Atmospheric Methyl Iodide at Cape Grim, Tasmania, from AGAGE Observations

Atmospheric mixing ratios of methyl iodide (CH₃I) and other methyl halides have been measured at Cape Grim, Tasmania (41°S, 145°E), since early 1998 as part of the Advanced Global Atmospheric Gases Experiment (AGAGE). This paper analyses about 1700 ambient air CH₃I measurements from the 14-month period (March 1998–April 1999). Mixing ratios peaked during the summer, despite faster photolytic loss, suggesting local oceanic emissions were about 2.2–3.6 times stronger in summer than in winter. Back trajectories show that CH₃I levels are strongly dependent on air mass origin, with highest mixing ratios in air from the Tasman Sea/Bass Strait region and lowest levels in air originating from the Southern Ocean at higher latitudes. CH₃I mixing ratios were not well correlated with other methyl halides in unpolluted marine air. The large variations with season and air mass origin suggest that high frequency, continuous data from key locations will make a significant contribution to the understanding of sources and sinks of this important short-lived atmospheric species.     

登陆热带气旋的大暴雨天气与一般暴雨对比分析及其雨强增幅原因的初探

本文以９０１５号热带气旋登陆后造成的省淮以南大暴雨天气为例，与８闪一般暴雨天气的热力动力条件进行对比，分析它们之间的异同点，并利用二维点尺度力学模式对地面中尺度锋区引起民环流进行模拟试验，结果表明，在热带气旋伸向东北部一条辐合线的偏北旗帜的中尺度锋区驱动扰动涡旋，在涡旋的上升部位可对大暴雨有增幅作用。     

热带森林生态系统气象观测铁塔的设计

讨论了西双版纳地区原始热带雨林和人工林气象观测铁塔的选择与设计，扼要地介绍了气象观测铁塔的塔形，结构及春功能，并提出了在高湿多雷热带雨林地区设计，安装铁塔应注意的事项及解决途径。     

中国热带东,西部地区冬季气候的差异与橡胶树的引种

由于青藏高原的动力影响，使得西部地区冬季出现下沉气流，多日照，利于橡胶树的越冬，而东部则出现上升气流，少日照，不利越冬，又由于青藏高原大山体，冬季明显地阻挡低层空气平流，导致高原南侧的西部地区冬季降温和缓，有利橡胶树越冬，而东部地区因无高大山体阻挡，寒潮初期降温剧烈，后期低温阴雨天气持续甚久，易导致橡胶树的严重寒害。     

发展互花米草开发华南热带海滩

互花米草是禾本科多年生高秆型草本植物，原产北美洲大西洋海岸，７０年代末引入我国，本文在大量试验基础上，对互花米草在华南热带海滩的生长适应性，生物量和收获量及其在促淤造陆，改良土壤等方面作了论述，并对互花米草的抗污染作用和作为饲料，饵料等的经济作用也进行了定量分析，认为互花米草在华南热带海滩具有广阔的开发应用前景。     

Stratigraphy of the upper cretaceous and lower tertiary strata in the Tethyan Himalayas of Tibet (Tingri area,China)

The 1500-m-thick marine strata of the Tethys Himalaya of the Zhepure Mountain (Tingri, Tibet) comprise the Upper Albian to Eocene and represent the sedimentary development of the passive northern continental margin of the Indian plate. Investigations of foraminifera have led to a detailed biozonation which is compared with the west Tethyan record. Five stratigraphic units can be distinguished: The Gamba group (Upper Albian - Lower Santonian) represents the development from a basin and slope to an outer-shelf environment. In the following Zhepure Shanbei formation (Lower Santonian - Middle Maastrichtian), outer-shelf deposits continue. Pebbles in the top layers point to beginning redeposition on a continental slope. Intensified redeposition continues within the Zhepure Shanpo formation (Middle Maastrichtian - Lower Paleocene). The series is capped by sandstones of the Jidula formation (Danian) deposited from a seaward prograding delta plain. The overall succession of these units represents a sea-level high at the Cenomanian/Turonian boundary followed, from the Turonian to Danian, by an overall shallowing-upward megasequence. This is followed by a final transgression — regression cycle during the Paleocene and Eocene, documented in the Zhepure Shan formation (?Upper Danian - Lutetian) and by Upper Eocene continental deposits. The section represents the narrowing and closure of the Tethys as a result of the convergence between northward-drifting India and Eurasia. The plate collision started in the Lower Maastrichtian and caused rapid changes in sedimentation patterns affected by tectonic subsidence and uplift. Stronger subsidence and deposition took place from the Middle Maastrichtian to the Lower Paleocene. The final closure of remnant Tethys in the Tingri area took place in the Lutetian.     

Current controlled sediment deposition from the shelf to the deep ocean: the cenozoic evolution of circulation through the SW pacific gateway

 The circulation of cold, deep water is one of the controlling factors of the Earth's climate. Forty percent of this water enters the world ocean through the Southwest Pacific as a deep western boundary current (DWBC) flowing northwards at bathyal to abyssal depths, east of the New Zealand microcontinent. South of latitude 50°S, the DWBC is intimately linked with the Antarctic circumpolar current (ACC), which is the prominent force for the shallow-water circulation. The Pacific DWBC is presently the largest single contributor of deep ocean water, and deciphering its evolution is of fundamental importance to understanding ocean and climate history, and global ocean hydrography. The evolution of the DWBC system, and of related circum-Antarctic currents, has taken place since 30–25 Ma when plate movements created the first oceanic gaps south of Australia and South America. The stratigraphic record preserved in sediment drifts of the Southwest Pacific, in eastern New Zealand, is the best available for deciphering the Neogene history of Southern Ocean water masses, and of the circulation of the ACC, DWBC and their precursor systems. Major current activity commenced on the New Zealand margin in the late Eocene or early Oligocene (Hoiho Drift; early ACC) and was widespread by the mid-late Oligocene (Marshall Paraconformity and Weka Pass Limestone drift; ACC). During the Neogene the eastern South Island continental shelf built seawards by accretion at its outer edge of large Miocene current drifts up to tens of kilometres long and hundreds of metres thick (Canterbury drifts). Also commencing in the mid-Cenozoic, but in depths >2000 m, the DWBC emplaced large deep-water sediment drifts. Rates of drift deposition accelerated considerably in the late Neogene, when climatic change (and particularly glacial sea-level falls) caused the delivery of large volumes of turbiditic sediment into the path of the DWBC via the Bounty and Hikurangi channels. Received: 9 August 1995 / Accepted: 15 January 1996     

多金属结核的沉积物地球化学场

远洋沉积物是多金属结核赖以生长的场所，本文系统地研究了沉积物中主要成矿元素水成组分在不同地球化学场和不同沉积阶段的地球化学特征，以及水成组分的含量比与成矿作用的相互关系。研究表明，Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ都是一些比较活泼的元素，它们共处于多金属结核、沉积物和大洋水的统一体系中，当结核形成时，Ｍｎ、Ｆｅ、Ｎｉ、Ｃｕ在结核与沉积物中的含量呈负相关，而Ｃｏ含量呈正相关。研究区东部结核以富含Ｍｎ、Ｎｉ、Ｃｕ贫Ｆｅ、Ｃｏ为特征，其伴生沉积物相对贫Ｍｎ、Ｎｉ、Ｃｕ、Ｃｏ，而富Ｆｅ，可称之为贫化的地球化学场。研究区西部结核富含Ｆｅ、Ｃｏ而贫Ｍｎ、Ｎｉ、Ｃｕ，其伴生沉积物则相应贫Ｆｅ，而富Ｍｎ、Ｎｉ、Ｃｕ、和Ｃｏ，可称之为富化的地球化学场。可以看出，贫化的沉积物地球化学场，恰恰是寻找富矿结核的最佳场所。早中新世以来的沉积物，根据水成组分的含量或含量比，也可相应于结核的形成分为三大沉积阶段，其中的第Ⅱ阶段具有贫化的地球化学特征，是多金属结核形成的最有利时期     

Attenuation differences in layer 2A in intermediate- and slow-spreading oceanic crust

In situ seismic attenuationQ⁻¹logs are derived from borehole velocity profiles and reveal sharp boundaries between morphologies of the extrusive volcanic layers in intermediate- and slow-spreading oceanic crust.Q⁻¹logs are calculated from the scattering attenuation associated with vertical velocity heterogeneity in Ocean Drilling Program Holes 504B and 896A and in Hole 395A, located in 5.9–7.3 Ma crust on the Pacific and Atlantic plates, respectively. Our results strongly tie crustal properties to seismic measurables and observed geological structures: we find that the scattering attenuation can be used to identify the extrusive volcanic sequence because it is closely related to changes in the degree of vertical heterogeneity. We interpret a distinct decrease in the Q⁻¹log at the transition below the extrusive volcanic layer to correspond with the seismic layer 2A/2B boundary. The boundary is located at 465 m depth below the sea floor in both Hole 395A and 504B, although this is likely to be a coincidence of the sediment thickness at these sites. Layer 2A is estimated to be approximately 150 m thick in Hole 504B and > 300 m thick in Hole 395A. Cyclic sequences of high-porosity pillows and low-porosity massive units in the uppermost 100 m of volcanics in Hole 395A result in large velocity heterogeneities which cause > 5 times more attenuation in this layer than in Hole 504B. In Hole 896A, by contrast, fewer pillows, more massive flows, and a greater volume of carbonate veins decrease the velocity heterogeneity and attenuation significantly over only 1 km distance from Hole 504B. We conclude that the attenuation in the extrusive volcanics of the ocean crust is largely controlled by variation in local heterogeneity and morphology as well as by subsequent hydrothermal alteration. The observed differences inQ⁻¹profiles and layer 2A thickness at these sites may be attributed to variations in the volume and duration of volcanic activity at mid-ocean spreading centers for these Pacific and Atlantic ridge segments.     

Paleogeographic maps of the Japanese Islands: Plate tectonic synthesis from 750 Ma to the present

Abstract A series of paleogeographic maps of the Japanese Islands, from their birth at ca 750–700 Ma to the present, is newly compiled from the viewpoint of plate tectonics. This series consists of 20 maps that cover all of the major events in the geotectonic evolution of Japan. These include the birth of Japan at the rifted continental margin of the Yangtze craton ( ca 750-700 Ma), the tectonic inversion of the continental margin from passive to active ( ca 500 Ma), the Paleozoic accretionary growth incorporating fragments from seamounts and oceanic plateaux ( ca 480-250 Ma), the collision between Sino-Korea and Yangtze (250–210 Ma), the Mesozoic to Cenozoic accretionary growth (210 Ma-present) including the formation of the Cretaceous paired metamorphic belts (90 Ma), and the Miocene back-arc opening of the Japan Sea that separated Japan as an island arc (25-15 Ma).