皮羌辉长岩体位于塔里木盆地柯坪断隆西部,皮羌村北约15 km处.该岩体的围岩包括志留系、泥盆系和石炭系一二叠系,新近系不整合覆盖其上.采集该辉长岩样品进行单矿物分离,取分离出的斜长石进行Ar-Ar定年.700～1 400 ℃的8个加热阶段析出的39Ar为总量的95.89%,在坪谱图上得到一个较稳定的坪,坪年龄为265.5±1.2 Ma;与之相对应的等时线年龄为267.29+5.62 Ma.结合区域地质分析,皮羌辉长岩体的侵入时代为中二叠世早期;是塔里木二叠纪岩浆活动的一部分.其侵入后基本未受后期构造热事件影响.

柯坪冲断带位于塔里木盆地西北缘,是新生代南天山褶皱冲断系的一部分.本文根据野外实际考察和地震剖面解释,总结了该冲断带的构造变形特征.它是发育于古生界中且以中寒武统膏盐层为主滑脱面的薄皮构造,是内部结构相对简单的叠瓦状冲断,因更新世才定型而具暴露式冲断前锋,有断层传播褶皱发育但已遭强烈剥蚀,前展式冲断.上新世晚期的冲断曾控制了磨拉石盆地发育(西域组砾岩),但该盆地已遭更新世的冲断推覆作用破坏.根据平衡剖面恢复,柯坪冲断带南部3排冲断层的总构造缩短量为29.1%-40.7%.

采样点位于314国道旁,库尔勒市北东缘,距市中心仅约10 km(图1).样品采集于兴地塔格群中所夹的一个硅岩块,硅岩块出露面积约10 m2,上直接覆以更新.全新世砾岩.该硅岩块发生了一定的重结晶作用,放射虫化石的保存很差,给放射虫化石的分离和鉴定造成了很大的困难.我们先后3次到该岩块采集共计32块硅岩样品,多次反复分析,终于发现了16颗放射虫化石个体,包括:Albaillella paradoxa Deflandre,Albaillella cf.paradoxa Deflandre和Albaillella sp..这是一个早石炭世早期的放射虫化石组合.

Kurgan is a frontier station at the western terminal of Chinese South Tianshan, NW margin of the Tarim Basin, where the Mesozoic coal-bearing molasse formation well developed. 30 specimens of chert gravel were collected from the bottom of conglomerate of the Middle-Upper Triassic Kelamayi Formation, from which 46 individual radiolarian fossils were found from 12 specimens. The fossils included Albaillella paradoxa Deflandre, Albaillella sp. cf. Albaillella paradoxa Deflandre, Albaillella sp., Latentifistula sp., Latentifistulidae gen. et sp. indet., Follicucullus sp. aff. Follicucullus bipartitus Caridroit et De Wever, Follicucullus sp. and Spumellaria gen. et sp. indet. Two radiolarian assemblages could be identified: one being early Early Carboniferous assemblage represented with Albaillella paradoxa and Albaillella sp. cf. Albaillella paradoxa, another being Middle-Late Permian assemblage represented with Follicucullus sp. and Follicucullus sp. aff. Follicucullus bipartitus. This new discovery indicated the Carbono-Permian chert provenance for Triassic deposits in Kurgan region, which might be from ophiolitic mélange of the Chinese South Tianshan orogenic belt.

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Wajilitag mountains, about 40km southeast to Bachu town, is located at western Tazhong tectonic belt (Central Rise), Tarim basin, NW China. There exists a set of slightly metamorphic unfossiliferous clastic rocks at Wajilitag. Basic-ultrabasic intrusions are developed in the clastic rocks. Two gabbro specimens were sampled from the intrusions. Plate ages of 825.0±2.0Ma and 837.3±2.0Ma and respective isochronal ages of 821.4±8.0Ma and 833.3±15.3Ma were got after Ar-Ar analysis. This is the first group of reliable Precambrian isotopic ages in the inner part of Tarim basin. It is an important data for study on the age, basement component and tectonic type, etc. of Tarim basin, and also significant for the petroleum exploration planning in that area.