Font Size: a A A

The Geochronology And Geochemistry Of The Erenhot City-Xianghuang Banner, Inner Mongolia

Posted on:2015-01-20Degree:MasterType:Thesis
Country:ChinaCandidate:D L HuangFull Text:PDF
GTID:2250330428469732Subject:Institute of Geochemistry
Abstract/Summary:PDF Full Text Request
The field geological characteristics, petrology, geochemistry, and zircon U-Pbgeochronology of granitic rocks from Erenhot City-Xianghuang Banner, InnerMongolia. The main points are as follows:(1)There are small voluminous, alkaline plutons in the Shangdu area, northernmargin of North China craton. Wulahada rocks is mainly composed ofquartz-monzonite. The bulk of Wulahada rocks were emplaces at ca.381.5Ma (zirconLA-ICPMS). They are metaluminous and possess high (Na2O+K2O) value from8.46to9.66. They have no Eu anomalies in the REE patterns but show strong positive Sr、Ba anomalies in the primitive-mantle-normalized spidergrams. The Wulanhada rockshave (87Sr/86Sr)t=0.70780and εNd(t)=-12.42, and show small variations in(176Hf/177Hf)t(0.281873~0.282049). We suspect that Wulanhada rocks formed bypartial melting of the ancient crust (>1.2GPa) at the temperature of about1000℃.The composition of the ancient crust is equal to garnet mica monzogneiss whichblongs to the khondalite series. melt containing residual garnet, rutile granulite facies,and southward subduction of the Paleo-Asian Ocean closely. This Devonian magmaemplacement was related to the southward subduction of the Paleo-Asian Ocean.(2) The early Carboniferous granitic rocks include Benbatu pluton (346.9±9.2Ma) and Bayinaobao pluton (346.9±9.2Ma), they behavior the characteristic asadakite. They are high SiO2, Al2O3, but low MgO(<3%),They have no Euanomalies in the REE patterns but show strong positive Sr、Ba anomalies in theprimitive-mantle-normalized spidergrams. The late Carboniferous granitic rocksinclude Baruncihule pluton(299.5±3.9Ma), Dalai pluton(302.4±2.0Ma),Daolunhuduge pluton (302.6±3.5Ma) and Donggounanshan pluton(312±4Ma and324.7±3.6Ma). Baruncihule pluton, Dalai pluton and Daolunhuduge pluton show thecharacteristic as highly fractionated I-type granite, whick have high SiO2, ASI<1.1, (87Sr/86Sr)t<0.705, depletes in Ba、Sr、P、Ti. Donggounanshan pluton behavior asC-Type adakite.(3)The early Permian granitic rocks include Suonier pluton(295.8±2.1Ma),Sayinwusu pluton(274.1±2.2Ma), Hujier pluton(290.7±1.7Ma), Chagantaolegaipluton(298.5±2.7Ma) and Saruletu pluton(286.7±2.5Ma). Suonier pluton,Sayinwusu pluton and Hujier pluton show as A-type granite, while Chagantaolegaipluton and Saruletu pluton show as highly fractionated I-type granite. The latePermian granitic rocks include Amenwusu pluton, which show the characteristic asC-Type adakite.
Keywords/Search Tags:Adakite, Highly fractionated I-type granite, A-type granite
PDF Full Text Request
Related items