Gao, Qiang, Yan, Mao-Qiang, Moritz, Robert, Huizenga, Jan, Zhu, Hong-Tao, Liu, Zhao-Tong, Qiu, Kun-Feng, Wei, Jun-Hao, and Deng, Jung (2026) Crustal architecture, accretionary evolution, and mineralization in the southern Central Asian orogenic belt (Solonker-Alxa region, Inner Mongolia) from the Paleozoic to early Mesozoic. Geological Society of America Bulletin. (In Press)

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Abstract

Understanding continental crustal architecture and its control on mineral systems is fundamental to the earth sciences. Here we integrate zircon U-Pb geochronology, whole-rock Nd-Hf isotopes, lithogeochemical data, and regional metallogenic records from Cambrian to Triassic magmatic rocks across the Solonker-Alxa region of Inner Mongolia to define crustal domains and their metallogenic significance. Two contrasting isotopic provinces are identified: (1) an enriched domain [εNd(t) < −4, εHf(t) < 0] encompassingthe North China Craton–Alxa Block and (2) a depleted domain [εNd(t) > −4, εHf(t) > 0]typifies the Central Asian orogenic belt (CAOB). These domains are separated by the Chifeng-Bayan Obo fault, the area north of Chaganhua, and the Quagan Qulu-Tebai fault. Crustal thickness patterns show a belt of thinned crust (<40 km) along the Mandula, Solonker, Ganqimandu, Yingba, and northern Enger Us fault zones, marking the boundary between the Mongolia collage and the Tarim-North China collage. Variations in crustal thickness suggest that the Alxa Block is a distinct Precambrian terrane, separate from the North China Craton. The protracted subduction-accretion and slab rollback of the Paleo-Asian Ocean have driven significant crustal growth in the Solonker-Alxa region, with juvenile crust contributions estimated at 37% in the southern CAOB. Crustal maturation and felsic differentiation resulted from polyphase melting events involving mafic lower crust, oceanic crust, and the middle to upper crust. A systematic correlation exists between isotopic domains, crustal architecture, and metallogenic distribution. Depleted domains with thin crust (<50 km) preferentially host porphyry Cu(± Au), epithermal Pb-Zn-Cu, and volcanicmassive sulphide-type Cu deposits, whereas enriched isotopic domains and their peripheries contain porphyry Mo, skarn Cu-Fe, vein-type Au deposits, and magmatic Cu-Ni sulfide deposits, indicating genetic links to ancient crustal recycling and metasomatized lithospheric mantle. This synthesis provides a coherent tectono-metallogenic framework for the Solonker-Alxa segment of the southern CAOB and offers guidance for mineral exploration.

Item ID:	93372
Item Type:	Article (Research - C1)
ISSN:	1943-2674
Copyright Information:	© 2026 Geological Society of America.
Date Deposited:	07 Aug 2026 05:23
FoR Codes:	37 EARTH SCIENCES > 3703 Geochemistry > 370303 Isotope geochemistry @ 50% 37 EARTH SCIENCES > 3705 Geology > 370508 Resource geoscience @ 50%
SEO Codes:	28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280107 Expanding knowledge in the earth sciences @ 100%
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