•Zaduo LIP erupted between 283 and 276 Ma on the North Qiangtang Block.•Demise of Late Paleozoic Ice Age partly linked to circum-Tethyan LIP activity.•Transition to Triassic greenhouse linked to ...reduced Tethyan tropical land area.
Plate tectonics plays a key role in shaping the long-term climate but on shorter time-scales large igneous provinces (LIPs) perturb the climate system through voluminous release of gases to the atmosphere. Three early Permian LIPs have been recognised globally, but geochronologic (283 to 276 Ma) and geochemical data reported here suggest a fourth, early Permian LIP (Zaduo) in North Qiangtang (central Tibet) that erupted at low southern latitudes along the eastern Tethyan margin. The late Paleozoic ice age (LPIA) lasted from about 330 to 260 Ma, but we argue here that increasing atmospheric CO2 levels and temperatures from ∼300 Ma – contemporaneous with a fast reduction in glacial frequency – was spearheaded by long-lasting circum-Tethyan LIP degassing. This process nearly ended icehouse conditions at ∼280 Ma with atmospheric CO2 levels (∼800 ppm) and tropical sea surface temperatures near glacial inception thresholds. The middle Permian (275-260 Ma) is characterized by a lowering of CO2 levels (∼400 ppm), which partly could have been related to enhanced weathering of juvenile LIP-lavas on short time-scales, but major changes in the Tethyan paleogeography, including the opening of the Neotethys from ∼275 Ma, led to the increase of exposed land in the Tethyan tropics during the middle Permian and thus enhanced silicate weathering and CO2 drawdown. Both the Emeishan LIP (∼260 Ma) and Siberian Traps (∼252 Ma) led to extraordinary climate perturbations, but the transition to a Triassic super-greenhouse we propose is linked to the radical reduction of Tethyan land areas within the tropics, at a time when the Central Pangean tropics was aridified, and that configuration led to the lowest global river runoff and silicate weathering efficiency for the entire Phanerozoic.
The Tethyside orogen, a direct consequence of the separation of the Gondwanaland and the accretion of Eurasia, is a huge composite orogenic system that was generated during Paleozoic–Mesozoic Tethyan ...accretionary and Cenozoic continent–continent collisional orogenesis within the Tethyan domain. The Tethyside orogenic system consists of a group of diverse Tethyan blocks, including the Istanbul, Sakarya, Anatolide–Taurides, Central Iran, Afghanistan, Songpan–Ganzi, Eastern Qiangtang, Western Qiangtang, Lhasa, Indochina, Sibumasu, and Western Burma blocks, which were separated from Gondwana, drifted northwards, and accreted to the Eurasian continent by opening and closing of two successive Tethyan oceanic basins (Paleo-Tethyan and Neo-Tethyan), and subsequent continental collision.
The Tethyan domain represents a metallogenic amalgamation across diverse geodynamic settings, and is the best endowed of all large orogenic systems, such as those associated with the Cordilleran and Variscan orogenies. The ore deposits within the Tethyan domain include porphyry Cu–Mo–Au, granite-related Sn–W, podiform chromite, sediment-hosted Pb–Zn deposits, volcanogenic massive sulfide (VMS) Cu–Pb–Zn deposits, epithermal and orogenic Au polymetallic deposits, as well as skarn Fe polymetallic deposits. At least two metallogenic supergroups have been identified within the eastern Tethyan metallogenic domain (ETMD): (1) metallogenesis related to the accretionary orogen, including the Zhongdian, Bangonghu, and Pontides porphyry Cu belts, the Pontides, Sanandaj–Sirjan, and Sanjiang VMS belts, the Lasbela–Khuzdar sedimentary exhalative-type (SEDEX) Pb–Zn deposits, and podiform chromite deposits along the Tethyan ophiolite zone; and (2) metallogenesis related to continental collision, including the Gangdese, Yulong, Arasbaran–Kerman and Chagai porphyry Cu belts, the Taurus, Sanandaj–Sirjan, and Sanjiang Mississippi Valley-type (MVT) Pb–Zn belts, the Southeast Asia and Tengchong–Lianghe Sn–W belts or districts, the Himalayan epithermal Sb–Au–Pb–Zn belt, the Piranshahr–Saqez–Sardasht and Ailaoshan orogenic Au belts, and the northwest Iran and northeastern Gangdese skarn Fe polymetallic belts. Mineral deposits that are generated with tectonic evolution of the Tethys form in specific settings, such as accretionary wedges, magmatic arcs, backarcs, and passive continental margins within accretionary orogens, and the foreland basins, foreland thrust zones, collisional sutures, collisional magmatic zones, and collisional deformation zones within collisional orogens.
Synthesizing the architecture and tectonic evolution of collisional orogens within the ETMD and comparisons with other collisional orogenic systems have led to the identification of four basic types of collision: orthogonal and asymmetric (e.g., the Tibetan collision), orthogonal and symmetric (Pyrenees), oblique and symmetric (Alpine), and oblique and asymmetric (Zagros). The tectonic evolution of collisional orogens typically includes three major processes: (1) syn-collisional continental convergence, (2) late-collisional tectonic transform, and (3) post-collisional crustal extension, each forming distinct types of ore deposits in specific settings. The resulting synthesis leads us to propose a new conceptual framework for the collision-related metallogenic systems, which may aid in deciphering relationships among ore types in other comparable collisional orogens. Three significant processes, such as breaking-off of subducted Tethyan slab, large-scale strike-slip faulting, shearing and thrusting, and delamination (or broken-off) of lithosphere, developed in syn-, late- and post-collisional periods, repsectively, were proposed to act as major driving forces, resulting in the formation of the collision-related metallogenic systems. Widespread appearance of juvenile crust and intense inteaction between mantle and crust within the Himalayan–Zagros orogens indicate that collisional orogens have great potential for the discovery of large or giant mineral deposits.
Drug delivery researches has drawn tons of attention to achieve the targeted therapies that work for many diseases. Nanogels, a type of polymeric hydrogels with a nanoscale size, are promising ...materials for drug delivery applications. However, many current polymers used for synthesizing nanogels are lack in biocompatibility, stability, and low biosafety. This review focus on the mannan-based nanogels with high loading capacity, biocompatibility, and multifunctional stimuli-response properties due to their unique structure and biochemical properties. These characteristics make mannan nanogels very suitable for drug delivery applications.
Abstract
In order to solve the problem of environmental pollution caused by construction waste, one typical waste of red bricks was selected as raw material in recycled concrete. This study presented ...recycled concrete by substituting some natural aggregates with treated red brick aggregates to study and analyze the degradation law mechanism of recycled brick aggregates concrete in the cold region. A total of fifteen categories of specimens and three experimental parameters were considered, which included numbers of freeze–thaw cycles (0, 50, and 100), steel fiber admixtures (0, 1, and 2%), and brick aggregate substitution rates (0, 25, 50, 75, and 100%), respectively. The quick freeze–thaw test method was selected to investigate recycled concrete's degradation mass loss rate and relative dynamic elastic modulus under various freeze–thaw cycles. The digital microscope and SEM were used to observe the internal microstructural changes in the specimens under different freeze–thaw times. In addition, the specimens’ microscopic damage morphology and damage mechanism were analyzed. Finally, the flexural strength of the frost-damaged specimens was tested to analyze the mechanical deterioration of the recycled concrete, and the numerical model corresponding to steel fiber dosing and recycled aggregate replacement rate was presented. The gray correlation analysis was used to quantify the influence of each experimental variable on the corresponding experimental indexes under various freeze–thaw cycles. Results showed that the specimen's mass decreased after freeze–thaw cycles, and the highest mass loss was found for the specimens with 50 and 75% brick substitution rates. In addition, the specimens showed the best relative dynamic modulus and the maximum flexural strength when the steel fiber doping was 1%. The numerical model agreed with experimental data and effectively predicted the specimens' mass loss rate, relative dynamic modulus, and flexural strength after freeze–thaw cycles. The gray correlation analysis showed that the steel fiber contents had a maximum correlation with the flexural strength, the brick substitution rates for the relative dynamic modulus, and mass loss controls the freeze–thaw cycles.
Most porphyry Cu deposits in the world occur in magmatic arc settings and are formed in association with calc-alkaline arc magmas related to subduction of oceanic lithosphere. This contribution ...reviews a number of significant porphyry Cu deposits in the eastern Tethyan metallogenic domain. They widely occur in a variety of non-arc settings, varying from post (late)-collisional transpressional and extensional environments to intracontinental extensional environments related to orogenic and anorogenic processes. Their spatial–temporal localization is controlled by strike–slip faults, orogen-transverse normal faults, lineaments and their intersections in these non-arc settings. These deposits are dominated by porphyry Cu–Mo deposits with minor porphyry Cu–Au and epithermal Au deposits, and exhibit a broad similarity with those in magmatic arcs. The associated magmas are generally hydrous, relatively high
fO
2, high-K calc-alkaline and shoshonitic, and show geochemical affinity with adakites. They are distinguished from arc magmas and/or oceanic-slab derived adakites, by their occurrence as isolated complexes, high K
2O contents (1.2–8.5%), and much wider range of ε
Nd(t) values(−
10 to +
3) and positive ε
Hf(t) values (+
4.6 to +
6.9). These potassic magmas are most likely formed by partial melting of thickened juvenile mafic lower-crust or delaminated lower crust, but also involving various amounts of asthenospheric mantle components. Key factors that generate hydrous fertile magmas are most likely crust/mantle interaction processes at the base of thickened lower-crust in non-arc settings, rather than oceanic-slab dehydration (as in arc settings). Breakdown of amphibole in thickened lower crust (e.g., amphibole eclogite and garnet amphibolite) during melting is considered to release fluids into the fertile magmas, leading to an elevated oxidation state and higher H
2O content necessary for development of porphyry Cu–Mo–Au systems. Copper and Au in hydrous magmas are likely derived from mantle-derived components and/or melts, which either previously underplated and infiltrated at the base of the thickened lower crust, or were input into the primitive magmas by melt/mantle interaction. In contrast, Mo and (part of the) S in the fertile magmas are probably supplied by old crust during melting and subsequent ascent.
► Propose a synthesis model of porphyry deposits in non-arc setting by detailed review. ► Crust/mantle interaction is reagrded to be key process to generate fertile adakitic porphyries. ► Cu, Au was derived from mantle-derived components, but Mo was provided by old crust.► Breakdown of amphibole in magma source is regared to have resulted in high fO2 and H2O content of magma.
The Paleo-Tethyan tectonic evolution of the central Sanjiang orogenic belt remains unclear, particularly regarding the types and tectonic setting of volcanic rocks in the Cuiyibi Formation in the ...Weixi area, southwest China. These volcanic rocks were previously thought to be bimodal, but our detailed geological mapping revealed that the Cuiyibi Formation volcanic rocks include basalt, andesite, and rhyolite. In this paper, we present new geological, geochronological, and geochemical data for the andesitic rocks in the Cuiyibi Formation. Zircon UPb ages of the andesitic rocks indicate they formed at 245–242 Ma. The andesitic rocks are part of the high-K calc-alkaline/shoshonite series, and they exhibit light rare earth and large-ion lithophile element (e.g., K, Rb, Th, and U) enrichment and heavy rare earth and high-field-strength element (e.g., Nb, Ta, and Ti) depletion. High Mg# values and Nb contents, low Sm/Yb and Lu/Yb ratios, and negative zircon εHf(t) and whole-rock εNd(t) values suggest these rocks were derived from an enriched mantle source. The Cuiyibi Formation volcanic rocks are geochemically similar to those formed in a continental arc. These rocks formed along a vast continental arc in the North Qiangtang–Lanping–Simao Block related to the subduction of the Paleo-Tethyan oceanic slab.
•A new suite of andesitic rocks was identified in the central Sanjiang belt.•The andesitic rocks were erupted during the Middle Triassic.•A vast continental arc formed in response to subduction of the Paleo-Tethys.
Reducing the switching energy of ferroelectric thin films remains an important goal in the pursuit of ultralow-power ferroelectric memory and logic devices. Here, we elucidate the fundamental role of ...lattice dynamics in ferroelectric switching by studying both freestanding bismuth ferrite (BiFeO
) membranes and films clamped to a substrate. We observe a distinct evolution of the ferroelectric domain pattern, from striped, 71° ferroelastic domains (spacing of ~100 nm) in clamped BiFeO
films, to large (10's of micrometers) 180° domains in freestanding films. By removing the constraints imposed by mechanical clamping from the substrate, we can realize a ~40% reduction of the switching voltage and a consequent ~60% improvement in the switching speed. Our findings highlight the importance of a dynamic clamping process occurring during switching, which impacts strain, ferroelectric, and ferrodistortive order parameters and plays a critical role in setting the energetics and dynamics of ferroelectric switching.
Moving shadow elimination plays an important role in the field of moving object detection. However, the accuracy of shadow elimination is an open question, due to illumination and complex texture. ...Furthermore, the problem of misclassification of moving object caused by shadow has also become increasingly serious. To address this problem, this paper presents a moving shadow elimination algorithm based on the fusion of multi-feature pattern, which can enhance the accuracy of moving object detection system. In this approach, a dual-channel HSV color space feature and a uniform extended scale invariant local ternary pattern (UESILTP) texture feature are synthesized to elimination shadow. It greatly overcomes the misjudgment of dark object by color feature and the false detection caused by inconspicuous texture characteristics of moving object. Meantime, a method of region growth is adopted to fill the existing cavities in the color space. Finally, qualitative and quantitative comparisons with state-of-the-art methods show that the algorithm is effective.
Grouping different transition metal oxides together by interface engineering is an important route toward emergent phenomenon. While most of the previous works focused on the interface effects in ...perovskite/perovskite heterostructures, here we reported on a symmetry mismatch-driven spin reorientation toward perpendicular magnetic anisotropy in perovskite/brownmillerite heterostructures, which is scarcely seen in tensile perovskite/perovskite heterostructures. We show that alternately stacking perovskite La
Sr
MnO
and brownmillerite LaCoO
causes a strong interface reconstruction due to symmetry discontinuity at interface: neighboring MnO
octahedra and CoO
tetrahedra at the perovskite/brownmillerite interface cooperatively relax in a manner that is unavailable for perovskite/perovskite interface, leading to distinct orbital reconstructions and thus the perpendicular magnetic anisotropy. Moreover, the perpendicular magnetic anisotropy is robust, with an anisotropy constant two orders of magnitude greater than the in-plane anisotropy of the perovskite/perovskite interface. The present work demonstrates the great potential of symmetry engineering in designing artificial materials on demand.
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