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Biotite granites and muscovite-bearing granites are dominant rock types of the widespread granites in SE China. However, their petrogenesis has been enigmatic. A combined study of zircon U–Pb dating and Lu–Hf isotopes, whole-rock element geochemistry and Sr–Nd–O isotopes was performed for three late Mesozoic granitic plutons (Xinfengjie, Jiangbei and Dabu) in central Jiangxi province, SE China. All the plutons are composed of biotite granites and muscovite-bearing granites that have been poorly investigated previously. The new data not only allow us to assess their sources and magma evolution processes, but also helps us to better understand the genetic link to the large-scale polymetallic mineralization in SE China. LA-ICP-MS zircon U–Pb dating shows that three plutons were emplaced in the Late Jurassic (159–148 Ma) and that the muscovite-bearing granites are almost contemporaneous with the biotite granites. The biotite granites have SiO 2 contents of 70.3–74.4 wt% and are weakly to strongly peraluminous with ASI from 1.00 to 1.26, and show a general decrease in ASI with increasing SiO 2 . They have relatively high zircon saturation temperatures ( T Zr  = 707–817 °C, most > 745 °C) and show a general decrease in T Zr with increasing SiO 2 . They have high initial 87 Sr/ 86 Sr ratios (0.7136 to 0.7166) and high δ 18 O values (9.1–12.8‰, most > 9.5‰) and clearly negative ε Nd (T) (− 9.5 to − 11.8) and ε Hf (T) (in situ zircon) (− 13.1 to − 13.5). The muscovite-bearing granites have high SiO 2 contents (74.7–78.2 wt%). They are also weakly to strongly peraluminous with ASI of 1.04–1.18 but show a general increase in ASI with increasing SiO 2 . They have relatively low T Zr (671–764 °C, most < 745 °C) and also show a general decrease in T Zr with increasing SiO 2 . The muscovite-bearing granites have high Rb (up to 810 ppm) and high (K 2 O + Na 2 O)/CaO (up to 270), Rb/Sr (up to 42) and Rb/Ba (up to 30) as well as low K/Rb (< 150, down to 50), Zr/Hf (< 24, down to 11) and Nb/Ta (< 6, down to 2). They show similar Nd–O–Hf isotopic compositions to the biotite granites with ε Nd (T) of − 8.7 to − 12.0, δ 18 O of 8.7–13.0‰ (most > 9.5‰) and ε Hf (T) (in situ zircon) of − 11.3 to − 13.1. Geochemical data suggest the origin of the biotite granites and muscovite-bearing granites as follows: Partial melting of Precambrian metasedimentary rocks (mainly two-mica schist) in the lower crust at temperatures of ca. 820 °C generated the melts of the less felsic biotite granites. Such primary crustal melts underwent biotite-dominant fractionation crystallization, forming the felsic biotite granites. Progressive plagioclase-dominant fractionation crystallization from the evolved biotite granites produced the more felsic muscovite-bearing granites. Thus, the biotite granites belong to the S-type whereas the muscovite-bearing granites are highly fractionated S-type granites. We further suggest that during the formation of the muscovite-bearing granites the fractional crystallization was accompanied by fluid fractionation and most likely the addition of internally derived mineralizing fluids. That is why the large-scale polymetallic mineralization is closely related to the muscovite-bearing granites rather than biotite granites in SE China. This is important to further understand the source and origin of biotite granites and muscovite-bearing granites in SE China even worldwide.

In contrast to I-type granites, which commonly comprise infracrustal and supracrustal sources, S-type granites typically incorporate predominantly supracrustal sources. The initial aim of this study was to identify the sources of three Scottish Caledonian (~460 Ma) S-type granites (Kemnay, Cove and Nigg Bay) by conducting oxygen, U–Pb and Hf isotope analyses in zircon in order to characterise one potential end-member magma involved in the genesis of the voluminous late Caledonian (~430–400 Ma) I-type granites. Field, whole-rock geochemical and isotopic data are consistent with the generation of the S-type granites by melting their Dalradian Supergroup country rocks. While Hf isotope compositions of magmatic zircon, U–Pb data of inherited zircons, and high mean zircon δ 18 O values of 9.0 ± 2.7‰ (2SD) and 9.8 ± 2.0‰ for the Kemnay and Cove granites support this model, the Nigg Bay Granite contains zircons with much lower δ 18 O values (6.8 ± 2.1‰), similar to those found in Scottish I-type granites. This suggests that the Nigg Bay Granite contains low-δ 18 O material representing either altered supracrustal material, or more likely, an infracrustal source component with mantle-like δ 18 O. Mixing trends in plots of δ 18 O vs. εHf for S-type granite zircons indicate involvement of at least two sources in all three granites. This pilot study of Scottish Caledonian S-type granites demonstrates that, while field and whole-rock geochemical data are consistent with local melting of only supracrustal sources, the oxygen isotopic record stored in zircon reveals a much more complex petrogenetic evolution involving two or more magma sources.

We present the geochemistry and intrusion pressures of granitoids from the Kohistan batholith, which represents, together with the intruded volcanic and sedimentary units, the middle and upper arc crust of the Kohistan paleo-island arc. Based on Al-in-hornblende barometry, the batholith records intrusion pressures from ~0.2 GPa in the north (where the volcano-sedimentary cover is intruded) to max. ~0.9 GPa in the southeast. The Al-in-hornblende barometry demonstrates that the Kohistan batholith represents a complete cross section across an arc batholith, reaching from the top at ~8-9 km depth (north) to its bottom at 25-35 km (south-central to southeast). Despite the complete outcropping and accessibility of the entire batholith, there is no observable compositional stratification across the batholith. The geochemical characteristics of the granitoids define three groups. Group 1 is characterized by strongly enriched incompatible elements and unfractionated middle rare earth elements (MREE)/heavy rare earth element patterns (HREE); Group 2 has enriched incompatible element concentrations similar to Group 1 but strongly fractionated MREE/HREE. Group 3 is characterized by only a limited incompatible element enrichment and unfractionated MREE/HREE. The origin of the different groups can be modeled through a relatively hydrous (Group 1 and 2) and of a less hydrous (Group 3) fractional crystallization line from a primitive basaltic parent at different pressures. Appropriate mafic/ultramafic cumulates that explain the chemical characteristics of each group are preserved at the base of the arc. The Kohistan batholith strengthens the conclusion that hydrous fractionation is the most important mechanism to form volumetrically significant amounts of granitoids in arcs. The Kohistan Group 2 granitoids have essentially identical trace element characteristics as Archean tonalite-trondhjemite-granodiorite (TTG) suites. Based on these observations, it is most likely that similar to the Group 2 rocks in the Kohistan arc, TTG gneisses were to a large part formed by hydrous high-pressure differentiation of primitive arc magmas in subduction zones.

There is ongoing debate around the origin of successive granitic magmatic events in transitional stages from compressional to extensional tectonic settings in orogens. In the eastern part of the Arabian Shield, the late Cryogenian–Ediacaran magmatism of the transitional stage contributed to the growth of the Ad-Dawadmi terrane. The late Neoproterozoic Abt schist Formation, which is found throughout the Ad-Dawadmi terrane, is intruded by batholiths of the Najirah granitoids (~ 641 Ma) followed by the Khurs granite of the Ar Ruwaydah Suite (~ 612 Ma). A switch in geodynamic regime from post-collision to intra-plate extension was attended by the Hadbet Tayma alkali granites. This study utilizes petrology and whole-rock geochemistry to decipher the genesis of these three granitic intrusive events. The Najirah granitoids are metaluminous, late-orogenic, I-type granitoids generated from magma derived by partial melting of lower crustal mafic rocks. The younger Khurs granite of the Ar Ruwaydah suite reflects a post-orogenic setting and has predominantly peraluminous nature with S-type granite characteristics, supporting an origin by partial melting of the metagraywacke crust. A final anorogenic magmatic event produced a suite of A-type (A2-subtype) alkaline granites of Hadbet Tayma, which formed after the termination of the accretion and microplate amalgamation phase of the northern East African Orogeny (EAO). These three successive magmatic events provide evidence for a range of magmatic sources in the thickened crust of the eastern Arabian Shield, reflecting its tectonic evolution over time. Graphical Abstract

Three principal granite provinces are defined across SE Asia, as follows. (1) The Western Thailand-Myanmar/Burma province consists of hornblende-biotite I-type granodiorite-granites and felsic biotite-K-feldspar (± garnet ± tourmaline) granites associated with abundant tin mineralization in greisen-type veins. New ion microprobe U-Pb dating results from Phuket Island show zircon core ages of 212 ± 2 and 214 ± 2 Ma and a thermal overprint with rims of 81.2 ± 1.2 and 85-75 Ma. (2) The North Thailand-West Malaya Main Range province has mainly S-type biotite granites and abundant tin mineralization resulting from crustal thickening following collision of the Sibumasu plate with Indochina during the Mid-Triassic. Biotite granites around Kuala Lumpur contain extremely U-rich zircons (up to 38000 ppm) that yield ages of 215 ± 7 and 210 ± 7 Ma. (3) The East Malaya province consists of dominantly Permian-Triassic I-type hornblende-biotite granites but with subordinate S-type plutons and A-type syenite-gabbros. Biotite-K-feldspar granites from Tioman Island off the east coast of Malaysia also yield a zircon age of 80 ± 1 Ma, showing Cretaceous magmatism in common with province 1. Geological and U-Pb geochronological data suggest that two east-dipping (in present-day coordinates) subduction zones are required during the Triassic, one along the Bentong-Raub Palaeo-Tethyan suture, and the other west of the Phuket-Burma province 1 belt. SUPPLEMENTARY MATERIAL: A full description of U-Pb analytical methods used and data tables are available at www.geolsoc.org.uk/SUP18523.

Accessory and minor phases are frequently used to infer the composition and intensive parameters of magmas. In granites, the most common ferromagnesian phases are biotite and amphibole, which raises the question as to what compositional domains are present among these phases and how do those domains relate to granite composition. Here we present a characterization of biotite and amphibole compositions from S-, I-, and A-type granites. A database of biotite (1215 data points) and amphibole (525 data points) compositions from previously classified S-, I-, and A-type granites has been compiled. Three characteristics can be used to describe the variations in biotite composition including XAnniteBt (fraction of Fe2+ in the octahedral site), XFeVI∗Bt (fraction of total iron in the octahedral site), and total aluminum (apfu). Three characteristics can also be used to describe variations in amphibole composition including, NK/CNK [i.e., (Na + K)/(Ca + Na + K)], Fe/(Fe + Mg), and total aluminum. Utilizing, for the first time, a random forest (machine learning) model the three characteristics for biotite and amphibole could discriminate the inferred source region of the granites with 82 and 96% accuracy, respectively. Biotite composition can also be used to broadly characterize fO2,fH2OfHF, fH2OfHCl, and fHFfHCl of each granite type at a given temperature and pressure. Thus, biotite and amphibole compositions can be used to further characterize granites; however, biotite and amphibole should not solely be used to infer the source of a granite.