Abstract The food source of hadal endemic fauna provides an insight into the carbon cycle in trenches and a biological adaptation to the impoverished and harsh trench environment. Here, we present the first Δ 14 C results of hadal amphipods from three trenches in the Pacific to define the organic matter source in these remote ecosystems. Amphipod muscle tissues contain a bomb 14 C signature (Δ 14 C from 10 ± 2‰ to 65 ± 2‰), thereby revealing a dietary preference for labile and fresh organic matter derived from the surface water. Thus, the carbon cycle in the deepest ocean trench has a tight linkage with the surface ocean via the food chain. The bomb 14 C dating result suggests that hadal amphipods have a low tissue turnover rate and an unexpectedly long lifetime (>10 years), at more than 4 times higher than the common longevity (~2 years) of amphipods in shallow waters.
Abstract Orogenic gold (Au) deposits are the most important type, accounting for more than half of the world's proven Au reserves. They are mainly controlled by three key factors: (1) abundant andesitic rocks (SiO2 of 55–60 wt.%) at depth, which have systematically higher Au contents than other rock types; (2) a pervasive transition from greenschist facies to amphibolite facies metamorphism within a short period, which releases S2−-rich fluids that may scavenge Au from host rocks; and (3) deformation and fracturing under a compressive/transpressive tectonic regime. Orogenic belts at convergent margins are the best places for such mineralization because convergent margins are rich in andesites; the transition from greenschist to amphibolite facies recrystallization commonly occurs as a result of collision, compression, and thickening at convergent margins, forming large amounts of Au-rich fluids within a short period of time; and strong deformation and fracturing during orogenic processes provide channels for fluid transportation. Moreover, the overlying plate is injected and enriched by auriferous fluids released during amphibolite facies metamorphism of the subducting plate. The Pacific plate changed course by ∼80° (from SW to NW) at approximately 125–122 Ma, reflecting an altered thermal structure and the elevation of the South Pacific plate attending the appearance of the plume head that formed the Ontong Java large igneous province. Consequently, the tectonic regime changed from extension to compressive/transpressive in eastern China, causing deformation, thickening, and metamorphism of the overriding plate, especially along weak crustal belts (e.g. overlying plates of palaeosutures), which resulted in world-class mineralization of orogenic Au deposits. During this process, pyrite changed to pyrrhotite during the transition from greenschist to amphibolite facies, releasing sulphur. Sulphur mobilized and scavenged Au and other chalcophile elements into metamorphic ore-forming fluids. A series of NE-trending compressive faults were formed at ˜120 Ma as a result of continuous compression of the subducting Pacific plate, releasing these ore-forming fluids. Auriferous carbonate-rich quartz veins and/or metasomatized Au-bearing wall rocks were formed due to the decompression of the ascending ore-forming fluids. Orogenic belts along the margins of the North China craton and the Jiangnan block were the most favourable regions for mineralization. Compared with the former, the latter has much smaller proven Au reserves. However, more exploration is needed along the margins of the Jiangnan block. Promising targets include accessory faults and kink points of large, NE-trending Cretaceous faults that transect greenschist facies metamorphic rocks of the Niuwu and Jingtan Groups, etc. Keywords: Pacific plate directional changeorogenic gold depositseastern Chinaandesitic rocksJiangnan blockNorth China craton Acknowledgements The study was supported by a major project of the Chinese Academy of Sciences (KZCX1-YW-15), Ministry of Science and Technology of China (2012CB416703), the Natural Science Foundation of China (nos 41090374 and 41121002), and the Commonweal Geological Prospecting Project of Anhui Province (2011-8). We thanks Professor S.Y. Jiang for his constructive review comments and Dr Chuck Magee and Miss Elaine Chang for proofreading the manuscript. Contribution No. IS-1495 from GIGCAS. Notes
The selection of host materials has a great impact on the performance of doping devices, especially near-infrared (NIR) emitters. In this investigation, four diverse host materials serve as a potential barrier layer (PBL) to confine and balance holes and electrons within the potential well layer (PWL), TPA-DCPP, for fabricating nondoped NIR thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) (NNT-OLEDs) with double quantum wells' (DQWs) structure. The hole-type host (mCP) forms an optimum interface energy barrier (IEB) and disperses carriers and excitons in each well, which helps to widen the recombination interval of carriers and restrain the quenching of excitons. Finally, OLEDs with pure red emission and a maximum external quantum efficiency (EQEmax) of nearly 15% (with 0.5 nm well width), deep-red emission with an EQEmax of 12% (with 1.0 nm well width), and NIR emission with an EQEmax of 3.3% (with 5.5 nm well width) are achieved with tunable emission peaks within the range of 641–700 nm by adjusting well width, which are significantly superior to those of doped devices based on the same emitter. This investigation demonstrates a simple, feasible, and effective design strategy for achieving efficient fluorescent OLEDs with controllable wavelength, which solves the blue shift problem in traditional NIR devices of host–guest structure.
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