scholarly journals Asbestos-like actinolite crystallization during late regional variscan exhumation in the South Armorican Massif (France)

2020 ◽  
Author(s):  
Geoffrey Aertgeerts ◽  
Didier Lahondère ◽  
Antoine Triantafyllou ◽  
Jean-Pierre Lorand ◽  
Christophe Monnier ◽  
...  
Keyword(s):  
Fluid Pressure ◽  
Principal Component ◽  
Optical Microscope ◽  
Clear Correlation ◽  
The South ◽  
Tectonic Structures ◽  
Late Step ◽  
Deformation Event ◽  
Armorican Massif ◽  
Greenschist Facies Metamorphism

<p>In this study, two types of natural asbestos-like actinolite occurrences were sampled in order to understand their tectonic and metamorphic signification. Studied rocks were collected within two Variscan ophiolitic formations (Tréogat and Pont de Barel Formations, South Armorican Massif, Western France), mainly composed of amphibolites, and which recorded amphibolite to greenschist facies metamorphism. In these localities, the natural asbestos-like actinolite occurrences are closely related with the development of tectonic structures such as extension veins, tension gashes, σ and δ-type boudins. Field and petrostructural studies together with optical microscope, SEM and electron-microprobe analyses (EPMA) allowed to link early steps of the retrograde deformation event, during which acicular hornblende crystallizes in extension veins showing fuzzy boundaries or in hosting rock, with the late step of the same deformation event, during which hornblende is downgraded into asbestos-like actinolite synchronous with felsic melt circulation and tectonic structures opening. Field and microtectonic observations point to a sinistral strike-slip shearing for Pont de Barel formation and to a sinistral transtensive shearing for the Tréogat formation, which is consistent with the late regional variscan exhumation of the South Armorican Terrane.  SEM observations show that asbestos-like actinolite originate from hornblende crystallographic plan fragmentation, starting first along the (110) plans and continue both along the (100) and (110) plans. EPMA analyses show that Na-Al-Si metasomatism is associated with this fragmentation. Temperature estimates of chlorite crystallization after hornblende are around 300°C for the Tréogat Formation and 200°C for the Pont de Barel Formation, suggesting that amphibole fragmentation can occur over a wide temperature range. Additionally, Principal Component Analysis was performed using crystallographic sites distribution. Results show a clear correlation between actinolite Si(T) and hornblende Al(T), Al(C) and Na(A) crystallographic sites, suggesting that asbestos-like actinolite after hornblende fragmentation is rather due to a decrease of pressure within the tectonic structures, as Al in amphibole is pressure-dependent. This decrease could be due to the fluid pressure, which is supra-lithostatic during tectonic structures opening.</p>

Morphometrical and molecular evidence suggests cryptic diversity among hookworms (Nematoda: Uncinaria) that parasitize pinnipeds from the south-eastern Pacific coasts

2018 ◽  
Vol 94 ◽  
Author(s):  
M.T. González ◽  
Z. López ◽  
J.J. Nuñez ◽  
K.I. Calderón-Mayo ◽  
C. Ramírez ◽  
...  
Keyword(s):  
Large Subunit ◽  
Principal Component ◽  
Eastern Pacific ◽  
Lsu Rdna ◽  
Molecular Evidence ◽  
South American ◽  
Southern Chile ◽  
The South ◽  
South Eastern ◽  
Neophoca Cinerea

AbstractHookworms of the genus Uncinaria parasitize pinniped pups in various locations worldwide. Four species have been described, two of which parasitize pinniped pups in the southern hemisphere: Uncinaria hamiltoni parasitizes Otaria flavescens and Arctocephalus australis from the South American coast, and Uncinaria sanguinis parasitizes Neophoca cinerea from the Australian coast. However, their geographical ranges and host specificity are unknown. Uncinaria spp. are morphologically similar, but molecular analyses have allowed the recognition of new species in the genus Uncinaria. We used nuclear genetic markers (internal transcribed spacer (ITS) and large subunit (LSU) rDNA) and a mitochondrial genetic marker (cytochrome c oxidase subunit I (COI)) to evaluate the phylogenetic relationships of Uncinaria spp. parasitizing A. australis and O. flavescens from South American coasts (Atlantic and Pacific coasts). We compared our sequences with published Uncinaria sequences. A Generalized Mixed Yule Coalescent (GMYC) analysis was also used to delimit species, and principal component analysis was used to compare morphometry among Uncinaria specimens. Parasites were sampled from A. australis from Peru (12°S), southern Chile (42°S), and the Uruguayan coast, and from O. flavescens from northern Chile (24°S) and the Uruguayan coast. Morphometric differences were observed between Uncinaria specimens from both South American coasts and between Uncinaria specimens from A. australis in Peru and southern Chile. Phylogenetic and GMYC analyses suggest that south-eastern Pacific otariid species harbour U. hamiltoni and an undescribed putative species of Uncinaria. However, more samples from A. australis and O. flavescens are necessary to understand the phylogenetic patterns of Uncinaria spp. across the South Pacific.

scholarly journals LED and UV Light Utilizing Flavonoids and Limonoids to Investigate the Effect of Post-harvest Light Irradiation

2020 ◽  
Author(s):  
Shengyu Liu
Keyword(s):  
White Light ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Red Light ◽  
Principal Component ◽  
Experimental Period ◽  
Light Irradiation ◽  
Flavonoid Glycosides ◽  
Clear Correlation ◽  
Post Harvest

To investigate the effect of post-harvest light irradiation on the accumulation of flavonoids and limonoids, harvestedNewhall navel oranges were continuously exposed to light-emitting diode (LED) and ultraviolet (UV) light irradiationfor 6 days, and the composition and content of flavonoids and limonoids in the segments were determined usingUPLC-qTOF-MS at 0, 6, and 15 days after harvest. In total, six polymethoxylated flavonoids (PMFs), fiveflavoneO/C-glycosides, seven flavanone-O-glycosides, and three limonoids were identified in the segments. Theaccumulation of these components was altered by light irradiation. Red and blue light resulted in higher levels ofPMFs during exposure periods. The accumulation of PMFs was also significantly induced after white light, UVBand UVC irradiation were removed. Red and UVC irradiation induced the accumulation of flavone and flavanoneglycosides throughout the entire experimental period. Single light induced limonoid accumulation during exposureperiods, but limonoid levels decreased significantly when irradiation was removed. Principal component analysisshowed a clear correlation between PMFs and white light, between flavonoid glycosides and red light and UVC,and between limonoids and UVC. These results suggest that the accumulation of flavonoids and limonoids in citrusis regulated by light irradiation. White light, red light and UVC irradiation might be a good potential method forimproving the nutrition and flavor quality of post-harvest citrus.

scholarly journals Heavy minerals in the Wajid Sandstone from Abha-Khamis Mushayt area, southwestern Saudi Arabia: implications on provenance and regional tectonic setting

GeoArabia ◽  
2004 ◽  
Vol 9 (4) ◽  
pp. 77-102 ◽  
Author(s):  
Mahbub Hussain ◽  
Lameed O. Babalola ◽  
Mustafa M. Hariri
Keyword(s):  
Saudi Arabia ◽  
Tectonic Setting ◽  
Principal Component ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Coarse Grained ◽  
Distribution Data ◽  
The South ◽  
Quartz Content ◽  
The North

ABSTRACT The Wajid Sandstone (Ordovician-Permian) as exposed along the road-cut sections of the Abha and Khamis Mushayt areas in southwestern Saudi Arabia, is a mediun to coarse-grained, mineralogically mature quartz arenite with an average quartz content of over 95%. Monocrystalline quartz is the dominant framework grain followed by polycrystalline quartz, feldspar and micas. The non-opaque heavy mineral assemblage of the sandstone is dominated by zircon, tourmaline and rutile (ZTR). Additional heavy minerals, constituting a very minor fraction of the heavies, include epidote, hornblende, and kyanite. Statistical analysis showed significant correlations between zircon, tourmaline, rutile, epidote and hornblende. Principal component R-mode varimax factor analysis of the heavy mineral distribution data shows two strong associations: (1) tourmaline, zircon, rutile, and (2) epidote and hornblende suggesting several likely provenances including igneous, recycled sedimentary and metamorphic rocks. However, an abundance of the ZTR minerals favors a recycled sedimentary source over other possibilities. Mineralogical maturity coupled with characteristic heavy mineral associations, consistent north-directed paleoflow evidence, and the tectonic evolutionary history of the region indicate a provenance south of the study area. The most likely provenances of the lower part (Dibsiyah and Khusayyan members) of the Wajid Sandstone are the Neoproterozoic Afif, Abas, Al-Bayda, Al-Mahfid, and Al-Mukalla terranes, and older recycled sediments of the infra-Cambrian Ghabar Group in Yemen to the south. Because Neoproterozic (650-542 Ma) rocks are not widespread in Somalia, Eritrea and Ethiopia, a significant source further to the south is not likely. The dominance of the ultrastable minerals zircon, tourmaline and rutile and apparent absence of metastable, labile minerals in the heavy mineral suite preclude the exposed arc-derived oceanic terrains of the Arabian Shield in the west and north as a significant contributor of the sandstone. An abundance of finer-grained siliciclastic sequences of the same age in the north, is consistent with a northerly transport direction and the existence of a deeper basin (Tabuk Basin?) to the north. The tectonic and depositional model presented in this paper differs from the existing model that envisages sediment transportation and gradual basin filling from west to east during the Paleozoic.

scholarly journals Key Environmental Factors Controlling Planktonic Foraminiferal and Pteropod Community’s Response to Late Quaternary Hydroclimate Changes in the South Aegean Sea (Eastern Mediterranean)

2020 ◽  
Vol 8 (9) ◽  
pp. 709
Author(s):  
Christina Giamali ◽  
George Kontakiotis ◽  
Efterpi Koskeridou ◽  
Chryssanthi Ioakim ◽  
Assimina Antonarakou
Keyword(s):  
Environmental Factors ◽  
Environmental Changes ◽  
Late Quaternary ◽  
Eastern Mediterranean ◽  
Planktonic Foraminifera ◽  
Explanatory Power ◽  
Principal Component ◽  
Aegean Sea ◽  
Late Glacial ◽  
The South

A multidisciplinary study was conducted in order to investigate the environmental factors affecting the planktonic foraminiferal and pteropod communities of the south Aegean Sea. Aspects of the Late Quaternary paleoceanographic evolution were revealed by means of quantitative analyses of planktonic foraminiferal and pteropod assemblages (including multivariate statistical approach; principal component analysis (PCA)), the oxygen (δ18O) and carbon (δ13C) isotopic composition of planktonic foraminifera and related paleoceanographic (planktonic paleoclimatic curve (PPC), productivity (E-index), stratification (S-index), seasonality) indices, extracted by the gravity core KIM-2A derived from the submarine area between Kimolos and Sifnos islands. Focusing on the last ~21 calibrated thousands of years before present (ka BP), cold and eutrophicated conditions were identified during the Late Glacial period (21.1–15.7 ka BP) and were followed by warmer and wetter conditions during the deglaciation phase. The beginning of the Holocene was marked by a climatic amelioration and increased seasonality. The more pronounced environmental changes were identified during the deposition of the sapropel sublayers S1a (9.4–7.7 ka BP) and S1b (6.9–6.4 ka BP), with extremely warm and stratified conditions. Pteropod fauna during the sapropel deposition were recorded for the first time in the south Aegean Sea, suggesting arid conditions towards the end of S1a. Besides sea surface temperature (SST), which shows the highest explanatory power for the distribution of the analyzed fauna, water column stratification, primary productivity, and seasonality also control their communities during the Late Quaternary.

scholarly journals Effect of Post-Harvest LED and UV Light Irradiation on the Accumulation of Flavonoids and Limonoids in the Segments of Newhall Navel Oranges (Citrus sinensis Osbeck)

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1755 ◽  
Author(s):  
Shengyu Liu ◽  
Linping Hu ◽  
Dong Jiang ◽  
Wanpeng Xi
Keyword(s):  
White Light ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Red Light ◽  
Principal Component ◽  
Light Irradiation ◽  
Flavonoid Glycosides ◽  
Clear Correlation ◽  
Post Harvest ◽  
Uv Light Irradiation

To investigate the effect of post-harvest light irradiation on the accumulation of flavonoids and limonoids, harvested Newhall navel oranges were continuously exposed to light-emitting diode (LED) and ultraviolet (UV) light irradiation for 6 days, and the composition and content of flavonoids and limonoids in the segments were determined using UPLC-qTOF-MS at 0, 6, and 15 days after harvest. In total, six polymethoxylated flavonoids (PMFs), five flavone-O/C-glycosides, seven flavanone-O-glycosides, and three limonoids were identified in the segments. The accumulation of these components was altered by light irradiation. Red and blue light resulted in higher levels of PMFs during exposure periods. The accumulation of PMFs was also significantly induced after white light, UVB and UVC irradiation were removed. Red and UVC irradiation induced the accumulation of flavone and flavanone glycosides throughout the entire experimental period. Single light induced limonoid accumulation during exposure periods, but limonoid levels decreased significantly when irradiation was removed. Principal component analysis showed a clear correlation between PMFs and white light, between flavonoid glycosides and red light and UVC, and between limonoids and UVC. These results suggest that the accumulation of flavonoids and limonoids in citrus is regulated by light irradiation. White light, red light and UVC irradiation might be a good potential method for improving the nutrition and flavor quality of post-harvest citrus.

Sur les rhyolites et les granites prevarisques en Normandie et en Vendee

1943 ◽  
Vol S5-XIII (4-6) ◽  
pp. 139-151
Author(s):  
Gilbert Mathieu
Keyword(s):  
Variscan Orogeny ◽  
The South ◽  
The North ◽  
Rigid Mass ◽  
Armorican Massif

Abstract An account of the pre-Carboniferous rhyolites and granites of Normandy and Vendee, France. Precambrian granite masses and Precambrian and Cambrian conglomerates containing ancient granite and rhyolite pebbles occur in both regions, and indicate that the Carboniferous granites of the Armorican massif were emplaced during the Variscan orogeny in a zone of subsidence between the rigid mass of Normandy to the north and Vendee to the south.

Crossitic amphibole and its possible tectonic significance in the Richmond Area, southeastern Quebec

1976 ◽  
Vol 13 (5) ◽  
pp. 711-714 ◽  
Author(s):  
W. E. Trzcienski Jr.
Keyword(s):  
Subduction Zone ◽  
Geophysical Data ◽  
Greenschist Facies ◽  
The South ◽  
Tectonic Significance ◽  
Facies Metamorphism ◽  
Greenschist Facies Metamorphism

Crossitic amphibole suggesting blueschist-type metamorphism has been found in the Richmond area, southeastern Quebec. Prehnite facies metamorphism to the northeast of Richmond and greenschist facies metamorphism to the south along with the blueschist-type metamorphism and geophysical data suggest that the Richmond area may represent a partially eroded Ordovician subduction zone.

scholarly journals Evaluation of physicochemical and trace metal qualities of rainwater in the south-eastern region of Bangladesh

2021 ◽  
Author(s):  
Md. Arif Hossen ◽  
Asiful Hoque ◽  
M. Salauddin ◽  
Sudip Kumar Pal ◽  
Mohammad Golam Muktadir ◽  
...  
Keyword(s):  
Trace Metals ◽  
Major Ions ◽  
Principal Component ◽  
Average Concentration ◽  
Anthropogenic Sources ◽  
Chemical Characteristics ◽  
Eastern Region ◽  
The South ◽  
Land Use Patterns ◽  
South Eastern

Abstract The chemical characteristics of rainwater in the south-eastern region of Bangladesh were investigated in this study in addition to identifying the potential sources of different precipitation constituents, which have often been unexplored or not well covered in the literature. Rainwater pH, major ions and trace metals were measured in samples collected from five different locations with different land-use patterns of the Chattogram Metropolitan area (CMA) during two rainy seasons. The results of this study showed variability in rainwater quality across the sites signifying site-specific influences. The mean concentration of all measured physicochemical parameters, ions and trace metals in rainwater samples was also found to be significantly lower compared with the drinking water quality standard of Bangladesh and WHO guidelines. The correlation matrix and principal component analysis (PCA) indicated that and originated from anthropogenic sources, while the average concentration of trace metals found in rainwater was exhibited in the following order: Zn>Cu>Fe>Cr>Mn>Pb>Cd. The findings of this study could be used as a reference to further investigate the influences of industrial, urban and agricultural emissions that regulate the chemical characteristics of the atmosphere in particular areas of study.

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