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Contemporaneous assembly of Western Gondwana and final Rodinia break-up:Implications for the supercontinent cycle

Geoscience Frontiers 2017年第6期8卷 1431-1445页

作者： Sebastián Oriolo Pedro Oyhantcabal klaus wemmer Siegfried Siegesmund Geoscience Center Georg-August-Universitat GottingenGoldschmidtstrae 337077 GottingenGermany Departamento de Geología Facultad de CienciasUniversidad de la RepúblicaMontevideoUruguay

Geological,geochronological and isotopic data are integrated in order to present a revised model for the Neoproterozoic evolution of Western Gondwana.Although the classical geodynamic scenario assumed for the period 800-700 Ma is related to Rodinia break-up and the consequent opening of major oceanic basins,a significantly different tectonic evolution can be inferred for most Western Gondwana cratons.These cratons occupied a marginal position in the southern hemisphere with respect to Rodinia and recorded subduction with back-arc extension,island arc development and limited formation of oceanic crust in internal oceans.This period was thus characterized by increased crustal growth in Western Gondwana,resulting from addition of juvenile continental crust along convergent margins.In contrast,crustal reworking and metacratonization were dominant during the subsequent assembly of Gondwana.The Rio de la Plata,Congo-Sao Francisco,West African and Amazonian cratons collided at ca.630-600 Ma along the West Gondwana Orogen.These events overlap in time with the onset of the opening of the Iapetus Ocean at ca.610-600 Ma,which gave rise to the separation of Baltica,Laurentia and Amazonia and resulted from the final Rodinia break-up.The East African/Antarctic Orogen recorded the subsequent amalgamation of Western and Eastern Gondwana after ca.580 Ma,contemporaneously with the beginning of subduction in the Terra Australis Orogen along the southern Gondwana margin.However,the Kalahari Craton was lately incorporated during the Late Ediacaran-Early Cambrian.The proposed Gondwana evolution rules out the existence of Pannotia,as the final Gondwana amalgamation postdates latest connections between Laurentia and Amazonia.Additionally,a combination of introversion and extroversion is proposed for the assembly of Gondwana.The contemporaneous record of final Rodinia break-up and Gondwana assembly has major implications for the supercontinent cycle,as supercontinent amalgamation and break-up do not necessarily represent alternating epis

关键词： BrasilianoePan-African Orogeny Neoproterozoic Collisional tectonics Pannotia Metacratonization Introversion-extroversion

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Silurian-Devonian and Jurassic Thermal Events in the Ordos Basin, China: Indications from K-Ar Dating on Illites

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Acta Geologica Sinica(English Edition) 1996年第4期70卷 435-446页

作者： Hans Ahrendt klaus wemmer Hans-J rgen Behr Institute of Geology and Dynamics of Lithosphere University of Gttingen G ttingen GermanyInstitute of Geology and Dynamics of LithosphereUniversity of Gttingen G ttingen GermanyInstitute of Geology and Dynamics of LithosphereUniversity of Gttingen G ttingen Germany

In the Ordos basin, two distinct thermal events of different ages have been identified for the first time by means of K-Ar dating combined with illite crystallinity analysis. For the Late Triassic and Late Permian samples, the K-Ar ages of the < 0.2μm fractions (159-173 Ma) reflect an illitization age related to the Yanshanian movement and indicate a short thermal event in the Middle Jurassic; the K-Ar ages of the <2 μm fractions (210-308 Ma) are interpreted as mixed ages of detrital material and authigenic illites. The K-Ar ages of both < 0.2μm and < 2μm fractions of a Middle Cambrian sample (368 Ma and 419 Ma) correspond to the ages of the metamorphism and earliest granite intrusion in the northern Caledonian Qinling fold zone (380-420 Ma) and show a thermal event during Silurian-Devonian time.

关键词： illite K-Ar dating illite crystallinity thermal event Ordos basin

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Isotope Dating of the Potash and Rock Salt Deposit at Bamnet Narong, NE-Thailand

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Open Journal of Geology 2016年第8期6卷 875-894页

作者： Bent T. Hansen klaus wemmer Monique Eckhardt Prinya Putthapiban San Assavapatchara Geoscience Center Gottingen University of Gottingen Gottingen Germany Geoscience Programme Kanchanaburi Campus Mahidol University Kanchanaburi Thailand Department of Mineral Resources Bureau of Geological Survey Bangkok Thailand

Bamnet Narong is located in northeastern Thailand (Chaiyaphum Province). It is the largest salt mine in the country and has been mined for decades. The landscape in this part of Thailand is characterised by a low plateau, which is called the Khorat Plateau. The plateau is divided into two basins by the Phu Phan Range, the Sakhon Nakhon Basin in the north and the Khorat Basin in the south. The analysed potashes and rock salts are deposited in the Maha Sarakham Formation, which represents the salt-bearing strata of the Khorat Basin. The stratigraphic age of this deposit has been debated since the late 1960’s. The assigned ages range from Mid-Cretaceous to Late Cretaceous and up to the Eocene. In this study different isotopic dating systems (Rb-Sr, Sr-Sr, K-Ar and K-Ca) were applied. The stratigraphic age for the time of deposition was confirmed to be Mid Cretaceous (Cenomanian). Furthermore, the homogeneity of the carnallites was investigated in order to trace a possible redistribution of rubidium.

关键词： Isotope Dating Salt Deposits Mid-Cretaceous Asian Potash Mine Thailand

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Do U/Pb-SHRIMP Dating and Pb Stepwise Leaching (PbSL) Analyses Confirm the Lack of Precambrian Basement Outcrops in Thailand?

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Open Journal of Geology 2014年第10期4卷 505-517页

作者： Bent T. Hansen klaus wemmer Prinya Putthapiban Ilka C. Kleinhanns Franziska Wilsky Geoscience Centre of the Georg-August-University Gottingen Germany Geoscience Programme Kanchanaburi Campus Mahidol University Tambon Salaya Thailand Department of Geoscience University of Tuebingen Tübingen Germany

U/Pb-SHRIMP dating and Pb stepwise leaching (PbSL) experiments on zircons and garnets, respectively have confirmed the lack of Precambrian outcrops within the crystalline basement of Thailand. The obtained data for the high grade metamorphism show Indosinian ages ranging from 225 - 200 Ma as previously suggested for the vast majority of outcrops in NW-Thailand ([1]?and references therein), as well as a small group of ages in the range of 445 Ma in the Lampang Province. Further, the age of a thermal imprint around 60 Ma was confirmed near Surat Thani, Peninsular Thailand, and only a few indications of older ages for the unknown source areas were detected in detrital components.

关键词： SHRIMP Dating Pb Stepwise Leaching (PbSL) Zircons Basement Thailand

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K－Ar测年法在确定沉积岩成岩时代中的应用——以鄂尔多斯盆地为例

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沉积学报 1996年第3期14卷 11-21页

作者：赵孟为 Hans Ahrendt klaus wemmer 德国哥廷根大学地质与岩石圈动力学研究所西安西北大学地质系

根据伊利石Ｋ－Ａｒ测年法研究，确定鄂尔多斯盆地存在两期与构造运动有关的成岩作用事件：即与早期燕山运动有关的侏罗纪（１７０—１６０Ｍａ）和与晚期加里东运动有关的志留－泥盆纪（４２０－３７０Ｍａ）成岩作用时代。为了揭示碎... 详细信息

根据伊利石Ｋ－Ａｒ测年法研究，确定鄂尔多斯盆地存在两期与构造运动有关的成岩作用事件：即与早期燕山运动有关的侏罗纪（１７０—１６０Ｍａ）和与晚期加里东运动有关的志留－泥盆纪（４２０－３７０Ｍａ）成岩作用时代。为了揭示碎屑物质对Ｋ－Ａｒ年龄的影响和伊利石成岩作用的机制，本文提出了一个通过观察Ｋ－Ａｒ年龄随深度变化的趋势来进行判断的模式。在Ｋ－Ａｒ年龄小于地层时代的条件下，Ｋ－Ａｒ年龄与深度呈正相关，或者很相近的Ｋ－Ａｒ年龄与深度变化无关均标志着没有或很少有碎屑物质的影响；同时，前者指示逐渐埋藏条件下的成岩作用，而后者则反映短暂的热事件引起的成岩作用事件。

关键词：沉积岩成岩时代同位素测年法钾氩

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鄂尔多斯盆地志留-泥盆纪和侏罗纪热事件——伊利石K-Ar年龄证据

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地质学报 1996年第2期70卷 186-194页

作者：赵孟为 Hans Ahrendt klaus wemmer Hans-Jürgen Behr 格丁根大学地质与岩石圈动力学研究所

利用伊利石K-Ar测年法,结合伊利石结晶度分析,首次在鄂尔多斯盆地确定出两期不同时代热事件。晚三叠世和晚二叠世<0.2μm粒级的岩石样品的K-Ar年龄(159-173Ma)反映了与燕山运动有关的伊利石化年龄,指示有一期中侏罗世的热事件;其<2μm... 详细信息

利用伊利石K-Ar测年法,结合伊利石结晶度分析,首次在鄂尔多斯盆地确定出两期不同时代热事件。晚三叠世和晚二叠世<0.2μm粒级的岩石样品的K-Ar年龄(159-173Ma)反映了与燕山运动有关的伊利石化年龄,指示有一期中侏罗世的热事件;其<2μm粒级的K-Ar年龄(210-308Ma)则被解释为碎屑物和自生伊利石的混合年龄。中寒武世<0.2μm和<2μm粒级的岩石样品K-Ar年龄(368Ma与419Ma)对应于北秦岭加里东褶皱带变质作用与最早期花岗岩侵入的时代(380-420Ma),表明在志留-泥盆纪发生了一期热事件。

关键词：伊利石 K-Ar测年法志留纪热事件鄂尔多斯盆地

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Testing and modelling of transient adhesion phenomena in rolling-sliding contacts

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Friction 2024年第5期12卷 1016-1027页

作者： Daniel KVARDA Alexander MEIERHOFER klaus SIX Faculty of Mechanical Engineering Brno University of TechnologyBrno61669Czech Republic Virtual Vehicle Research GmbH Graz8010Austria

Transient adhesion effects in rolling–sliding contacts influence all aspects of train–track interaction.This is of high importance specifically when these effects result in critically low adhesion,which poses a risk to traction and braking of railway vehicles.This study presents a model that can replicate the transient changes of the coefficient of adhesion with tested water and solid particle mix.The experimental data for the model are measured using a commercial ball-on-disc tribometer.The experimental results showed a liquid reservoir in front of the contact area that slowly reduces in size.This observation was used in the modelling approach to divide the calculation into two stages where the reservoir is present and when it disappears.The model was able to reproduce the occurrence of low adhesion region seen in experimental results with different particle concentrations.

关键词： coefficient of adhesion tribology transient effects wheel-rail contact

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Learning about good nutrition with the 5-color front-of-package label"Nutri-Score":an experimental study

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Food Science and Human Wellness 2024年第3期13卷 1195-1200页

作者： Robin C.Hau klaus W.Lange University of Applied Sciences Landshut Landshut 84036Germany Faculty of Human Sciences University of RegensburgRegensburg 93040Germany

The Nutri-Score is a 5-color front-of-pack nutrition label designed to provide consumers with an easily understandable guideline to the healthiness of food products.The impact that the Nutri-Score may have on consumers'choices is unclear since different experimental paradigms have found vastly different effect sizes.In the present study,we have investigated how student participants change a hypothetical personal 1-daydietary plan after a learning phase during which they learn about the Nutri-Scores of the available food items.Participants were instructed to compose a healthy diet plan in order that the question of whether the NutriScore would improve their ability to compose a healthy dietary plan could be investigated,independent of the question of whether they would apply this knowledge in their ordinary lives.We found a substantial(Cohen's d=0.86)positive impact on nutritional quality(as measured by the Nutrient Profiling System score of the Food Standards Agency)and a medium-sized(Cohen's d=0.43)reduction of energy content.Energy content reduction was larger for participants who had initially composed plans with higher energy content.The results suggest that the Nutri-Score has the potential to guide consumers to healthier food choices.It remains unclear,however,whether this potential will be reflected in real-life dietary choices.

关键词： Nutri-Score Front-of-package label Nudge Nutrition Health

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Dieback of managed spruce stands in western Germany promotes beetle diversity

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Journal of Forestry Research 2024年第3期35卷 55-71页

作者： Eva Plath Chantal Trauth Jan Gerhards Laura Griebel klaus Fischer Department Biology Institute of Integrated Natural SciencesKoblenz-Landau University56070 KoblenzGermany

Biodiversity loss is a significant problem at a global scale and may be amplified by climate change.In recent years,coniferous forests have had substantial die-back across Europe due to drought and subsequent bark-beetle outbreaks.As many studies on the consequences of disturbance and subsequent management have focused on natural stands,management implications for managed spruce stands are not well understood,even though such stands are widespread throughout Europe.In this study,beetle taxonomy,conservation value,and community com-position are compared among spruce plantations and four post-disturbance management approaches:standing dead-wood,lying deadwood,clear cuts,and long-term succession.Diversity and community composition differed significantly among management categories,while different beetle fami-lies responded similarly.Intact spruce stands harbored the lowest beetle diversity while the highest taxonomic diver-sity and conservation value was on clear cuts and stands with lying or standing deadwood.The proportion of forest specialists was highest in successional forests.In summary,different forest management categories harbored distinct beetle communities at the family-,species-,and ecological guild levels.Therefore,post-disturbance management should consider the landscape scale and include different management types.This enhances landscape heterogeneity and thus overall biodiversity but could also mitigate negative impacts of natural disturbances on ecosystem services.

关键词： Bark-beetle outbreak Forest dieback Spruce Deadwood Nature conservation Beetle biodiversity-Coleoptera Coniferous forests

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Book review “Wattles: Australian Acacia species around the world” by David M. Richardson, Johannes J. Le Roux and Elizabete Marchante

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Forest Ecosystems 2024年第2期11卷 140-141页

作者： klaus von Gadow Faculty of Forestry and Forest Ecology Georg-August-University GöttingenBüsgenweg 5D-37077GöttingenGermany Department of Forestry and Wood Science Faculty of AgriSciencesStellenbosch UniversityStellenbosch Private Bag X1Stellenbosch7602South Africa

In a world of Google and AI, developing an encyclopedic coverage of a theme that is of great interest to biologists, social scientists, politicians and environmental managers, is a daunting challenge. Wattles is a book that presents new knowledge, makes interesting reading, and has the potential to stimulate research in a variety of disciplines. We learn that Acacia, commonly known as the wattles or acacias, is a genus of shrubs and trees comprising 1,083 species of which 417 are known to have been introduced to areas outside their native range. We are surprised to read that Australian acacias are found almost everywhere, in virtually all terrestrial habitats, including woodlands, grasslands, alpine settings,rainforests, coastal dunes and deserts, causing major environmental and socio-economic changes in the invaded regions. Until recently, Acacia comprised a group of plant species native to Africa, South America and Australasia, but the name is now reserved for species predominantly from Australia, including some from Southeast Asia. The genus name Acacia is Neo-Latin, and refers to a preparation extracted from the leaves and fruit pods of Vachellia nilotica, the original type of the genus.

关键词： Richardson outside Latin

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