Sediment- and basalt-hosted regoliths in the Huronian supergroup: role of parent lithology in middle Precambrian weathering profiles

1993 ◽  
Vol 30 (1) ◽  
pp. 60-76 ◽  
Author(s):  
S. J. Sutton ◽  
J. B. Maynard
Keyword(s):  
Chemical Evolution ◽  
Bulk Composition ◽  
Mineral Chemistry ◽  
White Mica ◽  
Low Grade ◽  
Low Oxygen ◽  
Mafic Dike ◽  
Rock Types ◽  
Rock Bulk

Weathering profiles developed side-by-side on sandstone and a mafic dike provide an unusual opportunity to examine the role of parent rock bulk composition in the chemical evolution of middle Precambrian regoliths. Because the profiles are adjacent to one another, differences in topography can be eliminated in accounting for differences in the chemical evolution of the two profiles. Both profiles show upward increases in Al, Ti, K, and Rb and decreases in Mg, Ca, and Na. In addition, the mafic regolith increases upward in Zr and Nb and decreases in Zn and Ni. Total Fe decreases upward in both profiles, but the sandstone profile retains significantly more of its initial Fe than does the mafic dike. This difference in Fe loss is consistent with weathering in a low-oxygen atmosphere of rock types with very different initial Fe contents and therefore different atmospheric requirements for complete oxidation of the Fe present. The Fe in the sandstone was mostly oxidized and retained within the profile, whereas much of the Fe in the mafic dike was not oxidized and was removed from the profile in the more soluble ferrous state. Petrographic evidence indicates that both sandstone and mafic dike weathering profiles underwent preweathering diagenesis, postweathering K–Rb metasomatism, and very low-grade metamorphism. Mineral chemistry indicates that, in the absence of chlorite, white mica composition closely reflects variation in bulk composition. Where both white mica and chlorite are present, changes in bulk composition are accommodated by variations in the proportions of these two minerals rather than by variations in white mica composition.

scholarly journals Structure and Petrology of the Red Hill Complex, Nelson

2021 ◽  
Author(s):  
◽  
Richard Irving Walcott
Keyword(s):  
Bulk Composition ◽  
Mineral Chemistry ◽  
Parent Material ◽  
Preferred Orientation ◽  
Ultramafic Rocks ◽  
Rock Types ◽  
Basal Zone ◽  
Upper Paleozoic ◽  
Two Generations ◽  
Thick Lens

<p>The Red Hill Complex is an essentially concordant ultramafic body enclosed in Upper Paleozoic flysch facies sediments which include Pelorus Group (oldest), Lee River Group and Maitai Group. The Pelorus Group contains rare submarine lavas and is largely derived from spilitic volcanics. The Lee River Group consists of spilitic pillow lavas, volcanic breccias and spilitic basalts and dolerites. The Maitai Group consists of limestone, sandstone and argillite; an extensive conglomerate lens in the argillites is largely composed of andesitic pebbles. The Red Hill Complex is a 12,000 ft. thick lens and is part of a sheet of peridotites which may extend 40 miles northward to Dun Mountain. The Complex is divided into a 3000 ft thick Basal Zone of massive harzburgite and a 9000 ft thick Upper Zone of layered harzburgite and dunite with minor variants, feldspathic-peridotite, eucrite, lherzolite, wehrlite and pyroxenite. The bulk composition of both zones is approximately the same but the Upper Zone contains about 0.2 per cent feldspar not present in the Basal Zone. There is no significant regional change in mineral chemistry throughout the Complex and the average composition is about; olivine Fo91, 70 per cent; orthopyroxene, En88, 22 per cent; clinopyroxene, 5 per cent; feldspar An96, less than 0.2 per cent; spinel 2 per cent. Layering and foliation are common in the top of the Upper Zone. Layering is of at least two generations of which at least one is of metamorphic origin. Metamorphic layering was formed by metasomatic replacement probably along subhorizontal shear planes during intrusion of the ultramafic sheet. Pyroxene pegmatites formed after flow ceased. The diversity of rock types in the top of the Upper Zone is considered by the writer to have been caused by metamorphic differentiation of parent material the same composition as the Basal Zone. The preferred orientation of olivine in lineated, foliated, laminated and layered rocks has the same pattern suggesting a close genetic relationship between those structures. Evidence strongly supports a tectonic origin for the preferred orientation. Rocks in the Upper Zone are xenomorphic-granular in texture and those in the Basal Zone are typically protoclastic. Xenomorphic-granular textures are derived in part from protoclastic by post-deformational recrystallization. The ultramafic rocks are cut by a number of dykes composed of hornblende-labradorite, hypersthene-augite-bytownite assemblages or minor variants of these. The dykes were intruded shortly after emplacement of the ultramafic rocks. The Red Hill Complex is considered to have been emplaced as a sheet at shallow depths which intruded superficial deposits on the ocean floor and was later overlain by volcanics</p>

Multiple alteration events in the history of a sub-Huronian regolith at Lauzon Bay, Ontario

1992 ◽  
Vol 29 (3) ◽  
pp. 432-445 ◽  
Author(s):  
S. J. Sutton ◽  
J. B. Maynard
Keyword(s):  
Clay Minerals ◽  
Chemical Weathering ◽  
Analytical Techniques ◽  
Mineral Chemistry ◽  
White Mica ◽  
Low Grade ◽  
Plagioclase Feldspar ◽  
Fine Grained ◽  
History Of ◽  
Greenschist Facies Metamorphism

Confusion exists over the usefulness of chemical data from Precambrian weathering profiles in constraining models of atmospheric evolution. One difficulty is in correctly identifying ancient weathering effects and isolating them from numerous other processes that are likely to have affected such ancient rocks. In this study of a middle Precambrian granitic weathering profile, we have used several analytical techniques to separate weathering-related chemical and mineralogical changes from those resulting from other processes. The profile is exposed beneath the Huronian at Lauzon Bay in the Blind River area of Ontario and has a complex history of alteration events, addition of allochthonous material, and low-grade metamorphism. Much of this history can be deciphered, and changes in mineralogy and bulk and mineral chemistry can be assigned to separate alteration events. Specifically, the granite has undergone preweathering albitization, resulting in Na enrichment, followed by chemical weathering that corroded K-feldspar and nearly destroyed plagioclase feldspar and mica in the regolith. Clay minerals replaced feldspars, resulting in enrichment in Al, Ti, and Zr and depletion in Na, Ca, Sr, and K. Fe has also been leached. After weathering, a fine-grained 0.5 m layer of strongly weathered allochthonous material was deposited on the regolith, followed by deposition of the Matinenda Formation. Sometime after Matinenda deposition, K- and Rb-metasomatim affected the regolith and overlying sediments, converting some clays to illite and depositing secondary K-feldspar. Greenschist-facies metamorphism probably postdated this metasomatism and converted clay minerals to white mica and chlorite.

scholarly journals Structure and Petrology of the Red Hill Complex, Nelson

2021 ◽  
Author(s):  
◽  
Richard Irving Walcott
Keyword(s):  
Bulk Composition ◽  
Mineral Chemistry ◽  
Parent Material ◽  
Preferred Orientation ◽  
Ultramafic Rocks ◽  
Rock Types ◽  
Basal Zone ◽  
Upper Paleozoic ◽  
Two Generations ◽  
Thick Lens

<p>The Red Hill Complex is an essentially concordant ultramafic body enclosed in Upper Paleozoic flysch facies sediments which include Pelorus Group (oldest), Lee River Group and Maitai Group. The Pelorus Group contains rare submarine lavas and is largely derived from spilitic volcanics. The Lee River Group consists of spilitic pillow lavas, volcanic breccias and spilitic basalts and dolerites. The Maitai Group consists of limestone, sandstone and argillite; an extensive conglomerate lens in the argillites is largely composed of andesitic pebbles. The Red Hill Complex is a 12,000 ft. thick lens and is part of a sheet of peridotites which may extend 40 miles northward to Dun Mountain. The Complex is divided into a 3000 ft thick Basal Zone of massive harzburgite and a 9000 ft thick Upper Zone of layered harzburgite and dunite with minor variants, feldspathic-peridotite, eucrite, lherzolite, wehrlite and pyroxenite. The bulk composition of both zones is approximately the same but the Upper Zone contains about 0.2 per cent feldspar not present in the Basal Zone. There is no significant regional change in mineral chemistry throughout the Complex and the average composition is about; olivine Fo91, 70 per cent; orthopyroxene, En88, 22 per cent; clinopyroxene, 5 per cent; feldspar An96, less than 0.2 per cent; spinel 2 per cent. Layering and foliation are common in the top of the Upper Zone. Layering is of at least two generations of which at least one is of metamorphic origin. Metamorphic layering was formed by metasomatic replacement probably along subhorizontal shear planes during intrusion of the ultramafic sheet. Pyroxene pegmatites formed after flow ceased. The diversity of rock types in the top of the Upper Zone is considered by the writer to have been caused by metamorphic differentiation of parent material the same composition as the Basal Zone. The preferred orientation of olivine in lineated, foliated, laminated and layered rocks has the same pattern suggesting a close genetic relationship between those structures. Evidence strongly supports a tectonic origin for the preferred orientation. Rocks in the Upper Zone are xenomorphic-granular in texture and those in the Basal Zone are typically protoclastic. Xenomorphic-granular textures are derived in part from protoclastic by post-deformational recrystallization. The ultramafic rocks are cut by a number of dykes composed of hornblende-labradorite, hypersthene-augite-bytownite assemblages or minor variants of these. The dykes were intruded shortly after emplacement of the ultramafic rocks. The Red Hill Complex is considered to have been emplaced as a sheet at shallow depths which intruded superficial deposits on the ocean floor and was later overlain by volcanics</p>

The Role of Epicardial Adipose Tissue Lymphocytes in Low-Grade Inflammation and Coronary Artery Disease

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 469-P
Author(s):  
MILOS MRAZ ◽  
ANNA CINKAJZLOVA ◽  
ZDENA LACINOVÁ ◽  
JANA KLOUCKOVA ◽  
HELENA KRATOCHVILOVA ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Adipose Tissue ◽  
Coronary Artery ◽  
Epicardial Adipose Tissue ◽  
Low Grade ◽  
Artery Disease ◽  
Low Grade Inflammation

scholarly journals Evaluating Targeted Therapies in Ovarian Cancer Metabolism: Novel Role for PCSK9 and Second Generation mTOR Inhibitors

Cancers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 3727
Author(s):  
Dafne Jacome Sanz ◽  
Juuli Raivola ◽  
Hanna Karvonen ◽  
Mariliina Arjama ◽  
Harlan Barker ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Lipid Metabolism ◽  
Cell Survival ◽  
Drug Testing ◽  
Cancer Metabolism ◽  
Ex Vivo ◽  
Specific Inhibitor ◽  
Low Grade ◽  
Serous Ovarian Cancer

Background: Dysregulated lipid metabolism is emerging as a hallmark in several malignancies, including ovarian cancer (OC). Specifically, metastatic OC is highly dependent on lipid-rich omentum. We aimed to investigate the therapeutic value of targeting lipid metabolism in OC. For this purpose, we studied the role of PCSK9, a cholesterol-regulating enzyme, in OC cell survival and its downstream signaling. We also investigated the cytotoxic efficacy of a small library of metabolic (n = 11) and mTOR (n = 10) inhibitors using OC cell lines (n = 8) and ex vivo patient-derived cell cultures (PDCs, n = 5) to identify clinically suitable drug vulnerabilities. Targeting PCSK9 expression with siRNA or PCSK9 specific inhibitor (PF-06446846) impaired OC cell survival. In addition, overexpression of PCSK9 induced robust AKT phosphorylation along with increased expression of ERK1/2 and MEK1/2, suggesting a pro-survival role of PCSK9 in OC cells. Moreover, our drug testing revealed marked differences in cytotoxic responses to drugs targeting metabolic pathways of high-grade serous ovarian cancer (HGSOC) and low-grade serous ovarian cancer (LGSOC) PDCs. Our results show that targeting PCSK9 expression could impair OC cell survival, which warrants further investigation to address the dependency of this cancer on lipogenesis and omental metastasis. Moreover, the differences in metabolic gene expression and drug responses of OC PDCs indicate the existence of a metabolic heterogeneity within OC subtypes, which should be further explored for therapeutic improvements.

scholarly journals Waterlogging-Stress-Responsive LncRNAs, Their Regulatory Relationships with MiRNAs and Target Genes in Cucumber (Cucumis sativus L.)

2021 ◽  
Vol 22 (15) ◽  
pp. 8197
Author(s):  
Kinga Kęska ◽  
Michał Wojciech Szcześniak ◽  
Adela Adamus ◽  
Małgorzata Czernicka
Keyword(s):  
Target Genes ◽  
Recovery Period ◽  
Sufficient Information ◽  
Low Oxygen ◽  
Waterlogging Tolerance ◽  
Cucumis Sativus L ◽  
Waterlogging Stress ◽  
Non Coding Rna

Low oxygen level is a phenomenon often occurring during the cucumber cultivation period. Genes involved in adaptations to stress can be regulated by non-coding RNA. The aim was the identification of long non-coding RNAs (lncRNAs) involved in the response to long-term waterlogging stress in two cucumber haploid lines, i.e., DH2 (waterlogging tolerant—WL-T) and DH4 (waterlogging sensitive—WL-S). Plants, at the juvenile stage, were waterlogged for 7 days (non-primed, 1xH), and after a 14-day recovery period, plants were stressed again for another 7 days (primed, 2xH). Roots were collected for high-throughput RNA sequencing. Implementation of the bioinformatic pipeline made it possible to determine specific lncRNAs for non-primed and primed plants of both accessions, highlighting differential responses to hypoxia stress. In total, 3738 lncRNA molecules were identified. The highest number (1476) of unique lncRNAs was determined for non-primed WL-S plants. Seventy-one lncRNAs were depicted as potentially being involved in acquiring tolerance to hypoxia in cucumber. Understanding the mechanism of gene regulation under long-term waterlogging by lncRNAs and their interactions with miRNAs provides sufficient information in terms of adaptation to the oxygen deprivation in cucumber. To the best of our knowledge, this is the first report concerning the role of lncRNAs in the regulation of long-term waterlogging tolerance by priming application in cucumber.

The Metasomatized Mantle beneath the North Atlantic Craton: Insights from Peridotite Xenoliths of the Chidliak Kimberlite Province (NE Canada)

2019 ◽  
Vol 60 (10) ◽  
pp. 1991-2024 ◽  
Author(s):  
M G Kopylova ◽  
E Tso ◽  
F Ma ◽  
J Liu ◽  
D G Pearson
Keyword(s):  
North Atlantic ◽  
Thermal State ◽  
Mineral Chemistry ◽  
Mantle Metasomatism ◽  
Labrador Sea ◽  
The North ◽  
Rock Types ◽  
History Of ◽  
The North Atlantic ◽  
North Atlantic Craton

Abstract We studied the petrography, mineralogy, thermobarometry and whole-rock chemistry of 120 peridotite and pyroxenite xenoliths collected from the 156–138 Ma Chidliak kimberlite province (Southern Baffin Island). Xenoliths from pipes CH-1, -6, -7 and -44 are divided into two garnet-bearing series, dunites–harzburgites–lherzolites and wehrlites–olivine pyroxenites. Both series show widely varying textures, from coarse to sheared, and textures of late formation of garnet and clinopyroxene. Some samples from the lherzolite series may contain spinel, whereas wehrlites may contain ilmenite. In CH-6, rare coarse samples of the lherzolite and wehrlite series were derived from P = 2·8 to 5·6 GPa, whereas predominant sheared and coarse samples of the lherzolite series coexist at P = 5·6–7·5 GPa. Kimberlites CH-1, -7, -44 sample mainly the deeper mantle, at P = 5·0–7·5 GPa, represented by coarse and sheared lherzolite and wehrlite series. The bulk of the pressure–temperature arrays defines a thermal state compatible with 35–39 mW m–2 surface heat flow, but a significant thermal disequilibrium was evident in the large isobaric thermal scatter, especially at depth, and in the low thermal gradients uncharacteristic of conduction. The whole-rock Si and Mg contents of the Chidliak xenoliths and their mineral chemistry reflect initial high levels of melt depletion typical of cratonic mantle and subsequent refertilization in Ca and Al. Unlike the more orthopyroxene-rich mantle of many other cratons, the Chidliak mantle is rich (∼83 vol%) in forsteritic olivine. We assign this to silicate–carbonate metasomatism, which triggered wehrlitization of the mantle. The Chidliak mantle resembles the Greenlandic part of the North Atlantic Craton, suggesting the former contiguous nature of their lithosphere before subsequent rifting into separate continental fragments. Another, more recent type of mantle metasomatism, which affected the Chidliak mantle, is characterized by elevated Ti in pyroxenes and garnet typical of all rock types from CH-1, -7 and -44. These metasomatic samples are largely absent from the CH-6 xenolith suite. The Ti imprint is most intense in xenoliths derived from depths equivalent to 5·5–6·5 GPa where it is associated with higher strain, the presence of sheared samples of the lherzolite series and higher temperatures varying isobarically by up to 200 °C. The horizontal scale of the thermal-metasomatic imprint is more ambiguous and could be as regional as tens of kilometers or as local as &lt;1 km. The time-scale of this metasomatism relates to a conductive length-scale and could be as short as &lt;1 Myr, shortly predating kimberlite formation. A complex protracted metasomatic history of the North Atlantic Craton reconstructed from Chidliak xenoliths matches emplacement patterns of deep CO2-rich and Ti-rich magmatism around the Labrador Sea prior to the craton rifting. The metasomatism may have played a pivotal role in thinning the North Atlantic Craton lithosphere adjacent to the Labrador Sea from ∼240 km in the Jurassic to ∼65 km in the Paleogene.

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