GEOCHEMISTRY OF GNEISSIC ALKALINE GRANITES IN DONGHAI COUNTY, JIANGSU PROVINCE, AND ITS TECTONIC SIGNIFICANCES
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dc.contributor.author | Hu J. | |
dc.contributor.author | Qiu J. | |
dc.contributor.author | Wang R. | |
dc.contributor.author | Jiang S. | |
dc.contributor.author | Ni P. | |
dc.contributor.author | Yu J. | |
dc.date.accessioned | 2024-09-03T09:56:12Z | |
dc.date.available | 2024-09-03T09:56:12Z | |
dc.date.issued | 2006 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=41834633 | |
dc.identifier.citation | Acta Geologica Sinica (English Edition), 2006, 80, 12, 1877-1891 | |
dc.identifier.issn | 1000-9515 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/44806 | |
dc.description.abstract | The Donghai region is tectonically located in the southwestern margin of the Su-Lu Orogenic Belt. Several Neoproterozoic gneissic alkaline granite plutons, with typical mineral assemblages of quartz + K-feldspar + oligoclase-albite + aegirine (aegirine-augite)/arfvedsonite, were outcropped in this area. Chemically, these granites are characterized by rich in silicon (SiO2 = 73.43% - 77.38%), alkaline (K2O+Na2O = 8.19% - 9.53%), poor in calcium and magnesium, and high FeO*/(FeO* +MgO) ratios (=0.83-0-94). They also show enrichments of Ga, Y, Zr, Hf, and depletions of Sr, P, Ti, and display high 104XGa/Al ratios (=2.76 -5-15). Chondrite-normalized REE distribution patterns of them are right-inclined, with (La/Yb)N rarios of 2.08-17-89, and display moderate-strong europium depletions ((Eu=0.12-0.66). On the discrimination diagrams proposed by Whalen et al (1987) and Eby (1990), they are all plotted in the A-type granite field. Considering that the rocks have high values of agpacity index (=0.99-1.22) and low A/NKC ratios (=0.78 -0.93), thus they should be grouped into peralkaline A-type granites. These granites show lower Y/Nb and Y/Ta ratios, with values of 1.85-9.72 and 4.71-30.14 respectively, and display clearly depletions of Nb, Ta, Ti on the primitive mantle-normalized spidergrams, implying that they preserve some geochemical fingerprints of the foregoing arc magmatism. On the diagrams for subdivision of A-type granites proposed by Eby (1992), they fall in the A2 field, which was interpreted as a characteristic of post-collisional granites. Integration of mineral chemistry and whole-rock geochemistry with geodynamic considerations suggests that the Donghai gneissic alkaline granites were emplaced during the earliest extensional stage of orogenic collapse, rather than produced in syn-rift period. This understanding has important significances both in further revealing the Neoproterozoic tectonic evolutions of the Su-Lu Orogenic Belt and in profoundly probing the breakup mechanism of the Rodinian supercontinent. | |
dc.subject | DONGHAI | |
dc.subject | GEOCHEMISTRY | |
dc.subject | GNEISSIC ALKALINE GRANITE | |
dc.subject | JIANGSU | |
dc.subject | NEOPROTEROZOIC | |
dc.subject | TECTONIC SETTING | |
dc.title | GEOCHEMISTRY OF GNEISSIC ALKALINE GRANITES IN DONGHAI COUNTY, JIANGSU PROVINCE, AND ITS TECTONIC SIGNIFICANCES | |
dc.type | Статья | |
dc.subject.age | Докембрий::Протерозой::Неопротерозойская | |
dc.subject.age | Precambrian::Proterozoic::Neoproterozoic |
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