{"title":"Large granitoid batholith formed by episodic reworking of the continental basement","authors":"Qi-Wei Li , Jun-Hong Zhao , Yun-Lai Dong , Yu-Qing Huang","doi":"10.1016/j.precamres.2024.107568","DOIUrl":null,"url":null,"abstract":"<div><div>Large granitoid batholiths contain key information about the formation and evolution of the continental crust, but their growth mechanism and compositional diversity are still not clear. The Neoproterozoic Huangling batholith, one of the largest granitoid batholith in South China, comprises several plutons and covers an area of ∼ 970 km<sup>2</sup>. The largest trondhjemitic pluton was emplaced at ca. 840 Ma, and its magmatic zircons show large variable Th/U ratios (0.22–1.81) that are strongly correlated with Ti-in-zircon temperatures, zircon U/Yb and Ce<sup>4+</sup>/Ce<sup>3+</sup> ratios. These zircons have negative εHf (−28.3 to −14.6), variable δ<sup>18</sup>O (4.43–6.99 ‰) and δ<sup>94</sup>Zr values (−0.38 ‰ to + 0.21 ‰), as well as moderate zircon saturation temperatures (716–771 °C) and high <em>f</em>O<sub>2</sub> (FMQ+1.9). The trondhjemite is therefore proposed to have been derived from the Archean amphibolitic crust and underwent fractional crystallization of zircon, magnetite, apatite and/or titanite. In comparison, one smaller granitic pluton was emplaced at 831 ± 5 Ma. The magmatic zircons have more radiogenic εHf (−11.7 to −10.4), constant δ<sup>18</sup>O (6.09–6.66 ‰) and δ<sup>94</sup>Zr values (−0.31 ‰ to + 0.06 ‰), and they have slightly higher zircon saturation temperatures (767–803 °C) and <em>f</em>O<sub>2</sub> (FMQ+2.9). These geochemical features suggest that the granite was derived from a crustal source with mixed juvenile mafic materials and Archean amphibolitic rocks, and did not experience significant fractional crystallization. The Huangling granitoid batholith was formed by multiple injections of felsic melts with the compositional diversity that probably resulted from heterogeneous protoliths and complex magmatic processes in a prolonged magma evolution system.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2000,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Precambrian Research","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S030192682400281X","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Large granitoid batholiths contain key information about the formation and evolution of the continental crust, but their growth mechanism and compositional diversity are still not clear. The Neoproterozoic Huangling batholith, one of the largest granitoid batholith in South China, comprises several plutons and covers an area of ∼ 970 km2. The largest trondhjemitic pluton was emplaced at ca. 840 Ma, and its magmatic zircons show large variable Th/U ratios (0.22–1.81) that are strongly correlated with Ti-in-zircon temperatures, zircon U/Yb and Ce4+/Ce3+ ratios. These zircons have negative εHf (−28.3 to −14.6), variable δ18O (4.43–6.99 ‰) and δ94Zr values (−0.38 ‰ to + 0.21 ‰), as well as moderate zircon saturation temperatures (716–771 °C) and high fO2 (FMQ+1.9). The trondhjemite is therefore proposed to have been derived from the Archean amphibolitic crust and underwent fractional crystallization of zircon, magnetite, apatite and/or titanite. In comparison, one smaller granitic pluton was emplaced at 831 ± 5 Ma. The magmatic zircons have more radiogenic εHf (−11.7 to −10.4), constant δ18O (6.09–6.66 ‰) and δ94Zr values (−0.31 ‰ to + 0.06 ‰), and they have slightly higher zircon saturation temperatures (767–803 °C) and fO2 (FMQ+2.9). These geochemical features suggest that the granite was derived from a crustal source with mixed juvenile mafic materials and Archean amphibolitic rocks, and did not experience significant fractional crystallization. The Huangling granitoid batholith was formed by multiple injections of felsic melts with the compositional diversity that probably resulted from heterogeneous protoliths and complex magmatic processes in a prolonged magma evolution system.
期刊介绍:
Precambrian Research publishes studies on all aspects of the early stages of the composition, structure and evolution of the Earth and its planetary neighbours. With a focus on process-oriented and comparative studies, it covers, but is not restricted to, subjects such as:
(1) Chemical, biological, biochemical and cosmochemical evolution; the origin of life; the evolution of the oceans and atmosphere; the early fossil record; palaeobiology;
(2) Geochronology and isotope and elemental geochemistry;
(3) Precambrian mineral deposits;
(4) Geophysical aspects of the early Earth and Precambrian terrains;
(5) Nature, formation and evolution of the Precambrian lithosphere and mantle including magmatic, depositional, metamorphic and tectonic processes.
In addition, the editors particularly welcome integrated process-oriented studies that involve a combination of the above fields and comparative studies that demonstrate the effect of Precambrian evolution on Phanerozoic earth system processes.
Regional and localised studies of Precambrian phenomena are considered appropriate only when the detail and quality allow illustration of a wider process, or when significant gaps in basic knowledge of a particular area can be filled.