Geochemical/isotope characterization of sediments from the Great Indian Desert, Thar

2021 ◽  
Author(s):  
Rohan Bhattacharyya ◽  
Satinder Pal Singh
Keyword(s):  
Regional Climate ◽  
Source Region ◽  
River Sediments ◽  
Heavy Minerals ◽  
Geochemical Data ◽  
Indian Desert ◽  
Indus Delta ◽  
Chemical Index Of Alteration ◽  
Eolian Deposits

<p>The Great Indian Desert, Thar is a natural source of the atmospheric mineral dust burden over India and nearby landmasses/seas and regulates the regional climate and ecosystem health. However, the limited geochemical/isotope data of Thar sediments from the source region in Rajasthan restrict their source delineation and implication for characterization of the Thar dust signatures. For this purpose, we have measured major, trace, and rare-earth elemental concentrations, and radiogenic Sr and Nd isotope compositions in 51 surface sediment samples collected over a wide area from the Thar Desert, Rajasthan. The geochemical data reveals a low degree of the chemical index of alteration (CIA ~43–54), a quartz dilution of major oxides, and depletion of heavy minerals such as zircons. The UCC normalized spider diagram, as well as La/Yb–Eu anomaly plot, reveal that the Thar surface sediments collected in this study are geochemically similar to that of a sedimentary sequence from the Luni River originating from the Aravalli mountains. The <sup>87</sup>Sr/<sup>86</sup>Sr and ε<sub>Nd</sub> of Thar sediments overlap with the reported values for the Indus delta and Luni river sediments but are distinctly different from those of the Ghaggar river sediments. Thus, the sediment contribution from the Indus delta cannot be completely ruled out, while the Ghaggar sediment contributions are minimum. Furthermore, the radiogenic isotope compositions of the decarbonated Thar sediments are strikingly contrasting to the reported values for silicate fractions of eolian deposits in northwestern India. These differences could be due to grain size effects during the dust production/transport or local sediment contributions to the eolian deposits.</p>

Climatological characterization of tropical cyclones detected in the regional climate simulations over the CORDEX‐SEA domain

2021 ◽  
Author(s):  
Jennifer Tibay ◽  
Faye Cruz ◽  
Fredolin Tangang ◽  
Liew Juneng ◽  
Thanh Ngo‐Duc ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
Regional Climate ◽  
Climate Simulations

Stratigraphy of the Colorado Creek Mammoth Locality, Alaska

1992 ◽  
Vol 37 (2) ◽  
pp. 214-228 ◽  
Author(s):  
Robert M. Thorson ◽  
R. Dale Guthrie
Keyword(s):  
Regional Climate ◽  
Slope Aspect ◽  
Proxy Record ◽  
Radiocarbon Dates ◽  
West Central ◽  
Permafrost Table ◽  
Eolian Deposits ◽  
Paleoclimatic Proxy

AbstractThe Colorado Creek mammoth locality in west-central Alaska contains the remains of two mammoths that were scavenged by carnivores. Sedimentologic interpretations of the reworked eolian deposits surrounding the bones, supplemented by 10 radiocarbon dates, indicate that the lower and upper mammoths died and were buried within separate, but superimposed, thaw gullies about 23,000 and 16,000 yr ago, respectively. From our results, we propose a polycyclic taphonomic model for thaw gullies governed largely by slope aspect, rather than regional climate, and in which mixing between faunal horizons is more likely than not. Variations in the rate of silt influx and the position of the permafrost table provide a paleoclimatic proxy record that can be correlated to other records in eastern Beringia.

scholarly journals Synchrotron Radiation X-ray Analyses of Heavy Minerals and Heavy Elements in River Sediments of Kyushu for Constructing a Forensic Soil Database

2016 ◽  
Vol 65 (2) ◽  
pp. 93-98 ◽  
Author(s):  
Junko HIROKAWA ◽  
Issei MAEDA ◽  
Shunsuke FURUYA ◽  
Yoshinari ABE ◽  
Keiichi OSAKA ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
River Sediments ◽  
Heavy Elements ◽  
Heavy Minerals ◽  
X Ray ◽  
Soil Database

Characterization of the Pesticide Chlordane in Estuarine River Sediments

2005 ◽  
Vol 34 (2) ◽  
pp. 544-551 ◽  
Author(s):  
Y. Ouyang ◽  
L.-T. Ou ◽  
G. C. Sigua
Keyword(s):  
River Sediments

On the volcanic architecture, petrology and geodynamic setting of the 3.48 Ga Barberton komatiite suite, South Africa

2021 ◽  
Author(s):  
E.G. Grosch ◽  
J. Slama
Keyword(s):  
South Africa ◽  
Mantle Plume ◽  
Source Region ◽  
Crustal Contamination ◽  
Primitive Mantle ◽  
Geochemical Data ◽  
Geodynamic Setting ◽  
Crustal Material ◽  
Type Section ◽  
Formation Type

Abstract This study presents new field and petrological observations combined with geochemical data on a range of komatiitic to tholeiitic volcanic rocks from the ca. 3.48 Ga mid-lower Komati Formation type-section of the Barberton Greenstone Belt, South Africa. A range of mafic-ultramafic rocks is identified across a 1.44 km profile, leading to the proposition of a new preliminary volcanic architecture for the mid-lower Komati Formation type-section. Major, trace and rare earth element (REE) data in conjunction with Lu-Hf isotopic constraints indicate that the tholeiites, newly recognized high-magnesium basalts, basaltic komatiites and komatiites in the volcanic sequence have a primitive mantle signature with no geochemical affinity to Archaean or modern-day supra-subduction zone boninites. The whole rock initial εHf values of spinifex and massive komatiite flows in the lowermost part of the Komati type-section are negative, ranging between -1.9 and -3.1, whereas the second overlying spinifex and massive flow unit records positive initial εHf values between +0.5 and +4.7. A new geodynamic model involving crustal contamination of the mafic-ultramafic lavas is proposed for the Barberton mid-lower Komati Formation type-section, involving mantle plume-crust interaction. The new observations and data indicate that the komatiites erupted as a result of a mantle plume from a hot (>1 600oC) mid-Archaean mantle, in which the earliest volcanic flows were variably affected by crustal contamination during their ascent and eruption. The possibility of incorporation of lower crustal material and/or recycled crust residing in the mantle source region cannot be excluded. This indicates that modern-style plate tectonic processes, such as subduction, may not have been a requirement for the formation of the 3.48 Ga Barberton komatiite suite, with implications for the hydration state, geodynamic processes and secular thermal evolution of the Archaean mantle.

Guidelines for assessing the provenance of Mesozoic and Cenozoic clastic successions sourced by pre-Jurassic basement complexes in southernmost North America

2020 ◽  
Vol 90 (5) ◽  
pp. 513-532 ◽  
Author(s):  
Michelangelo Martini ◽  
Luigi Solari ◽  
Mariana Peña-Guerrero ◽  
Mildred Zepeda-MartÍnez ◽  
Chiara Montomoli
Keyword(s):  
North America ◽  
White Mica ◽  
Heavy Minerals ◽  
Geochemical Data ◽  
Provenance Analysis ◽  
Mineral Phases ◽  
The Face ◽  
Rank 2 ◽  
Available Information ◽  
Different Sources

ABSTRACT Mexico is an attractive place for provenance studies focused on reconstructing the tectonic evolution of North America. This is because Mexico hosts a well-preserved clastic record associated with some of the major Mesozoic and Cenozoic tectonic processes that shaped the face of this continent. However, the available information on Mexican pre-Mesozoic source terranes is presently insufficient for provenance analysis. With the aim of drawing the guidelines for provenance determination, we present here detrital modes, geochemical data, and zircon U-Pb ages for detritus derived from pre-Jurassic basement complexes of Mexico. Our data show that the various basement complexes produce distinctive detrital modes and supply diagnostic and compositionally different detrital heavy minerals that represent powerful provenance tracers. The Oaxacan Complex, Ayú Complex, and East Mexico Arc are the main sources of quartzo-feldspathic and feldspatho-quartzose detritus. Quartz with rutile needles, mesoperthitic K-feldspar, orthopyroxene, augitic to diopsidic clinopyroxene, and Mg- to Ca-rich almandine (Alm71–52Grs7–3Prp43–23Sps3–1Alm74–56Grs21–19Prp23–2Sps5–2) are common minerals in detritus from the Oaxacan Complex. The Ayú Complex supplies detritus marked by the occurrence of sagenitic biotite and white mica, as well as Mn-rich almandine (Alm69–66Grs4–3Prp18–11Sps19–10). Detritus from the East Mexico Arc contains any of these mineral phases ubiquitous in the Oaxacan and Ayú complexes. The Acatlán Complex is the main source of detritus dominated by metamorphic lithic grains and quartz, with minor amounts of feldspar. Lithic grains are rank 2–4 metabasitic, metapelitic, and metapsammitic–metafelsitic fragments. Diagnostic mineral phases are schorl–dravitic tourmaline, Na-amphibole, and helycitic garnet varying from a Ca- to Mn-rich almandine (Alm74–55Grs34–15Prp16–3Sps12–1-Alm70–46Grs20–15Prp3–1Sps32–12). Zircon U-Pb geochronology proves to have some virtues but also major limitations because: 1) the zircon U-Pb age signature of many different sources in Mexico is similar and 2) zircon documents a limited number of sources because of variations in zircon fertility.

Characterization of the Danube River sediments using the PMF multivariate approach

Chemosphere ◽  
2014 ◽  
Vol 95 ◽  
pp. 329-335 ◽  
Author(s):  
Sara Comero ◽  
Stefano Vaccaro ◽  
Giovanni Locoro ◽  
Luisa De Capitani ◽  
Bernd Manfred Gawlik
Keyword(s):  
River Sediments ◽  
Danube River ◽  
Multivariate Approach ◽  
The Danube River

Geochemical characterization of hydrocarbon source rocks of the Triassic-Jurassic time interval in the Mandawa basin, southern Tanzania: Implications for petroleum generation potential

2020 ◽  
Vol 123 (4) ◽  
pp. 587-596
Author(s):  
A. Emanuel ◽  
C.H. Kasanzu ◽  
M. Kagya
Keyword(s):  
Source Rocks ◽  
Geochemical Data ◽  
Time Interval ◽  
Type I ◽  
Hydrocarbon Generation ◽  
Type Ii ◽  
Geochemical Characterization ◽  
Type Iii ◽  
Petroleum Generation

Abstract Triassic to mid-Jurassic core samples of the Mandawa basin, southern Tanzania (western coast of the Indian Ocean), were geochemically analyzed in order to constrain source rock potentials and petroleum generation prospects of different stratigraphic formations within the coastal basin complex. The samples were collected from the Mihambia, Mbuo and Nondwa Formations in the basin. Geochemical characterization of source rocks intersected in exploration wells drilled between 503 to 4042 m below surface yielded highly variable organic matter contents (TOC) rated between fair and very good potential source rocks (0.5 to 8.7 wt%; mean ca. 2.3 wt%). Based on bulk geochemical data obtained in this study, the Mandawa source rocks are mainly Type I, Type II, Type III, mixed Types II/III and Type IV kerogens, with a predominance of Type II, Type III and mixed Type II/III. Based on pyrolysis data (Tmax 417 to 473oC; PI = 0.02 to 0.47; highly variable HI = 13 to 1 000 mg/gTOC; OI = 16 to 225 mg/g; and VR values of between 0.24 to 0.95% Ro) we suggest that the Triassic Mbuo Formation and possibly the mid-Jurassic Mihambia Formation have a higher potential for hydrocarbon generation than the Nondwa Formation as they are relatively thermally mature.

scholarly journals Characterization of the Heavy Mineral Suite in a Holocene Beach Placer, Barrytown, New Zealand

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 86
Author(s):  
Hannah C. Wells ◽  
Richard G. Haverkamp
Keyword(s):  
New Zealand ◽  
Heavy Minerals ◽  
Sem Images ◽  
Density Fractions ◽  
Icp Ms ◽  
Wide Range ◽  
Ore Minerals ◽  
Grain Size Distributions ◽  
Elemental Associations

The placer deposit at Barrytown, New Zealand, has been worked for gold and is known for high levels of ilmenite that has not been exploited. Other heavy minerals are present but have not been well characterized, which is the purpose of this research. Sand grains were separated into the density fractions and the heavier fractions analyzed by laser ablation ICP-MS for elemental composition and by scanning electron microscopy (SEM) EDS in whole grains and polished sections. Grain size distributions were determined from SEM images of polished grain mounts. Elemental associations have been identified with different minerals. A wide range of ore minerals, or potential useful industrial minerals, have been shown to be present largely as individual sand grains. These include gold, ilmenite, garnet, zircon, monazite, allanite, uraninite, thorite, cassiterite, wolframite, scheelite, and columbite. The ilmenite contains many inclusions, consisting of silicates and phosphates and 100–400 ppm Nb. Scandium is found to be present in zircon at 100–600 ppm along with 3000 ppm Y. Monazite is depleted in Eu relative to chondrite and contains Ga and Ge at 1000–3000 ppm. Because the sand grains are mostly individual minerals, it is suggested that separation may be possible using a combination of density, electrostatic and magnetic methods to obtain almost pure mineral fractions. This knowledge should inform decisions on potential exploitation of the resource.

Parental Magma Characterization of Salitre Cumulate Rocks (Alto Paranaíba Alkaline Province, Brazil) as Inferred from Mineralogical, Petrographic, and Geochemical Data

1997 ◽  
Vol 39 (8) ◽  
pp. 723-743 ◽  
Author(s):  
L. Morbidelli ◽  
C. B. Gomes ◽  
L. Beccaluva ◽  
P. Brotzu ◽  
C. Garbarino ◽  
...  
Keyword(s):  
Parental Magma ◽  
Geochemical Data
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