冲绳海槽中部热液活动与IODP331航次初步成果

伊平屋北部热液区（IheyaNoAhhydrothermalfield）位于冲绳海槽中部地区。综合大洋钻探计划（IODP）331航次于2010年9月1日至10月4日在该区钻探了5个站位（C0013-C0017）：C0016站位位于NoahBigChimney（NBC）地区活跃的热液烟囱和硫化物-硫酸盐丘状体上;在C00...     

Tectonic analysis and paleo-stress determination of the upper lava section at ODP/IODP site 1256 (East Pacific Ocean)

Research on the deep sea is of great importance for a better understanding of the mechanism of magma emplacement and the tectonic evolution of oceanic crust. However, details of the internal structure in the upper levels of the oceanic crust are much less complete than that of the more fully studied sub-aerial areas. For the first time, this study proposes a dynamic analysis using the inversion method on core data derived from the drilled basement of the present-day intact oceanic crust at ODP/IODP Site 1256 in the Cocos plate. The research is based on an innovative core reorientation process and combines different stress hypothesis approaches for the analysis of heterogeneous failure-slip data via exploitation of two distinct techniques. From the analysis of the failure-slip data, both techniques produce 5 distinct subsystem datasets. All calculated subsystems are mechanically and geometrically admissible. Interpretation of the results allows the researchers to note a complex local and regional tectonic evolution deriving from the interplay of (1) the ridge push and rotation of both the East Pacific Rise and the Cocos-Nazca Spreading Center, (2) the effect of the slab pull of the Middle America Trench, (3) the influence of lava emplacement mechanisms, and (4) intra-plate deformation.     

Pleistocene geochemical stratigraphy of the borehole 1317E (IODP Expedition 307) in Porcupine Seabight,SW of Ireland: applications to palaeoceanography and palaeoclimate of the coral mound development

Stable isotopes and element compositions of the fine‐grained matrix were measured for IODP Expedition 307 Hole U1317E drilled from the summit of Challenger Mound in Porcupine Seabight, northeast Atlantic, to explore the palaeoceanographic and palaeoclimatic background to development of the deep‐water coral mound. The 155 m long mound section was divided into two units by an unconformity at 23.6 mbsf: Unit M1 (2.6–1.7 Ma) and Unit M2 (1.0–0.5 Ma). Results from 519 specimens show a difference in δ¹³C value between Unit M1 (?0.6‰ to ?5.0‰) and Unit M2 (?1.0‰ to 1.0‰), but such a distinct difference was not seen in δ¹⁸O values (1.0‰–2.5‰), CaCO₃ content (40–60 wt%), Sr/Ca ratio (2.0–8.0 mmol mol^?1), and Mg/Ca ratio (10.0–20.0 mmol mol^?1) through the mound. Positive δ¹⁸O and negative δ¹³C shifts at the mound base are consistent with the oceanographic changes in the northeast Atlantic at the beginning of the Quaternary. The positive δ¹³C regression in Unit M2 suggests a linkage to the mid Pleistocene intensified glaciation in the Northern Hemisphere. Warm Mediterranean Upper Core Water of Mediterranean Outflow Water, Eastern North Atlantic Water and cold Labrador Sea Water of North Atlantic Deep Water are key oceanographic features that cause spikes and shifts in stable isotope and element composition. However, the stable isotope values of the sediment matrix could not primarily record the glacial–interglacial eustatic/temperature change, but indirectly indicate current regimes of the intermediate oceanic layer where the coral mound grew. Similarly, elemental ratios and CaCO₃ content may not represent the productivity and temperature of surface sea water, respectively, but superpose the fractions from both surface and bottom water. It is concluded that palaeoceanographic change coupled to the Pleistocene glacial/interglacial cycles is a key control on the geochemical stratigraphy of the matrix sediments of the carbonate mound developed in Porcupine Seabight. Copyright © 2011 John Wiley & Sons, Ltd.     

西南印度洋脊49°39′E热液活动区IODP钻探计划的科学意义

自20世纪70年代以来,现代海底热液活动调查研究一直是地球科学领域研究的热点和焦点.中国大洋19航次第Ⅰ、Ⅱ航段于2007年3月在西南印度洋脊首次发现的海底热液活动区,为IODP在超慢速扩张洋脊热液活动区进一步的调查和研究创造了条件.为了能够更深入地开展该热液区的地质地球物理、矿产资源和生物多样性调查研究,笔者建议应在该区域开展IODP钻探研究,以便对热液活动区硫化物矿体、基岩及深部物质的三维分布和结构物质组成,热液流体与岩石、沉积物相互作用关系,以及热液循环、热及物质通量和成矿机制、成矿物质来源演化关系等方面得到更深入的认识,进而探索地球深部极端环境下的微生物生命现象.     

Evaluation and modelling of Tertiary source rocks in the central Arctic Ocean

With the recently recovered organic-rich sediments of early Tertiary age from the Lomonosov Ridge by the Integrated Ocean Drilling Program (IODP) Expedition 302, the first data collection directly from source rocks of the central basins of the Arctic Ocean is now available. Using the results of seismic interpretations and published sedimentological and organic geochemical data from Expedition 302, the framework for the first quantitative assessment of source-rock quality and distribution of the Palaeogene sediments was modelled in the central Arctic Ocean. The modelling results suggest that an approximately 100-m-thick Early to Middle Eocene sedimentary sequence of good to very good source rocks exists along a 75 km long transect across the Lomonosov Ridge. In-situ generation of hydrocarbons is unlikely because the overburden (200–250 m) and consequently the thermal maturity are too low. Burial history and thermal modelling reveal that an additional overburden of at least 1000 m is necessary to start hydrocarbon generation along the ridge. However, source-rock modelling results show that good source-rock potential may exist in correlative units in the adjacent Amundsen Basin. Simulated organic carbon contents of 1.5–5%, coupled with an overburden of 1000–1200 m, and heat flow anomalies (117 and 100 mW m⁻²) due to the vicinity to the Gakkel Ridge spreading centre indicate that necessary conditions for hydrocarbon expulsion are already reached, and point to viability of a potential petroleum system. Our results support the hypothesis that deposition of a potentially good hydrocarbon source rock occurred across the entire Arctic Basin and adjacent margins during the early Tertiary.     

Microstructures documenting Cenozoic extension processes in the northern continental margin of the South China Sea

ABSTRACT

In order to investigate the thinning process of the northern continental margin of the South China Sea, petrographic and microstructural analysis were carried out on 20 greenschistfacies mylonite samples, which were obtained from Site U1504 of IODP Expedition 367/368 in the Outer Margin High of the region. The mineral assemblage of the greenschist-facies mylonite is chlorite + epidotite + albite (Ab = 94.7–99.9) + quartz, which contains 10-30% gravel components. Microstructural analysis indicates that the greenschist-facies mylonite experienced two episodes of deformation：early ductile deformation followed by a later stage of brittle deformatio. Both episodes of deformation suggest an extensional environment. The extensive development of bulging recrystallization (BLG) of quartz, microscopic fractures and fine granulation of albite suggest that the temperature of ductile deformation is about 300-400°C, compatiable with a ductile shearing at shallow crust levels (~5-10 km). Petrographic features suggest that the greenschist-facies mylonite might originate from volcanic sedimentary rocks or sedimentary rocks affected by the intrusion of mafic magma. Combined with seismic interpretation, we propose that the greenschist-facies mylonite might be formed by crustal exhumation after thick Mesozoic sediments were denuded by a major extension.     

南海IODP 367-368钻探区深地震探测的OBS站位设计分析

借助于国际大洋发现计划平台, 于2017年2月—6月间在南海实施第三次科学钻探(IODP 367-368航次)。海底地震仪(OBS)深地震探测和国际大洋发现计划(IODP)钻探成果相结合, 可以对南海北部洋陆转换带(COT)边界及地质属性的确定提供更好、更全面的深部地质过程解释。文章基于IODP 367-368钻探提出的三种可能设想(下地壳出露、最老洋壳出露、上地幔出露), 分别建立了三种初始速度模型。利用Rayinvr及Tomo2d软件, 对每一种初始模型分别开展了不同OBS间距的射线追踪和走时模拟测试对比, 以及模型的分辨率测试。测试结果表明: OBS间隔为7km比间隔为10km具有更好的射线路径与密度覆盖; 对于上地幔出露模型, 需要足够长的探测测线(>100km), 才能有效得到30km深处信息; 分辨率测试说明, OBS间距需要设置小于或等于7km时, 才能有效分辨20km速度异常体(即模糊带)。     

2002年3月ODP SCICOM/IODP IPC 会议介绍

2 0 0 2年 3月 1 8— 2 2日在日本海洋科技研究中心联合召开了 ODP SCICOM/ IODP IPC会议 ,即 IODP的第二次 IPC(计划委员会 ,相当于 ODP中的 SCICOM,是 ISAS的最高学术机构 )会议。会议主要听取了 ODP运作报告、工作报告、航次 ( 1 95、1 96、1 97)的科学报告等。会议讨论的重要内容是“ODP L egacy”报告 ,主要内容包括地球环境动力学和地球内部动力学等。会议听取了日本、美国、欧洲、加拿大、中国等国家在准备 IODP方面的进展汇报 ,中国代表介绍了中国参加 ODP4年以来的总结和对进行 IODP所做的努力     

基于TAPI 3.0的视频会议系统

在阐述TAPI接口背景的基础上，从开发的角度上介绍TAPI3.0的层次模型。TAPI对象，IP组播。以及H.323协议的结构，讨论了在Visual Basic6.0开发环境下，利用组件对象模型（COM-Com-ponent Object Model)技术开发视频会议系统的方法，介绍了基于TAPI3.0的中国地震局地震现场视频会议系统。     

IODP中的海陆对比和海陆相互作用

综合大洋钻探计划（IODP）将于2003年10月启动。与大洋钻探计划（ODP）相比,IODP规模更大,钻探和研究范围更宽,囊括地球科学的诸多领域,涉及海底生物圈、地球壳幔结构、俯冲工厂和地震活动、古环境记录和海底资源等。从海陆对比和海陆相互作用的角度,分析我国地球科学,尤其是新生代地质学研究中的一些特点和优势。中国新生代地质演化历史别具特色,如宏观地形格局的变化,喜马拉雅山和青藏高原的隆升,西太平洋边缘海的扩张,亚洲季风系统的形成等,这些特色成为中国科学家参与IODP科学研究计划的优势。