One of the most striking geological features of the Pamir is the south-dipping lithospheric slab beneath the orogen characterized by an intracontinental Wadati-Benioff zone. A widely accepted hypothesis over the past 40 years interprets the slab to represent southward subducted cratonic Asian continental lithosphere, which predicts significant cratonic Asia-sourced crustal materials (e.g., Tarim Basin) beneath the Pamir. Alternatively, recent studies have interpreted the slab to be lithosphere delaminated from the base of the Pamir. To test these hypotheses, depth–tectonic affinity relations of crustal xenoliths carried by Miocene volcanic rocks in the eastern Pamir, interpreted to be sourced from the Pamir deep lithosphere, are used to determine whether they represented Asian affinity cratonic crust. Thermodynamic calculations, zircon U–Pb geochronology combined with rare earth element analysis, and whole-rock major-trace element and Sr–Nd isotopic analyses document that (1) eclogite and pyroxenite xenoliths (~31–43 kbar/~960–1170°C) are the deepest sourced portions of the lithosphere from ~100 to 140 km depth, the protoliths of which represent the mid-lower crustal rocks of the Cretaceous Pamir magmatic arc, rather than material from cratonic Asia, and (2) granulite xenoliths (~20 kbar/~900°C) represent the Cenozoic lower crustal rocks of Pamir terranes from ~70 km depth. These results indicate the south-dipping slab represents delaminated Pamir lower crust and mantle lithosphere, rather than intracontinental subduction of Asian lithosphere, and further support the hypothesis of minimal Cenozoic northward translation of the Pamir.

中文翻译：

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克拉通亚洲是否深深地俯冲到帕米尔高原之下？新生代帕米尔地壳捕虏体的 P-T 条件和构造亲缘关系的证据

帕米尔高原最引人注目的地质特征之一是造山带下方的南倾岩石圈板片，其特征是陆内瓦达提-贝尼奥夫带。过去 40 年来，一个被广泛接受的假说将板块解释为向南俯冲的克拉通亚洲大陆岩石圈，这预示着帕米尔高原下方存在大量源自克拉通亚洲的地壳物质（例如塔里木盆地）。另外，最近的研究将板块解释为岩石圈从帕米尔高原底部分层。为了检验这些假设，利用帕米尔东部中新世火山岩携带的地壳捕虏体的深度-构造亲和关系（解释为源自帕米尔深部岩石圈）来确定它们是否代表亚洲亲和克拉通地壳。热力学计算，锆石 U-Pb 年代学结合稀土元素分析、全岩主痕量元素和 Sr-Nd 同位素分析证明 (1) 榴辉岩和辉石岩捕虏体 (~31–43 kbar/~960–1170°C)岩石圈的最深来源部分，深度约为 100 至 140 公里，其原岩代表白垩纪帕米尔岩浆弧的中下地壳岩石，而不是来自克拉通亚洲的物质，以及 (2) 麻粒岩捕虏体 (~20 kbar) /~900°C）代表了~70公里深度的帕米尔地体的新生代下地壳岩石。这些结果表明南倾板块代表了帕米尔下地壳和地幔岩石圈的拆层，而不是亚洲岩石圈的陆内俯冲，并进一步支持了帕米尔新生代最小北移的假说。