Tibet Leqingla And Mengyaa Pb-Zn Deposit Metallogenic Characteristics Of The Contrast

Based on the mountain, north of Pb-Zn-Ag polymetallic metallogenic belt, Leqingla,and Mengyaa as the research object, through the system of the ore deposit study, analysis anddiscussion on the skarn mineralogy characteristics, metallogenetic geochemical properties ofrock mass, each type of the metallogenic epoch of the ore bodies, and find out the nature andsource of ore-forming fluid and ore-forming materials, set the deposit formation mechanism,preliminary two deposit metallogenic model is established, and a thorough analysis of thetwo deposits, in order to reveal the same type of ore deposit metallogenic regularity, to themountain, the north rim to provide theoretical basis to the further exploration of metallogenicbelt.Leqingla polymetallic deposit in the mountain, the north side of silver in the lead-zincmetallogenic belt is a typical skarn type deposit, huge scale, rich in minerals, developmentCu-Pb-Zn-Fe a variety of molybdenum mineralization. Orebody from Mengyaa set oflimestone and calcareous sandstone formation, bedding production, all around the miningarea to help the sun of the great sun in the centre of distribution of rock mass, in thesouthwest of contact with outside is given priority to with the skarn type lead-zinc deposit,north is contact with mainly skarn type iron copper and molybdenum mineralization,concurrent with altered rock type mineralization and vein type mineralisation. Metallogenicperiod of time can be divided into the period of skarn and calcite-quartz-sulfide phase.Associated with sulphide quartz calcite minerals such as H, O, S, Pb isotopes show thatore-forming fluid mainly came from magma, later joined the amount of atmosphericprecipitation.The development in mining area have covered skarn type and porphyry type two kindsof different types of mineralization. Mengyaa Skarn type ore body (represented by14orebody), are layered, like under the layered on bedding from carboniferous-Permian series towin group clastic rocks and limestone stratum, and porphyry mineralization (represented by13ore body), the main vein, net vein, veinlet disseminated from Miocene porphyry granite. Skarn type ore mineralization is complex, but the relationship betweengenerations, and can be divided into skarn stage, quartz-sulfide stage and supergeneoxidation period. Porphyry mineralization is mainly related with quartz sulphide vein body.Quartz H-O and sulfide S, Pb isotopes show that the ore-forming fluid and material aremainly came from magma, and have a lot of atmospheric precipitation, the mechanism islikely to be the leading cause of sulfide precipitation.Leqingla skarn type ore body mining area of ore-forming age was60.4±1.8Ma,related to the ore-forming rock mass at the age of62.74±0.09Ma. Leqingla into a rockcoupling metallogenic age, reflects the Leqingla deposit development mainly in India-Asiacollision early primary collision. At the same time, green pull strong alteration of graniteporphyry deposit development age was13.09±0.5Ma, displayed in the time also had acertain scale of mineralized alteration. Leqingla pull ore deposit and the Mengyaa depositbelongs to the mountain, north lead-zinc mine belt, two metallogenic epoch is in the maincollision early and late stage after the collision. And deposit metallogenic characteristicsmostly the same, material sources are mainly magma, metallogenic mechanism issimilar.Two deposits of two stage of mineralization events lead to the same magma, andrespectively with India-the Eurasian plate collision and after collision phase is related to themagmatism. In rock mass of rock geochemistry and isotope geochemical studies show thatthe paleocene and Miocene magmatic source area are mainly composed of shell sourcematerial, and the contribution of shell source material is also covered the porphyry orebodiesin Pb-zinc the main reason for the Ag mineralization mainly. Combining previous researchdata shows that the mountain, the north rim Pb-zinc metallogenic belt is given priority towith Eocene mineralization, the ore-forming age is consistent with the main period ofmagmatism collision time, and thus shows its mineralization may also be India Asia plateroll back, cause the asthenosphere upwelling induced by the magmatism. Miocenemineralization may be with the mountain, the Miocene porphyry copper belt formed deepdynamics mechanism, namely the delamination of the lithosphere mantle. Comparison and analysis, Leqingla ore deposit and the Mengyaa deposit ofmetallogenic characteristics show that Leqingla deposit represents a basic complete skarntype deposit metallogenic system, and receive the deposit at present exploration of ore bodyonly belong to the upper part of the metallogenic system or the remote zone, speculated thatthe deep may also have close contact with into skarn alteration and copper molybdenum ironore body. Two comprehensive consideration, may draw the whole mountain, the north orezone skarn type deposit metallogenic model: namely around60ma, India-the Asiancontinent collision and subduction in the lower part of the tethys oceanic crust, happen boardclips from, around50ma plate was broken off, the resulting mantle-derived magmaupwelling, carrying a large amount of iron and copper metallogenic material, at the sametime cut along the shell in the process of breaking up the scores a lot of shell source material,the massive volcanic eruptions in the mountain development activities, Linzizong volcanicformation, and part of the magma due to tectonic minerallization, failed to rise to the surfaceand formed a large number of intrusive rocks with characteristics of arc volcanic rocks. Dueto the increasing magma differentiation or happened in the process of magma mingling,preliminary enrichment of ore-forming materials, at the same time through the surroundingrock, the contamination source material, a large number of shell in near surface to form thecharacteristic of crust-mantle mixed source of acidic intrusion, the intrusion contact withcontaining calcareous rock, copper and molybdenum iron, formed the rock mass near thedistal for lead and zinc skarn type deposit. Copper iron mainly comes from mantle-derivedmagma, molybdenum stems mainly from shell source magma, the lead and zinc is mainlyfrom the surrounding rock, part for blending in the earth’s crust in the process of magmarising lead and zinc.