Source Area Weathering Research Articles

Provenance, Intensity of Weathering, and Economic Potential of Placer-bearing Sediments on the Shelf off Quilon, Southwestern Coast, India

ABSTRACT In this study, the mineralogy and geochemistry of sediments of the continental shelf off Quilon, southwest coast, India is used as proxies to constrain their provenance, the intensity of weathering at source, and economic potential. The weathering index calculations were carried out on the sediments and the results showed that Chemical Alteration Index (CIA) (Average = 72.88), Chemical Index of Weathering (CIW) (Average = 92.72), and Plagioclase Alteration Index (PIA) (Average = 89.74) are high, indicating moderate to intense source area weathering. High source area weathering is also supported by high Th/U ratio (Average = 5.68) which is above the average crustal Th/U ratio of 3.8. The sediments are first-cycle sediments derived from the nearby source area, as evidenced by the identification of unaltered heavy minerals and rock-forming minerals, along with a high Average Composition Variability Index (ICV) (Average = 1.20). The high K2O/Na2O ratios (Average = 3.88), and LREE/HREE ratios (Average = 20), plotting of samples in the felsic field of various binary plots (SiO2 vs. Al2O3/TiO2, Zr vs. TiO2, Ce vs. La/Yb and La/Th vs. Hf binary plots) and normalized REE patterns with LREE enrichment and negative Eu anomaly indicate the sediments were primarily derived from Khondalites of the Trivandrum block and were transported by the Kallada and Ithikkara rivers. Average Σ REE, Th, and U concentrations are 222 ppm, 15.2 ppm, and 2.58 ppm respectively in the bulk sediments. The heavy mineral separates showed significantly increased concentrations of Σ REE (Average = 3009 ppm), Th (Average = 478 ppm), and U (Average = 30 ppm) due to the presence of monazite. Due to high Σ REE, Th, and U concentrations in the sediments due to monazite, present study recommend for further exploration of these sediments, which could contribute significantly to the resource base of the nation.

Geochemistry of Mallampalli Group Phyllite from Pakhal Supergroup, Western Belt of Pakhal Basin in Pg Valley, Telangana: Implications for Provenance & Source Area Weathering

Phyllites from the Mallampalli group from the Pakhal Supergroup rocks of Pakhal Basin in PG Valley, Telangana,India was analyzed for their major and trace element geochemistry in order to constrain their provenance and source area weathering. The analyses of the phyllites generally define a single geochemical group by their major- and trace-element abundances. The metamorphosed sediments may be classified as immature by their high index of compositional variability values of mostly < 1. HREE are generally depleted whereas LREE are typically enriched relative to average Proterozoic upper crust. Such geochemical characteristics suggest that the source of the phyllites dominantly consisted of felsic rocks. Average Cr and Ni abundances and Cr/Ni ratios of average phyllites of the Mallampalli metasediments indicate that the source consisted of granitic material. Major element data, plotted in Al2O3 – (CaO+Na2O) – K2O ternary diagram indicate that the phyllites have not undergone significant post-depositional K metasomatism. Low to moderately high chemical weathering of the source terrane is indicated by pre metasomatized chemical index of alteration values of 60 – 86. The geochemical data further suggest that the sediments were deposited within a passive margin setting and mostly supplied by the adjacent basement granitoids.

Geochemical and mineralogical proxies from the Messinian mudrocks (Catanzaro Basin, southern Italy): Paleoweathering and paleoclimate evolution during the onset of the Messinian salinity Crisis

The bulk mineralogy and geochemistry of mudrock samples from a representative section of the Calcare di Base Formation outcropping in the Catanzaro Basin (Calabria) were studied using X-Ray Diffraction and X-Ray Fluorescence techniques. Phyllosilicates are the main mineralogical constituents followed by quartz, calcite, feldspar, hematite and gypsum in the lower part of the studied succession, whereas calcite is the main mineralogical component in the upper part. The geochemical composition reveals that SiO2, Fe2O3, Al2O3, CaO and MgO are the most abundant oxides on average. The chemical weathering indices, such as the CIA (Chemical Index of Alteration) and its modifications, show low-medium values and thus suggest weak-moderate source area(s) weathering conditions, under a mainly dry/arid paleoclimate environment. The low kaolinite amounts confirm a low-moderate degree of weathering processes. The studied samples originate from an environment in which non-steady-state weathering conditions prevailed and active tectonism allows erosional processes. This trend suggests a paleoclimate characterized by persistent dry (arid) conditions alternating with relatively wet (humid) conditions. The studied mudrocks are characterized by recycling effects as recorded in the Al–Zr–Ti plot. The provenance of the studied samples is mainly related to a felsic source such as the rocks composing the Sila Massif.The composition of the studied samples was compared to that of similar samples from the Calcare di Base formation of the Rossano Basin to reconstruct the paleoclimate scenario of the Mediterranean area during the Messinian Salinity Crisis. The analogies between the mudrocks investigated in this work and the argillaceous marls from the Calcare di Base formation of the Rossano Basin suggest that they formed in the same (i) non-steady-state weathering and (ii) dry/arid paleoclimatic conditions. All the evidences allow to hypothesize that semi-closed basins, even if distant and not necessarily synchronous from each other, may have developed in a comparable way due to similar local climate condition, geochemistry of the body water and river run-off. The geochemical and mineralogical proxies from the mudrocks of the Calcare di Base Formation may open a new scenario for the understanding of paleoclimatic condition during the Messinian Salinity Crisis.

Geochemistry of Stream Sediments from Eastern Ghats Mobile Belt, India: Implications on Sediment Type, Maturity, Source-area Weathering and Provenance

Abstract During their flow through an area, the streams are used to erode, transport and re-deposit sediments in the number of cycles following the climatic variation in an area. This cycle in turn affect the chemistry of these sediments and hence the geochemical study of these sediments helps to understand the palaeo-climate, source-area weathering and provenance of the study area. In order to understand the geochemical classification of sediments, palaeoclimate, source-area weathering and provenance for stream sediments of the Eastern Ghats Mobile Belt (EGMB), 364 stream sediment samples were collected from the area around Daringbadi, Kandhamal district, Odisha, India and analyzed for major oxides, trace elements and rare earth elements. These sediments are geochemically classified as shaly and wacke type, moderately mature and derived through the high intensity of weathering of source rock under warm and humid climatic condition. The positive correlation between Al2O3 and Fe2O3, MnO, and MgO, indicates multiple sources for sediment and these oxides are associated with clay minerals. The discrimination function diagram suggests a felsic igneous as well as quartzo-sedimentary provenance for these sediments whereas the ratio of Al2O3/TiO2 and concentration of V-Ni-Th suggest a felsic igneous source rock. The high concentration of LREE, slight enrichment of HREE and negative Eu anomaly indicate terrestrial or continental crust source rock. Hence the source rock for these sediments are granite gneiss, charnokite and khondalite present in and around Daringbadi area.

Geochemical characterisation of mangrove sediments in Tiko (SW, Cameroon, West Africa): Implication for provenance, paleoweathering and sediment maturity

Geochemistry was performed on clastic core sediments from the Tiko Mangroves estuary, South western region of Cameroon, to categorise the rock source composition, tectonic setting, past weathering intensity of the source area in relation to past climate and sediment maturity in relation to sedimentary cycle. Plots of La/Co, La/Sc, Cr/Th, discriminant function (DF1&2), TiO2vs Al2O3 and TiO2 vs Zr point to an acid (felsic) and mixed (intermediate) rock source composition for the Tiko sediments. The acid composition portrayed by the sediments is also confirmed by their LREE (Light rare earth elements) abundance, and a negative Europium anomaly on chondrite normalisation, while the intermediate (mix) composition reflects the multiple sources of the sediments (Douala Basin and basaltic debris from Mount Cameroon). Binary plots Discriminant function (A-P) M, and Discriminant function (A-P) MT signpost active tectonic domain for the studied sediments, that resulted from the tectonothermal of the Pan African orogenic history and eruptive activity of the mount Cameroon. The weathering indexes denoted as CIX (chemical index of weathering) and PIX (plagioclase index of weathering) for the Tiko sediments advocate an intense source area weathering in a humid hot climate. The PIX advocate a high-level plagioclase lixiviation. The low values of ICV (index compositional variation) less than 1 (<1) couple with correlation plots Zr/Sc vs Th/Sc, and Zr vs (La/Yb)N confirms that Tiko mangrove sediments are matured recycled sediments with compositional variations. This is the first comprehensive provenance study of mangrove ecosystem sediments in Cameroon.

Paleoenvironmental changes in the coastal zone of the northwest South China Sea during the last 13 kyr

Marine sediments in coastal zones serve as valuable archives for understanding the history of silicate chemical weathering and summer monsoon rainfall in source areas, providing insights into terrigenous climate and environmental evolution. In this study, we investigated the grain size, clay minerals, and geochemistry of sediments retrieved from core KZK01 in the coastal zone of the northwest South China Sea during the past 13 thousand years before present (kyr BP). Our findings demonstrated that the illite crystallinity index served as a reliable proxy for assessing the intensity of chemical weathering in the source area. Moreover, it distinctly recorded significant climatic events such as the Younger Dryas and Bond events during the Holocene. The dominant driver of the regional East Asian summer monsoon was identified as summer solar radiation in the Northern Hemisphere at low latitudes. Cold climate events exhibited global consistency, potentially influenced by the presence of ice sheets at high latitudes. Lastly, our records revealed a distinct transition at 9.0 kyr, highlighting significant impacts of the Qiongzhou Strait and sea level rise on regional climate dynamics.

Geochemistry of Mesoproterozoic Bijaigarh Shale, Upper Vindhyan Group, Son Valley, India: Implications for source area weathering, provenance and tectonic setting

Geochemistry of Mesoproterozoic Bijaigarh Shale, Upper Vindhyan Group, Son Valley, India: Implications for source area weathering, provenance and tectonic setting

Geochemistry of Jutogh Metasediments, Lesser Himachal Himalaya, India, and their Implications in Source Area Weathering, Provenance, and Tectonic Setting during Paleoproterozoic Nuna Assembly

Abstract This paper reports the results of the geochemical study of the Jutogh metasedimentary rocks that occur as a tectonic window between the Lesser and the Higher Himalaya. The Jutogh Group of rocks are mostly mica-schists of different metamorphic grade. The weathering intensity parameters, such as chemical index of alteration (CIA), plagioclase index of alteration (PIA), and index of compositional variability (ICV), range from 81 to 65 (mean = 72), 97 to 68 (mean = 84), and 1.9 to 0.6 (mean = 1.2), respectively indicating low to moderate degrees of weathering. Transition element ratios [Ni/Co (6.98 to 2.88), and V/Ni (2.32 to 1.27)], and major and trace element geochemistry imply recycled, felsic to intermediate, Archean to post-Archean are the sources for Jutogh rocks. The tectonic discrimination diagram implies an active continental margin setting for the deposition of the Jutogh metasediments. The geochemical data from the Jutogh rocks, when combined with the S-type Paleoproterozoic granite magmatism, imply the existence of an active tectonic setting during the deposition of the Jutogh sediments at the northern margin of the Indian continent during Nuna assembly.

Paleoclimate characteristics of source area weathering and metallogenic implication of cretaceous black shales in the Mamfe basin, (SW Cameroon): Evidence from lithogeochemistry

Black shales are highly enriched in essential elements containing critical information on metallic richness and paleoclimatic imprints during deposition. The Cretaceous period marks the age of Basin formation from which the Mamfe Basin was formed from the Albian to Cenomanian. The purpose of this study is to investigate the geochemical behaviour of the shales in the Mamfe Basin and their paleoclimatic and metallogenic significance. Twenty-five representative shale samples were collected from seven sites outcrops in the Mamfe Basin. The major and trace elements composition in the shale samples were analysed using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In comparison with standard values for metalliferous shales, the shales from the Mamfe Basin are enriched in Boron (B), with only few samples enriched in Li, Rb, Cu, Pb and Zn. The Aluminium module (Alm) and ternary diagram plotted from Al–Fe–Mn shows that all the shales are considered as terrigenous sediments with only 02 samples (08%) falling within the zone of metalliferous sediments. The paleoclimatic characteristics that were inferred from the C-values (0.3–3.1), Sr/Cu (0.6–8.9), Sr/Ba (0.1–2.8), Rb/Sr (0.3–0.9), Fe/Mn (1.8–180), Al/Mg (0.31–31) and Mg/Ca (0.05–16.4) data of the shales in the Mamfe Basin indicate that the climate that existed during source area weathering ranged from a sub humid to a more humid climate with few samples ≤5% displaying arid climate.

Geochemistry of recent sediments of the Kurheri basin, Son River, Madhya Pradesh, Central India: implications for source area weathering, sediment provenance, maturity, and sorting

Geochemistry of recent sediments of the Kurheri basin, Son River, Madhya Pradesh, Central India: implications for source area weathering, sediment provenance, maturity, and sorting

Sediment routing systems to the Atlantic rifted margin of the Guiana Shield

Abstract Sediment routing systems of cratonic domains have not been studied extensively because their relief and erosion rates are very low, although their vast dimensions allowed them to contribute to a significant proportion of the sediments exported to the global ocean. To gain further insights into the behavior of cratonic sediment routing systems at geological time scales, we investigated the Guiana Shield and its Atlantic rifted margin (i.e., the Guiana-Suriname and Foz do Amazonas Basins, northern South America) over the Meso-Cenozoic with an emphasis on paleoenvironment and accumulation histories of the offshore sediments. We show that the basins of the Guiana Shield rifted margin record (1) periods of very low siliciclastic supply concomitant with the development of carbonate platforms, alternating with (2) phases of higher siliciclastic supply associated with sand-dominated clastic deposits and turbidites. Low siliciclastic supplies reflect either very limited rift-related relief growth and erosion such as during the Central Atlantic rifting in the Late Jurassic or intense lateritic weathering of the cratonic source area during Paleogene–Miocene climate optima. Higher siliciclastic supplies correspond either to (1) periods of rapid rift-related relief growth and erosion such as during the Equatorial Atlantic rifting (Early Cretaceous), (2) periods of drainage reorganization over a steadily eroding cratonic domain (Late Cretaceous), or (3) periods of tapping of sediments stored in the Andean retro-foreland basins via the presentday Orinoco and Amazon Rivers (Plio-Pleistocene).

Geochemical Assessment of River Sediments at the Outlets of Eastern Makran, Pakistan; Implications for Source Area Weathering and Provenance

The river sediments in the eastern Makran were investigated to determine the influence of climate, tectonics, and source rocks based on the geochemistry of sediment delivery to the offshore marine basin. Samples were collected at the outlets of four major drainage basins. The specimens were analyzed by XRF, ICP–MS, and ICP–AES. The geochemical concentrations of major, trace, and rare earth elements show great variation among the four outlets. The Rakhshan Kaur (RK), Shadi Kaur (SK), and Dasht Kaur (DK) represent more sorted and matured detrital sediments than those of the Hingol Kaur (HK). The detrital sediments at all outlets represent mostly humid climates except for the DK which falls at the junction of humid and semi-arid conditions. The studied samples show a low level of source area weathering. The sedimentary provenance of the RK and DK is due to the heterogeneous sources of detritus from Iran in the west and the older Eocene-Holocene sedimentary successions in the east. The sediment carried by SK is probably from the late Oligocene–Holocene succession from central and coastal Makran. The HK represents a heterogeneous provenance from the Kirthar-Sulaiman Belt, Bela Ophiolites, and sedimentary successions of central and coastal Makran. The tectonic environments of all river sediments signify a continental arc rather than an active continental margin.

Geochemical Provenance, Source Area Weathering, and Tectonic Setting of the Bida Sandstone in the Northern Bida Basin, Northcentral Nigeria

This paper aims to determine the geochemical provenance, source area weathering, and tectonic setting of the Bida sandstone exposed at Doko and Jima in the Northern Bida Basin, Northcentral Nigeria. Geological fieldwork was carried out and sandstone samples were collected and analyzed for major element concentrations using X-Ray Fluorescence (XRF) method. Major element abundance shows that the studied sandstone samples consist of SiO2 (average 71.42%), Al2O3 (average 15.16%), and CaO (average 0.26%) constituting about 90% of the bulk rock composition. While P2O5, Na2O, K2O, MgO, TiO2, MnO, and Fe2O3 constitute about 10% of the composition. The results obtained using the Al2O3/TiO2 ratios show that the sandstones derived from intermediate to felsic igneous rocks. The A-CN-K triangular diagram shows that majority of the analyzed samples plotted on the aluminum zone towards kaolinite shows predominantly intermediate degree of weathering except for one sample which falls towards the CN-K line, indicating the different degree of weathering (perhaps an existence of differential weathering in the area). The source area weathering indices which include CIA (68.6%), CIW (71.20%), and PIA (54.66%) further confirms that the sediments have been subjected to intermediate weathering. The K2O/Na2O versus SiO2 tectonic setting discriminant plot shows that the samples are dominantly deposited in the passive margin setting. It is, therefore, concluded that the Bida sandstone analyzed was sourced from predominantly felsic igneous rocks where the degree of chemical weathering was intermediate and in the passive margin setting.

Provenance and source area weathering of Siwalik foreland basin rocks in NW Himalayas: insights from hydrochemistry, petrography and geochemical signature

Provenance and source area weathering of Siwalik foreland basin rocks in NW Himalayas: insights from hydrochemistry, petrography and geochemical signature

Exploring the roles of sediment provenance and igneous activity on the development of synrift lacustrine source rocks, Pearl River Mouth Basin, northern South China Sea

Lacustrine mudstones developed in the synrift Wenchang and Enping formations are the major source rocks of the Pearl River Mouth Basin (PRMB) and vary in both richness and quality of hydrocarbons generated. While organic productivity is known to have played a role in the development of these rocks, it has been mostly neglected in prior research. In this study, new zircon geochronological data from igneous intrusive and volcanic rocks in boreholes of the PRMB are used alongside compiled detrital zircon U-Pb ages from Paleogene sandstones to decipher the roles of sediment provenance and volcanic activity in the development of source rocks. The result suggests that during deposition of the Wenchang Formation (49-39 Ma), sediments were mainly derived from intrabasinal structural highs dominated by Yanshanian igneous rocks (180-90 Ma). Similarities in young ages (42–45 Ma) in volcanic and clastic units of the Wenchang Formation suggest volcanic activity concurrent with its deposition. Chemical weathering of the proximal source area together with volcanic materials provided abundant nutrients for the basin and enhanced the primary organic productivity, resulting in the development of high-quality lacustrine source rocks, derived mainly from plankton. In contrast, the detrital zircon provenance of the Enping Formation (39-33 Ma) suggests sediments were derived from the South China Block (SCB), far to the north, with complicated lithologies and more older zircon grains. The long-distance transport of SCB sediments diluted the productive nutrition conditions of the larger and shallower lakes, and introduced organic matter derived from higher terrestrial plants. This study provides a new approach to evaluating the lacustrine source rocks especially for the deep-water areas with limited mudstone samples.

Source Area Weathering and Tectonic History Inferred from the Geochemistry of the Maastrichtian Sandstone from Patti Formation, Southern Bida Basin, North Central Nigeria

Sandstones sampled from Patti Formation, Southern Bida Basin, were studied geochemically using Inductively Coupled Plasma Atomic Emission Spectrophotometer (ICP-AES) and an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) technique to evaluate their weathering and tectonic setting as well as to deduce the paleo-climatic conditions that existed during their deposition. Geochemically, SiO2 range from 73.9% to 86.2%, Al2O3 (6.7%~17.1%), Fe2O3 (1.1%~1.9%), K2O (0.1%~0.7%) while MgO, CaO, Na2O, P2O5, MnO and TiO2 were &lt;1%. Enriched in Ba (Av. 622.94), Sr (Av. 153.63), Rb (Av. 55.08) and Zr (Av. 51.86) relatively similar in composition to UCC. High SiO2 but low other major oxides signify high mobility during processes of weathering. This was confirmed by high value (&gt;80%) for indices like chemical index of alteration, chemical index of weathering, plagioclase index of alteration, mineralogical index of alteration and relatively lower values for weathering index of parker, recently used alpha indices (αAl E) of sodium (326.17αΑl Na&lt;344.40), magnesium (100.54αΑl mg&lt;398.55), calcium (12.07αΑl Ca&lt;198.99), potassium (4.43αΑl K&lt;64.33), strontium (0.84αΑl E&lt;21.40), barium (0.45 αΑl Ba&lt;10.52) and rubidium (0.0008αΑl Rb&lt;0.06), supported by AI2O3-(CaO*+Na2O)-K2O and CIA vs. SiO2 plots that imply intense weathering in the source area. The obtained high CIA values (&gt;80) indicates a steady-state of weathering under a warm/humid climate as confirmed by the SiO2 vs. Al2O3+ K2O + Na2O plot. High average SiO2 (75.41wt%) with K2O/Na2O ratio &gt;1 (15.63), low Fe2O3 (1.27wt %), Al2O3 (15.82wt%) and TiO2 (0.46) suggest passive margin tectonic setting. This is supported by enriched ΣREE (209.64 ppm), ΣLREE (195.78), LREE/HREE (27.78) and negative Eu/Eu* (0.68), plots of log (K2O/Na2O) vs. SiO2 and SiO2/Al2O3 vs. K2O/Na2O. Major elements discriminant-function multi-dimensional diagram, DF1 (arcrift-col) vs. DF2 (arc-rift-col), for high-silica sediments revealed a continental rift tectonic setting. Thus, the Patti Formation sandstone underwent a high degree of weathering under a humid climatic condition within a continental rift tectonic setting.

Geochemical constraints on the Zola-Chay river sediments, NW Iran: Implications for provenance and source-area weathering

Geochemical constraints on the Zola-Chay river sediments, NW Iran: Implications for provenance and source-area weathering

Rare Earth and Trace Elements Composition of a Residual Clay from Sosan Akoko, Southwestern Nigeria: Implications for Weathering and Provenance

The aim of this study is to determine the source area weathering and provenance of a residual clay samples overlying Precambrian basement complex in Southwestern, Nigeria. Fifteen representative clay samples were collected from three pits dug in three locations across the study area. The mineralogy and chemical composition of samples was analyzed using X-ray diffractometer (XRD) and inductively coupled plasma-mass spectrometer (ICPMS) techniques respectively. The results of mineralogical analyses indicates that kaolinite (1.4%) and nontronite (2.77%) are the major clay minerals present while the non-clay minerals include quartz, orthoclase, labradorite and albite. Chemical indices of alteration (CIA) and weathering (CIW) values of 76.02% and 89.9% respectively, low alkali and alkaline earth elements content derived from the samples implies a comparatively intense source area. Furthermore, plots of TiO2/Al2O3 indicate provenance of predominantly acidic rocks and high concentrations of Rubidium (Rb) and Strotium (Sr) in the samples with values ranging from 113.4-138.2 ppm and 218.3-229.2 ppm respectively suggests ongoing chemical weathering of the clay body. The findings from this research through mineralogical composition, rare earth elemental normalized patterns, and ternary diagrams plotted implies that these samples are derived from felsic sources.

Compositional and Geochemical Signatures of Oligocene volcanoclastic sandstones of Abbasabad-Kahak area, NE Iran: Implications for provenance relations and paleogeography

Petrography and geochemistry of sandstone for the lower Oligocene volcanic-related sandstones of Abbasabad-Kahak area, NE Iran, are detected to decipher provenance, tectonic setting and paleo-weathering of source areas. Lower Oligocene sandstones are grey in colour and host copper mineralization as bedded and lenticular, vein-veinlets and disseminated textures and structures. Texturally, sandstones are medium to coarse grained, moderately to poorly sorted and compositionally have abundance of volcanic lithic fragments. Sandstones are lithofeldspathic to feldspatholithic, leading to a provenance from the progressive dismantling of a magmatic arc. Geochemical signatures suggest a derivation from mafic-to-intermediate volcanic sources. CIA values (56–61 with the average of 57) indicate a low level of chemical weathering in source areas, which may reflect arid to semi-arid climatic conditions in source terrains. These sandstones, deposited in a remnant backarc basin, are the results of the post-Eocene extensional stage of a dismantling magmatic arc.

Author Correction: Geochemistry of carbonate-clastic strata in NW Douala sub-basin, Cameroon: Implications for provenance, tectonics and source area weathering

Author Correction: Geochemistry of carbonate-clastic strata in NW Douala sub-basin, Cameroon: Implications for provenance, tectonics and source area weathering