Variations of b‐values at the western edge of the Ryukyu Subduction Zone,north‐east Taiwan

Using earthquakes relocated in north‐east Taiwan, we estimated b‐value distribution along a cross‐section located near the Ryukyu slab edge, and four b‐value anomalous areas are evidenced: (1) a high b‐value body lying on top of a low Vp, low Vs and high Vp/Vs sausage‐like body was considered as a region of enhanced partial melt or water supply above which seismicity occurs; (2) beneath the Ilan Plain, an anomalous area characterized by b‐values slightly higher than 1.1 might give evidence to the magma conduits to the Kueishantao Island; (3) above the Ryukyu Wadati‐Benioff zone, at depths ranging from 90 to 110 km, a high b‐value anomaly might correspond to the depth where dehydration occurs in the subducting oceanic plate; and (4) a low b‐value area located within the Ryukyu slab, at depths ranging from 70 to 90 km, might be linked to the compressive mechanisms shown by focal mechanisms and the bending of the subducting plate.     

拍卖“四荒”地使用权以加快山区建设步伐

拍卖“四荒”地使用权，是在新形势下运用市场机制，加快“四荒”资源开发、发展农村经济、群众脱贫致富的重要途径，阐述了“四荒”地使用权的拍卖原则、拍卖方式和购买形式，概括了拍卖后所取得的初步效果，并论述了拍卖“四荒”地使用权的政策措施。这一切有利于加快山区建设步伐。     

δ13C signature of early graphite and subsequently formed microdiamond from the Saxonian Erzgebirge,Germany

Microdiamond and graphite occur in quartzofeldspathic rocks (saidenbachites) of the central Erzgebirge in Saxony. Zircon from such rocks contains not only relatively high but also variable amounts of early formed graphite and later crystallized diamond, however no carbonate. Six purified zircon concentrates were analysed by mass spectrometry for δ₁₃C(PDB) values which were between −24 and −33‰. The carbon inclusions resulted in C contents of the concentrates as high as 0.5 wt%. It is hypothesized that the observed δ₁₃C signature results from organic material in the sedimentary protoliths of the saidenbachites probably deposited not earlier than Mid‐Devonian. This material was transformed to graphite during early metamorphism and subsequently to diamond after an anatectic event at great depths (>150 km). During these processes, the δ₁₃C signature of the carbon did not (significantly) change.     

First cosmic ray exposure dating (in situ produced 10Be) of the late pleistocene and holocene glaciation in the Nanhutashan Mountains (Taiwan)

In Taiwan, efficient climate‐driven strong erosion processes are the leading cause for low preservation of geomorphic landforms. Despite the absence of present‐day glaciers, glacial relicts have been reported in high altitude areas. These scarce landforms provide opportunities for reconstructing the timing of the last deglaciation in a region where glacial history is poorly documented. We have collected boulders and striated bedrocks in the Nanhutashan area and calculated surface exposure ages based on in‐situ produced ¹⁰Be concentrations. The oldest glacial remains, dated at 11.1 ± 3.3 ka, correspond to the last glacial advance. The Holocene is characterized by a continuous retreat of the ice‐cap until at least 7.2 ± 1.0 ka. Our results are in agreement with a scenario where changes of monsoon regimes lead to a strong reduction of the winter monsoon during the early Holocene, causing a decrease of snow supply and disequilibrium of the hydrological budget.