| Qinling orogen, a famous continental orogen in the world with a long and complexgeologic history, is one of hot points for studies on continental geosciences, and also is animportant tectono-minerogenic belt enriched in mineral resources, which makes it an idealdistrict for the study of regional minerogenetic series(RMS). Based on the principles ofminerogenetic series, integrated with detailed analysis of tectonic and metalogenic evolution, theregional minerogenetic series(RMS), tectono-minerogenic cycles and evolution of the Qinlingorogen are studied. The main results and achievements are as follows:(1) The basis and criterion for differenting and establishing regional minerogenetic series(RMS) are regional tectonic settings and major mineralizing process (or genetic type) decidedby time factor, rather than the three basic geological agents.(2) 18 RMSes, 28 sub-RMSes and 4 regional minerogenetic models of typical RMSes areestablished in this paper.(3) More than 400 mineral deposits in the Qinling mmerogenic belt were formed in the 6tectono-minerogenic cycles(TMC):①Ar-Pt11 TMC,②Pt1 TMC,③Pt2-Pt3 TMC,④Pt3-Pz1TMC,⑤Pz2 TMC, and⑥Mz-Kz TMC.(4) Every RMS in the Qinling orogen has its specific origin connected with the specialstage in the evolutionary history.(5) Based on the study of RMS related to the Pt3 regional metamorphism (the V RMS) andthe Songshugou chromite deposit associated with ophiolite (belong to theⅢRMS), the authorsuggests that the Qinling orogen began to be part of a plate regime m the end of the Middle tothe Late Proterozoic.(6) The Pb-Zn deposits in the carbonate rocks of the South Qinling zone were mainlyformed by hydrothermalism in the Early Mesozoic, two Rb-Sr isotopic ages from theDengjiashan-Mogou Pb-Zn deposit in Gansu province and the Gongguan-Qingtonggou Sb-Hgdeposit in Shanxi province are 263±9Ma and 250±14Ma, respectively.(7) The Dashui-type gold deposits in the south sub-zone of the western Qinling folded beltwere formed by hot-spring related to the Yanshanian alkali-intermediate to acidic pyrogenesis,most of the ores are actually synore 'hot water karst' formed by ore-forming fluids, hosted in theDevonian to the Triassic carbonate rocks, and a hot-spring metallogenic model is established inthis paper.(8) The relationship between evolution of metallogeny and tectonics is grouped into 4process-types:①rifting and splitting of land blocks or plates,②subduction-collision betweenland blocks or plates,③intracontinental postorogenic detachment, nappe, pull-apart and rift- faulting and④relatively stable environment process-type. Each process-type took place for atlest twice. Metallogeneses in this area is characterized by inheritance, polyphasees, polysourcespolygeneses and cyclicity. There are two important metallogenic periods: one is the MiddleProterozoic-Early Paleozoic during which the metallogenetic processes are related to thespreading rifting, the minerogenetic series of deposits are related genetically to the basic-ultrabasic intrusions and the bimodality pattern marine volcanism resulting from spreadingrifting and deep faulting; the other, related to the intracontinental subduction, is the Mesozoic,the minerogenetic series of deposits are related genetically to the intermediate-acid intrusionsand terrestrial volcanism, generated by postorogenic tectonism.(9) The tectono-mineralization associated with volcanism and splitting would haveexperienced a vibration between the north and south Qinling orogen through out the geologicalhistory.(10) "Minerogenetic Series Map of Main Deposits in the Qinling Orogen" (Scale: 1/1 000000) is drawn up, and its directions about 130 000 Chinese characters with 411 mineral depositsis also compiled.
|
PDF Full Text Request