There are six distinct classes of gold deposits, each represented by metallogenic provinces, having 100's to > 1 000 tonne gold production. The deposit classes are: (1) erogenic gold; (2) Carlin and Carlin-like...There are six distinct classes of gold deposits, each represented by metallogenic provinces, having 100's to > 1 000 tonne gold production. The deposit classes are: (1) erogenic gold; (2) Carlin and Carlin-like gold deposits; (3) epithermal gold-silver deposits; (4) copper-gold porphyry deposits; (5) iron-oxide copper-gold deposits; and (6) gold-rich volcanic hosted massive sul-fide (VMS) to sedimentary exhalative (SEDEX) deposits. This classification is based on ore and alteration mineral assemblages; ore and alteration metal budgets; ore fluid pressure(s) and compositions; crustal depth or depth ranges of formation; relationship to structures and/or magmatic intrusions at a variety of scales; and relationship to the P-T-t evolution of the host terrane. These classes reflect distinct geodynamic settings. Orogenic gold deposits are generated at mid-crustal (4-16 km) levels proximal to terrane boundaries, in transpressional subduction-accretion complexes of Cordilleran style erogenic belts; other orogenic gold provinces form inboard by delamina-tion of mantle lithosphere, or plume impingement. Carlin and Carlin-like gold deposits develop at shallow crustal levels (< 4 km) in extensional convergent margin continental arcs or back arcs; some provinces may involve asthenosphere plume impingement on the base of the lithosphere. Epithermal gold and copper-gold porphyry deposits are sited at shallow crustal levels in continental margin or intraoceanic arcs. Iron oxide copper-gold deposits form at mid to shallow crustal levels; they are associated with extensional intracratonic anorogenic magmatism. Proterozoic examples are sited at the transition from thick refractory Archean mantle lithosphere to thinner Proterozoic mantle lithosphere. Gold-rich VMS deposits are hydrothermal accumulations on or near the sea-floor in continental or intraoceanic back arcs.The compressional tectonics of orogenic gold deposits is generated by terrane accretion; high heat flow stems from crustal thickening, delamination of overthickened man展开更多
The North China Craton(NCC) hosts numerous gold deposits and is known as the most gold-productive region of China. The gold deposits were mostly formed within a few million years in the Early Cretaceous(130–120 Ma), ...The North China Craton(NCC) hosts numerous gold deposits and is known as the most gold-productive region of China. The gold deposits were mostly formed within a few million years in the Early Cretaceous(130–120 Ma), coeval with widespread occurrences of bimodal magmatism, rift basins and metamorphic core complexes that marked the peak of lithospheric thinning and destruction of the NCC. Stable isotope data and geological evidence indicate that ore-forming fluids and other components were largely exsolved from cooling magma and/or derived from mantle degassing during the period of lithospheric extension. Gold mineralization in the NCC contrasts strikingly with that of other cratons where gold ore-forming fluids were sourced mostly from metamorphic devolatization in compressional or transpressional regimes. In this paper, we present a summary and discussion on time-space distribution and ore genesis of gold deposits in the NCC in the context of the timing, spatial variation, and decratonic processes. Compared with orogenic gold deposits in other cratonic blocks, the Early Cretaceous gold deposits in the NCC are quite distinct in that they were deposited from magma-derived fluids under extensional settings and associated closely with destruction of cratonic lithosphere. We argue that Early Cretaceous gold deposits in the NCC cannot be classified as orogenic gold deposits as previously suggested, rather, they are a new type of gold deposits, termed as "decratonic gold deposits" in this study. The westward subduction of the paleo-West Pacific plate(the Izanagi plate) beneath the eastern China continent gave rise to an optimal tectonic setting for large-scale gold mineralization in the Early Cretaceous. Dehydration of the subducted and stagnant slab in the mantle transition zone led to continuous hydration and considerable metasomatism of the mantle wedge beneath the NCC. As a consequence, the refractory mantle became oxidized and highly enriched in large ion lithophile elements and chalcophile elements(e.g., Cu, Au,展开更多
文摘There are six distinct classes of gold deposits, each represented by metallogenic provinces, having 100's to > 1 000 tonne gold production. The deposit classes are: (1) erogenic gold; (2) Carlin and Carlin-like gold deposits; (3) epithermal gold-silver deposits; (4) copper-gold porphyry deposits; (5) iron-oxide copper-gold deposits; and (6) gold-rich volcanic hosted massive sul-fide (VMS) to sedimentary exhalative (SEDEX) deposits. This classification is based on ore and alteration mineral assemblages; ore and alteration metal budgets; ore fluid pressure(s) and compositions; crustal depth or depth ranges of formation; relationship to structures and/or magmatic intrusions at a variety of scales; and relationship to the P-T-t evolution of the host terrane. These classes reflect distinct geodynamic settings. Orogenic gold deposits are generated at mid-crustal (4-16 km) levels proximal to terrane boundaries, in transpressional subduction-accretion complexes of Cordilleran style erogenic belts; other orogenic gold provinces form inboard by delamina-tion of mantle lithosphere, or plume impingement. Carlin and Carlin-like gold deposits develop at shallow crustal levels (< 4 km) in extensional convergent margin continental arcs or back arcs; some provinces may involve asthenosphere plume impingement on the base of the lithosphere. Epithermal gold and copper-gold porphyry deposits are sited at shallow crustal levels in continental margin or intraoceanic arcs. Iron oxide copper-gold deposits form at mid to shallow crustal levels; they are associated with extensional intracratonic anorogenic magmatism. Proterozoic examples are sited at the transition from thick refractory Archean mantle lithosphere to thinner Proterozoic mantle lithosphere. Gold-rich VMS deposits are hydrothermal accumulations on or near the sea-floor in continental or intraoceanic back arcs.The compressional tectonics of orogenic gold deposits is generated by terrane accretion; high heat flow stems from crustal thickening, delamination of overthickened man
基金financially supported by the National Natural Science Foundation of China(Grant No.91414301)project of the State Key Laboratory of Lithospheric Evolution(Grant No.1303)
文摘The North China Craton(NCC) hosts numerous gold deposits and is known as the most gold-productive region of China. The gold deposits were mostly formed within a few million years in the Early Cretaceous(130–120 Ma), coeval with widespread occurrences of bimodal magmatism, rift basins and metamorphic core complexes that marked the peak of lithospheric thinning and destruction of the NCC. Stable isotope data and geological evidence indicate that ore-forming fluids and other components were largely exsolved from cooling magma and/or derived from mantle degassing during the period of lithospheric extension. Gold mineralization in the NCC contrasts strikingly with that of other cratons where gold ore-forming fluids were sourced mostly from metamorphic devolatization in compressional or transpressional regimes. In this paper, we present a summary and discussion on time-space distribution and ore genesis of gold deposits in the NCC in the context of the timing, spatial variation, and decratonic processes. Compared with orogenic gold deposits in other cratonic blocks, the Early Cretaceous gold deposits in the NCC are quite distinct in that they were deposited from magma-derived fluids under extensional settings and associated closely with destruction of cratonic lithosphere. We argue that Early Cretaceous gold deposits in the NCC cannot be classified as orogenic gold deposits as previously suggested, rather, they are a new type of gold deposits, termed as "decratonic gold deposits" in this study. The westward subduction of the paleo-West Pacific plate(the Izanagi plate) beneath the eastern China continent gave rise to an optimal tectonic setting for large-scale gold mineralization in the Early Cretaceous. Dehydration of the subducted and stagnant slab in the mantle transition zone led to continuous hydration and considerable metasomatism of the mantle wedge beneath the NCC. As a consequence, the refractory mantle became oxidized and highly enriched in large ion lithophile elements and chalcophile elements(e.g., Cu, Au,
