scholarly journals Origin of S-, A- and I-Type Granites: Petrogenetic Evidence from Whole Rock Th/U Ratio Variations

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 672
Author(s):  
Anette Regelous ◽  
Lars Scharfenberg ◽  
Helga De Wall
Keyword(s):  
Bohemian Massif ◽  
Large Scale ◽  
Classification Scheme ◽  
Gamma Ray ◽  
Tectonic Setting ◽  
Source Rocks ◽  
Classification Schemes ◽  
Origin And Evolution ◽  
Gamma Ray Spectrometer ◽  
Tectonic Settings

The origin and evolution of granites remain a matter of debate and several approaches have been made to distinguish between different granite types. Overall, granite classification schemes based on element concentrations and ratios, tectonic settings or the source rocks (I-, A-, S-type) are widely used, but so far, no systematic large-scale study on Th/U ratio variations in granites based on their source or tectonic setting has been carried out, even though these elements show very similar behavior during melting and subsequent processes. We therefore present a compiled study, demonstrating an easy approach to differentiate between S-, A- and I-type granites using Th and U concentrations and ratios measured with a portable gamma ray spectrometer. Th and U concentrations from 472 measurements in S- and I-type granites from the Variscan West-Bohemian Massif, Germany, and 78 measurements from Neoproterozoic A-type Malani granites, India, are evaluated. Our compendium shows significant differences in the average Th/U ratios of A-, I- and S-type granites and thus gives information about the source rock and can be used as an easy classification scheme. Considering all data from the studied A-, I- and S-type granites, Th/U ratios increase with rising Th concentrations. A-type granites have the highest Th/U ratios and high Th concentrations, followed by I-type granites. Th/U ratios in S- to I-type granites are lower than in A-type and I-type granites, but higher than in S-type granites. The variation of Th/U ratios in all three types of granite cannot be explained by fractional crystallization of monazite, zircon and other Th and U bearing minerals alone, but are mainly due to source heterogeneities and uranium mobilization processes.

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

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.

scholarly journals 3-D Seismic Structural Interpretation of High Field Offshore Western Niger Delta

2021 ◽  
Vol 25 (8) ◽  
pp. 1361-1369
Author(s):  
S.S. Adebayo ◽  
E.O. Agbalagba ◽  
A.I. Korode ◽  
T.S. Fagbemigun ◽  
O.E. Oyanameh ◽  
...  
Keyword(s):  
Niger Delta ◽  
High Field ◽  
Gamma Ray ◽  
Tectonic Setting ◽  
Source Rocks ◽  
Structural Interpretation ◽  
Resistivity Logs ◽  
Seismic Sections ◽  
Niger Delta Basin ◽  
Structural Closure

Seismic Structural interpretation of subsurface system is a vital tool in mapping source rocks and good trapping system which enhances good understanding of the subsurface system for productive drilling operation. This study is geared towards mapping the structural traps available within the hydrocarbon bearing zones of the “High field” with the use of well log and 3D seismic data. Seven horizons (H1, H2, H3, H4, H5, H6 and H7) were identified on well logs using gamma ray log and resistivity logs. Nine (9) faults were mapped on seismic sections across the field, two (2) of which are major growth faults (F1 and F2), two (2) synthetic faults (F3 and F7) and five (5) antithetic faults (F4, F5, F6, F8 and F9). Rollover anticlines which are structural closure and displayed on the depth structural maps suggest probable hydrocarbon accumulation at the down throw side of the fault F1. Structural interpretation of high field has revealed a highly fault assisted reservoir which depicts the tectonic setting of Niger Delta basin.

the TASTE mission: In situ DEIMOS terrain analyzer with smalls and miniturized lander

2021 ◽  
Author(s):  
Michelle Lavagna ◽  
John Brucato ◽  
Jacopo Prinetto ◽  
Andrea Capannolo ◽  
Michele Bechini ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Surface Composition ◽  
Landing Site ◽  
Organic Content ◽  
Elemental Abundance ◽  
Origin And Evolution ◽  
Gamma Ray Spectrometer ◽  
Close Orbit ◽  
Science Operations

<p>Deimos and Phobos are considered primary targets of investigation to understand the origin and evolution of Mars and more in general the terrestrial planets of the Solar System. </p> <p>TASTE mission aims complementing MMX investigation by focusing on Deimos surface, combining both <strong>global remote sensing</strong> observations from a close orbit and<strong> direct in-situ analyses</strong> of the surface thanks to a lander release on Deimos. With a synergy between orbital and in-situ investigations, the proposed mission will contribute to the Deimos global morphology understanding; its global elemental abundance; landing site morphology and texture; landing site organic content and surface composition. TASTE is conceived as a Cubesat-in-Cubesat mission: a 12U space asset composed by a <strong>9U orbiter </strong>and a<strong> 3U lander</strong>. The former embarks an <strong>X-gamma ray spectrometer</strong> developed by OAT and a multispectral camera, the second is equipped with a  <strong>miniaturized Surface Sample Analyser</strong> (SSA), composed by a new Sample Acquisition Mechanism (SAM), conceived by PoliMi and a Surface Analytical Laboratory (SAL)  developed by INAF OAA. <br />The mission is conceived to keep the orbiter on a QSO nearby Deimos to facilitate the lander release and the scientific operations in synergy with the lander itself. Details on science, space assets sizing and design and mission science operations will be discussed in deep. </p>

Petrology and Geochemistry of Mercury

2018 ◽  
Author(s):  
Shoshana Z. Weider
Keyword(s):  
Large Scale ◽  
Gamma Ray ◽  
Bulk Composition ◽  
Planetary Science ◽  
Iron Core ◽  
Forthcoming Article ◽  
Neutron Spectrometer ◽  
Gamma Ray Spectrometer ◽  
High Concentrations ◽  
Surface Mineralogy

This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Planetary Science. Please check back later for the full article. Although having knowledge of a terrestrial planet’s chemistry is fundamental to understanding the origin and composition of its rocks, until recently, the geochemistry of Mercury—the Solar System’s innermost planet—was largely unconstrained. Without the availability of geological specimens from Mercury, studying the planet’s surface and bulk composition relies on remote sensing techniques. Moreover, Mercury’s proximity to the Sun makes it difficult to study with Earth/space-based telescopes, or with planetary probes. Indeed, to date, only NASA’s Mariner 10 and MESSENGER missions have been sent to Mercury. The former made three “flyby” encounters of Mercury between 1974 and 1975, but did not carry any instrument to make geochemical or mineralogical measurements of the surface. Until the MESSENGER flyby and orbital campaigns (2008–2015), therefore, knowledge of Mercury’s chemical composition was severely limited and consisted of only a few facts. For example, it has long been known that Mercury has the highest uncompressed density of all the terrestrial planets (and thus a disproportionately large iron core). In addition, Earth-based spectral reflectance observations indicated a dark surface, largely devoid of iron within silicate minerals. To improve understanding of Mercury’s geochemistry, the MESSENGER payload included a suite of geochemical sensing instruments: namely the X-Ray Spectrometer, Gamma-Ray Spectrometer, and Neutron Spectrometer. Indeed, the datasets obtained from these instruments (as well as from other complementary instruments) during MESSENGER’s 3.5-year orbital mission allow a much more complete picture of Mercury’s geochemistry to be drawn, and quantitative abundance estimates for several major rock-forming elements in Mercury’s crust are now available. Overall, the MESSENGER data reveal a surface that is rich in Mg, but poor in Al and Ca, compared with typical terrestrial and lunar crustal materials. Mercury’s surface also contains high concentrations of the volatile elements Na, S, K, and Cl. Furthermore, the total surface Fe abundance is now known to be <2 wt%, and the planet’s low reflectance is thought to be primarily caused by the presence of C (in graphite) at a level of >1 wt%. Such data are key to constraining models for Mercury’s formation and early evolution. Large-scale spatial variations in the MESSENGER geochemical datasets have also led to the designation of several geochemical “terrains” across Mercury’s surface, which do not always align to otherwise mapped geological regions. Based on the MESSENGER geochemical results, several recent petrological experiments and calculations have been, and continue to be, performed to study Mercury’s surface mineralogy. The results show that there are substantial differences in the precise mineral compositions and abundances among the different terrains, but Mercury’s surface appears to be dominated by Mg-rich olivines and pyroxenes, as well as plagioclase and sulphide phases. Depending on the classification scheme used, Mercury’s ultramafic surface rocks can thus be described as similar in nature to terrestrial boninites, andesites, norites, or gabbros.

Granites and rhyolites from the northwestern U.S.A.: temporal variation in magmatic processes and relations to tectonic setting

1992 ◽  
Vol 83 (1-2) ◽  
pp. 71-81 ◽  
Author(s):  
Marc D. Norman ◽  
William P. Leeman ◽  
Stanley A. Mertzman
Keyword(s):  
Temporal Variation ◽  
Late Cretaceous ◽  
Crustal Structure ◽  
Large Scale ◽  
Tectonic Setting ◽  
Snake River Plain ◽  
Plate Convergence ◽  
Tectonic Settings ◽  
Silicic Magmatism ◽  
River Plain

ABSTRACTCretaceous and Cainozoic granites and rhyolites in the northwestern U.S.A. provide a record of silicic magmatism related to diverse tectonic settings and large-scale variations in crustal structure. The Late Cretaceous Idaho Batholith is a tonalitic to granitic Cordilleran batholith that was produced during plate convergence. Rocks of the batholith tend to be sodic (Na2O > K2O), with fractionated HREE, negligible Eu anomalies, and high Sr contents, suggesting their generation from relatively mafic sources at a depth sufficient to stabilise garnet. In contrast, Neogene rhyolites of the Snake River Plain, which erupted in an extensional environment, are potassic (K2O > Na2O), with unfractionated HREE patterns, negative Eu anomalies, and low Sr contents, suggesting a shallower, more feldspathic source with abundant plagioclase. Eocene age volcanic and plutonic rocks have compositions transi- tional between those of the Cretaceous batholith and the Neogene rhyolites. These data are consistent with a progressively shallowing locus of silicic magma generation as the tectonic regime changed from convergence to extension.

Multi-scale spatial distribution of K, Th and U in an Archaean potassic granite: a case study from the Heerenveen batholith, Barberton Granite-Greenstone Terrain, South Africa

2021 ◽  
Author(s):  
J-F. Moyen ◽  
M. Cuney ◽  
D. Baratoux ◽  
P. Sardini ◽  
S. Carrouée
Keyword(s):  
Large Scale ◽  
Gamma Ray ◽  
Shear Zones ◽  
Small Scale ◽  
Multi Scale ◽  
Gamma Ray Spectrometer ◽  
Rock Types ◽  
Large Scale Integration ◽  
Scale Integration

Abstract We describe the multi-scale distribution of K, Th and U in the ca. 3.1 Ga Heerenveen batholith of the Barberton Granite-Greenstone Terrain. Data were obtained with a combination of tools, including a portable gamma-ray spectrometer from the scale of the whole batholith to the scale of outcrops, and autoradiography for the thin section scale. U is concentrated preferentially in minor phases in the border shear zones of the batholith and, within these shear zones, in late pegmatites as well as fractures. The processes responsible for the concentration of U in the Heerenveen batholith is discussed in terms of magmatism, hydrothermalism (redistribution of U in fissures associated with magmato-hydrothermal fluids), and supergene alteration. The statistical properties of K, Th and U concentrations are different. K shows spatial correlation over large distance, largely mirroring mappable rock types, with increased variability at larger scales. In contrast, U is dominated by small-scale variations (“nugget effect”) and its variability is, averaged and smoothed by large-scale integration. Spatial and statistical features thus offer useful and complementary insights on petrogenetic and metallogenic processes in granitoids in addition to standard approaches (petrography, geochemistry).

scholarly journals Magmatic thickening of crust in non–plate tectonic settings initiated the subaerial rise of Earth’s first continents 3.3 to 3.2 billion years ago

2021 ◽  
Vol 118 (46) ◽  
pp. e2105746118
Author(s):  
Priyadarshi Chowdhury ◽  
Jacob A. Mulder ◽  
Peter A. Cawood ◽  
Surjyendu Bhattacharjee ◽  
Subhajit Roy ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Large Scale ◽  
Tectonic Setting ◽  
Underlying Mechanism ◽  
Magmatic Evolution ◽  
Granitoid Magmatism ◽  
Shallow Marine ◽  
Singhbhum Craton ◽  
Marine Sedimentation ◽  
Tectonic Settings

When and how Earth's earliest continents—the cratons—first emerged above the oceans (i.e., emersion) remain uncertain. Here, we analyze a craton-wide record of Paleo-to-Mesoarchean granitoid magmatism and terrestrial to shallow-marine sedimentation preserved in the Singhbhum Craton (India) and combine the results with isostatic modeling to examine the timing and mechanism of one of the earliest episodes of large-scale continental emersion on Earth. Detrital zircon U-Pb(-Hf) data constrain the timing of terrestrial to shallow-marine sedimentation on the Singhbhum Craton, which resolves the timing of craton-wide emersion. Time-integrated petrogenetic modeling of the granitoids quantifies the progressive changes in the cratonic crustal thickness and composition and the pressure–temperature conditions of granitoid magmatism, which elucidates the underlying mechanism and tectonic setting of emersion. The results show that the entire Singhbhum Craton became subaerial ∼3.3 to 3.2 billion years ago (Ga) due to progressive crustal maturation and thickening driven by voluminous granitoid magmatism within a plateau-like setting. A similar sedimentary–magmatic evolution also accompanied the early (>3 Ga) emersion of other cratons (e.g., Kaapvaal Craton). Therefore, we propose that the emersion of Earth’s earliest continents began during the late Paleoarchean to early Mesoarchean and was driven by the isostatic rise of their magmatically thickened (∼50 km thick), buoyant, silica-rich crust. The inferred plateau-like tectonic settings suggest that subduction collision–driven compressional orogenesis was not essential in driving continental emersion, at least before the Neoarchean. We further surmise that this early emersion of cratons could be responsible for the transient and localized episodes of atmospheric–oceanic oxygenation (O2-whiffs) and glaciation on Archean Earth.

Elemental analysis of medicinal plants from different sites by instrumental neutron activation analysis

2016 ◽  
Vol 5 (03) ◽  
pp. 4892 ◽  
Author(s):  
Ratna Raju M.* ◽  
Madhusudhana Rao P. V. ◽  
Seshi Reddy T. ◽  
Raju M. K. ◽  
Brahmaji Rao J. S. ◽  
...  
Keyword(s):  
Neutron Activation Analysis ◽  
Instrumental Neutron Activation Analysis ◽  
Activation Analysis ◽  
Medicinal Plants ◽  
Neutron Activation ◽  
Gamma Ray ◽  
Elemental Content ◽  
Soil Composition ◽  
Gamma Ray Spectrometer ◽  
Instrumental Neutron Activation

A study was undertaken to evaluate the inorganic elements for humans in two Indian medicinal plants leaves, namely Sphaeranthus indicus, and Cassia fistula by Instrumental Neutron Activation Analysis (INAA). INAA experiment was performed by using 20 kW KAMINI Reactor at Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam. The emitted gamma rays were measured using gamma ray spectrometer. The concentrations of Al, Br, Ca, Fe, K, La, Mg, Mn, Na, Sc, V and Zn were determined in the selected medicinal plants. The medicinal leaves are using in treatment of various important ailments. The elemental content in selected medicinal leaves is various proportions depending on the soil composition, location of plant specimen and the climate in which the plant grows.

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