Feng Zi, Wenzhou Xiao, Mabrouk Sami, Chenguang Zhang, Fenquan Xie, Ye Liu, Shuanglian Li
{"title":"了解含矿和贫矿赤铁矿的成因:对屯仓侵入体和南郯庐断层沿线飞地的地质年代和地球化学分析的启示","authors":"Feng Zi, Wenzhou Xiao, Mabrouk Sami, Chenguang Zhang, Fenquan Xie, Ye Liu, Shuanglian Li","doi":"10.1007/s00531-024-02465-z","DOIUrl":null,"url":null,"abstract":"<p>The relationships between metallogenic capacity and geochemical features of adakitic rocks along the South Tan-Lu Fault (STLF) remain unclear. In this study, the ore-barren adakitic rocks (Tuncang, Guandian and Wawuliu) exhibit higher K<sub>2</sub>O/Na<sub>2</sub>O ratios and lower Sr/Y ratios than the ore-bearing adakitic rocks (Chuzhou and Shangyaopu). These differences strongly suggest that the ore-barren adakitic rocks originated from the thickened lower continental crust (LCC), whereas the ore-bearing adakitic rocks were derived from oceanic slabs. Notably, the Tuncang granite exhibits higher Y/Yb and (Ho/Yb)<sub>N</sub> ratios than the Guandian granodiorite and Wawuliu intrusion. Accordingly, we suggest that the Tuncang granite likely originated from a delaminated eclogitic LCC, whereas the Guandian and Wawuliu intrusions were derived from a thickened basaltic LCC sources. The occurrence of diorite and gabbro mafic microgranular enclaves (MMEs) within the Tuncang granite strongly suggests a magma-mixing process. Considering their MgO contents and εNd(t) and (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>i</sub> values, we suggest that the gabbro MMEs were likely derived from an enriched mantle source previously metasomatized by subduction-related components and that the diorite MMEs were subsequently formed by magma mixing. Due to the slightly younger ages of the ore-bearing adakitic rocks, we propose a model in which the ore-barren adakitic rocks formed through LCC delamination at 130 Ma and the ore-bearing adakitic rocks formed through oceanic slab remelting at 125 Ma. Consequently, the exploration of Cu–Au mineralization along the STLF should focus on younger oceanic slab-derived adakitic rocks.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"38 1","pages":""},"PeriodicalIF":1.8000,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Understanding the genesis of ore-bearing and ore-barren adakitic rocks: insights from geochronology and geochemical analysis of the Tuncang intrusion and enclaves along the South Tan-Lu Fault\",\"authors\":\"Feng Zi, Wenzhou Xiao, Mabrouk Sami, Chenguang Zhang, Fenquan Xie, Ye Liu, Shuanglian Li\",\"doi\":\"10.1007/s00531-024-02465-z\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The relationships between metallogenic capacity and geochemical features of adakitic rocks along the South Tan-Lu Fault (STLF) remain unclear. In this study, the ore-barren adakitic rocks (Tuncang, Guandian and Wawuliu) exhibit higher K<sub>2</sub>O/Na<sub>2</sub>O ratios and lower Sr/Y ratios than the ore-bearing adakitic rocks (Chuzhou and Shangyaopu). These differences strongly suggest that the ore-barren adakitic rocks originated from the thickened lower continental crust (LCC), whereas the ore-bearing adakitic rocks were derived from oceanic slabs. Notably, the Tuncang granite exhibits higher Y/Yb and (Ho/Yb)<sub>N</sub> ratios than the Guandian granodiorite and Wawuliu intrusion. Accordingly, we suggest that the Tuncang granite likely originated from a delaminated eclogitic LCC, whereas the Guandian and Wawuliu intrusions were derived from a thickened basaltic LCC sources. The occurrence of diorite and gabbro mafic microgranular enclaves (MMEs) within the Tuncang granite strongly suggests a magma-mixing process. Considering their MgO contents and εNd(t) and (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>i</sub> values, we suggest that the gabbro MMEs were likely derived from an enriched mantle source previously metasomatized by subduction-related components and that the diorite MMEs were subsequently formed by magma mixing. Due to the slightly younger ages of the ore-bearing adakitic rocks, we propose a model in which the ore-barren adakitic rocks formed through LCC delamination at 130 Ma and the ore-bearing adakitic rocks formed through oceanic slab remelting at 125 Ma. 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Understanding the genesis of ore-bearing and ore-barren adakitic rocks: insights from geochronology and geochemical analysis of the Tuncang intrusion and enclaves along the South Tan-Lu Fault
The relationships between metallogenic capacity and geochemical features of adakitic rocks along the South Tan-Lu Fault (STLF) remain unclear. In this study, the ore-barren adakitic rocks (Tuncang, Guandian and Wawuliu) exhibit higher K2O/Na2O ratios and lower Sr/Y ratios than the ore-bearing adakitic rocks (Chuzhou and Shangyaopu). These differences strongly suggest that the ore-barren adakitic rocks originated from the thickened lower continental crust (LCC), whereas the ore-bearing adakitic rocks were derived from oceanic slabs. Notably, the Tuncang granite exhibits higher Y/Yb and (Ho/Yb)N ratios than the Guandian granodiorite and Wawuliu intrusion. Accordingly, we suggest that the Tuncang granite likely originated from a delaminated eclogitic LCC, whereas the Guandian and Wawuliu intrusions were derived from a thickened basaltic LCC sources. The occurrence of diorite and gabbro mafic microgranular enclaves (MMEs) within the Tuncang granite strongly suggests a magma-mixing process. Considering their MgO contents and εNd(t) and (87Sr/86Sr)i values, we suggest that the gabbro MMEs were likely derived from an enriched mantle source previously metasomatized by subduction-related components and that the diorite MMEs were subsequently formed by magma mixing. Due to the slightly younger ages of the ore-bearing adakitic rocks, we propose a model in which the ore-barren adakitic rocks formed through LCC delamination at 130 Ma and the ore-bearing adakitic rocks formed through oceanic slab remelting at 125 Ma. Consequently, the exploration of Cu–Au mineralization along the STLF should focus on younger oceanic slab-derived adakitic rocks.
期刊介绍:
The International Journal of Earth Sciences publishes process-oriented original and review papers on the history of the earth, including
- Dynamics of the lithosphere
- Tectonics and volcanology
- Sedimentology
- Evolution of life
- Marine and continental ecosystems
- Global dynamics of physicochemical cycles
- Mineral deposits and hydrocarbons
- Surface processes.