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The supra-subduction zone ophiolite or ophiolitic mélange formed in the forearc setting is generally considered to be a key geological record for subduction initiation (SI) with petrological characteristics comparable to the SI-related rock sequence from forearc basalt (FAB) to boninite in the Izu-Bonin-Mariana subduction zone. Nevertheless, the standard FAB and boninite are generally difficult to observe in the forearc rocks generated during SI. Yet, a typical rock sequence indicating the SI of the western Proto-Tethys Ocean is reported for the first time in the Qimanyute intra-oceanic forearc system in the western Kunlun Orogen, Northwest Tibetan Plateau. The magmatic compositions, which range from less to more high field strength element (HFSE)-depleted and large ion lithophile element (LILE)-enriched, are changing from oceanic plagiogranites (ca. 494 Ma) to forearc basalt-like gabbros (FAB-Gs, ca. 487 Ma), boninites, and subsequent Nb-enriched gabbros (NEGs, ca. 485 Ma), which are thus consistent with the Izu-Bonin-Mariana forearc rocks as well as the Troodos and Semail supra-subduction zone-type ophiolites. The geochemical data from the chemostratigraphic succession indicate a subduction initiation process from a depleted mid-oceanic-ridge (MORB)-type mantle source with no detectable subduction input to gradual increasing involvement of subduction-derived materials (fluid/melts and sediments). The new petrological, geochemical, and geochronological data, combined with the regional geology, indicate that the well-sustained FAB-like intrusive magmas with associated boninites could provide crucial evidence for SI and further reveal that the SI of the western Proto-Tethys Ocean occurred in the Late Cambrian (494-485 Ma). [ABSTRACT FROM AUTHOR]

The Dahongliutan granitic pluton consists of two-mica granites and is located in the eastern part of the Western Kunlun Orogen, northwestern Tibetan Plateau. Zircon separates from the pluton yield a SIMS U-Pb age of 217.5 ± 2.8 Ma. Rocks from the pluton contain relatively high and uniform SiO2 (72.32-73.48 wt%) and total alkalis (Na2O + K2O = 8.07-8.67 wt%) and are peraluminous and high-K calc-alkaline to shoshonitic in composition. The Dahongliutan granites are relatively depleted in the high-field-strength elements and the heavy rare earth elements (HREEs) and have relatively high Rb, and low Ba and Sr concentrations. They contain low total rare earth element (REE) concentrations. The light REEs are strongly enriched relative to the HREEs, with (La/ Yb)N values of 28.56-37.01. The εNd(t) values range from -10.6 to -8.8, and (87Sr/86Sr)i = 0.7142-0.7210. Zircons from the pluton yield εHf(t) values of -13.8 to -1.6, and δ18O = 10.5-11.6‰. Petrographic and geochemical features of the pluton indicate that the granites are S-type and were derived from parting melting of a mixture of metasedimentary and minor metaigneous sources in the middle--lower crust. Magmatic differentiation was dominated by the fractional crystallization of plagioclase, K-feldspar, muscovite, biotite, and accessory monazite, allanite, and Fe-Ti oxides. Regional granitoids were emplaced in the Early-to-Middle Triassic. Other younger granitoids, with ages of 240-200 Ma, are mostly I-type in character and were likely derived from multiple types of source rock, suggesting the source was heterogeneous Triassic crust. Such a scenario is consistent with their formation in a post-collisional setting. Our new data, combined with other geological evidence, suggest that the collision between the Tianshuihai and southern Kunlun terranes occurred between ca. 250 and 240 Ma, resulting in the closure of the Palaeo- Tethys. Post-collisional tectono-magmatic events may have occurred between 240 and 200 Ma. [ABSTRACT FROM AUTHOR]

The carbocation salt [Ph3C][BArF] has been identified as a viable Lewis acid catalyst for the Diels-Alder reactions between anthracene derivatives and unsaturated carbonyl compounds with good selectivity and high efficiency. [ABSTRACT FROM AUTHOR]

Stable carbocations such as tritylium ions have been widely explored as organic Lewis acid catalysts and reagents in organic synthesis. However, achieving asymmetric carbocation catalysis remains elusive ever since they were first identified over one century ago. The challenges mainly come from their limited compatibility, scarcity of chiral carbocations, as well as the extremely low barrier to racemization of chiral carbenium ions. We reported here a latent concept for asymmetric carbocation catalysis. In this strategy, chiral trityl phosphate is employed as the carbocation precursor, which undergoes facile ionic dissociation upon mild external stimulation (e.g., acid, H-bonding, polar substrates) to form a catalytically active chiral ion pair for substrate activation and chiral induction. The latent strategy provides a solution for the long sought-after asymmetric carbocation catalysis as illustrated in three different enantioselective transformations. [ABSTRACT FROM AUTHOR]

The success of an organism depends on the molecular and ecological adaptations that promote its beneficial fitness. Parasitoids are valuable biocontrol agents for successfully managing agricultural pests, and they have evolved diversified strategies to adapt to both the physiological condition of hosts and the competition of other parasitoids. Here, we deconstructed the parasitic strategies in a highly successful parasitoid, Trichopria drosophilae, which parasitizes a broad range of Drosophila hosts, including the globally invasive species D. suzukii. We found that T. drosophilae had developed specialized venom proteins that arrest host development to obtain more nutrients via secreting tissue inhibitors of metalloproteinases (TIMPs), as well as a unique type of cell—teratocytes—that digest host tissues for feeding by releasing trypsin proteins. In addition to the molecular adaptations that optimize nutritional uptake, this pupal parasitoid has evolved ecologically adaptive strategies including the conditional tolerance of intraspecific competition to enhance parasitic success in older hosts and the obligate avoidance of interspecific competition with larval parasitoids. Our study not only demystifies how parasitoids weaponize themselves to colonize formidable hosts but also provided empirical evidence of the intricate coordination between the molecular and ecological adaptations that drive evolutionary success. [ABSTRACT FROM AUTHOR]

The Triassic is an important transition period in the structural evolution of North China. The structural features and their controlling action over the sedimentation in the southern Ordos Basin were studied. In combination with modern sedimentology and sequence stratigraphy, the Triassic basin fills have been classified into four second order tectonic sequences bounded by unconformities and erosional surfaces. Tectonic sequence 1 (TS1) is composed of the Liujiagou and Heshanggou Formations. It represents the early stage before the formation of prototype of the foreland basin. Tectonic sequence 2 (TS2) is composed of the Zhifang Formation. The foreland basin formed in this stage. Tectonic sequence 3 (TS3) consists of the lower Yanchang Formation (Chang 10-chang 8). It represents the initial stage of the foreland basin development. Tectonic sequence 4 (TS4) consists of the upper Yanchang Formation (Chang 7-Chang 1). It represents the peak phase of the foreland basin development. The evolution of the Ordos Basin is associated with movement of the Indosinian plate and through analysis of the tectonic sequence, the characteristics of the subsidence and sedimentation in this region are documented. [ABSTRACT FROM AUTHOR]