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The Characteristics And Genesis Of Magmatic Rocks In Shapinggou Molybdenum Ore Disdrict, Jinzhai, Anhui

Posted on:2014-06-13Degree:MasterType:Thesis
Country:ChinaCandidate:P WangFull Text:PDF
GTID:2250330401489089Subject:Mineralogy, petrology of ore deposits
Abstract/Summary:PDF Full Text Request
The Jinzhaishapinggou porphyry molybdenum deposit locates in the easternBeihuaiyang metallogenic belt in Anhui, where Yanshanian intrusive rocks are widelyexposed. This study has investigated the intrusive rocks in the field, and discussed theformation timing, intrusion, as well as the genetic mechanism of intrusive rocks, using anintegrated method of zircon U-Pb dating, whole-rock major elements, trace elements andrare earth elements.The major rock types of Jinzhaishapinggou porphyry molybdenum deposit includedgranite, monzonite granite, granodiorite, quartz syenite (porphyry), granite porphyry, diorite,plagioclase hornblendite, includingplagioclase pyroxenite, olivine pyroxenite. The lithologywas mainly acidic, with some neutral and mafic. The rock chemical composition wasmainly low sodium and potassium alkali-rich, metaluminous-peraluminous, and most ofrocks belonged to calc-alkaline series except some quart syenite rock (alkaline series).According to the zircon LA-ICP-MS U-Pb dating results, the isotope geological ageof intrusive rocks were: the plagioclase hornblende rock133.7Ma,, monzonite granite133.0Ma,, granite129.6/126.0Ma, granodiorite and diorite129.2Ma, dioriterock127.4Ma,plagioclase pyroxenite128.5Ma, and quartz syenite rock115.9Ma granitic porphyry109.3Ma, respectively. These isotopic age data indicated a regional magmatic activity on theoverall evolution from acid and acidic to alkaline trend in the acid intrusive rocks, and asmall amount of neutral-alkaline rock emplaced in magmatic differentiation.The regional intrusive rocks were enriched in light rare earth elements and large ionlithophile elements, depleting in high field strength elements, which suggested that magmacontains a lot of crust-derived ingredients, and Sr-Nd-Pb isotopic compositions weresimilar to the exposing northern Dabie complex rocks. Therefore, the regional intrusiverocks may be a result of the melting of a mafic Dabie gneiss complex after the large-scalemantle upwelling of magma, and it contained a large number of crustal rocks brought in themigration process of magma from deep to surface. The diagenetic tectonic setting wasunder a post-orogenic extensional environment.
Keywords/Search Tags:Acidic intrusive rocks, geological and geochemical characteristics, petrogenesis, Shapinggou molybdenum deposit, Jinzhai in Anhui
PDF Full Text Request
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