WILDLIFE CONSERVATION AND BAMBOO MANAGEMENT IN CHINA'S SOUTHEAST UPLANDS*     

CHRISTOPHER R. COGGINS 《Geographical review》2000,90(1):83-111

ABSTRACT. The subtropical forests, grasslands, and wetlands of Southeast China's Wuyi‐Daiyun Mountain Range provide essential habitats for diverse wildlife, including a dwindling population of tigers. Three primary protected areas, the Meihuashan, Wuyishan, and Longxishan Nature Reserves, contain varied wildlife habitats and also provide natural resources for 7,000 people in several dozen villages. A field‐based study of land use and habitat quality in these reserves shows that anthropogenic bamboo forests are among the least valuable habitats for wildlife but that, as the primary source of household income, bamboo monoculture is spreading rapidly and replacing habitats of greater ecological value. Although authorities in Meihuashan have demarcated the many broadleaf forest patches for strict protection, household income and bamboo‐management research in all three reserves suggests that successful habitat conservation may ultimately depend on more equitable systems of land tenure, improved cooperative cottage industries, and greater local economic diversification.  相似文献   

Production of mud‐grade carbonates by marine fish: Crystalline products and their sedimentary significance     

MICHAEL A. SALTER  CHRISTOPHER T. PERRY  ROD W. WILSON 《Sedimentology》2012,59(7):2172-2198

Recent work has established that marine teleost (bony) fish represent a prolific source of mud grade, mainly high‐Mg calcite, carbonate sediment by means of primary precipitation within the intestine. Previously documented crystalline products display a diverse array of morphologies, many unique in shallow tropical marine settings, and have a wide range of magnesium contents (from 18 to 39 mol% MgCO₃). This study utilizes scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction and liquid ion chromatography to provide a more extensive and expansive morphological, mineralogical and chemical characterization of the crystalline forms produced by a wider range of piscine functional groups (covering 21 different fish species common in The Bahamas). Several crystal morphologies not previously described in fish‐derived carbonates are documented, and chemical composition is found to be more variable than previously reported: in addition to high‐Mg calcites with >18 mol% MgCO₃, high‐Mg calcites with lower MgCO₃ contents and low‐Mg calcites are identified. From the expanded species range, MgCO₃ content in fish‐derived carbonates ranges from ca 0˙5 to > 40 mol%, and particle length is in the range 0˙1 to >50 μm (typically <2 μm for individual crystals). Amorphous Mg‐carbonates (with detectable CaCO₃ of <2 mol%) are also found to varying extent in the precipitates of many species. Dominant mineralogy and MgCO₃ content varies with producing species and crystal morphology (itself a species‐dependent variable). Given the very small grain size and often high MgCO₃ contents of these carbonates, interesting questions arise about their preservation potential. Thus, the extent to which carbonates produced by different species may follow different post‐excretion preservation pathways is considered.  相似文献   

Facies architecture of individual basin‐plain turbidites: Comparison with existing models and implications for flow processes     

PETER J. TALLING  LAWRENCE A. AMY  RUSSELL B. WYNN  CHRISTOPHER J. STEVENSON  MICHAEL FRENZ 《Sedimentology》2012,59(6):1850-1887

Current understanding of submarine sediment density flows is based heavily on their deposits, because such flows are notoriously difficult to monitor directly. However, it is rarely possible to trace the facies architecture of individual deposits over significant distances. Instead, bed‐scale facies models that infer the architecture of ‘typical’ deposits encapsulate current understanding of depositional processes and flow evolution. In this study, the distribution of facies in 12 individual beds has been documented along downstream transects over distances in excess of 100 km. These deposits were emplaced in relatively flat basin‐plain settings in the Miocene Marnoso Arenacea Formation, north‐east Italy and the late Quaternary Agadir Basin, offshore Morocco. Statistical analysis shows that the most common series of vertical facies transitions broadly resembles established facies models. However, mapping of individual beds shows that they commonly deviate from generalized models in several important ways that include: (i) the abundance of parallel laminated sand, suggesting deposition of this facies from both high‐density and low‐density turbidity current; (ii) three distinctly different types of grain‐size break, suggesting waxing flow, erosional hiatuses and bypass of silty sediment; (iii) the presence of mud‐rich debrites demonstrating hybrid flow deposition; and (iv) dune‐scale cross‐lamination in fine‐medium grained sandstones. Submarine sediment density flows in basin‐plain settings flow over relatively simple topography. Yet, their deposits record complex flow events, involving transformation between different flow types, rather than the simple waning surges often associated with the distal parts of turbidite systems.  相似文献   

Speleogenetic evidence from Ogof Draenen for a pre‐Devensian glaciation in the Brecon Beacons,South Wales,UK          下载免费PDF全文

ANDREW R. FARRANT  CHRISTOPHER J. M. SMITH  STEPHEN R. NOBLE  MICHAEL J. SIMMS  DAVID A. RICHARDS 《第四纪科学杂志》2014,29(8):815-826

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Nature, origin and classification of peritidal tepee structures and related breccias   总被引：4，自引：0，他引：4  

RICCARDO L. A. M. ASSERETO  CHRISTOPHER G. ST C.  KENDALL† 《Sedimentology》1977,24(2):153-210

Distinctive peritidal tepee antiform structures, buckled margins of saucer-like megapolygons are common in marine vadose fenestral and pisolitic limestones and/or dolomites of carbonate platform sequences and occur in intertidal and supratidal carbonates ranging in age from Silurian to Holocene. These megapolygons commonly form and are sometimes truncated before the deposition of the next sedimentary layer. The megapolygons result from the expansion of surface sediments by as much as 15%. The expansion is caused by the following continuously repeated sequence of processes: (1) Desiccation and thermal contraction causing small fractures; (2) phases of wetting causing enlargement of fractures; (3) phases of crystallization of calcium carbonate and other minerals causing the enlargement, fill and cementation of the fractures. Precipitation is from brines and meteoric waters; (4) hydration of minerals, thermal expansion, breaking waves and faulting may add to this disruption. The development of the tepee fabric can be traced from an initially cemented subaerial fenestral crust, exhibiting expansion and compressional structures, to a completely disrupted and brecciated sediment riddled by a labyrinth of fractures and solution cavities. These spaces are filled by numerous phases of internal marine and fresh-water cement and sediment, the latter containing penecontemporaneous or younger marine faunas. Peritidal tepees are useful tools for geologic reconstruction and provide evidence of subaerial exposure; a tropical to subtropical climate; and back-beach or back-barrier deposition. Proper identification of tepees is of economic importance, because they provide good early porosity and permeability for petroleum entrapment and a site for mineralization. Aesthetically, tepee rocks are a fine kaleidoscopic decorative stone.  相似文献   

Development and application of an operational, relocatable, mesogamma-scale weather analysis and forecasting system     

CHRISTOPHER DAVIS  THOMAS WARNER  ELFORD ASTLING  JAMES BOWERS 《地球，A辑:动力气象学与海洋学》1999,51(5):710-727

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Linking ¹³C-based estimates of land and ocean sinks with predictions of carbon storage from CO₂ fertilization of plant growth     

JAMES T. RANDERSON  MATTHEW V. THOMPSON  CHRISTOPHER B. FIELD 《Tellus. Series B, Chemical and physical meteorology》1999,51(3):668-678

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A fast and accurate palaeomagnetic sampler for field use     

TIMOTHY J. F. AUSTIN  CHRISTOPHER T. BALDWIN 《Boreas: An International Journal of Quaternary Research》1984,13(3):273-277

The construction and operation of a sampler which takes accurately orientated cubes of soft sediment for palaeomagnetic analysis is described, and the accuracy of palaeomagnetic sampling techniques is dis-cussed. The sampler has been used for analysing recent estuarine muds.  相似文献   

Seeking the source of the gold used for Irish Bronze-Age goldwork     

THE PREHISTORIC GOLD RESEARCH GROUP 《Geology Today》1998,14(5):187-191

The Group describes how the characterization of alluvial gold from Britain and Ireland is shedding light on an important archaeological problem.  相似文献   

Monazite-Xenotime Thermochronometry and Al2SiO5 Reaction Textures in the Picuris Range, Northern New Mexico, USA: New Evidence for a 1450-1400 Ma Orogenic Event     

DANIEL  CHRISTOPHER G.; PYLE  JOSEPH M. 《Journal of Petrology》2006,47(1):97-118

Al₂SiO₅ reaction textures in aluminous schist and quartziteof the northern Picuris range, north-central New Mexico, recorda paragenetic sequence of kyanite to sillimanite to andalusite,consistent with a clockwise P–T loop, with minor decompressionnear the Al₂SiO₅ triple-point. Peak metamorphic temperaturesare estimated at 510–525°C, at 4·0–4·2kbar. Kyanite and fibrolite are strongly deformed; some prismaticsillimanite, and all andalusite are relatively undeformed. Monaziteoccurs as inclusions within kyanite, mats of sillimanite andcentimetre-scale porphyroblasts of andalusite, and is typicallyaligned subparallel to the dominant regional foliation (S₀/S₁or S₂) and extension lineation (L₁). Back-scatter electron imagesand X-ray maps of monazite reveal distinct core, intermediateand rim compositional domains. Monazite–xenotime thermometryfrom the intermediate and rim domains yields temperatures of405–470°C (±50°C) and 500–520°C(±50°C), respectively, consistent with the progradeto peak metamorphic growth of monazite. In situ, ion microprobeanalyses from five monazites yield an upper intercept age of1417 ± 9 Ma. Near-concordant to concordant analyses yield²⁰⁷Pb–²⁰⁶Pb ages from 1434 ± 12 Ma (core) to 1390± 20 Ma (rim). We find no evidence of older regionalmetamorphism related to the 1650 Ma Mazatzal Orogeny. KEY WORDS: Al₂SiO₅; metamorphism; monazite; thermochronometry; triple-point  相似文献