,形成于勘查过程中。勘查序列可以相同或不同于理论序列,但必须以理论序列为指导,从而实现快速、经济地阐明勘查目标的资源潜力。理论序列的推导是以某种成矿系统理论为依据,分析成矿系统时空结构中的事件与过程及其相互关系,从而构建成矿地质异常序列。基于透岩浆流体成矿理论,本文认为成矿系统的演化可以简单归结为含矿流体以岩浆侵入体为起点向远离岩体方向传输。在此过程中,含矿流体与传输路径中的屏蔽介质每发生一次强相互作用,都会留下显著的物质记录。因而可以预设每一个屏蔽介质和强相互作用的性质,预期可能的物质记录,构建成矿地质异常序列。勘查工作中可以同时发现一系列成矿地质异常和异常群,所发现的第一个异常也往往不是主矿体异常,其情形要比理论推导复杂得多。因此,勘查过程中要区分直接异常、间接异常和背景异常,并积极地将间接异常转换为直接异常。然后,根据异常分布密度归并异常群,构建勘查序列。可见,资源勘查遵循异常显著性和找矿有效性原则,不宜机械遵循理论序列。但是,勘查工作中需要不断应用理论序列,丰富理论序列,并最终产生新的理论序列,进而明确找矿方向。根据上述方法,将青海拉陵灶火中游勘查区已发现的成矿地质异常归并为两个勘查序列:(1)岩基产状异常→岩石结构异常→岩基矿化分带异常→伟晶岩异常;(2)岩基产状异常→夕卡岩异常→岩墙群异常(矿带分布异常)→岩体结构异常→矿物世代关系异常。根据成矿地质异常序列分析,推测涛歌岩体和河东岩体之下的隐伏岩体为含矿流体供给通道,因而建议勘探工程向这两个岩体方向推进。
One of the keys in exploration of metal resources is to find the geoanomalies matched to the geochemical and geophysical anomalies,and to relate the geoanomalies to the master orebody,step by step.In order to decipher such processes,a new concept is provided as the ore-related geoanomaly sequence(ORGAS)which is further divided into the theoretical and the exploration sequences,based on the observations in the Middle Exploration Area of the Lalingzaohuo River,Qinghai Province(MEAL).The theoretical sequence is the record of a series of ore-related geological processes occurred in the mineral system in the specified spatial and temporal sequences,which can be deduced based on a metallogeny theory.The exploration sequence is constructed in the exploration practice,and follows the principles of anomaly notability and prospecting efficiency.The exploration sequence may or may not identical to the theoretical,but its construction has to follow principles of the theoretical sequence in order to quickly and economically evaluate the resource potential of the exploration object.The deduction of the theoretical sequence is based on a theory of metallogeny system,deciphering the events and the processes in the spatial and temporal structure of the mineral system and their causal relations,and constructing an ORGAS.According to the theory or transmagmatic fluid metallogeny,the evolution of a mineral system can be simply attributed to that the metal-rich fluid is transferred from a magmatic intrusion to the places,far from the intrusion.In this process,the metal-rich fluid may strongly interact with every trapping media,leaving the remarkable material records.Accordingly,it can be assumed that the features of the trapping media and strong interactions are known,hence the material records can be predicted,and the ORGAS can be constructed.In the exploration,a series of the ore-related geoanomaly(ORGA)and anomaly populations can be found simultaneously,and the first ORGA is generally not the anomaly related to the master orebody;the scenario of the ORGAS is more complex than that of theoretically deduced one.Therefore,the anomalies are required to be divided into direct,indirect and background in the exploration,and the indirect anomaly is required to be translated to the direct.At the same time,the anomalies are incorporated to anomaly populations on the basis of anomaly distribution pattern,constructing the exploration sequence.It is obvious that the exploration sequence is not following thetheoretical sequence,because it follows the principles of the anomaly notability and the prospecting efficiency.However,in order to find the explicit prospecting variant,the explorers should continually use the theoretical sequences,enrich the theoretical sequences,and,finally,construct new theoretical sequences.According to the mentioned methodology,the ORGA discovered in the MEAL can be incorporated into two exploration sequences:(1)the batholith occurrence anomaly→the igneous texture anomaly→the mineralization pattern anomaly→the pegmatite anomaly;(2)the batholith occurrence anomaly→the skarn anomaly→the dike swarm anomaly(mineralized belt distribution anomaly)→the intrusion structure anomaly→the mineral generation anomaly.Based on the analysis of the ORGAS,the Taoge intrusion and the intrusion buried beneath the Hedong batholith are inferred to be the conduits of ore-bearing fluids.Accordingly,it is suggested that the two intrusions should be the targets of the next exploration program.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2016年第4期212-225,共14页
Earth Science Frontiers
基金
青海省地质调查院项目"拉陵灶火整装勘查区构造-岩浆活动与成矿作用"
中国地质调查局地质调查项目(1212011220921
1212011121266
12120113094100
1212011121075)
中俄国际合作项目(RFBR 14-05-91162-NSFC)
关键词
成矿地质异常序列
资源勘查
东昆仑
透岩浆流体
岩基后成矿作用
ore-related geoanomaly sequence
resource exploration
Eastern Kunlun
transmagmatic fluid
post-batholith metallogeny