Single Zircon LA-ICP-MS U-Pb Dating of the Guandimiao and Wawutang Granitic Plutons in Hunan, South China and Its Petrogenetic Significance

1 Introduction The South China Block (SCB), located between the Qinling-Dabie and Songma Indosinian sutures, experienced successively two important tectonic movements during the Mesozoic, i.e. the Indosinian movement (early Mesozoic) and the Yanshanian movement (late Mesozoic). Therefore, the generally accepted viewpoint is that the key geological problems during the Mesozoic are essentially the dynamics and material expression of these two tectonic movements in South China (Chen et al.…     

Coastal permafrost landscape development since the Late Pleistocene in the western Laptev Sea,Siberia

Winterfeld, M., Schirrmeister, L., Grigoriev, M. N., Kunitsky, V. V., Andreev, A., Murray, A. & Overduin, P. P. 2011: Coastal permafrost landscape development since the Late Pleistocene in the western Laptev Sea, Siberia. Boreas, 10.1111/j.1502‐3885.2011.00203.x. ISSN 0300‐9483. The palaeoenvironmental development of the western Laptev Sea is understood primarily from investigations of exposed cliffs and surface sediment cores from the shelf. In 2005, a core transect was drilled between the Taymyr Peninsula and the Lena Delta, an area that was part of the westernmost region of the non‐glaciated Beringian landmass during the late Quaternary. The transect of five cores, one terrestrial and four marine, taken near Cape Mamontov Klyk reached 12 km offshore and 77 m below sea level. A multiproxy approach combined cryolithological, sedimentological, geochronological (¹⁴C‐AMS, OSL on quartz, IR‐OSL on feldspars) and palaeoecological (pollen, diatoms) methods. Our interpretation of the proxies focuses on landscape history and the transition of terrestrial into subsea permafrost. Marine interglacial deposits overlain by relict terrestrial permafrost within the same offshore core were encountered in the western Laptev Sea. Moreover, the marine interglacial deposits lay unexpectedly deep at 64 m below modern sea level 12 km from the current coastline, while no marine deposits were encountered onshore. This implies that the position of the Eemian coastline presumably was similar to today's. The landscape reconstruction suggests Eemian coastal lagoons and thermokarst lakes, followed by Early to Middle Weichselian fluvially dominated terrestrial deposition. During the Late Weichselian, this fluvial landscape was transformed into a poorly drained accumulation plain, characterized by widespread and broad ice‐wedge polygons. Finally, the shelf plain was flooded by the sea during the Holocene, resulting in the inundation and degradation of terrestrial permafrost and its transformation into subsea permafrost.     

Study on Flow Field Around Vertical Breakwater Under Different Overtopping Conditions Based on Numerical Simulation

A numerical wave flume is constructed based on the Reynolds Averaged Navier-Stokes (RANS) equations with turbulence closure by a modified k-ε model to study the viscous interactions of waves with vertical breakwaters for different overtopping cases. The governing equations,the turbulence model,boundary conditions,and solution method for the numerical wave flume are introduced briefly. The reliability of the numerical wave flume is examined by comparing the numerical results with the experimental measurement...     

Evolution of pore space in the Poza Rica trend (Mid-Cretaceous), Mexico

ABSTRACT The Poza Rica trend of the Tampico embayment, Mexico, will ultimately produce more than 2.3 × 10⁹ barrels of oil from Mid-Cretaceous (Albian-Cenomanian) basin-margin deposits. Bioclastic grainstone, packstone, and wackestone are interbedded with polymictic lime breccia and dolomitized debris; all were deposited by sediment gravity flow. Indigenous sediment was pelagic lime mud. Typical reservoir porosities are about 10%; permeabilities average 2 md and rarely exceed 100 md. Porosity is largely the result of selective dissolution of rudist fragments, which were originally aragonite. Detailed petrographic study, with emphasis on the diagenetic products, allows quantitative assessment of porosity at various diagenetic stages from original sediment to reservoir rock. A relatively simple diagenetic history is reflected by about 90% of the samples studied: primary porosity was reduced through lithification of matrix mud and initial cementation by clear, equant to bladed, non-ferroan calcite. Later dissolution produced extensive skelmoldic and minor vuggy porosity. Subsequently, non-ferroan calcite cement reduced porosity before the emplacement of hydrocarbons. Reconstructed sediment porosities are comparable to, but lower than, modern counterparts. The initial phase of cementation and presumed lithification of mud greatly reduced porosity in all lithologies, but appreciably more porosity persisted in grainstone and packstone than in wackestone or mudstone. Dissolution produced a porosity resurrection, which exceeded that of the initial sediment in some grainstones. Calcite cementation and local multiphase quartz cementation and dolomitization reduced porosity to present average values of 8–12% in grain-supported rocks and 3% in mud-supported rocks. The greater persistence of primary porosity and, therefore, permeability in grain-supported rocks probably accounts for their greater secondary porosity development and ultimate reservoir quality. Geometrically averaged permeabilities range from only 0.17 md in wackestone to 3.85 md in dolomite, but differ significantly with rock type and grain size. Permeability increases with porosity in all lithologies; the rate of increase is greater at higher porosities and with coarser grain sizes. The agent for both early cementation and development of secondary porosity appears to have been meteoric water. Subaerial exposure appears to be ruled out, however, by a basin-margin depositional environment and continued burial beneath Upper Cretaceous pelagic sediments. Early exposure to meteoric water can be explained by a hydrologic head developed during penecontemporaenous exposure that produced cavernous porosity in the adjacent Golden Lane trend. Descending meteoric water likely emerged as submarine springs along the Tamabra trend. Deposition of pelagic limestone during the Turonian blanketed part of the Golden Lane escarpment to enhance development of a large freshwater lens; gaps in the blanket localized springs and influenced flow patterns within the Poza Rica field. Analogous freshwater circulation exists today in northern Florida.     

关于我国1957年旧重力基本网的精度与系统转换

简述了原国家重力基本网(57网)的历史和技术要点,详细地分析了57网的各类误差和产生原因,提出了新、旧系统转换的方法。本文研究表明,57网基本点相对观测的实际精度约为±0.06mgal,仪器平均值误差为1.6×10~(-4)。基本点重力值含-13.56mgal的基准误差和1.9×10~(-4)的尺度差,并含有±0.1～0.2mgal的非线性系统误差。对基本点实行新、旧系统转换误差为±0.05mgal,基本不损失其观测精度。     

The Mathematic Models of the Kalman Filtering for Across-Fault Measurement

This paper makes a probe into the application of the Kalman filtering method to the data processing of across-fault measurements.On the basis of statistical regression,the mathematic and stochastic models of filtration are established by combining the regression method with Kalman filtering.In the filtering computation,not only the randomness of fault movements but also the time-dependent variation of environmental effects have been taken into consideration.By use of the adaptive filtering method,an estimation of the dynamic noise variance matrix is obtained through iteration.Models for one measuring line(leveling line or baseline),two measuring lines(both leveling lines or both baselines)and four measuring lines(two leveling lines and two baselines)are derived and established systematically.By means of these models,the data of across-fault measurements can be processed dynamically in real-time to provide the filtered values of height difference between benchmarks or baseline length at different time in     

Relocation of Hypocenters in the Bohai Sea and Adjacent Areas

In this paper a method of relocating hypocenter in inhomogeneous medium is introduced.Based on the velocity from the latest results on the crust and mantle structure of the Bohai Sea and its adjacent areas,by using the data recorded in Shandong,Hebei,Beijing,and Liaoning networks around the Bohai Sea we apply the method to relocate hypocenter parameters of 598 events occurring in the Bohai Sea and its adjacent areas.The accuracy of hypocenter relocation is discussed.We present the results of events ML≥4.0 in the Bohai Sea in recent years and discussed the distribution of focal depths.     

Flow speed and calving rate of Kongsbreen glacier, Svalbard, using SPOT images

Kongsbreen, a tide-water glacier located in Kongsfjorden, is the most active calving glacier in Svalbard. Three SPOT images are used to determine its flow speed and calving rate. The position of fourteen reference points was determined on the coast or mountain sides, and the changes in position of 144 characteristic features on the glacier surface were calculated. The obtained speed profiles arc consistent with the findings from previous works from 1962-64 and 1983-86. When comparing the obtained longitudinal profile to the data from 1962–64. it is found that the flow velocity at a given distance from the front has been nearly constant.
The results from the SPOT images analysis are completed by using existing topographic works. The present study shows that SPOT images (panchromatic as well as multichannel), recorded with a periodicity of one year, can be used to determine precisely the annual flow speed and calving rate of active glaciers such as Kongsbreen. Images recorded with a periodicity of two, three or four weeks can allow identical determination on tide-water glaciers during a surging active phase.     

From Sustainable Development Objectives to Indicators of Progress

Local communities are adopting sustainable development goals as outlined in Agenda 21. The pressure-state-response model proposed by the OECD and adopted in Australia is extended with environmental sustainability and environmental health indicators to emphasise interaction between the bio-physical and socio-economic sub-systems. Indicators are selected with the participation of local residents to monitor sensitive local environmental concerns, to motivate change and to provide benchmarks for comparison with other areas. Partnerships are proposed to use established programmes to provide much of the data required.     

船舶气象导航随船验证

通过横流太平洋往返两个航次随船调查，研究了采用气象导航对减少燃油消耗和保证船舶安全、班期等，不但有定的经济效益，而且是一种非常有效的航运管理方法。