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喀喇沁地区位于大兴安岭中生代构造岩浆岩带与华北克拉通交汇部位。研究区的闪长岩侵入到太古宙基底中。闪长岩中含有二辉岩、辉长岩、苏长岩、角闪岩、斜长岩等不同组分的镁铁质 超镁铁质堆晶岩捕虏体和基性麻粒岩捕虏体 ,它们是幔源玄武质岩浆底侵作用的产物。分别用Rb Sr法、K Ar法和Ar Ar法 ,对堆晶岩捕虏体及其寄主岩全岩或单矿物进行了详细的同位素地质年代学研究 ,共获得各种年龄数据8件。橄榄辉石岩的全岩Rb Sr等时线年龄为(229±23)Ma ,87Sr/86Sr初始比值为0 70554±0 00012。斜长岩捕虏体中斜长石40Ar 39Ar坪年龄为(228±1)Ma ,相应的等时线年龄为(240±5)Ma ;苏长岩中斜长石的40Ar 39Ar坪年龄为(230±2)Ma ,相应的等时线年龄为(232±60)Ma ,两个样品的40Ar/36Ar初始比值分别为290和296 ,接近于大气Ar组成 ,说明年龄是真实可信的。斜长岩捕虏体中斜长石和角闪岩中角闪石的K Ar年龄分别为(237±8)Ma和(220 9±4 1)Ma ,暗示尽管堆晶岩捕虏体都是早中生代形成的 ,但并非是同一批次岩浆分异结晶的产物。捕虏体的寄主岩石———闪长岩的全岩K Ar年龄为(218 5±4 5)Ma和(221 3±4 3)Ma ,角闪石单矿物K Ar年龄为(223 3±3 3)Ma ,角闪石和全岩的K Ar年龄之间几乎没有差别 ,表明闪长岩体从(530±40)°
The Karaqin area is located in the intersection of the Mesozoic tectonic magmatic belt and the North China Craton in the Greater Xing’an Mountains. The study area of diorite intrusive Archean basement. The diorite contains mafic ultramafic xenoliths and basic granulite xenoliths with different compositions such as dacite, gabbro, tephrite, amphibolite and plagioclase, They are the products of mantle-derived basaltic magma underplating. Rb Sr, K Ar and Ar Ar methods were used to conduct a detailed isotopic geochronology study on the whole rock or single ore of the pluton and its host rocks, respectively. Eight kinds of age data were obtained. The olivine pyroxene rock Rb Sr isochronary age of (229 ± 23) Ma, 87Sr / 86Sr initial ratio of 0 70554 ± 0 00012. The age of 40Ar 39 Ar plateau in plagioclase xenoliths is (228 ± 1) Ma and the corresponding isochron age is (240 ± 5) Ma. The age of 40Ar 39 Ar plateau in plagioclase is (230 ± 2) Ma, the corresponding isochron age is (232 ± 60) Ma. The initial 40Ar / 36Ar ratios of the two samples are 290 and 296, respectively, which are close to the composition of Ar in the atmosphere, indicating that age is true and credible. K Ar ages of amphiboles from plagioclase and amphibolite in plagioclase xenoliths were (237 ± 8) Ma and (220 9 ± 4 1) Ma, respectively, suggesting that although the pyrite xenoliths are early Mesozoic formation, but not the same batch of magmatic differential crystallization product. The K_Ar ages of the whole rock of the xenoliths are (218 5 ± 45) Ma and (221 3 ± 4 3) Ma, respectively, and the K Ar ages of the amphibole single minerals are (223 3 ± 3 3) Ma, there is almost no difference between the K Ar age of amphibole and the whole rock, indicating that the diorite body changes from (530 ± 40) °