Geochemistry of the mudrocks and sandstones from the Bredasdorp Basin, offshore South Africa: Implications for tectonic provenance and paleoweathering

Abstract An inorganic geochemical investigation of mudrocks and sandstone from the southern Bredasdorp Basin, off the south coast of South Africa was carried out to unravel the provenance, paleoweathering, and tectonic setting of the basin. Seventy-seven representative samples from exploration wells E-AH1, E-AJ1, E-BA1, E-BB1, and E-D3 underwent geochemical analysis involving major and trace elements. The major oxide compositions show that the sandstones could be classified as sub-arkose and sub-lithic arenite. The provenance discrimination diagrams based on major oxide geochemistry revealed that the sandstones are mainly of quartzose sedimentary provenance, while the mudrocks are of quartzose sedimentary and intermediate igneous provenances. The discrimination diagrams indicate that the Bredasdorp sediments were mostly derived from a cratonic interior or recycled orogen. The bivariate plots of TiO2 versus Ni, TiO2 against Zr, and La/Th versus Hf as well as the ternary diagrams of V–Ni–Th∗10 suggest that the mudrocks and sandstones were derived from felsic igneous rocks. The tectonic setting discrimination diagrams support passive-active continental margin setting of the provenance. Also, the closely similar compositions of the analysed samples and recent sedimentary rocks of the East African Rift System perhaps suggest a rifted basin tectonic setting for the Bredasdorp Basin. Chemical index of alteration (CIA) indices observed in the sandstones suggest that their source area underwent low to moderate degree of chemical weathering. However, the mudrocks have high CIA indices suggesting that the source area underwent more intense chemical weathering, possibly due to climatic and/or tectonic variations.

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Petrography and geochemistry of the Carboniferous–Triassic Trinity Peninsula Group, West Antarctica: implications for provenance and tectonic setting

Geological Magazine ◽

10.1017/s0016756814000454 ◽

2014 ◽

Vol 152 (4) ◽

pp. 575-588 ◽

Cited By ~ 15

Author(s):

PAULA CASTILLO ◽

JUAN PABLO LACASSIE ◽

CARITA AUGUSTSSON ◽

FRANCISCO HERVÉ

Keyword(s):

Antarctic Peninsula ◽

Tectonic Setting ◽

Active Continental Margin ◽

Source Area ◽

Major And Trace Elements ◽

Cold Climate ◽

West Antarctica ◽

Continental Arc ◽

Uplift And Erosion ◽

The Antarctic

AbstractThe Carboniferous-Triassic Trinity Peninsula Group is a metasedimentary sequence that crops out widely in the northern Antarctic Peninsula. These are some of the most extensive outcrops in the area and hold the key to evaluating the connections of the Antarctic Peninsula in Gondwana; however, they are still poorly understood. Here we present our provenance study of the Trinity Peninsula Group using petrographic and geochemical approaches in combination with cathodoluminescence of detrital quartz in order to constrain its source characteristics and tectonic setting. Using differences in modal composition and quartz cathodoluminescence characteristics, we define three petrofacies derived from the progressive uplift and erosion of a volcano-plutonic continental arc, which exposed the plutonic-metamorphic roots. As indicated by major and trace elements, the source is felsic with a composition ranging from tonalitic to granodioritic. The relatively unweathered condition of the source area points to a dry and cold climate at the time of deposition, but this does not necessarily mean that it was glaciated. Deposition of the sediments occurred within an active continental margin, relatively close to the source area, probably along the south Patagonia–Antarctic Peninsula sector of Gondwana. Strong chronological, petrological and chemical similarities with the sediments of the Duque the York Complex in Patagonia suggest that they were derived from the same source.

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Geochemistry of Onshore Deposits From Rio-Del-Rey Sub-Basin of The Western Atlantic Margin of Cameroon (Coastal Basin, South West Cameroon): Provenance And Environments of Sedimentation

10.21203/rs.3.rs-802894/v1 ◽

2021 ◽

Author(s):

Milan Stafford Tchouatcha ◽

Pafouly Kassi Kassi ◽

Cecile Olive Mbesse ◽

Romeo Kuété Noupa ◽

Wallace Junior Mam ◽

...

Keyword(s):

Chemical Weathering ◽

Tectonic Setting ◽

Active Continental Margin ◽

Major And Trace Elements ◽

Source Rocks ◽

Humid Climate ◽

High Chemical ◽

Western Atlantic ◽

Silica Rocks ◽

Chemical Index Of Alteration

Abstract The Rio del Rey Basin belongs to the coastal basins of Cameroon with Cretaceous to Cenozoic deposits. The Cretaceous (Cenomanian and Campanian-Maastrichtian) and Cenozoic (Paleocene) sediments were studied using major and trace elements geochemistry associated with mineralogical data. The studied samples are mainly made up of Fe-shale and shale with rare intercalations of Fe-sand in the Cenomanian deposits, Fe-shale and shale in the Campanian-Maastrichtian deposits and sub-litharenite, Fe-sand, shale and Fe-shale in the Paleocene deposits. These samples contain high LREE/HREE ratios (9.27 -24.23), no to slight positive Eu anomalies (Eu/Eu*= 1.02 – 1.44), moderate to high Al2O3/TiO2 (10.42 – 112.93) ratio and their position in the Ce vs. La/Yb, Zr vs. TiO2 and La/Sc vs. Th/Co diagrams indicate that they derivate from mainly felsic associated with subordinate intermediate igneous rocks. The CIA (Chemical Index of Alteration; 61.69 – 92.76), PIA (Plagioclase Index of Alteration; 62.16 – 99.47), K2O/Na2O ratios (0.08 – 22.125) and Zr/Sc vs. Th/Sc diagram suggest the source rocks have experienced low to high recycling and weathering (Paleocene deposits), high chemical weathering (Campanian-Maastrichtian) and moderate to high chemical watering (Cenomanian deposits). The SiO2 vs. Al2O3 + K2O + Na2O plot suggests a predominant semi-arid to arid climate with periodically semi-humid climate during the Paleocene, attested by the evolution of the clay minerals composition with association of illite-chlorite/vermiculite/kaolinite in the Cenomanian sediments and periodic appearance of siderite in the Campanian-Maastrichtian and Paleocene deposits. The Sr/Ba (0.41 – 2) and U/Th (0.16 – 0.28) ratios indicate brackish to shallow marine environment of deposition. The Arc-Rift-Collision of two sets of high and low silica rocks and SiO2 vs. K2O/Na2O diagrams indicate a Collisional or Active Continental Margin tectonic setting similar as the Cretaceous (Lower Mundeck and Logbadjeck Formation) and Paleocene (Nkapa Formation) deposits from the Douala sub-basin, which could reflect the Precambian basement history linked to the Neoproterozoic orogeny.

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Early Cretaceous redbeds from the Minle Basin, Hexi Corridor, northwest China: Mineralogy and geochemistry implications for paleoweathering, provenance, and tectonic settings

Interpretation ◽

10.1190/int-2018-0120.1 ◽

2019 ◽

Vol 7 (2) ◽

pp. T525-T545

Author(s):

Yaxiong Sun ◽

Wenlong Ding ◽

Yang Gu ◽

Gang Zhao ◽

Siyu Shi ◽

...

Keyword(s):

Early Cretaceous ◽

Lower Cretaceous ◽

Chemical Weathering ◽

Tectonic Setting ◽

Active Continental Margin ◽

Northwest China ◽

Hexi Corridor ◽

Sediment Supply ◽

Compositional Variation ◽

Tectonic Settings

Redbeds with a large thickness in the lower Cretaceous record abundant geologic information in the Minle Basin. We have conducted the paleoweathering conditions, provenance, and tectonic settings based on mineralogy and geochemistry. Our results indicate that mudstone samples are characterized by abundant illite with negligible amounts of K-feldspars and analcime. The lower part of the lower Cretaceous is rich in quartz, whereas the upper part is dominated by dolomite and analcime. We suggest that this is caused by the decreasing input of the clastic influx during the middle-late early Cretaceous. High index of compositional variation values (average 1.33) indicate first-cycle sediment supply, suggesting an overall compositional immaturity and short-distance transportation. These characteristics are consistent with an active regional extension tectonic setting. The [Formula: see text] system ([Formula: see text];[Formula: see text];[Formula: see text]) and Th/U versus Th consistently reveal that the lower Cretaceous experienced a positive gradient in chemical weathering from young to old formations. Although the patterns of trace elements in three formations of the lower Cretaceous are different, those of the rare earth elements (REEs) tend to be consistent. The significant enrichment of light REEs, heavy REEs fractionation, and distinctive negative Eu anomalies suggest derivation from an old, upper continental crust composed of predominantly felsic sediments. This interpretation is supported by several discrimination diagrams such as titanium dioxide-nickel ([Formula: see text]), which shows the characteristics of immature recycled sediments. A few sensitive elements, ratios, and normalized REE patterns indicate a provenance of an active continental margin and a continental island arc (CIA). The La-Th-Sc, Th-Co-Zr/10, and Th-Sc-Zr/10 discrimination plots further confirm the CIA signature. Thus, we conclude that the early Cretaceous redbeds in the Minle Basin, Hexi Corridor, were deposited in a dustpan-shaped half-graben basin in a CIA setting when northwest China was influenced by intense regional extension.

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Geochemical Classification and Determination of Maturity Source Weathering in Beach Sands of Eastern San’ in Coast, Tango Peninsula, and Wakasa Bay, Japan

Earth Science Research ◽

10.5539/esr.v5n1p44 ◽

2016 ◽

Vol 5 (1) ◽

pp. 44 ◽

Cited By ~ 5

Author(s):

Bah Mamadou Lamine Malick ◽

Hiroaki Ishiga

Keyword(s):

Chemical Weathering ◽

Tectonic Setting ◽

Passive Margin ◽

Beach Sand ◽

Moderate Degree ◽

Font Size ◽

Chemical Index ◽

Wakasa Bay ◽

Beach Sands ◽

Sand Sediments

<span style="font-size: 10.5pt; font-family: 'Times New Roman','serif'; mso-bidi-font-size: 10.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA;" lang="EN-US">Geochemistry of beach sand sediments collected from the Eastern San’in coast (n=17), Tango Peninsula (n=14) and Wakasa Bay (n=7) shorelines were investigated using XRF analyses for major and trace elements to characterize their composition, classification, maturity, provenance, tectonic setting and degree of weathering in source areas. Investigated sands from all sites were very similar showing depletion in all elements except SiO2, K2O and As relative to the UCCN and JUCN, suggesting a moderate geochemical maturation. Beach sand sediments from these locations can be classified as arkose, subarkose and litharenite that are chemically immature and formed under arid/semi-arid conditions with a tendency towards increasing chemical maturity suggesting that they are from multiple sources. The relatively low to moderate values of weathering indices of Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA) and Chemical Index of Weathering (CIW), the beach sands from all sites in the source area have undergone low to moderate degree of chemical weathering. A-CN-K and A-CNK-FM plots, which suggest a granitic source composition, also confirm that the sand samples from these sites have undergone low to moderate degree of chemical weathering in consistent with CIA, PIA and CIW values. A plot of the analyzed beach sands data on the provenance discriminating function F1/F2 showed that most of the investigated beach sand sediments in all locations fall within mafic to intermediate ocean island arc source; similar to the tectonic setting discrimination diagrams based on major elements suggesting a passive margin.

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Provenance and weathering index of the Upper Cretaceous São Carlos Formation and its tectonic significance in the eastern Bauru Basin, SE Brazil

Geologia USP Série Científica ◽

10.11606/issn.2316-9095.v19-144173 ◽

2019 ◽

Vol 19 (3) ◽

pp. 77-94

Author(s):

Lara Ferreira Neves ◽

Alessandro Batezelli

Keyword(s):

Trace Elements ◽

Chemical Weathering ◽

Upper Cretaceous ◽

Source Area ◽

Sedimentary Basins ◽

Major And Trace Elements ◽

Published Data ◽

Weathering Index ◽

Se Brazil ◽

Eastern Border

Geochemistry of major and trace elements has been used as an important tool for the study of provenance and tectonic and climatic evolution of sedimentary basins. The São Carlos Formation is an Upper Cretaceous unit that lies on the eastern border of the Bauru Basin. Despite the paleontological and paleodepositional studies performed in this unit in the last years, little is known about the correspondence between tectonic and climatic conditions acting during the first stages of sedimentation. The hypothesis of this paper is to evaluate São Carlos and Araçatuba formations and understand the evolution of the eastern border of the basin. Thus, were conducted geochemical studies using X-ray fluorescence on sandstones, siltstones, and shales from the São Carlos Formation. According to the chemical weathering index, which presented values ranging from 57.12 to 71.58%, the oxides of major elements indicate that moderate weathering processes affected the source area, possibly associated with the arid-semiarid climate. Alkaline rocks, granites, gneisses, and metasediments were the main lithotypes of the source area. Ternary diagrams show that the tectonic environment was equivalent to the passive continental margin, coinciding with the Serra do Mar and, secondarily, Alto Paranaíba Uplift regions. Based on major and trace elements, their ratios, and published data on the basin, was elaborated a paleogeographic model of the eastern border of the Bauru Basin, concluding that the source area of the sediments was constituted by intermediate and felsic rocks, sometimes recycled by sedimentary processes.

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Thermal signature of the lithosphere below sedimentary basins in extensional, compressive and transform settings

10.5194/egusphere-egu2020-22518 ◽

2020 ◽

Author(s):

Magdalena Scheck-Wenderoth ◽

Judith Bott ◽

Mauro Cacace ◽

Denis Anikiev ◽

Maria Laura Gomez Dacal ◽

...

Keyword(s):

Tectonic Setting ◽

Internal Heat ◽

Sedimentary Basins ◽

Rift System ◽

Upper Rhine Graben ◽

East African Rift System ◽

Forming Mechanism ◽

Passive Margins ◽

The North ◽

Thermal Signature

The configuration of the lithosphere below sedimentary basins varies in response to the basin-forming mechanism, the lifetime of the causative stress fields and the lithological heterogeneity inherited from pre-basin tectonic events. Accordingly, the deep thermal configuration is a function of the tectonic setting, the time since the thermal disturbance occurred and the internal heat sources within the lithosphere. We compare deep thermal configurations in different settings based on data-constrained 3D lithosphere-scale thermal models that consider both geological and geophysical observations and physical processes of heat transfer. The results presented come from a varied range of tectonic settings including: (1) the extensional settings of the Upper Rhine Graben and the East African Rift System, where we show that rifts can be hot for different reasons; (2) the North and South Atlantic passive margins, demonstrating that magma-rich passive margins can be comparatively hot or cold depending on the thermo-tectonic age; (3) the Alps, where we find that foreland basins are influenced by the conductive properties and heat-producing units of the adjacent orogen; and (4)the Sea of Marmara, along the westernmost sector of the North Anatolian Fault Zone, that suggest strike-slip basins may be thermally segmented.

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Geochemistry of the Paleocene Clastic Rocks From the Southwestern Jianghan Basin, Central China Reveal Their Provenance, Tectonic Setting, and Palaeoenvironment

10.21203/rs.3.rs-956386/v1 ◽

2021 ◽

Author(s):

Kai Yan ◽

Chun-lian Wang ◽

Jiu-yi Wang ◽

Xiao-can Yu ◽

Xiao-hua Teng ◽

...

Keyword(s):

Tectonic Setting ◽

Active Continental Margin ◽

Source Area ◽

Source Rocks ◽

Central China ◽

Clastic Rocks ◽

Ree Distribution ◽

C Value ◽

Tectonic Settings ◽

Jianghan Basin

Abstract This paper intends to learn about the provenance, tectonic setting and paleoenvironment of the Paleocene Shashi Formation in the southern Jianghan Basin by the bulk-rock geochemistry. The K2O/Al2O3 and SiO2/Al2O3 ratios indicate that the major proportion of samples are litharenite. The chondrite-normalized REE distribution pattern of the Shashi Formation’s mudstones are characterized by enriched LREE and flat HREE similar to those of UC with negative Eu anomalies. Combined with the geochemical element ratio discriminant diagram, such as Al2O3-TiO2, Zr-TiO2, La/Sc-Co/Th, and Hf-La/Th, so on, these samples were sourced from mixed felsic/basic rock. Moreover, the discriminant diagrams of K2O/Na2O-SiO2/Al2O3, La-Th-Sc, and Th-Co-Zr/10 suggest that the samples were formed under the tectonic settings of active continental margin and continental island arc. The values of CIA, CIW, PIA, ICV, Zr/Sc-Th/Sc, and ternary diagrams of A-(CN)-K and Al2O3-Zr-TiO2 indicate that weathering in the source area was weak and source rocks have not been reformed by depositional recirculation and hydraulic sorting. And the palaeoenvironmental indicators of C-value, Ni/Co, V/Cr, V/(V+Ni) and Sr/Cu, Ga/Rb indicate that the climate was cool and arid during the evaporite deposition period in the southern Jianghan Basin, and the water was in the condition of oxidation.

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Geochemistry of Recent Brahmaputra River Sediments: Provenance, Tectonics, Source Area Weathering and Depositional Environment

Minerals ◽

10.3390/min10090813 ◽

2020 ◽

Vol 10 (9) ◽

pp. 813

Author(s):

Md Aminur Rahman ◽

Sudeb Chandra Das ◽

Mark I. Pownceby ◽

James Tardio ◽

Md Sha Alam ◽

...

Keyword(s):

Rare Earth ◽

Rare Earth Element ◽

Chemical Weathering ◽

Earth Element ◽

Tectonic Setting ◽

River Sediments ◽

Source Area ◽

Source Rocks ◽

Heavy Minerals ◽

Brahmaputra River

Sediments from stable sand bars along a 40 km section of the Brahmaputra River in northern Bangladesh were analyzed for their major, trace and rare earth element contents to determine their provenance, compositional maturity, source area weathering and tectonic setting. Geochemically, the sediments were classified as litharenites and the Index of Compositional Variability (ICV) varied between 1.4 and 2.0, indicating low compositional and mineralogical maturity. A high mean SiO2 concentration (72.9 wt.%) and low Al2O3 (11.1 wt.%) were consistent with a low abundance of shale and clay components. The depletion of the oxide components Na2O, CaO and K2O relative to average upper crustal compositions (UCC) reflected loss of feldspar during chemical weathering in the source region. Average TiO2 values for most samples were higher than average crustal levels, consistent with the northern section of the Brahmaputra River being a potential resource for valuable Fe-Ti oxide heavy minerals. Major and trace element ratios indicated the sediments represented erosional products from typical felsic upper continental crustal materials with contamination (30%–40%) from more intermediate/mafic compositions. The rare earth element patterns showed negative Eu anomalies (0.57–0.71), indicating they were derived mainly from fractionated felsic rocks. Resemblance of the sediment compositions to mean compositions from Higher Himalaya crystalline rocks pointed to these being potential source rocks but with components from a mafic source also present. Major element chemistries and low to intermediate weathering indices for all sediments indicated a lack of substantial chemical weathering. Evidence from tectonic discrimination diagrams suggested the Brahmaputra River sediments were derived from rock types that formed in a transitional tectonic setting ranging from an ancient passive margin to an active continental margin. Deposition occurred under cool to semi-arid climatic conditions in an oxic environment.

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U-Pb Detrital Zircon Ages and Geochemical Features of the Jingxing Formation, (Qamdo Basin, Tibet: Implications): Inferences for the Metallogenic Model of the East Tethys Evaporite

Minerals ◽

10.3390/min11070745 ◽

2021 ◽

Vol 11 (7) ◽

pp. 745

Author(s):

Wenhua Han ◽

Haizhou Ma ◽

Weixuan Fang ◽

Huaide Cheng ◽

Yongshou Li ◽

...

Keyword(s):

Trace Elements ◽

Continental Margin ◽

Detrital Zircon ◽

Tectonic Setting ◽

Active Continental Margin ◽

Age Distribution ◽

Major And Trace Elements ◽

Jinsha River ◽

The North ◽

Detrital Zircon Ages

Qamdo basin is located between the suture zone of Jinsha River (Ailao Mountains) and that of Ban Gong Lake (Nujiang) in the eastern Tethys. Part of the Jingxing Formation is deposited in the southwest of the basin. In this study, two profiles were investigated from the north and south of Qamdo basin. The characteristics of detrital zircon LA-ICP-MS U-Pb age, and the main and trace elements of sandstone were analyzed. The characteristics of major and trace elements showed that the tectonic setting of the study area is mainly composed of a relatively stable active continental margin and a passive continental margin, showing characteristics of a continental island arc. The weathering degree of Jingxing Formation in the Qamdo area is lower than that in the Lanping-Simao area, which may be closer to the origin. The age distribution characteristics of detrital zircon grains indicate that the Qiangtang Block, Youjiang basin, and Yangtze area jointly constitute the provenance of the Qamdo-Lanping-Simao basin. Both basins may be part of a large marine basin with unified water conservancy connection before evaporite deposition. Metamorphic seawater from the Qamdo basin may migrate to the Lanping-Simao basin and even the Khorat basin, where evaporite was deposited.

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Petrographic and geochemical interpretations of source provenance and tectonic setting of the Lokoja Sandstone, Bida Basin, Nigeria

International Journal of Advanced Geosciences ◽

10.14419/ijag.v8i2.31196 ◽

2020 ◽

Vol 8 (2) ◽

pp. 279

Author(s):

G. U. Ozulu ◽

A. U. Okoro ◽

V. O. Ndubueze

Keyword(s):

Trace Elements ◽

Inductively Coupled Plasma ◽

Tectonic Setting ◽

Source Area ◽

Climatic Conditions ◽

Source Rocks ◽

Heavy Minerals ◽

Petrographic Analysis ◽

Moderate Degree ◽

X Ray

The petrography and geochemistry of major and trace elements distribution pattern for the Lokoja Sandstones, Southern Bida Basin, Nigeria; were used to interpret their provenance, weathering conditions and paleotectonic setting. A total of seven (7) representative sandstone samples were selected for petrographic, heavy minerals and inorganic geochemical analyses; that is X- ray diffraction (XRD), X-ray fluorescence (XRF) and Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Results of the petrographic analysis showed 52.14 % quartz, 39.29 % feldspar, 2.00 % rock fragments, 5.14 % matrix and cement fraction as well as 1.43 % unfilled voids. Results of major elements and oxides suggests intermediate to felsic source rocks while the dominance of Na-rich feldspar to the k-feldspar and high value of Fe2O3+MgO shows contribution from ferromagnesian minerals of mafic igneous source provenance and oceanic island arc region. Average concentrations of designated trace elements in the studied sandstones are low in concentrations. The lower concentrations of Cr, Co, and Ni and higher concentrations of Zr, Ba, and Sr suggest a felsic progenitor rock. But significantly high values of Ni (7.02 ppm), La/Co (7.99), and Ni/Co (3.28) as well as the low concentration value of Y, (3.23 ppm) suggests contributions from mafic source rocks. Low average ratios for La/Co, Th/Co, Th/Sc, Ni/Co, Cr/Ni, Cr/Sc, Cr/Th, Ni/Co, Cr/Ni, Cr/Th, Cr/Sc, Th/Sc, La/Co and Th/Co also suggest a felsic source provenance. An average CIA value of 78.04% is indicative of an intense recycling in the source area while an average MIA value of 56.13% suggests a moderate degree of weathering. The high clay matrix and feldspar content have been used to classify the sandstones as feldspathic greywackes deposited in dry arid climatic conditions under a basement uplifted tectonic setting.

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