Lithosphere architecture characterized by crust–mantle decoupling controls the formation of orogenic gold deposits

Abstract

This study, via combined analysis of geophysical and geochemical data, reveals a lithospheric architecture characterized by crust-mantle decoupling and vertical heat-flow conduits that control orogenic gold mineralization in the Ailaoshan gold belt on the southeastern margin of Tibet. The mantle seismic tomography indicates that the crust-mantle decoupled deformation, defined from previous seismic anisotropy analysis was formed by upwelling and lateral flow of the asthenosphere driven by deep subduction of the Indian continent. Our MT and seismic images show both a vertical conductor across the Moho and high Vp/Vs anomalies both in the uppermost mantle and lowest crust, suggesting that crust-mantle decoupling promotes ponding of mantle-derived basic melts at the base of the crust via a heat-flow conduit. Noble gas isotope and halogen ratios of gold-related ore minerals indicate a mantle source of ore fluid, and a rapid decrease in Cl/F ratios of lamprophyres under P-T conditions of 1.2 Gpa and 1050 C suggests that the ore fluid was derived from degassing of the basic melts. Similar lithospheric architecture is recognized in other orogenic gold provinces, implying analogous formational controls.

Receiver Function Adjoint Tomography for Three‐Dimensional High‐Resolution Seismic Array Imaging: Methodology and Applications in Southeastern Tibet

“…Zhang et al, 2020b), a thin lithosphere (Pasyanos et al, 2014;, and low-resistivity anomalies (Yu et al, 2020). The RRF was reactivated in the Cenozoic (Tapponnier et al, 1990), making it a potential channel for the asthenospheric upwelling to the crust (Hou et al, 2022). The LVZs and eastward-dipping Moho under the RRF, revealed by our study, provide direct evidence for the detailed transport of the hot mantle materials.…”

“…This interpretation is further supported by geophysical observations, such as the LVZs in the uppermost mantle found by our study and previous results (Han et al., 2022; Nábělek et al., 2009; Z. Zhang et al., 2020b), a thin lithosphere (Pasyanos et al., 2014; M. Xu et al., 2022), and low‐resistivity anomalies (Yu et al., 2020). The RRF was reactivated in the Cenozoic (Tapponnier et al., 1990), making it a potential channel for the asthenospheric upwelling to the crust (Hou et al., 2022). The LVZs and eastward‐dipping Moho under the RRF, revealed by our study, provide direct evidence for the detailed transport of the hot mantle materials.…”

The Formation of the Jiaodong Gold Province

“…In Triassic, the continental collision between the NCC and YC allowed the metasomatization of lithospheric mantle via continental components, such as Proterozoic sediments of YC (Deng et al, 2020b). In the Mesozoic, with the subduction of Paleo-Pacific Plate, water and other volatiles were released from the slab and overlying sediments, further hydrating the lithospheric mantle (Zhai and Santosh, 2013), which has been proposed to be a pivotal drive mechanism for the gold mineralization (e.g., Zhao et al, 2019bZhao et al, , 2022Wang et al, 2020a, b;Deng et al, 2022;Hou et al, 2022).…”

Crustal Anatexis and Initiation of the Continental‐Scale Chongshan Strike‐Slip Shear Zone on the Southeastern Tibetan Plateau

“…Geophysical observations provide evidence of an upwelling asthenosphere driven by eastward deep subduction of the Indian lithosphere. A large low‐Vp body with a mushroom shape extends laterally beneath the rigid Asian mantle lithosphere east of the subducted Indian slab (Bai et al., 2010; Hou et al., 2022; Ling et al., 2020; Sun et al., 2014; Zhao et al., 2013). A recent study shows that the foundered lithosphere has already sunk into the mantle transition zone and partly penetrated the lower mantle (Figure 14b) (Feng et al., 2022).…”

“…Geophysical observations have proposed widespread partial melting zones with low velocity, high reflectivity, and high conductivity in the southeastern margin of the Tibetan Plateau (Bai et al., 2010; Feng et al., 2022; Ling et al., 2020; Sun et al., 2014; Zhao et al., 2013). These partial melting zones are interpreted as partial melting of deep crust triggered by asthenospheric upwelling related to the subduction of the Indian plate (Hou et al., 2022; Huang et al., 2015; Ling et al., 2020). The abnormal thermal state resulted in high‐temperature medium‐pressure amphibolite–granulite facies metamorphism and crustal anatexis (Figures 4 and 5).…”