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Reservoirs in the dolomites of the Middle Permian Qixia Formation in the Sichuan Basin are currently important oil and gas exploration objects in China. However, the questions concerning the sources of the dolomitized fluids and the control factors of the Qixia hydrothermal dolomites remain unclear. In this study, the original hydrothermal dolomites (the replacement dolomites (RDs) and saddle dolomites (SDs)) from the Qixia Formation in the southwestern Sichuan Basin (the PR1 well and Baoxing section) were mainly examined using novel in situ carbonate U-Pb dating with clumped isotopes (∆47). Our results show that the U-Pb ages of the latest SDs from the PR1 well (located in the middle zone of the Emeishan large igneous province (ELIP) and distanced from the Orogenic Belt of Longmenshan) are 257.9–251.0 Ma, coincident with the period of main activity of the ELIP. Combined with the previous U-Pb dating, we propose that the high-temperature T∆47 (82.2–108.4 °C and 127.5–205.9 °C) recorded for SDs from the PR1 well and Baoxing section may have responded to ELIP activity and Longmenshan orogeny activity, respectively. In addition, in the entire southwestern Sichuan Basin, the RDs and SDs yield similar δ13C and δ18O values, indicating that the dolomites were formed by hydrothermal fluids of similar sources, with marine hydrothermal fluids being a highly possible source. Finally, this study proposes a new hydrothermal dolomite genesis model for the Qixia Formation, emphasizing that the formation of hydrothermal dolomites mainly depends on the proximity to tectonic thermal events in space and time. [ABSTRACT FROM AUTHOR]

[Display omitted] • The migmatite records the evolution of the Dabie orogen from Triassic to Cretaceous. • The upwelling asthenosphere provided a heat source for the Triassic metamorphism. • The migmatite is the product of multiple anatexis of the subducted continental crust. The Dabie orogen underwent a 'complete' orogenic cycle from Triassic collisional orogeny to Early Cretaceous tectonic collapse. Zircons of the migmatite in the North Dabie terrane recorded the processes from Triassic granulite-facies metamorphism to Early Cretaceous anatexis. Three types of zircon are recognized in the migmatite: the Neoproterozoic inherited magmatic zircon, the Triassic metamorphic zircon, and the Late Jurassic–Early Cretaceous anatectic zircon. The Neoproterozoic inherited magmatic zircons suggest the protolith of the migmatite has a tectonic affinity with the Yangtze Craton (YC). The Triassic metamorphic zircon domains have variable ε Hf (t) values from −4.1 to 3.6 and low δ18O compositions ranging from −4.36‰ to −0.30‰. The anatectic zircon domains have clearly negative ε Hf (t) values of −19.8 to 0.8 (mostly less than −10.0) and relatively high δ18O values from −4.24‰ to 3.49‰. Based on the chronological and isotopic data of migmatite and the results of previous studies, the Triassic granulite-facies metamorphism was closely related to the asthenosphere upwelling after the slab break-off during the orogenic stage, and the Early Cretaceous anatexis respond to widely heat event during the collapse stage of orogen. [ABSTRACT FROM AUTHOR]

Titanium isotopes recorded in glacial diamictites with depositional ages between 2.9 and 0.3 Ga show that the upper continental crust became significantly more felsic relative to the present-day crust during the amalgamation of the Paleoproterozoic Nuna and the Neoproterozoic Gondwana supercontinents. This can be attributed to the continental collisions involved in the assembly of Nuna and Gondwana. The resulting high topographic relief of Nuna and Gondwana orogens must have resulted in an enhanced erosional supply from the continents to oceans. The step changes in the development of organismal complexity from prokaryotes to eukaryotes, and eventually metazoans, appear to be temporally correlated to instances where collisional mountain-building sustained an elevated nutrient supply from the continents to oceans. The nutrient surge associated with the rise of the Gondwana mountains likely provided the necessary impetus for the Neoproterozoic ecological expansion of eukaryotes and the eventual radiation of metazoans. A similar link between the enhanced nutrient supply from Nuna mountains and the radiation of early eukaryotes is plausible, although its mechanistic underpinnings remain unclear. The termination of Nuna orogeny and its transition to Rodinia without significant breakup and subsequent collisional orogenesis corresponds to the long lull in Earth's redox and biological evolution in its middle age. • Pronounced variations in the felsic character of Proterozoic upper crust. • These variations can be temporally linked to the assembly of Nuna and Gondwana. • High continental relief brackets the mid-Proterozoic lull in eukaryote evolution. • Gondwana orogeny likely facilitated the Neoproterozoic redox and biological changes. • Enhanced erosion linked to Nuna orogeny may have aided the radiation of eukaryotes. [ABSTRACT FROM AUTHOR]

• The Linte massif reveals a protracted magmatism which lasted at least 60 Ma. • Rocks show geochemical affinities of I-type, shoshonitic and metaluminous granitoids. • The 660 and 630 Ma rocks originate from source involving mantle material which could have been mingled or mixed with crustal component while the 600 Ma rocks come from crustal material. • They were formed during the syn- collisional phase of the Pan-African orogeny. The Central African Fold Belt (CAFB) holds a key position in understanding the process and implications of the Pan-African orogeny in central Africa. However, it has not been fully understood as geological information on some vital domains is not yet available. The Linte massif in the Adamawa-Yade, one of the unrepresented terranes, was investigated and its whole rock geochemical, zircon U-Pb geochronology and Hf-O isotope characteristics and whole rock Sr-Nd data are presented and discussed here. The Linte massif is largely constituted of syenite and subordinate monzonite. The zircon U - Pb dating reveals three major ages at 660, 630 and 600 Ma, indicating a protracted magmatism which lasted at least 60 Ma, during the Neoproterozoic. The rocks are shoshonites, I-type and metaluminous. They have high LILEs (Cs, Rb, Ba and Sr), HFSEs (Th and U) and LREE contents. Their Nb/U, Ta/U, Ce/Pb, Th/La and Th/U ratios, δ18O zrn (5.3–7.6‰) and zircon εHf(t) (−14.7 to +3.2), point toward predominantly crustal with or without a mantle component in the sources. The negative εNd(t) values (−8.1 to −10.0), Paleoproterozoic Nd-T DM model ages (ca. 1700–1900 Ma), Hf-T DM2 ages of ca. 1300–2400 Ma of zircon grains in Neoproterozoic rocks underline their derivation from Mesoproterozoic to Paleoproterozoic basement rocks. The lithospheric mantle-generated heat facilitated partial melting in the sources region, as inferred from the shoshonitic affinity and the subduction-related geochemical features (Nb, Ta and Ti depletion). A mainly crustal source with a minor mantle component is inferred for the 660 Ma magmatism and for the 630 Ma rocks emplaced during crustal thickening. On the other hand, the 600 Ma (youngest) magmatic rocks were derived from a crustal source. We infer a subduction-collision setting for the Linte massif during the 660–600 Ma interval. The 630–600 Ma interval of the culmination of collision is consistent with the timing of the main convergence of the Brasiliano Orogeny recorded in South America (∼630–600 Ma), suggesting continuation of tectonic features into the western Gondwana. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zartorosht is a typical orogenic gold deposit hosted in Sanandaj-Sirjan zone of SE Iran. • The ore-forming fluids in Zartorosht may have had a mixed metamorphic and mantle source. • Temperature-pressure-salinity diagram of Zartorosht favors a downward trend of temperature. • Crack-filling Au in pyrite reveals mineralization was associated with pressure drop. Orogenic-type deposits are widely developed in the Sanandaj-Sirjan Zone (SSZ) of Iran, but few studies were done on the gold metallogeny in the southern SSZ. Here, we conducted fluid inclusion (FI) studies on the auriferous quartz veins from the Zartorosht deposit, in order to unravel the ore-fluid nature and key controls on ore element transport and deposition. Vein-type gold mineralization at Zartorosht is hosted along E-W-trending normal faults in greenschist-facies metamorphic rocks. Fluid inclusion analysis of the main-ore stage quartz suggests that the ore-forming fluids belong to the H 2 O-NaCl-CO 2 system, with homogenization temperatures of 230–290 °C and salinities of 3–7 wt% NaCl eqv., resembling that of typical orogenic gold deposits. The ore-forming fluids display a mixed metamorphic-mantle source based on multi-isotope evidence: 1) the ore-fluid δD V-SMOW (−69.8 to −45.1‰), δ18O H2O-SMOW (2.3–6.0‰), and δ13C V-PDB (−21.1 to −6.2‰) values are similar to mantle-derived fluids; 2) the ore-fluids have high 3He/4He (2.51–8.00 Ra) and 40Ar/36Ar (296–389) values, suggesting that mantle-derived gases were trapped inside the FIs; 3) calculation suggests that mantle-derived helium in the FIs accounts for (average) 8.34% of the total helium. Consequently, we propose that the Zartorosht gold mineralization is of orogenic-type. The decreasing pressure trend from early- to late-ore stage and the microfracture-filling gold occurrence suggest that temperature and pressure drop is the key trigger for gold deposition. Integrated with previous studies, we demonstrate that the ore-forming fluids were likely produced during the Cenozoic extension and post-peak metamorphism of the Zagros orogeny. Crustal-scale ductile shearing may have allowed the mantle-derived fluids to ascend into their secondary brittle structures, where the ores were precipitated in fracture-filling auriferous sulfide-quartz veins, forming the Zartorosht Au deposit. [ABSTRACT FROM AUTHOR]

Among the three cratons (North China, Yangtze, and Tarim) in China, the Tarim Craton during Precambrian is the least known for its evolution due to its broad Phanerozoic cover. The affinity of the Tarim Craton with Gondwana supercontinent during the Cryogenian-Ediacaran interval has long been debated. In this contribution, we report carbon and oxygen isotopes of the Ediacaran-Cambrian siliciclastic‑carbonate from successions in the northwestern Tarim Craton. The results exhibit one pronounced negative and one positive carbon isotopic excursions (CIE) in the Ediacaran sections (N3 and P1), and a distinct negative CIE at the base of the Cambrian (N4). With the constraints of geochronological data, we proposed that the Ediacaran-lower Cambrian chemostratigraphy of the northwestern Tarim basin correlates well with the lower Ediacaran and lower Cambrian from Yangtze, Oman, Australia, Namibia, and Canada basins. N3 in the Tarim Craton possibly represents a new contribution to the Shuram-Wonoka anomaly globally. With these data, together with previously published tectonostratigraphic and paleogeographic reconstructions, we propose that the Tarim Craton may have been involved in the Pan-African Orogeny during the assembly of Gondwana, and was positioned close to the Yangtze, Oman, and Namibia cratons along the northern periphery of the Gondwana supercontinent • Global correlation of the Ediacaran isotope excursions of the Tarim craton • A new contribution to the Shuram-Wonoka carbon isotopic anomaly • The affinity of the Tarim Craton with the Gondwana supercontinent [ABSTRACT FROM AUTHOR]