西昆仑东南构造样式及其对增生弧造山作用的意义

西昆仑东南甜水海地区表现为由东北往西南以麻扎-康西瓦冲断系、泉水沟冲断系、甜水海冲断系和南南西边缘盲冲断系而限定数个招皱-逆冲构造带或者褶皱构造带的构造格局构造变形样式总体上以向南逆冲的褶席和逆冲叠瓦扇为特征,以由东北往西南构造变形样式依次出现复式背形堆垛和叠瓦扇组合,到侏罗山式语皱构造带的变化其中用皱样式依次出现大型紧闭平卧卜倒转招皱、中尺度尖棱招皱和具圆筒状转折端的开阔格皱,而断层变化则由断层面产状几乎水平的多重复杂冲精席系到缓倾的顶板冲断层-底板冲断层组合样式到叠瓦扇冲断层．大地构造相分析表明研究区构造变形强度自北东向南西呈递减趋势,与库地一麻扎一带的增生楔杂岩可能组成了复杂的增生楔造山作用的增生楔和前陆招皱冲断带的复杂组合因此,研究区的构造格局并非简单的“塔什库尔干一甜水海地体”,而是复杂的增生弧造山带．

STRUCTURAL STYLES OF THE SOUTHEASTERN WEST KUNLUN MOUNTAINS AND THEIR IMPLICATION TO GROWING-ARC OROGENESIS

The tectonic framework of Tianshuihai region of the southeastern West Kunlun Mountains is characterized by several fold-thrust belts or fold belts separated, from the northeast to the southwest, by the Mazar--Kangxiwar thrust system, Quanshuigou thrust syStem, Tianshuihai thrust system, and southwest blind marginal thrust system,respeCtively. The structural styles generally is characterized by duplexes and thrust imbricate fans, which vary southwestly from multi-antiformal stacks to imbricate fans, then to Jura Mountain-type fold belt, with fold styles varying from large-scale recumbent-overturn folds tO chevron folds, then to broad folds. The thrusts vary from horizontal multi-duplexes to assemblies of roof-floor thrusts to imbricate fans. Analysis of tectonic factes indicates that the deformtional degree of the study area decreases from the northeast to the southwest.Together with the accretionary complexes distributed in Kuda-Mazar, the tectonics of the Tianshuihai thrust belt forms a complicated accretionary complex-foreland fold-thrust belt assembly Of a growing-arc orogenesis. Thus the structural framework of the study area is growing-arc orogen instead of simple"Taxkorgan-Tianshuihai terrane".Keywods:Tianshuihai, Foreland fold-thrust belt, Southwestward thrusting,Multi-duplex, Structural style.