scholarly journals Chemical weathering east and west of the emerging Caledonides in the Silurian – Early Devonian, with implications for climate

2016 ◽  
Vol 53 (8) ◽  
pp. 774-780 ◽  
Author(s):  
Enli Kiipli ◽  
Tarmo Kiipli ◽  
Toivo Kallaste ◽  
Tiiu Märss
Keyword(s):  
Chemical Weathering ◽  
Sedimentary Rocks ◽  
Clay Fraction ◽  
Climatic Conditions ◽  
Chemical Compositions ◽  
Tropical Zone ◽  
Early Devonian ◽  
Marine Carbonates ◽  
Latitudinal Position ◽  
Mountain Chain

The late Llandovery (Silurian) – early Lochkovian (Devonian) climate of the tropical zone is tracked considering orogenesis, global glaciation events, and cratonic drift. Mineral and chemical compositions of clay fractions of Canadian (the Franklinian Basin) and Estonian (the Baltoscandian Basin) sedimentary rocks from different sides of the emerging Caledonides were studied, using clay as an index of climatic conditions of the provenance area. Illite is the main clay mineral, with addition of orthoclase, muscovite, and chlorite in both regions. Authigenic chert is present in some Canadian sections. The similarity of clay minerals and elemental composition in the two regions suggest common chemical weathering conditions. Nevertheless, the Al/Ti ratio of the <1 μm clay fraction, the proxy for climate’s aridity–humidity and weathering intensity, reveals differences. The Franklinian Basin in Laurentia shows a shift of climate from humid to semi-humid in pace with the uplift of the Caledonides. The sub-meridional mountain chain in the east reduced the amount of rainfall and, therefore, caused drier climate than could have been expected from the low latitudinal position of the area. The material from the Baltoscandian Basin reveals semi-arid and arid climate for most of the Silurian. Although the southern part of the Fennoscandian Shield was situated in desert latitudes, the evidence from the provenance of clay suggests that the climate was not fully arid. In Baltoscandia, covariation between low Al/Ti of clay and negative shifts of δ13C of marine carbonates is recorded at some stratigraphical levels, suggesting a link between humid climatic episodes in mainland and waning of glaciers at the South Pole.

scholarly journals Mineralogy of recent pelitic sediments from the Fiskenæsset region, southern West Greenland

1976 ◽  
Vol 73 ◽  
pp. 100-108
Author(s):  
D Heling
Keyword(s):  
Chemical Weathering ◽  
Clay Fraction ◽  
Soil Formation ◽  
Mineralogical Composition ◽  
Climatic Conditions ◽  
Formation Processes ◽  
Grab Sampling ◽  
West Greenland ◽  
Fast Transport ◽  
Mineral Alteration

Recent muds were sampled during the summer of 1973 from different fjords and lakes in the Fiskenæsset region of southern west Greenland. The samples were analysed for their mineralogical composition in order to study sorting effects and possibie mineral alteration by transport action under subarctic climatic conditions. In an investigation of the composition of sands from the Fiskenæsset region Kalsbeek et al. (1974) revealed a close correspondence between the mineralogical composition of the coarser clastic components and that of the bedrock. Such relationships occur when chemical weathering of the sediment material is negligibie due to low temperatures and in connection with fast transport (high relief) and corresponding high sedimentation rates. All these influencing factors are active in southern west Greenland. Sampling was undertaken in Buksefjorden, Sermilik, Grædefjord, Fiskenæsfjorden, Bjørnesund and at the margin of Frederikshåbs Isblink. Further bottom samples were taken from the lakes marked in fig. 45. A total of 121 samples were recovered from depths ranging from Oto 275 m using grab sampling devices. Almost the entire sediment material under consideration has been produced by glacial abrasion and only a negligibie proportion by soil formation processes. Both bed load and suspension load are brought by melt water streams from beneath the glaciers. The melt waters run into glaciaIly eroded lakes, where most of the coarse sediment material and some of the clay fraction is trapped. Most of the clay fraction remains in suspension, however, and is transported downstream to sea level. Considerable amounts of clay in suspension are carried far into the fjords.

scholarly journals Origin and occurrence of clay minerals in the Ariyalur Group of sedimentary rocks, Cauvery basin, Tamil Nadu, India

1999 ◽  
Vol 19 ◽  
Author(s):  
J. Madhavaraju ◽  
S. Ramasamy
Keyword(s):  
Clay Minerals ◽  
Tamil Nadu ◽  
Chemical Weathering ◽  
Sedimentary Rocks ◽  
Climatic Conditions ◽  
Temperate Climate ◽  
X Ray Diffraction ◽  
Mineral Assemblages ◽  
Lower Maastrichtian ◽  
Climatic Transition

Clay mineral assemblages in the Ariyalur Group of sedimentary rocks were studied by X-ray diffraction analysis. The results of the study indicate that illite and smectite are the predominant clay minerals whereas kaolinite and chlorite occur in minor amounts. The Campanian-Lower Maastrichtian rocks (i.e., Sillakkudi and Kallankurichchi Formations) contain a large amount of illite. The study reveals that these sediments were derived from the continental erosion of pre-existing rocks that were subjected to low intensity chemical weathering associated with a temperate climate. A significant decrease in illite content is observed in the Ottakkovil Formation. It implies a climatic transition (from temperate to warm) during the Middle Maastrichtian time. On the other hand, a high content of pedogenic smectite in the Kallamedu Formation is indicative of warm climatic conditions with alternating dry and wet periods during the formation of this mineral.

scholarly journals Soil and Leaf Nutrients Drivers on the Chemical Composition of the Essential Oil of Siparuna muricata (Ruiz & Pav.) A. DC. from Ecuador

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2949
Author(s):  
Juan I. Burneo ◽  
Ángel Benítez ◽  
James Calva ◽  
Pablo Velastegui ◽  
Vladimir Morocho
Keyword(s):  
Gas Chromatography ◽  
Chemical Composition ◽  
Secondary Metabolites ◽  
Essential Oil ◽  
Chemical Elements ◽  
Climatic Conditions ◽  
Gas Chromatography Mass Spectrometry ◽  
Chemical Compositions ◽  
Leaf Nutrients ◽  
First Time

Chemical compositions of plants are affected by the initial nutrient contents in the soil and climatic conditions; thus, we analyzed for the first time the effects of soil and leaf nutrients on the compositions of the essential oils (EOs) of Siparuna muricata in four different localities in Ecuador. EOs were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry (GC/MS) and a gas chromatography/flame ionization detector (GC/FID). Enantiomeric distribution by GC/MS was determined, modifying the enantiomeric separation of β-pinene, limonene, δ-elemene, β-bourbonene, cis-cadina-1 (6), 4-diene and atractylone. A total of 44 compounds were identified. The most representative for L1 were guaiol, atractylone and 4-diene; for L2, cis-cadina-1(6),4-diene and myrcene; for L3, atractylone, myrcene and germacrene B; and finally, L4 germacrene B, myrcene and cis-cadina-1(6),4-diene. Correlations between soil- leaf chemical elements such as Al, Ca, Fe, Mg, Mn, N and Si in the different localities were significant with chemical composition of the essential oil of Siparuna muricata; however, correlations between soil and leaf K, P, and Na were not significant. Cluster and NMDS analysis showed high dissimilarity values of secondary metabolites between four localities related with changes in soil- leaf nutrients. Thus, the SIMPER routine revealed that not all secondary metabolites contribute equally to establishing the differences in the four localities, and the largest contributions are due to differences in guaiol, cis-cadina-1(6),4-diene, atractylone and germacrene. Our investigation showed for the first time the influences of altitude and soil- leaf chemical elements in the chemical composition of the EOs of S. muricata.

scholarly journals Thermokarst lake waters across the permafrost zones of western Siberia

2014 ◽  
Vol 8 (4) ◽  
pp. 1177-1193 ◽  
Author(s):  
R. M. Manasypov ◽  
O. S. Pokrovsky ◽  
S. N. Kirpotin ◽  
L. S. Shirokova
Keyword(s):  
Western Siberia ◽  
Chemical Elements ◽  
Chemical Compositions ◽  
Thermokarst Lakes ◽  
Thermokarst Lake ◽  
Surface Areas ◽  
Discontinuous Permafrost ◽  
Latitudinal Position ◽  
Hydrochemical Composition ◽  
Lake Waters

Abstract. This work describes the hydrochemical composition of thermokarst lake and pond ecosystems, which are observed in various sizes with different degrees of permafrost influence and are located in the northern part of western Siberia within the continuous and discontinuous permafrost zones. We analysed the elemental chemical composition of the lake waters relative to their surface areas (from 10 to 106 m2) and described the elemental composition of the thermokarst water body ecosystems in detail. We revealed significant correlations between the Fe, Al, dissolved organic carbon (DOC) and various chemical elements across a latitude gradient covering approximately 900 km. Several groups of chemical elements that reflect the evolution of the studied water bodies were distinguished. Combining the data for the studied latitude profile with the information available in the current literature demonstrated that the average dissolved elemental concentrations in lakes with different areas depend specifically on the latitudinal position, which is presumably linked to (1) the elements leached from frozen peat, which is the main source of the solutes in thermokarst lakes, (2) marine atmospheric aerosol depositions, particularly near the sea border and (3) short-range industrial pollution by certain metals from the largest Russian Arctic smelter. We discuss the evolution of the chemical compositions observed in thermokarst lakes during their formation and drainage and predict the effect that changing the permafrost regime in western Siberia has on the hydrochemistry of the lakes.

scholarly journals Lithostructural and Petrochemical Survey of Djarkadougou Gold Prospect (South West Burkina Faso / West Africa)

2017 ◽  
Vol 6 (1) ◽  
pp. 155
Author(s):  
Yao Honoré Koffi ◽  
Sagbrou Chérubin Djro ◽  
Urbain Wenmenga
Keyword(s):  
West Africa ◽  
Burkina Faso ◽  
Sedimentary Rocks ◽  
Ductile Deformation ◽  
Chemical Compositions ◽  
Calc Alkaline ◽  
Basaltic Rocks ◽  
Bimodal Volcanism ◽  
South West ◽  
Western Burkina Faso

The Djarkadougou gold prospect is located on the Birimian greenstone belt of the Houndé exploration permit held by the company Orezone Inc. The permit is at 275 km far from the capital Ouagadougou south- western Burkina Faso, West Africa. This area is based on sheared and metamorphosed greenschist facies rocks. Metamorphism locally reaches to the amphibolite facies around intrusions. There are two major lithological units whose interface is marked by a NW-SE trending shear corridor: an unit of andesite-basaltic rocks of andesitic breccias in the East and volcaniclastic and sedimentary unit composed flows, tuffs and felsic to mafic breccia, interbedded volcano-sedimentary rocks. All this together is intruded by plutonic rocks, and various felsic to mafic dykes. These rocks have undergone ductile to brittle heterogeneous deformations and hydrothermal alteration sericite ±carbonate ±quartz±sulphide within deformation corridors. The rocks of the East and West domains affected by three phases of brittle-ductile deformation (D1, D2, and D3) and the meteoric alteration is systematic in superficial facies of Djarakadougou core drilling.Geochemical analysis shows a tholeiitic to calc-alkaline volcanic serie characteristic a bimodal volcanism. The spectra of normalized REE chondrites are generally flat and constant reminding those of N-MORB basalt. The chemical compositions of andesite and basalt are deferred on several discrimination diagrams especially Th / Yb - Nb / Yb and 2 Nb - Zr / 4 - Y show that andesites and basalts of the prospect are issued in geotectonic setting of volcanism preponderant arc.

Clay resources in the Nelas region (Beira Alta), Portugal. A contribution to the characterization of potential raw materials for prehistoric ceramic production

Clay Minerals ◽  
2010 ◽  
Vol 45 (3) ◽  
pp. 353-370 ◽  
Author(s):  
R. Marques ◽  
A. Jorge ◽  
D. Franco ◽  
M. I. Dias ◽  
M. I. Prudêncio
Keyword(s):  
Chemical Elements ◽  
Raw Materials ◽  
Bulk Material ◽  
Clay Fraction ◽  
Size Fraction ◽  
Chemical Compositions ◽  
River Bank ◽  
Clay Size Fraction ◽  
Ancient Ceramic

AbstractMineralogical and chemical compositions of residual and sedimentary clays (bulk and <2 μm fraction) from the Nelas region (schist, aplite-pegmatites, granites and Tertiary sediments from both Mondego River margins), Portugal, were studied, aiming to establish indicators for raw materials in ancient ceramic provenance studies. The mineralogy of bulk material does not provide a clear distinction between samples. Among clay minerals, kaolinite dominates, except in the aplite-pegmatites where illite prevails. Smectite was only found in sediments of the left river bank.A more successful result was the geochemical differentiation of clay types. The weathered schist presents greater enrichment in Cr, whereas the clay fraction of aplite-pegmatites shows enrichment in all the chemical elements studied. The sediments and weathered granites are not easy to differentiate; the best geochemical indicators are U (lower contents in clay-size fraction of sediments) and REE patterns in both bulk and clay-size fraction.

Chemical weathering response to extreme global warming during Paleocene-Eocene Hyperthermals, Southern Pyrenees, Spain

2021 ◽  
Author(s):  
Rocio Jaimes-Gutierrez ◽  
Thierry Adatte ◽  
Emmanuelle Puceat ◽  
Jean Braun ◽  
Sebastien Castelltort
Keyword(s):  
Climatic Change ◽  
Chemical Weathering ◽  
Numerical Models ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Foreland Basin ◽  
Isotopic Analysis ◽  
Feedback Mechanism ◽  
Horizon 2020 ◽  
Sediment Routing

&lt;p&gt;The Paleocene and early Eocene were periods yielding multiple hyperthermal events. The most pronounced of them was the Paleocene-Eocene Thermal Maximum (PETM), which was characterized by an abrupt increase in global temperature (5&amp;#8211;8 &amp;#176;C) over a short time (20 ka). A negative carbon isotope excursion marks the onset of the PETM, which resulted in the fast injection of CO&lt;sub&gt;2&lt;/sub&gt; into the ocean-atmosphere system, triggering global climatic changes. Geochemical, mineralogical, and sedimentological markers record the resulting increase in continental weathering. This is important, as enhanced chemical erosion influences both the CO&lt;sub&gt;2&lt;/sub&gt; concentration in the atmosphere and ocean acidity, generating a feedback mechanism. Hence, constraining the rates and intensity of weathering response can further clarify the causes for the PETM and Eocene hyperthermals. This study focuses on the well-preserved Pyrenean foreland basin and intends to assess the continental chemical weathering response of the sediment routing system during the PETM. Clay mineralogy is a climate-sensitive proxy, which records changes in continental erosion. Therefore, clay mineral proportions will be analyzed using X-ray diffraction and major element chemistry on clay-rich samples from the entire source-to-sink system (continental to deep marine deposits). Kaolinite and smectite will be separated from the detrital clay fraction and further subjected to &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O and &amp;#948;D isotopic analysis for paleoclimatic reconstruction. The combined Lu-Hf and Sm-Nd isotope systems in the clay fraction of the sediments will be used to track the evolution of chemical weathering intensity. The outcome of this project will serve to validate numerical models to understand erosion as a function of rapid climatic change. This topic is of keen interest, as the PETM and its sedimentological signal work as a natural analog for anthropogenically-induced climatic change. The project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No 860383.&lt;/p&gt;

3. Sedimentary rocks

2016 ◽  
pp. 29-50
Author(s):  
Jan Zalasiewicz
Keyword(s):  
Sedimentary Rock ◽  
Chemical Weathering ◽  
Sedimentary Rocks ◽  
Chemical Environment ◽  
Combined Effects ◽  
Star System ◽  
The Earth ◽  
Different Types ◽  
Physical And Chemical

The Earth has the greatest abundance and variety of sedimentary strata in our star system, dating back some 3.8 billion years. ‘Sedimentary rocks’ describes the processes that create different types of sedimentary rocks, which form a key guideline in reconstructing Earth’s history. Particles are created by both physical and chemical weathering. These particles are then moved by different modes of transport and sorted by size, which affect the resulting sedimentary rock. Sedimentary layers can remain as soft muds or loose sands for millions of years, but most buried sedimentary layers harden and turn into rock, under the combined effects of increasing heat and pressure, and of changes in chemical environment.

scholarly journals Geochemical Significance of Clay Minerals and Elements in Paleogene Sandstones in the Center of the Northern Margin of the Qaidam Basin, China

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 505 ◽  
Author(s):  
Guoqiang Sun ◽  
Meng Wang ◽  
Jiajia Guo ◽  
Yetong Wang ◽  
Yongheng Yang
Keyword(s):  
Clay Minerals ◽  
Chemical Weathering ◽  
Qaidam Basin ◽  
Sedimentary Environment ◽  
Climatic Conditions ◽  
Northern Margin ◽  
Magmatic Arc ◽  
Average Value ◽  
Geochemical Significance ◽  
Continental Magmatic Arc

The average thickness of Paleogene sandstones reaches about 3000–4000 m at the northern margin of the Qaidam Basin. However, the provenance and sedimentary environment of these sandstones are uncertain; thus, more comprehensive research is needed. Integrated research is conducted on the provenance and weathering process based on petrographic characteristics, clay minerals, and geochemical compositions of sandstones in the center of the northern Qaidam Basin. The results of lithofacies analysis show that the Paleogene sandstones were mainly derived from an active continental magmatic arc, subduction accretion, or a fold-thrust belt. The average illite content in the Paleogene clay minerals is more than 50%, followed by chlorite and smectite, which reflect climatic and environmental characteristics that were arid to semi-arid, whereas the characteristics of carbon–oxygen isotopes reveal a mainly freshwater sedimentary environment. The corrected chemical index of alteration (CIAcorr) is between 56.3 and 75.7, with an average value of 66.5. These results indicate that the provenance of the Paleogene sandstones in the center of the northern Qaidam Basin mainly formed under cold and dry climatic conditions and experienced limited chemical weathering with a small amount that underwent intermediate chemical weathering under warm and humid conditions.

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