Abstract:

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 the theoretical 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.

Key words: ore related geoanomaly sequence, resource exploration, Eastern Kunlun, transmagmatic fluid, post batholith metallogeny