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新疆东北部三塘湖地区是中亚造山带的重要组成部分,其二叠纪岩浆活动的动力学机制颇有争议.该区中二叠世条湖组出露一套厚层火山岩,以玄武岩为主,并有少量苦橄质岩、安山岩等.苦橄质岩具橄榄石的堆晶结构,其Mg#值高达0.68~0.77;玄武岩具有斑状和粗玄结构,其Mg#值相对较低(0.41~0.54),显示出演化的特征.条湖组基性-超基性岩具轻稀土略富集的右倾稀土配分模式,虽然在微量元素蛛网图上表现出Nb和Ti的负异常,但是总体具有较高的Ti O2含量,而且Nb,Zr含量以及Nb/Y,Zr/Yb比值远高于弧火山岩,较低的Sr同位素初始比值和高正?Nd(t)和?Hf(t)值表明未受古老大陆地壳物质的混染,该区条湖组基性-超基性岩很可能是遭受俯冲流体交代,萃取而相对难熔的亏损岩石圈地幔部分熔融形成的.另外,苦橄质岩中橄榄石的堆晶高达38%,显示亏损岩石圈地幔部分熔融程度高,而条湖组下伏地层芦草沟组显示有深部地幔过碱性岩浆活动,表明三塘湖地区发生了大范围的高热地幔物质底垫作用,该过程可能与地幔柱作用有关.
The Santanghu area in northeastern Xinjiang is an important part of the Central Asian orogenic belt, and the dynamics mechanism of Permian magmatism is quite controversial. The Middle Permian Tienhu Formation exposed a set of thick volcanic rocks, basalt With a small amount of bitter olivine, andesite, etc. The bituminous rock has a peridotitic crustal structure with a Mg # value of up to 0.68-0.77. The basalts have a spotted and coarse basaltic structure with a relatively low Mg # value (0.41 ~ 0.54), showing the evolution characteristics.The right-leav- ing REE patterns of the basic-ultrabasic rocks with light rare earth enrichment in the Wuhu Formation show a negative anomaly of Nb and Ti on the trace element cobweb, But generally has a higher content of Ti O2, and the Nb, Zr contents and the ratios of Nb / Y and Zr / Yb are much higher than those of the arc volcanic rocks. The lower initial ratios of Sr isotopes and high positive? Nd (t) and? Hf ) Values indicate that they are not contaminated by crustal material of the ancient continental continent, and the Liaohu Formation basic-ultrabasic rocks are likely to be partially melted due to partial melting of the depleted lithospheric mantle subjected to subduction fluidization and extraction. In addition, The olivine in the kibbler has a heap height of 38%, indicating a high degree of melting in the mantle of the lithosphere, while the lower Layer Lucaogou showed deep mantle is too alkaline magmatism, suggesting Santanghu region has witnessed high fever mantle underplating large range, the process may be related to the role of mantle plume.