地质学报2017，Vol.91Issue(1)：55-79,25.
阿尔泰东南缘泥盆纪花岗质岩石的锆石U-Pb年龄、成因演化及构造意义:钙碱性—高钾钙碱性—碱性岩浆演化新证据
Zircon U-Pb Ages and Genetic Evolution of Devonian Granitic Rocks in the Southeastern Chinese Altai and Its Tectonic Implications:New Evidence for Magmatic Evolution of Calc-alkaline-High-K Calc-alkaline-Alkaline Rocks
摘要
Abstract
Many researches on the granitoids in most area of the Chinese Altai have been carried out,but retracing the entire tectono-magmatic evolutionary history of the Chinese Altai orogen is still being restricted due to the lack of understanding on the southeastern Altai.This study is based on four samples of granitic plutons (Kungeyite,Kujierte,Butiewu and Kalateyubie),zircon U-Pb (LA-ICP-MS) dating yields the ages of 382 ± 4Ma,381 ± 4Ma,385± 5Ma and 363 ± 6Ma,respectively.These granitic rocks belong to high-K calc-alkaline and metaluminous-weakly peraluminous series of type I,depending on their petrological and geochemical characteristic.They have negative whole rock εNd (t) values of-2.42～ -0.53 with Nd model ages tDM of 1.6 ～ 1.3Ga and zircon εHf (t) values of-3.43 ～ + 12.89 (mostly positive),with Hf model ages tDM-2 of 2.5～0.6Ga,suggesting complex sources.These data indicates mantle-derived substances involved during the process of generation of granitoids as well as ancient crustal compositions.The Devonian granitic rocks in the Chinese Altai can be classified as Early Devonian (420～390Ma) and Middle-Late Devonian (390 ～ 360Ma);the former is mostly calc-alkaline series of metaluminous-peraluminous and the latter is high-K calc-alkaline series of metaluminous-weakly peraluminous.It provides new evidence for the features of evolvement of the Early-Middle Devonian granitoids from calc-alkaline series (480～390Ma) to high-K calc-alkaline series (390～360Ma),then to alkine granite (354Ma),because of the certainty of high-K calc-alkaline granitic rock (363Ma) in this area.This evolvement further confirmed the evolution process of the Chinese Altai are consistent with tectonic settings from subduction to collision and then to post-collision extentional environment.Combined with the analysis of isotope and regional geological data,we conclude that the Middle-Late Devonian granitoids in the southeastern Chinese altai are active continental arc environment in the background of subduction.The Late Devonian granitoids have the characteristics of collision,followed by the Early Carboniferous post-collision alkaline granite.关键词
花岗质岩石/锆石年龄/岩浆演化/同位素/泥盆纪/阿尔泰Key words
Granitic rocks/LA-ICP-MS zircon U-Pb ages/Magmatic evolution/Isotope geochemistry/Devonian/Altai引用本文复制引用
宋鹏,童英,王涛,秦切,张建军,宁东旭..阿尔泰东南缘泥盆纪花岗质岩石的锆石U-Pb年龄、成因演化及构造意义:钙碱性—高钾钙碱性—碱性岩浆演化新证据[J].地质学报,2017,91(1):55-79,25.基金项目
本文受NSFC-新疆联合基金重点支持项目(U1403291)和中国地质调查局项目(编号:12120113094000、1212010811033、12120113096500、1212010611803)联合资助. （U1403291）
