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Large‐scale Cenozoic magmatic rocks from the interplay between the Indian and Eurasian plate are exposed in the Yulong porphyry copper belt in the northern Jinshajiang–Ailaoshan domain. Alkali‐rich magmas along the Yulong porphyry copper belt can reveal the tectono‐magmatic processes in the Sanjiang region. In this study, we present new zircon U–Pb–Hf isotopes and whole rock geochemistry of Cenozoic granitoids from the Zhalaga area in the northern Yulong porphyry copper belt. The Zircon U–Pb dating results show that the Zhalaga granitic porphyry crystallized at ca. 42–38 Ma. These porphyry deposits are depleted in Nb, Ta, Sr, and Ti enriched in alkaline and rare earth elements (REEs), and exhibit high zircon saturation temperatures, that strongly indicate A‐type affinity. These data and the generally positive ∊Hf(t) values (2.0–4.5) suggest the magmas originated from a hybrid of partial melting of subduction‐modified lithospheric mantle, possibly triggered by upwelling of the asthenospheric mantle. Geochronological and geochemical data of the current and previous studies distinguish three magmatic phases during the Cenozoic in the Jinshajiang–Ailaoshan region: (1) ca. 62–48 Ma; (2) ca. 44–30 Ma; and (3) ca. 28–16 Ma. The strong collision between the Indian and Eurasian plates produced relatively fast convergence rates during the first episode (ca. 62–48 Ma), whereas the subsequent right‐lateral strike‐slip faulting in the Jinshajiang fault zone initiated at ca. 43 Ma is associated with the relatively low India–Eurasia convergence rates during ca. 44–30 Ma. These significantly impacted the nature and spatial distribution of the magmatism and the large‐scale metallogeny during the Cenozoic in the Sanjiang region. We suggest that the Zhalaga alkali‐rich magmas occurred in a transition period from involving soft to hard collisional settings. This remarkable example demonstrates that alkali‐rich magmas with A‐type affinity are also generated in an orogenic tectonic setting. [ABSTRACT FROM AUTHOR]

The Beikang Basin is located in the southern part of the South China Sea (SCS), which is one of most tectonically complex sea areas. It is a deepwater sedimentary basin that was mainly deposited during the Cenozoic era. Owing to data restrictions, the research on carbonate platforms of this area is still in its infancy. High‐resolution seismic data are analyzed to identify the Miocene carbonate platforms and reconstruct the architecture and growth history. The carbonate platforms of Beikang Basin began to develop in the Late Oligocene‐Early Miocene, were extended in the Middle Miocene, and declined in the Late Miocene. The carbonate platform mainly developed during two periods: the Oligocene to the Early Miocene, and the Middle Miocene. The carbonate platforms that developed in the Middle Miocene were the most prosperous. The Middle Miocene carbonate platform in the Beikang Basin can be divided into three stages. In the first stage, the platforms had wide range which were thin. During the second stage, the platforms had a smaller range that was controlled by faults. In the third stage, the platforms were gradually submerged. The platform structure developed in the Middle Miocene at the Beikang Basin was controlled by the rate of rising/falling of the sea level and the carbonate growth rate. Based on an analysis of these changes and relationship, the platform can be divided into several patterns: retrogradation, submerged, aggradation, progradation, outward with up‐stepping, outward with down‐stepping, and down‐stepping platforms. At the top of the carbonate platforms in the Beikang Basin a set of carbonate wings or mushrooms usually appeared. These were formed during a period of relative sea‐level decline. It is believed that the Miocene carbonate platforms in the Beikang Basin are mainly controlled by tectonic and sedimentary environments, and are also affected by terrestrial detritus. [ABSTRACT FROM AUTHOR]

New zircon U–Pb ages, whole‐rock geochemistry and zircon Hf isotopes from the Habo porphyry Western Yunnan, China, were determined to provide constraints on the timing of uplift of the Eastern Tibetan Plateau. The intrusive rocks consist of shoshonitic porphyry (syenite porphyry and monzonite porphyry). Zircon laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) U–Pb dating indicates coeval emplacement ages of ~35 Ma. The porphyries have alkaline affinities, enrichment in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) (e.g., Rb, Th, U, Pb), with depletion of high field strength elements (HFSEs) (e.g., Nb, Ti, Ta) and weak Eu anomalies. They display uniform Lu–Hf isotopic compositions with negative zircon εHf(t) values ranging from ‐3.9 to ‐0.6. The chemical characteristics of the syenite porphyries indicated that they most likely originated from the lower crust, with mantle‐derived material involved in their generation. Geochemically, the monzonite porphyries are similar to the syenite porphyries; however, the lower MgO contents suggest that they were produced by different degrees of partial melting of the same lower crust source. Combined with the geochemical and isotopic data in this paper, imply that the alkali‐rich porphyries of the Habo polymetallic deposit were derived from the partial melting of lower crust, enriched by mantle magma, formed in a conversion stage from stress extrusion (a strike‐slip shear process) to local stress relaxation (a strike‐slip pull‐apart process) at the Ailaoshao tectonic zone. [ABSTRACT FROM AUTHOR]

This work restored the erosion thickness of the top surface of each Cretaceous formations penetrated by the typical well in the Hari sag, and simulated the subsidence burial history of this well with software BasinMod. It is firstly pointed out that the tectonic subsidence evolution of the Hari sag since the Cretaceous can be divided into four phases: initial subsidence phase, rapid subsidence phase, uplift and erosion phase, and stable slow subsidence phase. A detailed reconstruction of the tectono–thermal evolution and hydrocarbon generation histories of typical well was undertaken using the EASY Ro% model, which is constrained by vitrinite reflectance (Ro) and homogenization temperatures of fluid inclusions. In the rapid subsidence phase, the peak period of hydrocarbon generation was reached at c.a. 105.59 Ma with the increasing thermal evolution degree. A concomitant rapid increase in paleotemperatures occurred and reached a maximum geothermal gradient of about 43–45°C/km. The main hydrocarbon generation period ensued around 105.59–80.00 Ma and the greatest buried depth of the Hari sag was reached at c.a. 80.00 Ma, when the maximum paleo–temperature was over 180°C. Subsequently, the sag entered an uplift and erosion phase followed by a stable slow subsidence phase during which the temperature gradient, thermal evolution, and hydrocarbon generation decreased gradually. The hydrocarbon accumulation period was discussed based on homogenization temperatures of inclusions and it is believed that two periods of rapid hydrocarbon accumulation events occurred during the Cretaceous rapid subsidence phase. The first accumulation period observed in the Bayingebi Formation (K1b) occurred primarily around 105.59–103.50 Ma with temperatures of 125–150°C. The second accumulation period observed in the Suhongtu Formation (K1s) occurred primarily around 84.00–80.00 Ma with temperatures of 120–130°C. The second is the major accumulation period, and the accumulation mainly occurred in the Late Cretaceous. The hydrocarbon accumulation process was comprehensively controlled by tectono–thermal evolution and hydrocarbon generation history. During the rapid subsidence phase, the paleo temperature and geothermal gradient increased rapidly and resulted in increasing thermal evolution extending into the peak period of hydrocarbon generation, which is the key reason for hydrocarbon filling and accumulation. [ABSTRACT FROM AUTHOR]

Abstract: As a window of insight into the lower crust, high pressure granulite has received much attention since last decade. Yushugou high pressure granulite‐peridotite Complex was located in the northeast margin of Southern Tianshan, NW China. Previous ideas agreed that the peridotite unit in Yushugou, combined with the ultramafic rocks in Tonghuashan and Liuhuangshan, represent an ophiolite belt. However, the metamorphic evolution and tectonic mechanism of the Yushugou high pressure (HP) granulite remain controversial. Petrological investigations and phase equilibrium modelling for two representative felsic granulite samples suggest two stages metamorphism of the rocks in Yushugou Complex. Granulite facies metamorphism (Stage I) with P‐T conditions of 9.8–10.4 kbar at 895–920°C was recorded by the porphyroblastic garnet core; HP granulite facies metamorphism (Stage II) shows P‐T conditions of 13.2–13.5 kbar at 845–860°C, based on the increasing grossular and decreasing pyrope contents of garnet rims. The Yushugou HP felsic granulites have recorded an anticlockwise P‐T path, characterized by the temperature decreasing and pressure increasing simultaneously. The LA‐ICP‐MS isotopic investigations on zircons from the felsic granulite show that the protolith ages of the granlulites are ∼430 Ma, with two age groups of ∼390 Ma and 340–350 Ma from the metamorphic rims of zircon, indicating the Stage I and II metamorphic events, respectively. A tectonic model was proposed to interpret the processes. The investigated felsic granulite was derived from deep rooted hanging wall, with Stage I granulite facies metamorphism of ∼390 Ma, which may be related to the Devonian arc magmatic intrusion; Stage II HP granulite facies metamorphism (340–350 Ma) may due to the involvement of being captured into the subducting slab and experienced the high pressure metamorphism. [ABSTRACT FROM AUTHOR]

The article presents a study that highlights geochronology constraints on the petrogenesis of gneissic alkali-granite in the Dabie-Sulu ultra-high pressure metamorphic terrain, Donghai County in eastern China. Topics include analysis of zircons in gneissic alkali-granites, the protolith of alkali granite genesis, and rock-forming minerals such as plagioclase, quartz and biotite found in the region.

The wedge shaped Dong Tso ophiolitic block is distributed near the transition point from the western to the middle sub-belt of the Bangong-Nujiang suture zone. The ophiolite is characterized by well-developed cumulate rocks that are mainly composed of cumulate and massive gabbros. In the cumulate gabbros, the adcumulate amphiboles are distributed extensively around the plagioclase and residual pyroxene grains; hence, the rocks are named adcumulate amphibole-gabbro. In this study, the formation age of the ophiolite has been estimated to be 166 ± 4 million years (Ma) by the sensitive high-resolution ion microprobe (SHRIMP) II U-Pb isotopic analysis of the zircons from the adcumulate amphibole-gabbro; the 40Ar/39Ar plateau age was estimated to be 148.19 ± 1.53 Ma, which should represent the emplacement time of the ophiolite, by isotopic dating of the pure amphibole mineral from the amphibole-schist. Two different suits of volcanic lavas have been recognized in this work. The purple colored pillow basalts have high TiO2 and P2O5 contents, and are rich in light rare earth elements (LREEs), large-ion lithospheric elements (LILEs) and high-field-strength elements (HFSEs), the characteristics that are the typical of the oceanic island basalt (OIB). On the other hand, other massive basaltic andesites of celadon color are poor in MgO; rich in Fe2O3, LREEs, LILEs, and HFSEs; and especially characterized by negative Nb and Ta anomalies, the properties that establish the andesites as continental arc volcanic rocks. It is concluded that hotspots had developed in the old Dong Tso basin, the oceanic basin that had been developing from middle Jurassic (166 Ma) or even before and emplaced northward in late Jurassic (about 148 Ma). [ABSTRACT FROM AUTHOR]

The Pulan-Xiangquanhe ophiolite in the western Yarlung Tsangpo suture zone of Tibet is investigated for its geochemistry, geochronology, and tectonic implications in detail. Sensitive high resolution ion micro-probe zircon U-Pb dating reveals that diabases in the ophiolite from the three locations of Xugugab, Mapam Yum Co and La'nga Co are dated at 122.3 ± 2.5 Ma, 118.8 ± 1.8 Ma and 120.5 ± 1.9 Ma, respectively. These early Cretaceous mafic rocks have Na2O+K2O, rare earth element patterns, trace elemental spider diagram and other geochemical fingerprints of typical mature back-arc basin affinity. Therefore, the Pulan-Xiangquanhe ophiolite formed under a mature back-arc basin environment, which was a product of this intra-oceanic subduction system. A suprasubduction system could have existed in the southern margin of Eurasia, which involved both intra-oceanic and continent-ward subductions. Extension dominated the southern margin of the Eurasian continent during the early Cretaceous. [ABSTRACT FROM AUTHOR]

The article talks about Miocene tropical carbonates deposition in the South China Sea, carbonate platforms developed in topographic highs during the Eocene to Early Oligocene rifting phase, exhibiting platform fragmentation and contraction and controlled by syn-depositional. It talks about rise in sea level, growth of carbonates, accumulation rate of carbonate rocks, development of the outward progradation platform and differences in tectonic subsidence.

The article talks about the tectonic compression pamir syntax in the Tibetan Plateau, the distribution of Taxkorgan alkalic complex, being the largest intrusive rock in the region and its importance in lithosphere shortening and thickening. It talks about zankangou rock mass located in Taxkorganarae, diopside syenite which has gray and equigranular texture, the mineral composed of granet, titanite and apatite and diopside syenites being rich in alkali.

The article talks about the Ailaoshan tectonic belt that is banded with alkali rich porphyry belt developing copper, gold deposits, the Xiaoqiaotou quartz monozygotic porphyry body located in Cenozoic Jianchuan basin and in the intersection of Yangtze continental block and the Ailaoshan tectonic belt. It talks about the quartz monozygotic porphyry, being enriched in rare earth elements, ion lithophile elements and with field strength.

The article discusses the tectonic-thermal evolution history and its controls on petroleum geology of Weibei Uplift. Topics discussed include analysing thermal evolution history of Ordovician carbonate rock with bitumen reflectance, maximum Paleotemperature of the Weibei Uplift Ordovician strata in the Early Cretaceous, and study of petroleum geology with determination of the Weibei Uplift tectonic-thermal evolution history.

The article is a study on the Yushugou high-pressure granulite-peridotite complex from the Southern Tianshan mountains in China. They contain a rare association of granulite and peridotite and the article discusses a study proposing a subduction model for the granulites based on the U-Pb zircon dating and petrological study. The high-pressure mafic granulites are grouped into two types namely the hypersthene-bearing and the hypersthene-free granulite.