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Magmatic sources of porphyry deposits in postcollisional settings remain controversial. We have used new and published petrological and geochemical data for the Eocene–Oligocene porphyry Cu ± Mo ± Au deposits in the Sanjiang region, SW China, to address this outstanding issue. New data for three deposits (Machangqing, Tongchang, and Beiya) in the Ailaoshan–Red River porphyry Au-Cu-Mo belt (southern part of the Sanjiang region) suggest that ore-forming porphyries were emplaced at ~ 35 Ma, have high (87Sr/86Sr)i (0.7068–0.7071) and negative εNd(t) (− 6.9 to − 5.0), low zircon εHf(t) (− 5.3 to 4.5), and relatively high δ18O (5.9–9.0‰). Magmatic amphibole phenocryst compositions indicate that the parental magmas are all relatively oxidized (ΔFMQ = 1.7 ± 0.6), and H2O-rich (3.8 ± 0.3 wt% H2O). These results are consistent with those estimated from zircon compositions (ΔFMQ = 1.8 ± 0.8) and high whole-rock Sr/Y ratios (75 ± 31), respectively. Based on the new and published data, we suggest that the parental magmas for the Ailaoshan–Red River porphyry Au-Cu-Mo belt were derived from a preserved juvenile arc lower-crust and the underlying metasomatized subcontinental lithospheric mantle (SCLM) attributed to a Neoproterozoic subduction event, whereas the parental magmas for the Yulong porphyry Cu-Mo belt (northern part of the Sanjiang region) originated from the Permian–Triassic juvenile arc lower-crust and metasomatized SCLM. Additionally, parental magmas for these porphyry deposits are all oxidized and H2O-rich, and we attribute such characteristics to inheritance from mixed mantle-crust sources that were modified by previous oceanic slab subduction. [ABSTRACT FROM AUTHOR]

The reduced nature of the subducting slab has been used to explain the relatively poor endowment of economic porphyry copper deposits in Paleo-Tethyan arc systems. The presence of numerous porphyry Cu deposits in the southern Yidun terrane potentially challenges this model, because these deposits are thought to be the product of Paleo-Tethyan subduction. To investigate this, two representative deposits (i.e., Pulang and Songnuo porphyry Cu deposits) from the southern Yidun terrane have been studied. Zircon U-Pb ages of pre- and syn-mineral porphyries in Pulang are 221 ± 2 Ma (MSWD = 0.89) and 215 ± 2 Ma (MSWD = 1.50), respectively. Zircon and garnet U-Pb ages of the Songnuo syn-mineral porphyry are 217 ± 2 Ma (MSWD = 1.15) and 223 ± 5 Ma (MSWD = 0.97), respectively. The Pulang and Songnuo porphyries both have high whole-rock Sr/Y ratios with minor or no negative Eu anomalies, consistent with derivation from hydrous magmas that underwent minor early plagioclase crystallization but abundant amphibole fractionation. The two porphyry intrusions are characterized by high large-ion-lithophile elements (LILE: Th, U, Ba, Rb) abundances, and low concentrations of high-field-strength elements (HFSE: Nb, Ta, Ti, Zr, Hf). They have similar initial Sr isotope ratios from 0.7055 to 0.7073, ƐNd (t) values from − 4.3 to − 1.6 and zircon ƐHf (t) values of − 1.81 ± 1.34 (n = 47) that are distinct from published results for the Permian–Early Triassic Paleo-Tethyan arc granitoids in the Sanjiang region but similar to the Neoproterozoic arc intrusions in the nearby western Yangtze craton. The Pulang and Songnuo porphyries have relatively high zircon EuN/EuN* ratios (0.59 ± 0.04, n = 52) and calculated Δ log fO2 (FMQ) values (1.61 ± 0.23, n = 52), consistent with relatively oxidized magmas. This feature is similar to the published data for the Neoproterozoic arc intrusions (EuN/EuN* = 0.55 ± 0.08; Δ log fO2 (FMQ) = 2.14 ± 0.60), but distinct from the published data for the reduced normal Paleo-Tethyan arc magmas (EuN/EuN* = 0.29 ± 0.10; Δ log fO2 (FMQ) = − 0.68 ± 0.88). Given that the most recent tectonic reconstruction models suggest that the Paleo-Tethys Ocean closed before ~ 220 Ma, we propose that the Pulang and Songnuo porphyries Cu deposits were formed in a postsubduction setting from oxidized melts generated by reactivating the Neoproterozoic arc root, unrelated to Paleo-Tethyan subduction. [ABSTRACT FROM AUTHOR]

The Sarduiyeh granitoid (SG) is intruded in the southeastern part of the Dehaj-Sarduiyeh volcano-sedimentary belt in the southeastern end of the Urumieh-Dokhtar Magmatic Arc (UDMA) in Iran. The medium-to-coarse-grained granitoid unit, with granular texture consists mainly of diorite, tonalite, granodiorite and monzogranitic rocks. Mineralogically, these rocks consist mainly of plagioclase, K-feldspar, quartz, biotite and hornblende. The whole rock geochemical analyses indicates that the SG is calc-alkaline, I-type, metaluminous, enriched in large ion lithophile elements (LILE; such as K, Cs, Pb) and depleted in high field strength elements (HFSE; such as Ti, Nb, Ta, Zr). Chondrite normalized plot of SG rare earth elements (REE) show light rare earth element enrichments with (LaN/YbN = 2.44–8.68) and flat heavy rare earth element patterns with (GdN/YbN = 1.02–1.36). The rather high Y (av. 19.35 ppm), low Sr content (av. 293.76 ppm) and low Cr and Ni contents (av. 20.1 and 4.69 ppm, respectively) of the SG demonstrate its normal calc-alkaline and non-adakitic nature, the features of Jebal Barez-type granitoids. The geochemical characteristics and isotopic composition, low ISr (0.7046–0.7049) and positive ɛtNd (+3.4 to +4.03) values, of the SG suggest that its parental magma formed as a result of partial melting from metabasic rocks of lower crust in a subduction-related arc setting. Fractionation of an assemblage dominated by plagioclase, K-feldspar, amphibole and magnetite may have been responsible for the evolution of the SG magma. U-Pb zircon geochronology gives an age of 27.95 ± 0.27 Ma for the SG, suggesting that the final collision between the Arabian plate and Central Iranian microcontinent may have happened in the Late Oligocene. [ABSTRACT FROM AUTHOR]

The Xikuangshan Sb deposit in central Hunan, South China is the largest Sb deposit in the world, which has supplied more than 50% of the world's Sb and with total Sb metal reserves of about 2.5 Mt. However, the age of this deposit is still not well constrained due to a lack of suitable minerals for reliable radiometric dating, which hampered the generation of a generally accepted genetic model of mineralization. Since the fluid-inclusion data suggest that the temperature of ore-forming fluids in the Xikuangshan deposit is up to 360 °C, zircon (U-Th)/He thermochronometry with the closure temperature of 160–200 °C was chosen here to elucidate the age of Sb mineralization. Detrital zircons in the altered host rocks from the Xikuangshan deposit yielded two (U-Th)/He age populations of 156–117 and 97–86 Ma. The older age population (156–117 Ma), which is well in accordance with previous Sm-Nd dating on hydrothermal calcite (156–124 Ma), probably represents the timing of main-stage Sb mineralization in the Xikuangshan Sb deposit, while the younger zircon (U-Th)/He ages may result from partial loss of He in zircon caused by the distal effect of deep-seated intrusions beneath the deposit. This study demonstrates that the (U-Th)/He dating of zircon in altered host rocks can be viable for constraining the timing of low-temperature mineralization. [ABSTRACT FROM AUTHOR]

The Paleo-Tethyan arc belt is host to a small number of porphyry Cu deposits the key controls on which remains poorly understood. It has been hypothesized that the Paleo-Tethyan arc magmas were reduced and therefore less fertile for porphyry Cu formation but few studies have been conducted to directly assess the magmatic oxygen fugacity. We investigate the magma fertility of eastern Paleo-Tethyan arc igneous rocks in the Sanjiang region, SW China, represented by the Maoding (268.3 ± 2.3 Ma), Suwalong (275.6 ± 1.4 Ma to 264.7 ± 1.4 Ma) and Baimaxueshan (255.7 ± 1.5 Ma to 249.3 ± 1.1 Ma) granitoids. They have geochemical features consistent with typical continental arc rocks, formed from partial melting of the mantle wedge, with increasing contamination of crust-derived melts over time. The presence of amphibole, high Sr/Y ratios (35 ± 20, n = 17), and lack of negative Eu anomalies (Eu N /Eu N ⁎ = 1.04 ± 0.3, n = 17) are consistent with derivation from hydrous magmas. Zircons from the intrusive rocks have relatively low Eu N /Eu N ⁎ (mostly <0.4) ratios and calculated ΔFMQ values (−2.1 ± 1.2, n = 86). Combined with apatite microphenocrysts with extremely low sulfur contents (< 0.12 wt% SO 3), it suggests that the intrusions originated from water-rich but reduced arc magmas, that were less fertile for porphyry Cu formation. Our study highlights that magmatic f O 2 is probably a critical control on the prospectivity of arc systems and confirms that zircon and apatite compositions can be used to evaluate porphyry Cu fertility. • The Paleo-Tethyan arc igneous rocks were dated from ~275 to 249 Ma. • They were derived from partial melting of mantle wedge during MASH processes. • These arc magmas were reduced and less fertile for porphyry Cu formation. • Zircon and apatite compositions can be used to evaluate porphyry Cu fertility. [ABSTRACT FROM AUTHOR]

Triassic granites crop out extensively in central Hunan Province, South China. Representative granites include the Baimashan, Weishan, and Ziyunshan plutons. Lithologically, these granites mainly comprise biotite monzogranite, two-mica granites, hornblende-biotite granite, hornblende-biotite monzogranite, and garnet-muscovite granite. These granites havein situzircon secondary ion mass spectrum U–Pb ages between 223.2 ± 3.3 and 209.3 ± 4.0 Ma, indicating that they likely formed predominantly in the Late Triassic. These granitic plutons have similar zircon Hf and O isotopic compositions, withεHf(t) values of −0.8 to −9.0, two-stage depleted mantle model ages (TDM2) of 1.81–1.31 Ga, and weighted mean ofδ18OZrcvalues of 8.53 ± 0.58‰ to 9.12 ± 0.28‰. Combined with U–Pb dating and Hf isotopic data, the elevated and variableδ18O andεHf(t) values of the individual granites indicate that these Triassic granites were likely produced by partial melting of upper Paleoproterozoic to lower Mesoproterozoic metasedimentary rocks and are S-type granites. The variable proportions of inherited zircons in certain samples with U–Pb ages of 627–992 Ma indicate the involvement of lower–middle Neoproterozoic crustal materials during magma crystallization through wall-rock contamination, which resulted in the wide range of isotopic compositions. Underplating of mantle-derived magma may have provided the thermal energy for partial melting of the upper Paleoproterozoic and lower Mesoproterozoic basements, thereby generating these late Triassic granites. The lack of positiveεHf(t) values and highδ18OZrcvalues indicate that the contribution of mantle-derived magmas to these granites may be insignificant. [ABSTRACT FROM AUTHOR]

Dolerite dike swarms are widespread across the North China Craton (NCC) of Hebei Province (China) and Inner Mongolia. Here, we report new geochemical, Sr–Nd–Pb isotope, and U–Pb zircon ages for representative samples of these dikes. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U–Pb analysis yielded consistent Permian ages of 274.8 ± 2.9 and 275.0 ± 4.5 Ma for zircons extracted from two dikes. The dolerites have highly variable compositions (SiO2 = 46.99–56.18 wt.%, TiO2 = 1.27–2.39 wt.%, Al2O3 = 14.42–16.20 wt.%, MgO = 5.18–7.75 wt.%, Fe2O3 = 8.03–13.52 wt.%, CaO = 5.18–9.75 wt.%, Na2O = 2.46–3.79 wt.%, K2O = 0.26–2.35 wt.%, and P2O5 = 0.18–0.37 wt.%) and are light rare earth element (LREE) and large ion lithophile element (LILE, e.g. Rb, Ba, and K, and Pb in sample SXG1-9) enriched, and Th and high field strength element (HFSE, e.g. Nb and Ta in sample SXG1-9, and Ti) depleted. The mafic dikes have relatively uniform (87Sr/86Sr)ivalues from 0.7031 to 0.7048, (206Pb/204Pb)ifrom 17.77 to 17.976, (207Pb/204Pb)ifrom 15.50 to 15.52, (208Pb/204Pb)ifrom 37.95 to 38.03, and positive ϵNd(t) (3.6–7.3), and variable neodymium model ages (TDM1 = 0.75–0.99 Ga, TDM2 = 0.34–0.74 Ga). These data suggest that the dike magmas were derived from partial melting of a depleted region of the asthenospheric mantle, and that they fractionated olivine, pyroxene, plagioclase, K-feldspar, and Ti-bearing phases without undergoing significant crustal contamination. These mafic dikes within the NCC formed during a period of crustal thinning in response to extension after Permian collision between the NCC and the Siberian Block. [ABSTRACT FROM AUTHOR]

Highlights: [•] New geochronology data to constrain the duration of magmatic-hydrothermal activity. [•] Two stages cooling history, early rapid cooling and late slow cooling. [•] Hydrothermal fluid circulation related to multiple stages of magma emplacement. [ABSTRACT FROM AUTHOR]

Post-orogenic mafic rocks from Northeast China consist of swarms of dolerite dikes. We report a new U–Pb zircon age, as well as whole-rock geochemical and Sr–Nd–Hf isotopic data. Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) U–Pb zircon analysis yielded an age of 210.3 ± 1.5 million years (i.e. Triassic) for these mafic dikes. Most Dalian mafic rocks exhibit low K2O + Na2O contents, and span the border between alkaline and calc-alkaline rock associations in the total alkali–silica diagram. The investigated dikes are also characterized by relatively high (87Sr/86Sr)i ratios (0.7061–0.7067) and negative ϵNd (t) (−4.7 to −4.3) and ϵHf (t) values (−4.1 to −1.1), implying that they were derived from an enriched lithospheric mantle source. The mafic dikes are characterized by relatively low MgO (4.65–5.44 wt.%), Mg# (41–44), and compatible element content [such as Cr (89.9–125 ppm) and Ni (56.7–72.2 ppm)], which are the features of an evolved mafic magma. No evidence supports the idea that the mafic rocks were affected by significant assimilation or crustal contamination during emplacement. We conclude that the dolerites formed in a post-orogenic extensional setting, related to lithospheric delamination or ‘collapse’ of the Central Asian Orogenic Belt (CAOB), also termed the Xingmeng Orogenic Belt in China. [ABSTRACT FROM AUTHOR]

Geochronological, geochemical, and whole-rock Sr–Nd isotopic analyses were performed on a suite of Palaeozoic nepheline syenites from Zijinshan to characterize their ages and petrogenesis. Laser ablation inductively coupled plasma-mass spectrometry U–Pb zircon analyses yield consistent ages of 525.7 ± 2.8 million years for a sample (HYK01). These intrusive rocks belong to the foid syenite magma series in terms of K2O + Na2O contents (14.3–15.2 wt.%) and to the shoshonitic series based on their high K2O contents (5.42–5.61 wt.%). The nepheline syenites are further characterized by high light rare earth element contents [(La/Yb) N  = 29.1–36.1]; show modest negative Eu anomalies (δEu = 0.5–0.6) and positive anomalies in Rb, Th, U, Pb, Zr, and Hf; are depleted in Ba and high field strength elements (P and Ti). In addition, all the nepheline syenites in this study display relatively low radiogenic Sr (87Sr/86Sr) i (0.7042–0.7043) and positive ϵNd (t) (0.7–0.8). These results suggest that the nepheline syenites were derived from depleted continental crust. The parent magmas likely experienced fractional crystallization of plagioclase, Ti-bearing oxides (e.g. rutile, ilmenite, and titanite), apatite, and zircon during ascent, with negligible crustal contamination before final emplacement at a high crustal level. [ABSTRACT FROM PUBLISHER]

Abstract: Precambrian mafic dykes in the North China Craton (NCC) consist of dolerite. Geochronological, geochemical, and whole-rock Sr–Nd isotopic analyses were performed on this suite of mafic dykes to characterise their ages and petrogenesis. Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) U–Pb zircon analyses yield consistent ages ranging from 837.9±4.8Ma to 2510±18Ma for seven of the mafic dykes (SHS01, TDG01, LJZ01, LQS02, HB02, WJ01, and DST01) from NCC. Based on these, the mafic dykes can be divided into three groupings: ~2.4–2.5Ga, ~1.8–1.9Ga and 0.8–1.0Ga. The studied dykes belong to the alkaline and sub-alkaline magma series in terms of K2O+Na2O contents (2.6–6.2wt.%), and to the Tholeiitic, calc-alkaline and high-K calc-alkaline series based on their K2O contents (0.1–2.1wt.%). The mafic dykes are further characterised by low and variable light rare earth elements (~2.4–2.5Ga mafic dykes, (La/Yb)N =3.83–10.4; ~1.8–1.9Ga mafic dykes, (La/Yb)N =1.45–2.35); 0.8–1.0Ga mafic dykes, (La/Yb) N =0.66–4.27, show variable Eu anomalies (δEu=0.94–1.35, 0.77–1.21; 0.92–1.28, respectively), positive anomalies in Ba, U, La and Pb, and are depleted in Rb and high field strength elements (Nb, Ta, Ti, and minor Zr and Hf). In addition, the studied mafic dykes all display relatively low radiogenic Sr [(87Sr/86Sr)i =0.6747–0.6921; 0.7017–0.7025; 0.7005–0.7049, respectively for the ~2.4–2.5Ga, ~1.8–1.9Ga and 0.8–1.0Ga mafic dyke groups] and large εNd (t) (13.2–13.5; 10.4–11.8; 6.5–8.5, respectively). These results suggest that all the mafic rocks were derived from a depleted mantle source hybridised by foundered lower crust. The parent mafic magmas likely experienced fractional crystallisation of olivine, pyroxene, hornblende, plagioclase and Fe–Ti oxides (e.g., rutile, ilmenite, titanite, etc.) during dyke ascent, with negligible evidence for crustal contamination prior to emplacement at a high crustal level. [Copyright &y& Elsevier]

Abstract: Mesozoic post-collisional andesites occur in the Gerze area within the Qiangtang Terrane of northern Tibet, China. Geochronological, geochemical, and whole-rock Sr–Nd isotopic analyses were performed on this suite of volcanic rocks to characterize their petrogenesis. Laser ablation-inductively coupled plasma-mass spectrometry U–Pb zircon analyses yielded consistent ages ranging from 122.4±0.4Ma to 124.4±0.4Ma for two andesite samples (JC01 and GZ01). The andesites belong to the alkaline and sub-alkaline magma series in terms of K2O+Na2O contents (4.7–10wt.%), and belong to the high-K calc-alkaline and calc-alkaline series on the basis of their high K2O contents (1.0–3.3 wt.%). The volcanic rocks are further characterized by the enrichment of light rare earth elements [(La/Yb)N =7.4–11.5] and large-ion lithophile elements (e.g., Rb), slightly negative Eu anomalies (Eu/Eu* =0.79–0.94), and negative anomalies in high field strength elements (e.g., Nb, Ta, and Ti) relative to primitive mantle. The samples show slightly elevated (87Sr/86Sr)i values that range from 0.7049 to 0.7057, and low ε Nd(t) values of −3.4 to 0.7. These results suggest that the rocks were derived from a compositionally heterogeneous mantle source and that their parent magmas are basalt magma. The parent mafic magmas may have undergone fractional crystallization of olivine, pyroxene, hornblende, and to a lesser extent, plagioclase during ascent through the thickened crustal pile, with minor or no crustal contamination, before the finally erupting as andesites. [Copyright &y& Elsevier]

TPost-orogenic intrusive complexes from the Sulu belt of eastern China consist of pyroxene monzonites and dioritic porphyrites. We report new U-Pb zircon ages, geochemical data, and Sr-Nd-Pb isotopic data for these rocks. Laser ablation-inductively coupled plasma-mass spectrometry U-Pb zircon analyses yielded a weighted mean 206Pb/238U age of 127.4 ± 1.2 Ma for dioritic porphyrites, consistent with crystallization ages (126 Ma) of the associated pyroxene monzonites. The intrusive complexes are characterized by enrichment in light rare earth elements and large ion lithophile elements (i.e. Rb, Ba, Pb, and Th) and depletion in heavy rare earth elements and high field strength elements (i.e. Nb, Ta, P, and Ti), high (87Sr/86Sr)i ranging from 0.7083 to 0.7093, low εNd(t) values from ε14.6 to - 19.2, 206Pb/204Pb = 16.65-17.18, 207Pb/204Pb = 15.33-15.54, and 208Pb/204Pb = 36.83-38.29. Results suggest that these intermediate plutons were derived from different sources. The primary magma-derived pyroxene monzonites resulted from partial melting of enriched mantle hybridized by melts of foundered lower crustal eclogitic materials before magma generation. In contrast, the parental magma of the dioritic porphyrites was derived from partial melting of mafic lower crust beneath the Wulian region induced by the underplating of basaltic magmas. The intrusive complexes may have been generated by subsequent fractionation of clinopyroxene, potassium feldspar, plagioclase, biotite, hornblende, ilmenite, and rutile. Neither was affected by crustal contamination. Combined with previous studies, these findings provide evidence that a Neoproterozoic batholith lies beneath the Wulian region. [ABSTRACT FROM AUTHOR]

Abstract: Post-orogenic granitic and associated mafic rocks from northeastern (NE) China consist of granodiorite and gabbro intrusions. We report here upon new U–Pb zircon ages, geochemical data and Sr–Nd–Hf isotopic data for these rocks. LA-ICP-MS U–Pb zircon analysis yields an age of 262.8±1.0Ma for the granitic rocks, and a uniform age of 262.1±0.7Ma for the gabbro. Most of the granitic and mafic rocks are characterised by low K2O+Na2O, and pertain to the subalkaline series in the total alkali–silica diagram. The granodiorite samples show low (87Sr/86Sr) i ranging from 0.700 to 0.705, positive ε Nd(t) values from +0.3 to +0.8, and large variation in ε Hf(t) values of between −4.0 and +2.5, indicating that both newly underplated basalt (70–80%) and ancient lower crustal sources (20–30%) contributed to their origin. Furthermore, positive ε Hf(t) values with two-stage model ages (T DM2) of 1123–1260Ma, together with Nd model ages (960–1000Ma), suggest an important episode of crustal growth during the Meso-Neoproterozoic beneath the Songliao Block. In contrast, the investigated gabbro is characterised by relatively high (87Sr/86Sr) i ratios (0.707–0.708), negative ε Nd(t) (−5.9 to −5.3) and ε Hf(t) values (−5.0 to −2.3), implying that this was derived from an enriched mantle source. The geochemical data indicate that the granitic magmas underwent separation of clinopyroxene, hornblende, K-feldspar, plagioclase, Ti-bearing phases (e.g., rutile, ilmenite, titanite), apatite and zircon during their evolution. Whereas the gabbro is characterised by low MgO (2.92–3.92wt.%), Mg# (35–41) and compatible elements content, such as Cr (10–68ppm), Co (16–31ppm) and Ni (5.7–33ppm), features of a more evolved mafic magma. There is no evidence that the granitic and mafic rocks were affected by crustal contamination during emplacement. Our interpretation is that the two coeval intrusive suites were both formed in a post-orogenic extensional setting, related to lithospheric delamination or ‘collapse’ of the Central Asian Orogenic Belt (CAOB) (Xingmeng orogenic Belt in China). [Copyright &y& Elsevier]

Abstract: Herein we present new U–Pb zircon ages, whole-rock geochemical data and Nd–Sr–Hf isotopic data for an Early Palaeozoic monzogranite batholith from the Tengchong–Baoshan Block, Western Yunnan Province, China. Mineralogical and geochemical features suggest that this granitoid is a high-K, calc-alkaline, I-type granite. SHRIMP and laser ablation ICP-MS (LA-ICP-MS) analysis of zircon yields ages of between 499±5Ma and 502±5Ma, for three samples from the batholith. The monzogranite is characterised by high initial 87Sr/86Sr (0.7132–0.7144), negative ε Nd(t) (−9.7 to −9.40) and ε Hf(t) (−10 to −13.1), and is interpreted to derive from remelting of pre-existing Palaeoproterozoic, high-K, metabasaltic rocks of the upper crust. The granitoid magma underwent extensive fractional crystallisation of biotite±hornblende, ilmenite, titanite, K-feldspar and plagioclase during emplacement. The crystallisation temperature of the magma lies in the range 633–733°C, however, there is no evidence to suggest crustal assimilation occurred during its ascent. Like the ∼500Ma, I-type granite of this study, there occur numerous granitoid rocks of Early Palaeozoic age (490–470Ma) in adjacent regions across the entire Tengchong–Baoshan Block (). This episode of plutonism is coeval with the widespread granitoid magmatism found throughout the Indian Plate and the Himalayan Orogenic Belt that are both subordinate parts of the ancient, Gondwana supercontinent. We infer, therefore, that the Tengchong–Baoshan Block may also have formed part of Gondwana, and that it separated from this supercontinent along with other crustal blocks during the Late Palaeozoic. Moreover, based on the findings of this study, we document the occurrence of arc-related magmatism in the Tengchong–Baoshan Block during the late Palaeoproterozoic. [Copyright &y& Elsevier]

• The age of the Carlin-type gold deposits in southwestern Guizhou is constrained to 132–160 Ma. • Three mineralization-unrelated thermal events with ages of 192–216 Ma, 88 Ma and 19–40 Ma, respectively, are identified. • The decrease of hydrothermal temperature and duration from lower to upper strata is revealed in the Huijiabao anticline. The Dian-Qian-Gui area in southwestern China is the second-largest concentration of the Carlin-type gold deposits in the world, and the southwestern Guizhou is the most important gold-producing district of the Dian-Qian-Gui area. Dating of the Carlin-type gold deposits is always a challenge due to the lack of ore-stage minerals which are suitable for conventional radiometric dating. Low-temperature thermochronometers, including fission track and (U-Th)/He, are temperature-sensitive radiometric dating techniques and have been successfully applied to elucidate many aspects of ore deposits, including the timing and duration of mineralization processes. In this study, zircon fission track, zircon (U-Th)/He and apatite fission track dating techniques were applied to the Carlin-type gold deposits in southwestern Guizhou. Samples for zircon and apatite analyses were collected from mineralized or altered sedimentary rocks in Shuiyindong, Taipingdong, Bojitian, Yata and Getang gold deposits. Four groups of thermochronological ages were obtained, i.e., 192–216 Ma, 132–160 Ma, 88 Ma, and 19–40 Ma, which are considered to be the records of four geological thermal events. Of them, most zircon fission track ages and all zircon (U-Th)/He ages concentrate in 132–160 Ma. Thermochronological constraints, combined with field relationships, suggest that the mineralization of the Carlin-type gold deposits in southwestern Guizhou most likely occurred in this period. Partial zircon fission track ages are in 192–216 Ma. They may record the cooling timing of a pre-ore thermal event caused by the Indosinian orogeny, which is supported by the paleogeotemperature restoration. A few zircon grains with high U content yield fission track age of 88 Ma, which may record a post-ore thermal event associated with the intrusion of local mafic dykes. All apatite fission track ages range in 19–40 Ma, which may record a lower temperature but extensive hydrothermal superimposition in the Cenozoic. Additionally, a corresponding relationship between zircon fission track ages and stratigraphic sequences was identified in the Huijiabao anticline, which is considered to reflect the decrease of temperature and duration of ore-forming hydrothermal activity from lower to upper stratigraphic sequences. [ABSTRACT FROM AUTHOR]

• The Sb mineralization in the Banxi deposit primarily occurred during 130–120 Ma. • Zircon (U-Th)/He system in altered host rocks can be completely reset by hydrothermal Sb mineralization and record its age. • This study proves zircon (U-Th)/He dating can be viable for constraining the timing of low-temperature hydrothermal mineralization. The Banxi Sb deposit is one of world-class Sb deposits located in the Xiangzhong Sb-Au metallogenic province in southern China. However, the mineralization age of this deposit is still not well constrained due to a lack of suitable minerals for reliable radiometric dating. Since the fluid-inclusion data suggest that the temperature of ore-forming fluids in the Banxi deposit is up to 330 °C, zircon (U-Th)/He thermochronometry with the closure temperature of 160–200 °C was chosen here to elucidate the timing of Sb mineralization of this deposit. Detrital zircons within three samples of altered host rocks in the Banxi deposit yielded (U-Th)/He dates of 132–113 Ma (weighted mean = 121 ± 12 Ma), 132–124 Ma (weighted mean = 129 ± 3 Ma) and 142–113 Ma (weighted mean = 125 ± 10 Ma), respectively, which are broadly consistent with the Rb-Sr and Sm-Nd isochron ages of hydrothermal sulfide minerals (~130 Ma). Combining with the reported ages of adjacent Sb deposits, we propose that Sb mineralization in the Banxi deposit may have primarily taken place during 130–120 Ma. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrothermal zircons intergrown with gold-related minerals and containing primary fluids inclusions were identified from the Badu gold deposit in the Youjiang basin, SW China. • The hydrothermal zircons display high LREE contents and relatively flat light rare-earth element patterns, consistent with hydrothermal zircon reported worldwide. • In-situ SIMS and LA-ICP-MS U-Pb datings on the hydrothermal zircons reveal that the Badu deposit formed at ca. 140 Ma, probably in response to the Early Cretaceous large-scale lithospheric extension of South China. Selecting a robust chronometer is crucial to determine the primary mineralization age of the deposits that have witnessed multiple hydrothermal events. The Youjiang basin of South China hosts the world's second-largest Carlin-type gold province. However, the age of the Carlin-type gold mineralization remains highly debated, partly due to the presence of multiple hydrothermal events that may have disturbed the primary isotopic system with low durability. Hydrothermal zircon is a robust chronometer that can survive multiple hydrothermal events. To this end, in this study, we report in-situ secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) U–Pb dating results of hydrothermal zircon identified in carbonate–sericite–sulfide–altered dolerite from the Badu Carlin-type gold deposit to constrain the timing of gold mineralization. The hydrothermal zircons exhibit subhedral to anhedral morphologies, sector cathodoluminescence zonings, and contain gold-related mineral assemblages of arsenian pyrite, quartz, sericite, and carbonate. Primary two-phase fluid inclusions also commonly occur in the hydrothermal zircons. Compositionally, these zircons feature relatively flat light rare-earth element (REE) patterns, high La contents, low (Sm/La) N values, and small Eu and Ce anomalies, which are different from the magmatic counterparts of the Badu pluton but consistent with those of hydrothermal zircons reported worldwide. These features indicate that the hydrothermal zircons are probably paragenetically associated with the gold mineralization. Consequently, the U–Pb ages of ca. 140 Ma of these zircons, which are much younger than those of the magmatic zircon in the fresh dolerite, can represent the timing of primary gold mineralization of Badu. Our new data suggests that there truly was an episode of gold mineralization during the Early Cretaceous in the Youjiang basin, which may have been driven by large-scale lithospheric extension in the interior of South China. This study demonstrates that hydrothermal zircon could be a robust clock for investigating the timing of magmatic rock-hosted Carlin-type gold deposits. [ABSTRACT FROM AUTHOR]

Abstract: The Jinshajiang–Red River porphyry Cu–Mo metallogenic belt is an important Cenozoic porphyry Cu–Mo mineralization concentrating zone in the eastern Indo‐Asian collision zone. New zircon U–Pb and molybdenite Re–Os ages and compilation of previously published ages indicate that porphyry Cu–Mo deposits in the belt did not form at the same time, i.e., the porphyry emplacement and relevant Cu–Mo mineralization ages of the Ailaoshan–Red River ore belt in south range from 36.3Ma to 34.6Ma, and from 36.0Ma to 33.9Ma, respectively, which are obviously younger than the porphyry emplacement ages of 43.8–36.9Ma and the relevant Cu–Mo mineralization ages of 41.6–35.8Ma of the Yulong ore belt in north. Tectonic studies indicated that the Jinshajiang fault system in north and Ailaoshan–Red River fault system in south of the Jinsjiang–Red river belt had different strike-slip patterns and ages. The right-lateral strike-slip motion of the Jinshajiang fault system initiated at ca. 43Ma with corresponding formation of the Yulong porphyry Cu–Mo system, whereas the left-lateral strike-slip motion of the Ailaoshan–Red River fault system initiated at ca. 36Ma with corresponding formation of the Ailaoshan–Red River porphyry Cu–Mo system. Therefore, the different ages of porphyry Cu–Mo systems, between in north and south of the Jinshajiang–Red River belt, indicate that the porphyry Cu–Mo mineralization is closely related to the divergent strike-slip movements between the Jinshajiang and Ailaoshan–Red River strike-slip faulting resulted from the Indo‐Asian collision. The tanslithospheric Jinshajiang–Red River faulting caused partial melting of the enriched mantle sources of alkali-rich porphyries by depressurization or/and asthenospheric heating, and facilitated the migration of alkali-rich magmas and the corresponding formation of alkali-rich porphyries and relevant Cu–Mo deposits in the belt. [Copyright &y& Elsevier]

A genetic link between Sb mineralization and magmatism has previously been proposed, yet little is known about the mobility of Sb during magma degassing. We have carried out a series of experiments to understand the effects of fluid composition, oxygen fugacity (f O 2), pressure and temperature on the partitioning of Sb between magmatic fluids and a rhyolitic melt at crustal conditions (T = 850 °C, P = 200 MPa). The experiments were carried out in Molybdenum - Hafnium Carbide (MHC) pressure vessel assemblies at T = 850 to 1000 °C, P = 100 to 200 MPa and log f O 2 from 1.64 log units below to 1.78 log units above the Ni-NiO buffer. Antimony partitions into aqueous chloride-bearing fluids weakly, with the fluid/silicate melt partition coefficient of Sb (D Sb fluid/melt) increasing from 0.48 ± 0.11 (1σ) to only 0.85 ± 0.17 (1σ) as the total chlorine concentration in the fluid increases from 0.99 to 16.24 m, indicating the lack of significant Sb-chloride species in the fluid. In contrast, D Sb fluid/melt increased from 0.89 ± 0.19 to 1.49 ± 0.19 as the aluminum saturation index (ASI) of the melt increased from 1.02 to 1.24. The moderate increase in D Sb fluid/melt with increasing ASI of the melt (and HCl/metal chloride in the fluid) most likely relates to decreasing Sb solubility in the melt and further demonstrates the lack of significant chloride complexing of Sb. We also found that D Sb fluid/melt is only slightly influenced by f O 2 suggesting that Sb does not change oxidation state (Sb3+) at redox conditions typical of arc magmatism. Furthermore, the presence of reduced S species in the fluid phase caused only a minor increase in D Sb fluid/melt indicating that Sb-sulfide complexes are not particularly stable in magmatic fluids. Our data also show that pressure and temperature, within the range of 100 to 200 MPa and 850 to 1000 °C, do not significantly influence D Sb fluid/melt. Thus it is apparent that at most possible conditions at which rhyolitic melts degas in the upper crust, Sb will only weakly partition into the fluid phase and it is likely that the Sb budget of large epithermal Sb deposits is not directly derived from primary magmatic fluids. [ABSTRACT FROM AUTHOR]

Highlights: [•] Late Paleoproterozoic mafic dykes in the North China Craton were dated at ∼1620Ma. [•] The dykes were derived from depleted mantle source. [•] The origin of the dykes is related to the foundered lower crustal. [ABSTRACT FROM AUTHOR]

Mafic dolerite dykes form a series of swarms that are widespread across the North China Craton (NCC). We present U–Pb zircon ages, geochemical data, and Sr–Nd–Hf isotopic data for representative samples of the Shaanxi dolerite dykes in the southern NCC. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb zircon analyses for three samples yield ages ranging from 448.1±1.2 to 489.6±0.9Ma (i.e., Cambro-Ordovician). The dolerites are characterised by a wide range of rock compositions. They display enrichments in light rare earth element (LREEs) and large ion lithophile element (LILE) (i.e., Ba, U, K and Pb), as well as depletion in high field strength (HFSE) (Nb, Ta, Hf and Ti). The mafic dykes have relatively uniform (87Sr/86Sr) i ranging from 0.7049 to 0.7076, (176Hf/177Hf) i from 0.282187 to 0.282236, low εNd (t) values, from −4.1 to −4.9, εHf (t) values of between −7.9 and −9.8, for zircon, and high hafnium model ages (TDM1 =1366–1535Ma, TDM2 =1924–2081Ma). These results suggest that the dykes are derived by partial melting of an enriched, lithospheric mantle source. The magmas underwent fractionation of olivine, pyroxene, plagioclase, and Ti-bearing phases (rutile, ilmenite, titanite), along with crustal contamination. The formation of the Shaanxi Province, NCC mafic dykes can be attributed to the collision between the NCC and south Qinling Block. Specifically, these magmas formed as a result of crustal thinning in response to extension that followed this collision. [ABSTRACT FROM AUTHOR]