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

Minerals ◽  
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.

Chemical weathering of S-type granite and formation of Rare Earth Element (REE)-rich regolith in South China: Critical control of lithology

2019 ◽  
Vol 520 ◽  
pp. 33-51 ◽  
Author(s):  
Wei Fu ◽  
Xiaoting Li ◽  
Yangyang Feng ◽  
Meng Feng ◽  
Zhao Peng ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
South China ◽  
Chemical Weathering ◽  
Earth Element ◽  
Type Granite

Rare earth element geochemistry of petroleum source rocks from northwestern Niger Delta

2016 ◽  
Vol 77 ◽  
pp. 409-417 ◽  
Author(s):  
A. Akinlua ◽  
F.S. Olise ◽  
A.O. Akomolafe ◽  
R.I. McCrindle
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Niger Delta ◽  
Earth Element ◽  
Source Rocks ◽  
Element Geochemistry

Stratigraphy and geochemistry of the igneous rocks in the Elu Link between Hope Bay and Elu greenstone belts, northeast Slave craton: tectonic setting and implications for gold mineralization

2013 ◽  
Vol 50 (2) ◽  
pp. 148-170 ◽  
Author(s):  
H. Mvondo ◽  
D. Lentz ◽  
M. Bardoux
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Tectonic Setting ◽  
Crustal Contamination ◽  
Primitive Mantle ◽  
Lake Area ◽  
Calc Alkaline ◽  
Greenstone Belts ◽  
Hope Bay

Geological investigation of the rocks in the Elu Link has provided new information on the geodynamic origin of the Neoarchean (ca. 2716–2663 Ma) Hope Bay and Elu granite–greenstone belts. Stratigraphic and geochemical features of these rocks and those of the nearby Flake Lake area in the Hope Bay belt suggest that the two greenstone belts are contiguous, having similar mafic-dominated bimodal rocks comprising abundant basalts to andesites and less common dacites and rhyolites hosting gabbroic and trondhjemite–tonalite–granodiorite (TTG) intrusions. The corresponding parental magmas, whose evolution likely occurred via fractional crystallization and juvenile crustal contamination, formed from both deep and shallow mantle sources. The basalts, andesites, gabbros, and felsic volcanic rocks are variably tholeiitic to calc-alkaline. Chondrite- and primitive mantle-normalized profiles demonstrate (1) flat to slightly fractionated heavy rare-earth element (HREE) patterns with a weak negative Eu anomaly and (2) light rare-earth element (LREE) enriched and strongly fractionated HREE patterns with variable negative to positive Eu anomalies. In contrast, TTG rocks are calc-alkaline, with strong LREE enrichment, HREE depletion, and variable positive Eu anomalies. Altogether, the rocks exhibit Nb and Ti troughs, and variable Nb/Ta, La/Ta, and Zr/Hf ratios indicative of crustal contamination. Chalcophile elements and related ore deposits in the area are inferred to be formed from hydrothermal fluids mobilized during emplacement and after crystallization of their host rocks. An extensional, high-heat-flow back-arc tectonic environment is proposed to explain the stratigraphic and geochemical characteristics and the presence of large gold resources in these greenstone belts.

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

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.   

Eu anomaly- reliability of the proxy in inferring source composition of clastic Sedimentary rocks: A case study from western Dharwar craton, Karnataka, India

2020 ◽  
Author(s):  
Anirban Mitra ◽  
Sukanta Dey
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Sedimentary Rocks ◽  
Dharwar Craton ◽  
Source Rocks ◽  
Granitic Rocks ◽  
Negative Anomaly ◽  
Eu Anomaly ◽  
Ree Pattern

<p>Use of trace and rare earth element concentration of terrigenous sedimentary rocks to deduce the composition of their source rocks in the hinterland is a very common and efficient practice. The results of geochemical analysis of the metaquartzarenites located at the basal part of Bababudan and Sigegudda belt, late Archean greenstone sequences of western Dharwar craton show that the sediments were most possibly supplied from Paleo to Mesoarchean granitoids of western Dharwar Craton. Rare earth element patterns of these basal quartzites display fractionated REE pattern in variable degree (La<sub>N</sub>/Yb<sub>N</sub> =1.47-10.63) with moderate to highly fractionated LREE (La<sub>N</sub>/Sm<sub>N</sub>=2.67-8.93) and nearly flat to slighly elevated HREE (Gd<sub>N</sub>/ Yb<sub>N</sub>=0.62-1.29) and a significant Eu negative anomaly (avg. Eu/Eu*=0.67). In general, presence of negative Eu anomaly in clastic rocks reflect the widespread occurrence of granitic rocks in the source area, which possess negative Eu anomaly. On the other hand, mechanical enrichment of zircon (having negative Eu anomaly, high HREE concentration and low La<sub>N</sub>/Yb<sub>N</sub>), if present, will hamper the whole REE pattern of the sediments and necessarily, do not actually mimic the source composition. Here, in our study, the Th/Sc vs Zr/Sc diagram show mineral Zircon has been concentrated by mechanical concentration in the sedimentary rocks. Few quartzite samples which have high Zr content typically exhibit low La<sub>N</sub>/Yb<sub>N</sub> values, reflecting pivotal role of mineral zircon in controlling the REE pattern of the sediments. Hence, in this case, we should be cautious in interpreting of the Eu negative anomaly of the basal quartzites for meticulously identifying their source rock composition. More geochemical and other analytical approaches are required in this regard.</p>

scholarly journals Supplemental Material: LA-ICP-MS U-Pb dating and geochemical characterization of oil inclusion-bearing calcite cements: Constraints on primary oil migration in lacustrine mudstone source rocks

2021 ◽  
Author(s):  
Ao Su ◽  
et al.
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Source Rocks ◽  
Oil Migration ◽  
Geochemical Characterization ◽  
Icp Ms

Table S1: LA-ICP-MS U-Pb contents (ppm), and 238U/206Pb-207Pb/206Pb ratios of the microcrystalline-granular calcite (MGC) and blocky calcite (BC) in vein samples FSX1-1 and FSX1-2; Table S2: LA-ICP-MS rare earth element (REE) data (ppm) for calcite cements in vein samples FSX1-1 and FSX1-2.

Sign in / Sign up

Export Citation Format

Share Document