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CO2released from subduction zones plays a vital role in the tectonic carbon cycle. However, the contribution of submarine backarc components to carbon emissions remains poorly understood compared to subaerial arc volcanos. This study utilized a combination of geochemical and hydrodynamic approaches to investigate the sources and flux of dissolved inorganic carbon (DIC) in the deep basin of the southwestern Okinawa Trough. Most deep‐water (depth ≥1,000 m) samples, even those retrieved from sites distant from active venting, exhibited mild geochemical anomalies of elevated 3He/4He ratios and higher DIC content than reference sites. Hydrodynamic observations using bottom‐mounted acoustic instruments in the deep basin revealed strong tidal currents and enhanced turbulent mixing. These findings suggest that active solute dispersal and mixing are responsible for the prevalence of mild geochemical anomalies in the basin. Mixing models indicated that hydrothermal vent fluids are the primary source of excess 3He and DIC above background levels in the deep basin, whereas both CO2and mineral acid in hydrothermal fluids cause excess acidity. Based on hydrodynamic and geochemical data, a box model estimated a hydrothermal DIC flux of 0.62 ± 1.40 × 1010mol y−1, equivalent to 40% of CO2emissions from persistently degassing volcanos in the Ryukyu Arc. Our results suggest that submarine carbon emissions are quantitatively important in subduction systems with subaqueous backarc components. The CO2released from subduction zones, where tectonic plates collide, is important for the Earth's carbon cycle. However, we know little about CO2released from submarine backarc basins compared to volcanoes on land. This study examined dissolved inorganic carbon (DIC) sources and quantities released into the deep basin of the southwestern Okinawa Trough. Even far from active hydrothermal vents, deep‐water samples had higher DIC levels than expected. Using instruments placed on the seabed, we discovered strong tidal currents and increased water mixing in the basin. These findings suggest that water movement and mixing contribute to the widespread occurrence of elevated DIC levels. Our calculations show that the primary source of the extra DIC in the deep basin is fluids released from hydrothermal vents, and both CO2and mineral acid cause excess acidity in the water. Based on our data, we estimate that hydrothermal vents release approximately 6 billion moles of DIC per year, equivalent to 40% of the CO2emissions from continuously active volcanoes in the Ryukyu Arc. These results demonstrate the potential significance of underwater carbon emissions in submerged backarc basins within subduction zones. Mild geochemical anomalies in 3He and dissolved inorganic carbon were widespread in the southwestern Okinawa Trough deep waterMixing models confirmed that hot vent fluids are the primary source of excess dissolved inorganic carbon in the deep waterThe carbon outgassing flux of the Ryukyu subduction system increases by at least 27% when the backarc contribution is considered Mild geochemical anomalies in 3He and dissolved inorganic carbon were widespread in the southwestern Okinawa Trough deep water Mixing models confirmed that hot vent fluids are the primary source of excess dissolved inorganic carbon in the deep water The carbon outgassing flux of the Ryukyu subduction system increases by at least 27% when the backarc contribution is considered

In this study, we analyzed the carbon and nitrogen stable isotopic composition of human bone collagen in 33 individuals found at the Fantzuyuan site in Taiwan in order to investigate the dietary patterns of this Iron Age group. Forty-three faunal collagen samples were also analyzed to ascertain the variability of baseline isotopic signatures in the area. Mean δ13C and δ15N values of −12.5±0.7‰ and 8.1±0.5‰, respectively, were found in 26 human individuals. In conjunction with archaeological evidence, this study showed that human diet at this site derived mainly from terrestrial animals, with a minor component derived from marine shellfish. No significant difference in isotopic compositions was detected between male and female adults or between adults and juveniles. However, six individuals had dietary patterns that were different from others, which probably reveals that they had special social status and/or non-local origins.

Carbon and nitrogen stable isotope analyses were conducted on Neolithic Yuan-Shan faunal bone collagen to reconstruct a site-specific dietary isotope baseline, and to evaluate the contribution of potential food resources to the diet of Yuan-Shan people. The mean δ13C and δ15N values of terrestrial mammals were −17.7±3.6‰ and 5.4±1.3‰, respectively. The mean δ13C and δ15N values of freshwater fish were −20.8±2.2‰ and 7.7±2.0‰; while the marine fish had the highest mean δ13C (−11.8±1.2‰) and δ15N values (12.1±1.7‰). Combined with archeological evidence and previous isotopic data derived from Yuan-Shan human bone collagen, we suggest that the subsistence strategies of Yuan-Shan people were broad. They relied on rice cultivation, hunting, fishing and gathering food resources from the wild; in addition, they probably raise pigs, as early as 4200yrBP. Although the Yuan-Shan people relied on broad-spectrum food resources, the foods they mainly consumed were terrestrial herbivores and freshwater fish based on the result of multi-source mixing model. Besides, marine fish, shellfish, and C3plants also contributed substantially to their diet. By comparison, the contribution of C4plants was minor.

We report on magnetotransport results for an Al0.15Ga0.85N/GaN high-electron-mobility-transistor structure grown on a p-type Si (111) substrate. Our results show that there exists an approximately temperature (T)-independent point, which could be ascribed to a direct transition from a weak insulator to a high Landau level filling factor quantum Hall state, exists in the longitudinal resistivity ρxx. The Hall resistivity decreases with increasing T, compelling experimental evidence for electron-electron interaction effects in a weakly-disordered two-dimensional (2D) system. We find that electron-electron interaction effects can be estimated and eliminated, giving rise to a corrected nominally temperature-independent Hall slope. By fitting the low-field magnetotransport data to conventional 2D weak localization theory, we find that the dephasing rate 1/τϕis proportional to T. Moreover, 1/τϕis finite as T→ 0, evidence for zero-temperature dephasing in our system.We report on magnetotransport results for an Al0.15Ga0.85N/GaN high-electron-mobility-transistor structure grown on a p-type Si (111) substrate. Our results show that there exists an approximately temperature (T)-independent point, which could be ascribed to a direct transition from a weak insulator to a high Landau level filling factor quantum Hall state, exists in the longitudinal resistivity ρxx. The Hall resistivity decreases with increasing T, compelling experimental evidence for electron-electron interaction effects in a weakly-disordered two-dimensional (2D) system. We find that electron-electron interaction effects can be estimated and eliminated, giving rise to a corrected nominally temperature-independent Hall slope. By fitting the low-field magnetotransport data to conventional 2D weak localization theory, we find that the dephasing rate 1/τϕis proportional to T. Moreover, 1/τϕis finite as T→ 0, evidence for zero-temperature dephasing in our system.

In order to better understand the uplift history of the Sulu ultrahigh-pressure metamorphic terrane, 40Ar-39Ar thermochronological analysis was conducted on minerals extracted from both metamorphic (gneiss and retrograded eclogite) and igneous (pegmatite, granite, and mafic intrusion) rocks from this terrane. Samples of the major lithotectonic units were collected from key localities, including Rongcheng, Laoshan, Yangkou, Taohang, and Rizhao. The analyses of metamorphic rocks yielded ages for hornblende ranging from 222 to 186 Ma, biotite from 130 to 119 Ma, and K-feldspar from 112 to 108 Ma. Hornblende, biotite, and K-feldspar from igneous rocks yielded exclusively late Mesozoic ages from 137 to 97 Ma. A two-stage cooling path for the metamorphic rocks were revealed. A slow cooling (1.9 to 3.8°C/m.y.) during the period of ∼220 to ∼130 Ma was followed by fast cooling (6.8 to 16.7°C/m.y.) during ∼130 to ∼100 Ma. The time span and cooling rate of the second stage coincide with those of the analyzed post-collisional igneous rocks as well as with the formation of rift basins in the region. The study strongly indicates that extensional tectonics played an important role in the final stage of rapid exhumation of the ultrahigh-pressure rocks in the Sulu terrane.