RUMINATIONS ON THE SILVER CAMEL: LESSONS FROM THE BLACK ROCK DESERT'S MINING LANDSCAPE*     

PETER B. MIRES 《Geographical review》2011,101(4):592-599

  相似文献   

Spatial variability of watermass conditions within the European Epicontinental Seaway during the Early Jurassic (Pliensbachian–Toarcian)     

DARIO HARAZIM  BAS VAN DE SCHOOTBRUGGE  KATRIN SORICHTER  JENS FIEBIG  ANDRIES WEUG  GUILLAUME SUAN  WOLFGANG OSCHMANN 《Sedimentology》2013,60(2):359-390

In order to constrain spatial variability in watermass conditions within the European Epicontinental Seaway prior to, during and after the Toarcian Oceanic Anoxic Event, carbon (δ¹³C_bel, δ¹³C_carb) and oxygen (δ¹⁸O_bel, δ¹⁸O_carb) isotope records were obtained from three sections in the Grands Causses Basin (southern France). These data were then compared with similar records along a north–south transect across the European Epicontinental Seaway. As the conclusions reached here strongly depend on the reliability of belemnite calcites as archives of palaeoceanographic changes, an attempt was made to improve the understanding of isotope signals recorded in belemnite calcite. Intra‐rostral carbon and oxygen‐isotope data from six belemnite specimens belonging to the genus Passaloteuthis were collected. Intra‐rostral carbon‐isotopes are influenced by vital effects, whereas oxygen‐isotopes reflect relative changes in temperature and salinity. Palaeotemperatures calculated from δ¹⁸O_bel‐isotope records from the Grands Causses Basin confirm relatively low temperatures throughout the Late Pliensbachian. Similar cool water conditions have previously been shown in Germany, England, Spain and Portugal. A temperature increase of up to 6 °C is observed across the Pliensbachian–Toarcian boundary. A pronounced negative shift of at least ?3‰ (Vienna‐Pee Dee Belemnite) is recorded in bulk carbonate carbon during the lower Harpoceras serpentinum zone, typical of the Toarcian Oceanic Anoxic Event. Before and after the Toarcian Oceanic Anoxic Event, a good correlation between δ¹³C_carb and δ¹³C_bel exists, indicating well‐ventilated bottom‐waters and normal marine conditions. Instead, data for the Toarcian Oceanic Anoxic Event indicate the development of a strong north–south gradient in salinity stratification and surface‐water productivity for the Western Tethyan realm. This study thus lends further support to a pronounced regional overprint on carbon and oxygen‐isotope records in epicontinental seaways.  相似文献   

Greater India Basin Hypothesis and A Two-Stage Cenozoic Collision Between India and Asia     

Douwe VAN HINSBERGEN  Lippert Peter  Dupont-Nivet Guillaume  McQuarrie Nadine  Doubrovine Pavel  Spakman Wim  Torsvik Trond 《《地质学报》英文版》2013,87(Z1):15-15

  相似文献   

Identifying Accessory Mineral Saturation during Differentiation in Granitoid Magmas: an Integrated Approach   总被引：19，自引：4，他引：15  

HOSKIN  PAUL W. O.; KINNY  PETER D.; WYBORN  DOONE; CHAPPELL  BRUCE W. 《Journal of Petrology》2000,41(9):1365-1396

Numerical reconstructions of processes that may have operatedduring igneous petrogenesis often model the behaviour of importanttrace elements. The geochemistry of these trace elements maybe controlled by accessory mineral saturation and fractionation.Determination of the saturation point of accessory mineralsin granitoid rocks is ambiguous because assumptions about crystalmorphology and melt compositions do not always hold. An integratedapproach to identifying accessory mineral saturation involvingpetrography, whole-rock geochemical trends, saturation calculationsand mineral chemistry changes is demonstrated here for a compositionallyzoned pluton. Within and between whole-rock samples of the BoggyPlain zoned pluton, eastern Australia, the rare earth element(REE)-enriched accessory minerals zircon, apatite and titaniteexhibit compositional variations that are related to saturationin the bulk magma, localized saturation in intercumulus meltpools and fractionation of other mineral phases. Apatite isidentified as having been an early crystallizing phase overnearly the whole duration of magma cooling, with zircon (andallanite) only saturating in more felsic zones. Titanite andmonazite did not saturate in the bulk magma at any stage ofdifferentiation. Although some trace elements (P, Ca, Sc, Nb,Hf, Ta) in zircon exhibit compositional variation progressingfrom mafic to more felsic whole-rock samples, normalized REEpatterns and abundances (except Ce) do not vary with progressivedifferentiation. This is interpreted to be a result of limitationsto both simple ‘xenotime’ and complex xenotime-typecoupled substitutions. Our data indicate that zircon REE characteristicsare not as useful as those of other REE-rich accessory mineralsas a petrogenetic indicator. KEY WORDS: saturation; zircon; apatite; titanite; magma differentiation; trace elements; REE patterns  相似文献   

超固结粘土的二元介质模型   总被引：6，自引：1，他引：5  

沈珠江  邓刚 《岩土力学》2003,24(4):495-499

为了分析超固结粘土边坡的变形和稳定的需要,在岩土破损力学的框架内建议了一个适用于这类土的二元介质模型。该模型考虑了土体内在的不均一性,把它看作由结构块和结构带组成的复合体,两者共同分担外荷载,模型包含10参数,并拟定了这些参数的测定方法。通过模拟三轴试验的计算表明,该模型可以反映London粘土的应力-应变特征。  相似文献   

成矿系统分析与新类型矿床预测   总被引：27，自引：3，他引：24  

翟裕生  彭润民  邓军  王建平 《地学前缘》2000,7(1):123-132

新类型矿床的发现常能带来矿产储量的巨量增长 ,是新世纪中保障矿产资源供应的一个重要途径。成矿系统分析对发现新类型矿床有重要意义。 (1)掌握一个区域成矿系统中各矿床类型间相互关系 ,由已知矿床类型找寻未知矿床类型 ,这已在长江中下游成矿带的找矿历史中得到证实。 (2 )认识成矿系统的空间结构 ,主要是垂向分带 ,有助于找寻深部的隐伏矿床类型。 (3)查明成矿系统的时间结构 ,包括成矿过程中矿床类型的迭变关系 ,可由已知矿化链条查找缺失的矿化链条 (矿床类型 ) ,这在岩浆热液成矿系统中常能奏效。 (4 )查明成矿系统中矿床类型多样性的制约因素 ,可据此分析相关区域中发现新类型矿床的潜力。 (5)研究新的成矿环境和新的成矿作用 ,从而发现新的矿床类型。在生物成矿系统、深海成矿系统、低温成矿系统、构造成矿系统及叠加成矿系统中有更大的发现新类型矿床的几率。文中提出近期内可能发现的新的铂族元素矿床类型。笔者还指出今后的找矿目标 ,应是整个成矿系统 ,而不是局限于单个矿床及单个矿床类型 ,这样才可能不失去发现新类型矿床的机会。  相似文献   

Rural Self-Reliance in Bondolfi, Zimbabwe: the role of beekeeping     

ETIENNE NEL  PETER M. ILLGNER  K. WlLKlNS  M.P. ROBERTSON 《The Geographical journal》2000,166(1):26-34

Community-based economic self-reliance has become critical in many African countries because of the severity of prevailing soci-economic and environmental constraints. Concerns over food security have encouraged a re-evaluation of the importance of indigenous technical knowledge. This study examines a rural area in Zimbabwe where members of the local community have established a successful beekeeping association to improve their livelihoods. The history of the initiative, its broader impact on the community and the role played by external facilitation feature in the study.  相似文献   

Mountain Biking in the Manawatu Region: Participants, Perceptions, and Management Dimensions     

SARAH LEBERMAN  PETER MASON 《New Zealand geographer》2000,56(1):30-38

The increase in the number of mountain bikers world‐wide has raised a number of issues associated with impacts and appropriate management strategies. Studies in the USA, UK and New Zealand have indicated a growing concern with environmental impacts, demonstrated attitudes of other recreationalists to mountain bikers and identified a number of management issues. This article presents the findings from field research conducted during the southern summer of 1997/8. The research was carried out in association with the Palmerston North City Council (PNCC) and the Manawatu Mountain Bike Club. The aims of the research were to investigate the demographics of mountain bikers and related management issues. Key findings of the field research were that: access to mountain biking opportunities was a problem; information provision was poor; there was conflict between user groups; there was a lack of agreement on whether there should be dedicated or multi‐use tracks. The article discusses how the research findings have been used to assist in the creation of an outdoor recreation and tourism strategy for Palmerston North. A model for managing recreation /tourism activities is also suggested.  相似文献   

Multiproxy diet analysis of the last meal of an early Holocene Yakutian bison          下载免费PDF全文

BAS VAN GEEL  ALBERT PROTOPOPOV  IAN BULL  ELZA DUIJM  FIONA GILL  YOURI LAMMERS  ALINE NIEMAN  NATALIA RUDAYA  SVETLANA TROFIMOVA  ALEXEI N. TIKHONOV  RUTGER VOS  SNEZHANA ZHILICH  BARBARA GRAVENDEEL 《第四纪科学杂志》2014,29(3):261-268

  相似文献   

The Geological Conservation Review: Progress and problems     

PETER J. SMITH 《Geology Today》1986,2(5):153-155

  相似文献