Reading Virginia's Paleoclimate From The Geochemistry And Sedimentology Of Clastic Cave Sediments

2007 ◽  
pp. 95-106 ◽  
Author(s):  
Elizabeth P. Knapp ◽  
Dennis O. Terry ◽  
David J. Harbor ◽  
Robert C. Thren
Keyword(s):  
Cave Sediments

A TRACE METALS DATABASE OF CAVE SEDIMENTS OF THE MIDCONTINENT U.S.A. 

2016 ◽  
Author(s):  
Matthew D. Smith ◽  
◽  
Douglas R. Gouzie
Keyword(s):  
Trace Metals ◽  
Cave Sediments

Cave sediments

2006 ◽  
pp. 172-173 ◽  
Author(s):  
Brian Ones
Keyword(s):  
Cave Sediments

scholarly journals DATAÇÃO DE SOTERRAMENTO UTILIZANDO OS ISÓTOPOS COSMOGÊNICOS 10Be E 26Al: SÍNTESE METODOLÓGICA E BREVE REVISÃO DE SUAS APLICAÇÕES EM GEOCIÊNCIAS

2014 ◽  
Author(s):  
Fernando V. Laureano ◽  
Darryl E. Granger ◽  
Ivo Karmann ◽  
Valdir F. Novello
Keyword(s):  
Cosmic Rays ◽  
Single Layer ◽  
Cosmic Ray ◽  
Cosmogenic Isotopes ◽  
Fluvial Terraces ◽  
River Incision ◽  
Cave Sediments ◽  
Shallow Crust ◽  
Multiple Samples ◽  
Quartz Grains

Isótopos cosmogênicos são formados na atmosfera, na superfície e nos primeiros metros da crosta terrestre através da colisão de partículas sub-atômicas com núcleos de elementos químicos ali existentes. Entre um largo espectro de isótopos gerados 10Be e 26Al produzidos no interior do mineral quartzo podem ser utilizados para calcular o soterramento de sedimentos e superfícies geológicas previamente expostos aos raios cósmicos. Três diferentes abordagens podem ser evocadas na obtenção de idades: (i) o soterramento simples para quando há um soterramento completo das amostras (> 10m); (ii) idades máximas e mínimas quando as amostras não se encontram a uma profundidade suficiente para interromper a produção pós-soterramento destes isótopos e (iii) o método da isócrona derivado de uma solução gráfica onde múltiplas amostras de uma mesma camada são utilizadas para obtenção de uma idade. Além das idades em si o emprego destes isótopos carrega outro importante resultado em estudos geomorfológicos, quer seja a taxa de erosão pré-soterramento. O método possui um alcance compreendido entre 100 mil e 4-5 milhões de anos antes do presente e uma resolução nunca inferior a 60 mil anos. A literatura registra a obtenção de idades em sedimentos de caverna, terraços fluviais, dunas, solos, entre outros, e soma resultados no campo da determinação de taxas de incisão fluvial, no balizamento geocronológico da evolução do modelado, na investigação da dinâmica de solos, bem como em investigações paleoclimáticas e arqueológicas.Palavras-chave: Isótopos cosmogênicos; Datação de soterramento; Sedimentos Abstract: BURIAL DATING WITH COSMOGENIC ISOTOPES 10BE AND 26AL: METHODOLOGICAL SYNTHESIS AND A BRIEF REVIEW OF APPLICATIONS IN GEOSCIENCES. Comogenic isotopes are formed in Earth’s atmosphere, surface and very shallow crust as a result of the collision of sub-atomic particles (cosmic ray) with nuclei in the atmosphere and rock. The cosmogenic isotopes 10Be and 26Al generated inside quartz grains may be used in burial dating of sediments or geological surfaces previously exposed to cosmic rays. Three different approaches can be used for age determinations: (i) simple burial dating when samples are totally buried from cosmic rays; (ii) minimum and maximum ages when samples did not get deep enough to avoid post burial production and (iii) an isochron method derived from a graphical solution where multiple samples from a single layer are used to obtain a single burial age. Burial dating also brings to light another important geomorphic result: the pre-burial erosion rate. The method can be applied in samples buried in a range of 100 thousand to 4-5 million years ago, with a resolution limited to about 60 thousand years. The literature records burial ages from cave sediments, fluvial terraces, dunes, soil related materials, and others, allowing researchers to constrain river incision rates, landscape evolution, soil dynamics and paleoclimate and archeological issues as well.Keywords: Cosmogenic isotopes; Burial dating, Sediments.

scholarly journals Speleogenesis and depositional hystory of paleokarst phreatic caves/cavities; Podgrad, SW Slovenia

2021 ◽  
Author(s):  
Bojan Otoničar
Keyword(s):  
Host Rock ◽  
Upper Cretaceous ◽  
Coarse Grained ◽  
Mixing Zone ◽  
Carbonate Sediment ◽  
Lower Eocene ◽  
The Third ◽  
Cave Sediments ◽  
Upper Paleocene ◽  
Δ13c And Δ18o

The studied palaeokarst corresponds to an uplifted peripheral foreland bulge when Upper Cretaceous diagenetically immature eugenetic carbonates were subaerially exposed, karstified and subsequently overlain by upper Paleocene/lower Eocene palustrine limestone. Among the subsurface paleokarstic features, both vadose and phreatic forms occur.  The phreatic caves/cavities include features characteristic of the mixing zone speleogenesis at the interface between freshwater (brackish water) lenses and the underlying seawater. They were found in various positions with respect to the paleokarstic surface, the deepest being about 75 m below the surface. Three indistinct horizons of cavities/caves and intermediate vugs were recognized. Subsequently, all cavities were completely filled with detrital sediments and speleothems in the phreatic and vadose zones. In general, the phreatic cavities of the lower two horizons are geopetally filled with mudstone derived from incomplete dissolution of the host rock and overlain by coarse-grained, blocky calcite. Shallower below the paleokarst surface, a large phreatic cave of the third horizon is filled with flowstone overlain by reddish micritic carbonate sediment with intercalated calcite rafts. In the upper part of the cave, sediments derived from the paleokarst surface are gradually becoming more abundant. Vadose channels, which may also intersect the cave sediments, are mainly filled with "pedogenic" material derived from the paleokarst surface. Immediately prior to marine transgression over the paleokarst surface, some cavities were filled with marine-derived microturbidites. In general, the diversity of cave fills and the amount of surface material decrease with distance from the paleokarst surface. Below the paleokarst surface, the δ13C and δ18O values of a host rock and cavity deposits show good correlation with trends significant for meteoric diagenesis. It is shown that deposits associated with phreatic caves can be of great importance for the study of the speleogenetic, geomorphological and hydrogeological evolution of certain palaeokarst regions.

scholarly journals The Effect of Formation Processes on The Frequency of Palaeolithic Cave Sites in Semi-Arid Zones: Insights From Kazakhstan

2021 ◽  
Author(s):  
Aristeidis Varis ◽  
Christopher Miller ◽  
Patrick Cuthbertson ◽  
Abay Namen ◽  
Zhaken Taimagambetov ◽  
...  
Keyword(s):  
Central Asia ◽  
Arid Zones ◽  
Arid Environments ◽  
Formation Processes ◽  
Cave Deposits ◽  
Central Asian ◽  
Cave Sediments ◽  
Analytical Potential ◽  
Sediment Cover ◽  
Semi Arid

Central Asian caves with Palaeolithic deposits are few but they provide a rich record of human fossils and cultural assemblages that has been used to model Late Pleistocene hominin dispersals. However, previous research has not yet systematically evaluated the formation processes that influence the frequency of Palaeolithic cave sites in the region. To address this deficiency, we combined field survey and micromorphological analyses in the piedmont zone of south Kazakhstan. Here we present our preliminary results focusing on selected sites of the Qaratau mountains. Sediment cover varies among the surveyed caves and loess-like sediments dominate the cave sequences. The preservation of cave deposits is influenced by reworking of cave sediments within the caves but also by the broader erosional processes that shape semi-arid landscapes. Ultimately, deposits of potentially Pleistocene age are scarce. Our study provides new data in the geoarchaeologically neglected region of Central Asia and demonstrates that micromorphology has great analytical potential even within the limitations of rigorous survey projects. We outline some of the processes that influence the formation and preservation of cave deposits inKazakhstan, as well as broader implications for the distribution of Palaeolithic cave sites in Central Asia and other semi-arid environments.

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