中文摘要：

西准噶尔东部哈拉阿拉特山南麓的乌尔禾地区新发现大量中基性岩墙群。岩墙群侵位于早二叠世佳木河组磨拉石建造中,展布方向与达尔布特大断裂延伸方向相一致。岩墙群岩性为辉绿岩、辉绿玢岩和辉长闪长岩,地球化学特征显示其具有低钾钙碱性玄武岩安山岩特征。稀土总量偏低（34.53×10^-6-82.43×10^-6）,δEu（0.74-0.98）和δCe（0.98-1.15）负异常不明显,稀土元素分配模式皆呈LREE/HREE富集（LREE/HREE=2.47-7.18）的右倾型配分型式,富集K、Rb、Ba、Sr等大离子亲石元素,而高场强元素Nb、Ta强烈亏损,Zr、Hf适度亏损,具有岛弧俯冲作用的地球化学特征。正的εNd（t）值（5.51-5.71）和相对低的初始^87Sr/^86Sr比值（0.703 802-0.704 223）表明亏损地幔是岩墙群的源区。岩浆来自于亏损的地幔楔,且受到俯冲组分的改造。该岩墙群表明在早二叠世地表完成汇聚造山后,深部的弧岩浆作用仍在进行,所代表的＂滞后型＂弧岩浆作用晚于西准中西部的俯冲增生作用,表明整个西准地区俯冲造山作用结束的最终时限应在早二叠世晚期。

英文摘要：

Intermediate to mafic dyke swarms were newly discovered in Urho area in the south of the Hala ＇alat Mountain which is located in the east of Western Junggar. The dyke swarms intruded into the Permian Jiamuhe molasse formation. The nearly NE-SW-trending dyke swarms are parallel to Darbut Fault. The rocks are mainly composed of diabase, diabase porphyrite and gabbro-diorite, which have features of low K calc-alkaline basalt to andesite series, as shown by geochemical analyses. The dyke swarms have low REE（ 34. 53 × 10^- 6~ 82. 43 × 10^- 6） and the anomalies of δEu（ 0. 74 ~ 0. 98） and δCe（ 0. 98 ~ 1. 15） are not obvious. REE distribution patterns are of the right-oblique type（ LREE / HREE = 2. 47 ~ 7. 18）. All samples are characterized by the enrichment of LILEs（ K,Rb, Ba, Sr） and depletion of HFSE（ especially Nb, Ta）, showing the characteristics of island-arc zone. PositiveεNd（ t） values（ 5. 51 ~ 5. 71） and relatively low initial Sr isotopic ratios（ 0. 703 802 ~ 0. 704 223） indicate the depleted mantle-related source. The source was the depleted mantle wedge and the magma was genetically influenced by the subduction components. The dyke swarms in Urho area suggest that the subduction between plates still went on after the completion of the compressional orogeny in early Permian. The lagged arc magmatism occurred later than the subduction in the west and middle of Western Junggar, suggesting that the final completion of the subduction in Western Junggar was in late Early Permian.