Present study reports the PGE-geochemistry of mantle peridotites and Nd-isotope geochemistry of arc related mafic rocks from the Indus Suture Zone (ISZ), western Ladakh. The total PGE concentration of the Shergol and Suru Valley peridotites (∑PGE = 96–180 ppb) is much higher than that of the primitive mantle and global ophiolitic mantle peridotites. The studied peridotites show concave upward PGE-distribution patterns with higher palladium-group PGE/Iridium-group PGE ratios (i.e., 0.8–2.9) suggesting that the partial melting is not the sole factor responsible for the evolution of these peridotites. The observed PGE-distribution patterns are distinct from residual/refractory mantle peridotites, which have concave downward or flat PGE-distribution patterns. Relative enrichment of palladium-group PGE as well as other whole-rock incompatible elements (e.g., LILE and LREE) and higher Pd/Ir ratio (1.1–5.9) reflects that these peridotites have experienced fluid/melt interaction in a supra-subduction zone (SSZ) tectonic setting. Also, the Shergol mafic intrusives and Dras mafic volcanics, associated with the studied peridotites, have high ¹⁴³Nd/¹⁴⁴Nd ratios (i.e., 0.512908–0.513078 and 0.512901–0.512977, respectively) and positive ε_Nd(t) (calculated for t = 140 Ma) values (i.e., +5.3 to +8.6 and + 5.1 to +6.6, respectively), indicating derivation from depleted mantle sources within an intra-oceanic arc setting, similar to Spongtang and Nidar ophiolites from other parts of Ladakh Himalaya. The transition from SSZ-type Shergol and Suru Valley peridotites to Early Cretaceous tholeiitic Shergol mafic intrusives followed by tholeiitic to calc-alkaline Dras mafic volcanics within the Neo-Tethys Ocean exhibit characteristics of subduction initiation mechanism analogous to the Izu-Bonin-Mariana arc system within western Pacific.

本研究报告了拉达克西部印度河缝合带（ISZ）的地幔橄榄岩的PGE-地球化学和弧相关的镁铁质岩的Nd-同位素地球化学。Shergol和Suru Valley橄榄岩的总PGE浓度（∑PGE = 96–180 ppb）远高于原始地幔和整体脂滑质地幔橄榄岩。研究的橄榄岩显示出向上凹的PGE分布模式，钯族PGE /铱族PGE比率较高（即0.8-2.9），这表明部分熔融不是造成这些橄榄岩演化的唯一因素。观察到的PGE分布模式与残留/难熔的幔橄榄岩不同，后者具有向下凹或平坦的PGE分布模式。钯族PGE以及其他全岩不相容元素（例如LILE和LREE）的相对富集和较高的Pd / Ir比（1.1-5.9）反映出这些橄榄岩在超俯冲带中经历了流体/熔体相互作用（SSZ）构造背景。而且，与所研究的橄榄岩相关的Shergol基性侵入岩和Dras基性火山岩具有较高的¹⁴³的Nd / ¹⁴⁴的Nd比（即，0.512908-0.513078和0.512901-0.512977，分别地）和正ε_钕（吨）（用于计算吨 值（即= 140马），5.3至8.6和5.1 + 6.6到，分别表示来自洋内弧形环境中枯竭的地幔源，类似于拉达克喜马拉雅山其他地区的海绵岩和尼达尔蛇绿岩。在新特提斯海洋内，从SSZ型Shergol和Suru Valley橄榄岩到早白垩纪Shergol黑铁质侵入体的过渡，然后由Tholeitic到钙碱性Dras黑铁质火山岩，具有俯冲启动机制的特征，类似于Izu-Bonin-Mariana弧系在西太平洋。