【摘要】 东昆仑造山带不仅产出夏日哈木超大型Ni-Co硫化物矿床，还产出多个同期的含岩浆硫化物的镁铁-超镁铁质岩体，如石头坑德、浪木日和阿克楚克塞等，是我国重要的镍钴战略资源新基地之一，也是未来镍钴找矿勘查与增储的重要区带。尽管地质学家们期望在东昆仑造山带发现下一个“夏日哈木”，但近十年的找矿勘查工作始终未能取得新突破。因此，该带是否还存在以及如何寻找新的“夏日哈木型”矿床，成为当前亟待解决的重要科学问题。玛新达坂岩体是笔者及团队成员在东昆仑造山带西段祁漫塔格岩浆岩带中新发现的一个镁铁-超镁铁质岩体。该岩体主要由二辉橄榄岩、橄榄斜方辉石岩和辉长苏长岩组成，其中超镁铁质岩相发育有磁黄铁矿、镍黄铁矿和黄铜矿等岩浆硫化物矿物。锆石U-Pb定年结果表明，玛新达坂岩体辉长苏长岩的成岩年龄为390.7±1.1Ma，是原特提斯洋闭合-碰撞后伸展诱发的镁铁质岩浆活动的响应。全岩主量和微量元素组成表明，分离结晶过程控制了岩体母岩浆的化学成分演化，且岩浆在上侵过程中经历了一定程度的地壳混染。岩体全岩微量元素组成具有典型的弧岩浆特征，亏损高场强元素，富集大离子亲石元素，Nb-Ta负异常显著，指示其母岩浆可能源自交代的、富集型次大陆岩石圈地幔（SCLM）的部分熔融。稀土元素λ值表明，玛新达坂岩体的地幔源区含有富集尖晶石相的辉石岩组分，该辉石岩可能与地幔橄榄岩和俯冲洋壳来源熔/流体的反应有关。岩体全岩的δ³⁴S值（5.9‰～7.2‰）显著高于MORB地幔的值，表明岩浆在演化过程中有明显地壳硫的加入，地壳S的混染是触发岩浆达到S饱和、发生硫化物熔离的关键过程。基于岩体的岩性学、年代学、元素-同位素地球化学特征，笔者提出玛新达坂含硫化物镁铁-超镁铁质岩体具有良好的Ni-Co硫化物成矿潜力，是东昆仑造山带内岩浆Ni-Co硫化物找矿勘查潜在的重要对象，值得开展系统的找矿勘探工作。更多还原

【Abstract】 The East Kunlun Orogenic Belt hosts the giant Xiarihamu Ni-Co sulfide deposit,along with several coeval sulfide-bearing mafic-ultramafic intrusions,such as Shitoukengde,Langmuri,and Akechukesai intrusions. It represents one of significant new strategic bases of Ni-Co resources and a key area for future Ni-Co exploration and reserve increase in China. Despite the hopes of geologists to discover another “Xiarihamu” in the East Kunlun Orogenic Belt,exploration efforts have yielded no significant breakthroughs over the past ten years. Whether additional “Xiarihamu-type” deposits exist in this belt and how to identify them are critical scientific issues that urgently require resolution. The Maxindaban intrusion is a newly-discovered mafic-ultramafic intrusion discovered by the authors in the western segment of the East Kunlun Orogenic Belt,within the Qimantag magmatic belt. This intrusion is composed mainly of lherzolite,olivine orthopyroxenite,and gabbronorite. Magmatic sulfide minerals such as pyrrhotite,pentlandite,and chalcopyrite occur primarily in the ultramafic facies. Zircon U-Pb dating indicates that the gabbronorites crystallized at 390. 7 ± 1. 1 Ma,representing a response to post-collisional extension following the closure of the proto-Tethys Ocean. Whole-rock major and trace element compositions reveal that fractional crystallization controlled the chemical differentiation of the parental magma,which experienced a certain degree of crustal contamination during ascent. The intrusion exhibits typical arc-magmatic characteristics,including depletion in high-fieldstrength elements（ HFSE）, enrichment in large-ion-lithophile elements（ LILE）, and pronounced negative Nb-Ta anomalies,suggesting that its parental magma was derived from partial melting of a metasomatized,enriched subcontinental lithospheric mantle（ SCLM）. REE λ-values further indicate that the mantle source contained a considerable amount of spinel-bearing pyroxenite component,likely resulting from reactions between mantle peridotite and melts/fluids derived from subducted oceanic crust. Wholerock δ³⁴S values（ 5. 9‰ ～ 7. 2‰） are markedly higher than those of the MORB-type mantle,indicating substantial addition of crustal sulfur during magmatic differentiation. Crustal contamination of sulfur was thus a key process in driving the magma to sulfur saturation and triggering sulfide segregation. Integrating lithological, geochronological, and geochemical evidence, we propose that the Maxindaban sulfide-bearing mafic-ultramafic intrusion has significant potential for Ni-Co sulfide mineralization. It should be regarded as a promising exploration target of Ni-Co sulfides within the East Kunlun Orogenic Belt and warrants systematic prospecting.更多还原