克拉麦里—塔克札勒—大黑山蛇绿岩建造稀土元素特征

克拉麦里—塔克札勒—大黑山蛇绿岩建造稀土元素含量由变质橄榄岩—堆积橄榄岩—堆积辉长岩—玄武岩有规律增高 ,总体表现为轻稀土弱富集 ,L/H值大多数大于 1,局部有轻稀土亏损的特征。蛇绿岩建造各单元间稀土元素分布模式不尽相同 ,即使是同一单元在不同地段亦有差异 ,反映地幔岩浆的复杂性。基性熔岩稀土元素分布模式既有洋脊玄武岩的平坦曲线 ,又有轻稀土富集型的夏威夷等洋岛玄武岩的特征 ,反映该蛇绿岩带混杂着洋壳残骸和洋岛碎块。由清水—南明水东—塔克札勒基性熔岩稀土元素含量有规律递增 ,分别是球粒陨石的 9.4、15.4、18.9倍 ,反映玄武质岩浆分异程度逐渐增高 ,间接说明该岩带闭合时间由西向东从中泥盆世—晚石炭世末 ,再向东甚至延续至二叠纪

REE FEATURES OF OPHIOLITIC SUITE OF KELAMEILI TAKEZHALE DAHEISHAN

The content of REE increases regularly from metamorphic peridotite to cumulate peridotite to cumulate gabbro to basalt in Kelameili Takezhale Daheishan ophiolitic suite.It generally shows the feature of a week enrichment of LREE,most of L/H value are greater than 1,and partly lack of LREE.The REE distribution pattern in each unit of the ophiolitic construction is different,even in the same unit,it varies from one place to another ,which reflects complexity of mantle magmatic rock.The REE partition pattern of basic lava not only consists of flat curve of mid oceanic ridges basalt but also includes the characteristic of Hawaii oceanic island basalt with LREE abundant type,which reflects this ophiolitic belt mixed ocean crust wrecked with oceanic island fragment.REE content of basic lava in Qingshui Nanmingshui Takezhale increases regularly,it is 9.4 times ,15.4 times and 18.9 times respectively of that of chondrites,which shows that basalt magmatic crystallization differentiation level increases gradually and it indriectly manifests that from west to east this rock belt closed in Mid Devonian,then Late Carboniferous,then Permian.