In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough

© 2018, The Author(s). The study investigates the in-situ strength of sediments across a plate boundary décollement using drilling parameters recorded when a 1180-m-deep borehole was established during International Ocean Discovery Program (IODP) Expedition 370, Temperature-Limit of the Deep Biosphere off Muroto (T-Limit). Information of the in-situ strength of the shallow portion in/around a plate boundary fault zone is critical for understanding the development of accretionary prisms and of the décollement itself. Studies using seismic reflection surveys and scientific ocean drillings have recently revealed the existence of high pore pressure zones around frontal accretionary prisms, which may reduce the effective strength of the sediments. A direct measurement of in-situ strength by experiments, however, has not been executed due to the difficulty in estimating in-situ stress conditions. In this study, we derived a depth profile for the in-situ strength of a frontal accretionary prism across a décollement from drilling parameters using the recently established equivalent strength (EST) method. At site C0023, the toe of the accretionary prism area off Cape Muroto, Japan, the EST gradually increases with depth but undergoes a sudden change at ~ 800 mbsf, corresponding to the top of the subducting sediment. At this depth, directly below the décollement zone, the EST decreases from ~ 10 to 2 MPa, with a change in the baseline. This mechanically weak zone in the subducting sediments extends over 250 m (~ 800–1050 mbsf), corresponding to the zone where the fluid influx was discovered, and high-fluid pressure was suggested by previous seismic imaging observations. Although the origin of the fluids or absolute values of the strength remain unclear, our investigations support previous studies suggesting that elevated pore pressure beneath the décollement weakens the subducting sediments. [Figure not available: see fulltext.]

电弧熔炼制备标准样品-X射线荧光光谱法测定钕铁硼磁性材料成分

采用电弧熔炼炉制备系列钕铁硼标准样品,并通过三家实验室用电感耦合等离子体光谱法对样品中各元素准确定值。然后选用基本参数法,在X射线荧光光谱仪上,用自制标准样品建立测定钕铁硼磁性材料的校准曲线。本法测定结果与ICP-AES测定结果相符,测定值的相对标准偏差(n=11)小于1.5%

中药植物川牛膝基因组从头测序及分析

川牛膝是我国重要大宗药材,但近年来品质退化严重,品种真伪混杂。为深入研究川牛膝有效成分积累的分子基础,采用第二代测序技术利用Illumina Hi-seq 2000测序平台对川牛膝进行全基因组测序,使用AByss进行初步组装,得到一个包含大量基因组序列信息的数据集,并对其进行重复序列及编码序列注释。在该测序结果基础上,初步预测得到川牛膝体内甾体合成途径,并对鉴定川牛膝真伪的SCAR分子标记进行了初步定位,为研究川牛膝主要有效成分杯苋甾酮的合成途径,改良川牛膝品质提供了基础

Long-term sensor monitoring equipped with the Kuroko cultivation apparatus on the deep-sea artificial hydrothermal vent at the middle Okinawa Trough

http://www.godac.jamstec.go.jp/darwin/cruise/kairei/kr16-17/

Long-term observations of pressure, temperature and flow rate for deep-sea hydrothermal fluid at the middle Okinawa Trough

http://www.godac.jamstec.go.jp/darwin/cruise/kairei/kr16-17/