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1. What drives elevational pattern of phytolith diversity in Thysanolaena maxima (Roxb.) O. Ktze? A study from the Darjeeling Himalayas.

Author

Dey, Subha Brata, Ghosh, Ruby, Shekhar, Mayank, Mukherjee, Biswajit, and Bera, Subir

Subjects
*PHYTOLITHS, *PLANT diversity, *GRASSES, *EFFECT of temperature on plants, *METEOROLOGICAL precipitation
Abstract

Phytolith formation in plants is commonly thought to be influenced by variations in temperature, precipitation and other environmental factors. The objective of this study is to test how variations in different climatic and edaphic factors i.e., temperature, rainfall, actual evapotranspiration (AET), potential evapotranspiration (PET), moisture index (MI) and soil pH along a tropical–temperate elevation gradient (150–2456 m a.s.l.) in the Darjeeling Himalayas would influence the variability and plasticity of formation and frequencies of phytoliths in Thysanolaena maxima . Among the 16 phytolith types, frequency, diversity and morphometric sensitivity of some consistently occurring morphs viz., stomate, cuneiform bulliform, three-lobates and bilobates have been studied in detail to trace their sensitivity to changing environmental factors along the studied elevation gradient in Darjeeling. We used regression analysis to establish elevational pattern of phytolith diversity and sensitivity of T. maxima and to relate environmental factors with morphometric attributes. Frequencies of bilobate, three-lobates and stomate types increase with increasing elevation and MI, but decrease with MAT (mean annual temperature), AET, PET and soil pH. However, a reverse trend is noticed in frequency of bulliform types. Morphometric measurements show a positive correlation between dimensions of stomate, three-lobates and bilobates with MAT, AET, PET and soil pH and a negative correlation with MI. Length of bilobate shanks and dimension of bulliform cells are found to be negatively correlated with MAT, AET, PET and soil pH and positively correlated with MI; however, an opposite trend is noticed for shank width. No significant relationship is observed with rainfall, but MI, which is a measure of the water balance between rainfall and PET of an area shows significant correlation with morphometric traits. The study thus demonstrates that the diversity and morphometric attributes of T. maxima phytoliths are plastic in their response to different environmental factors. [ABSTRACT FROM AUTHOR]

Published
2015
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2. Treatment of a sacral pressure ulcer and extensive hyperkeratosis with OPAL A filtrate and cream: A case study.

Author

Baldwin, Christopher and Bonham, Susan

Abstract

OPAL A, derived from the pawpaw fruit, is a promising treatment for chronic skin ulcers. We report the case of a 75-year-old man with paraplegia who presented with a chronic sacral pressure ulcer and extensive hyperkeratosis on his buttocks. After two weeks of treatment with OPAL A filtrate and cream and ongoing bed rest, the ulcer showed evidence of healing and there was a marked reduction in the hyperkeratotic coverage. Five weeks later, the condition of the ulcer was further improved, but the wound was not fully closed. The hyperkeratosis had disappeared. The patient was discharged and continued OPAL A treatment at home. Follow-up examination 24 days after discharge revealed the ulcer to be in good condition, with granulation tissue present on the surface of the ulcer. Hyperkeratosis remained absent and the skin surrounding the ulcer appeared healthy. Although further studies are clearly needed, the encouraging results in this patient contribute to the increasing evidence base justifying rigorous clinical trials of OPAL A for chronic skin ulcers. [ABSTRACT FROM AUTHOR]

Published
2011

3. Effect of the novel wound healing agent, OPAL A on leukotriene B4 production in human neutrophils and 5-lipoxygenase activity.

Author

Russell, Fraser D., Windegger, Tanja, Hamilton, Karina D., and Cheetham, Norman

Abstract

OPAL A is a papaya pulp that is heated and alkalised with bicarbonate (the OPAL process) and is undergoing clinical trials for treatment of chronic wounds. The aim of this study was to investigate possible inhibitory effects of OPAL A and a non-alkalised papaya filtrate on the 5-lipoxygenase signalling pathway. Human isolated neutrophils were incubated with or without OPAL A, non-alkalised papaya or sodium bicarbonate and then exposed to the calcium ionophore, ionomycin to stimulate leukotriene B4 (LTB4) production. The production of LTB4 was inhibited in a dose-dependent manner by all three treatments. The effect of these treatments on 5-lipoxygenase activity, the enzyme involved in the production of precursors of LTB4 was investigated using a cell-free assay. 5-Lipoxygenase activity was inhibited by OPAL A and non-alkalised papaya, but not bicarbonate. Column chromatography was used to show that the active components within OPAL A were non-proteinaceous polar compounds. The inhibitory effects of OPAL A and a non-alkalised papaya filtrate on 5-lipoxygenase activity and LTB4 production suggest a possible anti-inflammatory mode of action. [ABSTRACT FROM AUTHOR]

Published
2011

4. Giant clastic intrusions primed by silica diagenesis.

Author

Davies, Richard J., Huuse, Mads, Hirst, Philip, Cartwright, Joe, and Yuesou Yang

Subjects
*SEDIMENT transport, *SEDIMENTATION & deposition, *FLUID mechanics, *SEDIMENTARY basins, *SILICON compounds, *SEDIMENTOLOGY, *PERMEABILITY, *SEDIMENTARY rocks, *GEOLOGICAL basins
Abstract

Postdepositional sediment mobilization is a common phenomenon that occurs over large areas of sedimentary basins, usually within mudstone-rich successions; however, defining the exact mechanism that initiates this process has proved elusive. Here we describe a number of large-scale clastic intrusions (injectites), 50 to >300 m in height, hosted within fine-grained biosiliceous upper Eocene to Pliocene strata in four sedimentary basins. Within these basins diagenetic conversion of opal A into opal CT (cristobalite and tridymite) causes a marked reduction in sediment porosity and the liberation of bound water, often at relatively shallow burial (<0.5 km). We propose that this occurs over geologically short time periods over large expanses of sedimentary basins, causing rapid pore fluid expulsion and overpressure buildup within interbedded sands. The liberated fluids primed these sands, rendering them susceptible to remobilization. This mechanism should have broad applicability. [ABSTRACT FROM AUTHOR]

Published
2006
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5. Differential compaction and subsidence in sedimentary basins due to silica diagenesis: A case study.

Author

Davies, Richard J.

Subjects
*SEDIMENT compaction, *SEDIMENTARY basins, *GEOLOGICAL basins, *SILICA, *GEOLOGY, *CASE studies, *RESEARCH
Abstract

The conversion of opal A to opal CT is a thermochemical diagenetic process that can cause kilometer-scale differential compaction and differential subsidence within clastic sedimentary basins. This is demonstrated for an opal A to opal CT conversion imaged by three-dimensional seismic data on the northeastern Atlantic margin. This diagenetic ‘front’ has a circular to polygonal ridge-depression morphology. The ridges have a relief of 10–50 m and separate circular to polygonal depressions that have diameters of 1–2 km, some of which link up to form interconnected networks. This morphology initially developed because the host sediments mantled an underlying polygonal fault system and the front tracked deformed stratigraphy. Ridges formed above the lips of the underlying faults, and depressions formed between them. Ridge relief and width then progressively increased due to earlier opal A to opal CT conversion above ridges as well as conversion laterally along beds or bed sets. This caused compaction and concomitant subsidence in the overburden and the development of a circular to polygonal network of overburden troughs aligned with the ridge system. A positive feedback loop was established where additional overburden sediment above the growing ridges reached the depth of conversion ahead of adjacent areas, driving more compaction and differential subsidence. This paper provides the first insights into the large-scale morphological characteristics of opal A to opal CT diagenetic fronts. It demonstrates the potential for a local stratigraphic control on diagenetic front development and morphology and lastly highlights the potential utility of seismic reflection data for understanding diagenetic processes. [ABSTRACT FROM AUTHOR]

Published
2005
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6. Zur Taphonomie von Spongilliden (Porifera) - I. Korrosionserscheinungen an fossilen Skleren der Grube Messel.

Author

Richter, Gotthard and Baszio, Sven

Abstract

Copyright of Senckenbergiana Lethaea is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2000
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7. Los sedimentos con diatomeas del Mioceno en la Cuenca del Guadalquivir: edad y composición litológica

Author

López García, M. J. and Bustillo, M. A.

Subjects
diatomeas, QE1-996.5, Mioceno Medio-Superior, «coastal upwelling», Middle and Late Miocene, Geology, coastal upwelling, ópalo A, ópalo a, diatoms, opal A, mioceno medio-superior
Abstract

The lithological composition and biostratigraphy of diatomaceous marls have been defined in 93 outcrops of the Guadalquivir Basin. The diatomaceous marls display a wide variety of lithological types, mainly comprised of opal A (10-85 %) (mainly diatoms and to a lesser extent silicoflagellates, spicules and radiolarians), calcite (5-80 %) (principally foraminifers, nannoplankton, sparite, micrite and microspar), c1ay minerals (5-40 %) (smectite in greater quantities than illite; and kaolinite in small quantities) and terrigenous quartz (< 15 %). The diatom assemblages in the marls reflect the occurrence of temperate to warm water conditions in this area during middle and late Miocene. The diatoms are dominated by the fol1owing upwelling species: Thalassiosira nitzshoides, Thalassiotrix longuissima and Thalassionema baci//aris. Benthic diatoms are scarce but they have great species diversity. However, in sorne outcrops the genus Delphineis is more frequent thus indicating environments c10ser to shore areas. Three episodes based on Barron's (1985) low latitude zonation have been defined. The Lower Episode includes Cestodiscus peplum and Coscinodiscus lewisianus Zone and is assigned to the upper Langhian- lower Serravalian. After a period of no diatom occurrence (e. gigas var. diorama Zone is missing), the Middle Episode is defined by Craspedodiscus coscinodiscus and Actinocyclus moronensis Zones and covers the latest Serravalian-early Tortonian. The Upper Episode corresponds to Thalassiosira yabei Zone and it is assigned to middle Tortonian. The fundamental types of dilutants in diatomic sedimentation (biogenic calcareous, terrigenous and c1ay minerals), do not vary throughout the three episodes but there are great variations in the proportions. The coastal upwelling regime produces tongue-like patterns of sedimentation and the sedimentary record displays different changes of facies. The Upper Episode, where the c1ay-terrigenous dilutants predominate over calcareous dilutants and Delphineis appear in greater quantities, is interpreted as having been formed in an environment closer to the shore than other episodes. El estudio de 93 puntos en el Mioceno de la cuenca del Guadalquivir ha permitido definir en esta cuenca la situación, bioestratigráfica y composición litológica de las margas con diatomeas o «moronitas». Dichas rocas incluyen gran variedad de términos litológicos estando constituidos principalmente por ópalo A (10-85 %) (mayoritariamente diatomeas; silicoflagelados, espículas de esponja y radiolarios en menor proporción), calcita (5-80 %) (microforaminíferos, nanoplancton calcáreo, micrita y esparita fundamentalmente), minerales de la arcilla (5-40 %) (esmectita predominando sobre illita y caolinita en menores proporciones) y cuarzo terrígeno « 15 %). Las asociaciones de diatomeas están constituidas fundamentalmente por diatomeas planctónicas de aguas templado-cálidas, con dominio de Thalassionema nitzschoides, Thalassionema bacillaris y Thalassiotrix longuissima, definiendo áreas de alta productividad (upwelling) en la zona durante el Mioceno Medio y Superior. El componente bentónico es escaso y diversificado, sin embargo localmente adquiere importancia el género Delphineis indicando zonas más litorales. Se determinan tres episodios de sedimentación diatomítica basados en la zonación de baja latitud de Barron (1985c). El Episodio Inferior definido por las biozonas Cestodiscus peplum y Coscinodiscus lewisianus, comprende desde el Langhiense superior al Serrava¡ iense inferior. Después de un período de tiempo sin deposición de diatomeas comienza el Episodio Medio definido por las biozonas Craspedodiscus coscinodiscus y Actinocyclus moronensis, y que incluye el techo del Serravaliense y el Tortoniense Inferior. El Episodio Superior que corresponde a la biozona Thalassiosira yabei comprende el Tortoniense Medio. Los tipos de diluyentes fundamentales de la sedimentación diatomítica (componentes biogénicos calcáreos, terrígenos y arcillas), se mantienen en los tres episodios pero presentan gran variación en sus proporciones debido a la morfología «en lenguas» y composición de los depósitos sedimentarios formados bajo zonas de «coastal upwelling». El Episodio Superior diferenciado por el predominio del diluyente arcilloso-terrígeno y por una mayor proporción de Delphineis en las asociaciones de diatomeas. se interpreta formado más cerca del continente.

Published
1994
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8. Los sedimentos con diatomeas del Mioceno en la Cuenca del Guadalquivir: edad y composición litológica

Author

Bustillo, M. A. and López García, M. J.

Subjects
diatomeas, lcsh:Geology, Mioceno Medio-Superior, lcsh:QE1-996.5, Middle and Late Miocene, coastal upwelling, «coastal upwelling», ópalo A, diatoms, opal A
Abstract

The lithological composition and biostratigraphy of diatomaceous marls have been defined in 93 outcrops of the Guadalquivir Basin. The diatomaceous marls display a wide variety of lithological types, mainly comprised of opal A (10-85 %) (mainly diatoms and to a lesser extent silicoflagellates, spicules and radiolarians), calcite (5-80 %) (principally foraminifers, nannoplankton, sparite, micrite and microspar), c1ay minerals (5-40 %) (smectite in greater quantities than illite; and kaolinite in small quantities) and terrigenous quartz (< 15 %). The diatom assemblages in the marls reflect the occurrence of temperate to warm water conditions in this area during middle and late Miocene. The diatoms are dominated by the fol1owing upwelling species: Thalassiosira nitzshoides, Thalassiotrix longuissima and Thalassionema baci//aris. Benthic diatoms are scarce but they have great species diversity. However, in sorne outcrops the genus Delphineis is more frequent thus indicating environments c10ser to shore areas. Three episodes based on Barron's (1985) low latitude zonation have been defined. The Lower Episode includes Cestodiscus peplum and Coscinodiscus lewisianus Zone and is assigned to the upper Langhian- lower Serravalian. After a period of no diatom occurrence (e. gigas var. diorama Zone is missing), the Middle Episode is defined by Craspedodiscus coscinodiscus and Actinocyclus moronensis Zones and covers the latest Serravalian-early Tortonian. The Upper Episode corresponds to Thalassiosira yabei Zone and it is assigned to middle Tortonian. The fundamental types of dilutants in diatomic sedimentation (biogenic calcareous, terrigenous and c1ay minerals), do not vary throughout the three episodes but there are great variations in the proportions. The coastal upwelling regime produces tongue-like patterns of sedimentation and the sedimentary record displays different changes of facies. The Upper Episode, where the c1ay-terrigenous dilutants predominate over calcareous dilutants and Delphineis appear in greater quantities, is interpreted as having been formed in an environment closer to the shore than other episodes.El estudio de 93 puntos en el Mioceno de la cuenca del Guadalquivir ha permitido definir en esta cuenca la situación, bioestratigráfica y composición litológica de las margas con diatomeas o «moronitas». Dichas rocas incluyen gran variedad de términos litológicos estando constituidos principalmente por ópalo A (10-85 %) (mayoritariamente diatomeas; silicoflagelados, espículas de esponja y radiolarios en menor proporción), calcita (5-80 %) (microforaminíferos, nanoplancton calcáreo, micrita y esparita fundamentalmente), minerales de la arcilla (5-40 %) (esmectita predominando sobre illita y caolinita en menores proporciones) y cuarzo terrígeno « 15 %). Las asociaciones de diatomeas están constituidas fundamentalmente por diatomeas planctónicas de aguas templado-cálidas, con dominio de Thalassionema nitzschoides, Thalassionema bacillaris y Thalassiotrix longuissima, definiendo áreas de alta productividad (upwelling) en la zona durante el Mioceno Medio y Superior. El componente bentónico es escaso y diversificado, sin embargo localmente adquiere importancia el género Delphineis indicando zonas más litorales. Se determinan tres episodios de sedimentación diatomítica basados en la zonación de baja latitud de Barron (1985c). El Episodio Inferior definido por las biozonas Cestodiscus peplum y Coscinodiscus lewisianus, comprende desde el Langhiense superior al Serrava¡ iense inferior. Después de un período de tiempo sin deposición de diatomeas comienza el Episodio Medio definido por las biozonas Craspedodiscus coscinodiscus y Actinocyclus moronensis, y que incluye el techo del Serravaliense y el Tortoniense Inferior. El Episodio Superior que corresponde a la biozona Thalassiosira yabei comprende el Tortoniense Medio. Los tipos de diluyentes fundamentales de la sedimentación diatomítica (componentes biogénicos calcáreos, terrígenos y arcillas), se mantienen en los tres episodios pero presentan gran variación en sus proporciones debido a la morfología «en lenguas» y composición de los depósitos sedimentarios formados bajo zonas de «coastal upwelling». El Episodio Superior diferenciado por el predominio del diluyente arcilloso-terrígeno y por una mayor proporción de Delphineis en las asociaciones de diatomeas. se interpreta formado más cerca del continente.

Published
1994

9. Los sedimentos con diatomeas del Mioceno en la Cuenca del Guadalquivir: edad y composición litológica

Author

López García, Mª J. and Bustillo, Mª Ángeles

Subjects
Diatoms, Diatomeas, Ópalo A, Mioceno Medio-Superior, Opal A, Middle and Late Miocene, coastal upwelling
Abstract

20 páginas, 7 figuras, 3 tablas, 1 anexo., [ES] El estudio de 93 puntos en el Mioceno de la cuenca del Guadalquivir ha permitido definir en esta cuenca la situación, bioestratigráfica y composición litológica de las margas con diatomeas o «moronitas». Dichas rocas incluyen gran variedad de términos litológicos estando constituidos principalmente por ópalo A (10-85 %) (mayoritariamente diatomeas; silicoflagelados, espículas de esponja y radiolarios en menor proporción), calcita (5-80 %) (microforaminíferos, nanoplancton calcáreo, micrita y esparita fundamentalmente), minerales de la arcilla (5-40 %) (esmectita predominando sobre illita y caolinita en menores proporciones) y cuarzo terrígeno « 15 %). Las asociaciones de diatomeas están constituidas fundamentalmente por diatomeas planctónicas de aguas templado-cálidas, con dominio de Thalassionema nitzschoides, Thalassionema baci//aris y Thalassiotrix longuissima, definiendo áreas de alta productividad (upwelling) en la zona durante el Mioceno Medio y Superior. El componente bentónico es escaso y diversificado, sin embargo localmente adquiere importancia el género Delphineis indicando zonas más litorales. Se determinan tres episodios de sedimentación diatomítica basados en la zonación de baja latitud de Barron (1985c). El Episodio Inferior definido por las biozonas Cestodiscus peplum y Coscinodiscus lewisianus, comprende desde el Langhiense superior al Serrava¡ iense inferior. Después de un período de tiempo sin deposición de diatomeas comienza el Episodio Medio definido por las biozonas Craspedodiscus coscinodiscus y Actinocyc/us moronensis, y que incluye el techo del Serravaliense y el Tortoniense Inferior. El Episodio Superior que corresponde a la biozona Thalassiosira yabei comprende el Tortoniense Medio. Los tipos de diluyentes fundamentales de la sedimentación diatomítica (componentes biogénicos calcáreos, terrígenos y arcillas), se mantienen en los tres episodios pero presentan gran variación en sus proporciones debido a la morfología «en lenguas» y composición de los depósitos sedimentarios formados bajo zonas de «coastal upwelling». El Episodio Superior diferenciado por el predominio del diluyente arcilloso-terrígeno y por una mayor proporción de Delphineis en las asociaciones de diatomeas. se interpreta formado más cerca del continente., [EN] The lithological composition and biostratigraphy of diatomaceous marls have been defined in 93 outcrops of the Guadalquivir Basin. The diatomaceous marls display a wide variety of lithological types, mainly comprised of opal A (10-85 %) (mainly diatoms and to a lesser extent silicoflagellates, spicules and radiolarians), calcite (5-80 %) (principally foraminifers, nannoplankton, sparite, micrite and microspar), c1ay minerals (5-40 %) (smectite in greater quantities than illite; and kaolinite in small quantities) and terrigenous quartz « 15 %). The diatom assemblages in the marls reflect the occurrence of temperate to warm water conditions in this area during middle and late Miocene. The diatoms are dominated by the fol1owing upwelling species: Thalassiosira nitzshoides, Thalassiotrix longuissima and Thalassionema baci//aris. Benthic diatoms are scarce but they have great species diversity. However, in sorne outcrops the genus Delphineis is more frequent thus indicating environments c10ser to shore areas. Three episodes based on Barron's (1985) low latitude zonation have been defined. The Lower Episode includes Cestodiscus peplum and Coscinodiscus lewisianus Zone and is assigned to the upper Langhian- lower Serravalian. After a period of no diatom occurrence (e. gigas var. diorama Zone is missing), the Middle Episode is defined by Craspedodiscus coscinodiscus and Actinocyclus moronensis Zones and covers the latest Serravalian-early Tortonian. The Upper Episode corresponds to Thalassiosira yabei Zone and it is assigned to middle Tortonian. The fundamental types of dilutants in diatomic sedimentation (biogenic calcareous, terrigenous and c1ay minerals), do not vary throughout the three episodes but there are great variations in the proportions. The coastal upwelling regime produces tongue-like patterns of sedimentation and the sedimentary record displays different changes of facies. The Upper Episode, where the c1ay-terrigenous dilutants predominate over calcareous dilutants and Delphineis appear in greater quantities, is interpreted as having been formed in an environment c10ser to the shore than other episodes., Este trabajo ha sido financiado por la DGICYT a través del proyecto PB-920069.

Published
1994

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