Bragin, Ivan V., Chelnokov, Georgy A., Lavrushin, Vasily Yu.
et al.
We present the results of a comprehensive study of high PCO2 mineral waters of Primorsky Krai, aimed
at identifying their genesis and conditions of formation. For the first time, a joint analysis of the chemical and micro
component composition of water, the gas phase (CO2, N2, CH4, H2, He, and Ar), and stable isotopes of oxygen
and hydrogen (δ18O, δ2H) was carried out for a number of poorly studied springs, gained either during this study
or previously by our group. Three genetic groups of waters were identified based on hydrogeochemical data: 1)
Ca-HCO3 type waters (Bolshoy Klyuch and Fabrichny springs) formed in terrigenous strata; 2) deep silicate-type
waters (Pokrovsky and Glukhovka springs) associated with interaction with crystalline basement rocks and
enriched with lithium, rubidium, and barium; 3) acidic waters of the sulfide oxidation zone (Nerobinsky spring),
which are indicators of ore mineralization; 4) mixed-type waters showing the features of the three types described
above. Gas-geochemical studies confirmed the predominance of CO2 of mantle genesis ( >96.9 vol.%) and the
redox environment. Unique anomalies were identified, such as a high methane content (up to 2.26 vol.%) in the
Pokrovsky spring, indicating possible thermogenic processes. The isotopic composition of the waters (δ18O from –14.71 to –8.70 ‰, δ2H from –103.79 to –60.28 ‰) clearly indicates their meteoric origin from cold climate
precipitation, while the shift relative to the global meteor line indicates intensive isotope exchange in the water
rock–gas system. The results of the study are of fundamental importance for understanding the fluid dynamics of
the Sikhote-Alin subsurface and can be applied for expanding the mineral resource base, developing balneology,
and conducting geological prospecting in the Primorsky region.
The Dongshang Uranium Deposit is situated in the southern section of the Ganfang Pluton in the Jiuling Orogenic Belt of northwestern Jiangxi Province. The U-bearing granites consist mainly of medium- to coarse-grained, porphyritic biotite(binary) granite. Through zircon and monazite U-Pb geochronology, petrology, and rock geochemistry studies, the U-bearing granites' age, source characteristics, and rock genesis were determined, and their uranium metallogenic potential was also discussed. The LA-ICP-MS analysis showed that the zircon U-Pb intercept and weighted average ages are both 152±1 Ma, and the monazite U-Pb intercept and weighted average ages are 151±1 Ma and 151±2 Ma, respectively, indicating the formation of the U-bearing granites during the early Yanshan period. The major elements exhibit the characteristic of high silica content (SiO2 ranging from 72.1% to 75.6%), high alkalis content (K2O+Na2O ranging from 7.26% to 8.43%), potassium-rich and sodium-poor (K2O/Na2O=1.07 to 1.42), high aluminum (A/CNK=1.12 to 1.29), low titanium content (TiO2 ranging from 0.07% to 0.17%), and iron-poor magnesium (FeOT ranging from 0.75% to 1.28%, MgO ranging from 0.19% to 0.31%), classifying the U-bearing granites as high potassium calcalkaline peraluminous granites. Trace elements Ba, Sr, Nb, and Ti are depleted, while Rb, U, Pb, and Ta are enriched, representing a typical low Ba, Sr granite. The total rare earth elements (ΣREE) are relatively low (∑REE=21.6×10−6 to 50.7×10−6), exhibiting a right-dipping light rare earth enrichment pattern with a prominent negative Eu anomaly, which belongs to S-type granites. Based on geochronology and rock geochemical features, it's suggested that the Dongshang U-bearing granites were formed during the syn-collision compressional setting, resulting from the partial melting of the muscovite-rich metapelites of the Anlelin Formation in the Neoproterozoic Shuangqiaoshan Group. High uranium content, high Rb/Sr ratios, Th/U ratios less than 3, and high zircon uranium contents indicate the potential for uranium ore-forming conditions within these granites.
Abstract There are many nanoscale pores in deep low permeability coal seams. The flow of coalbed methane (gas) in nanoscale pores belongs to the gas flow in porous media with medium and high Knudsen numbers. Its flow mechanism is one of the key unsolved scientific problems. In order to explore the gas transport law in nanopores of coal, a gas transport model based on microscopic boundary restriction was adopted to describe the gas flow law, and its rationality was verified by experimental data. The Field Emission Scanning Electron Microscope was used to scan the nanopores of customized anodized aluminum membrane. Then, the Maximally Stable Extremal Regions (MSER) algorithm of MATLAB and binarization algorithm were employed to quantify the pore structure parameters (equivalent pore size and porosity) of the membrane nanoscale pores. Finally, PMI micro-flow permeability tester was used to carry out different rarefied degree gas penetration experiments through anodized aluminum membranes, and the adopted gas transport model was verified. The results show that the binarization method is more accurate to characterize sample whose theoretical pore sizes are 20–35 nm, while MSER characterizes samples whose theoretical pore sizes are 110–150 nm and 200–300 nm more accurately. In other words, binarization method is more accurate for characterizing mesopores, while MSER algorithm is more accurate for macropores. The results have important reference value for more accurate extraction of nanopore parameters of porous media. Compared with traditional gas transport model, the adopted model considering the microscopic boundary restriction in this paper is closer to the experimental results. Moreover, it is suitable for describing the gas flow law in multiscale nanopores. The study provided important guiding significance for ascertaining the gas migration law in low permeability coal seam, improving the prediction accuracy of gas extraction and taking effective measures to increase production. The research results can further enrich the theoretical system of gas transport in coal, which is conducive to the efficient gas extraction, and is of great significance to promote the realization of carbon peak and carbon neutrality.
Olivier Bernard, Olivier Bernard, Olivier Bernard
et al.
Unlike their silicic counterparts, mafic eruptions are known for being on the low-end of the explosivity spectrum with eruption styles commonly ranging from effusive to Hawaiian fire fountaining. However, there are increasing discoveries of large mafic Plinian eruptions, sometimes generating ignimbrites, suggesting that this phenomenon might not be so uncommon. So, what processes lead a mafic magma to fragment violently enough to generate extensive ignimbrites?We sampled pumices from ignimbrites and PDCs with a compositional range from basaltic-andesite (Curacautín ignimbrite, Volcàn Llaima, Chile), andesite (Marapi, Indonesia) to trachyte (Gunungkawi ignimbrite, Batur, Indonesia). We use SEM imagery and X-ray Microtomography on pyroclasts from these deposits to characterize phenocryst, microlite and vesicle textures. From vesicle number densities we estimate fragmentation decompression rates in the range of 0.4–1.6 MPa/s for the three deposits. With a combination of EPMA and SIMS analyses we characterise pre-eruptive storage conditions. Based on the bulk and groundmass compositions, the storage temperature (1,050–1,100°C), pressure (50–100 MPa) and phenocryst content (1.0–2.5 vol%), we conclude that the basaltic-andesitic Curacautín magma was at sub-liquidus conditions, which allowed fast and widespread disequilibrium matrix crystallization (0–80 vol%) during ascent to the surface. Combined with the important decompression rate, this intense crystallization led to a magma bulk viscosity jump from 103 up to >107 Pa s and allowed it to fragment brittlely. Conversely, for the Marapi PDC and Gunungkawi ignimbrite, similar decompression rates coupled with larger initial bulk viscosities of 105–106 Pa s were sufficient to fragment the magma brittlely. The fragmentation processes for these latter two deposits were slightly different however, with the Marapi PDC fragmentation being mostly driven by vesicle overpressure, while a combination of bubble overpressure and intense strain-rate were the cause of fragmentation for the Gunungkawi ignimbrite. We conclude that mafic ignimbrites can form due to a combination of peculiar storage conditions that lead to strongly non-linear feedback processes in the conduit, particularly intense microlite crystallization on very short timescales coupled with intense decompression rates. Conversely, the high viscosity determined by pre-eruptive storage conditions, including temperature and volatile-content, are key in controlling the formation of more evolved magmas PDCs'.
Abadullah Toulabi Nejad, Ahmad Ahamadi Khalaji, Mohammad Ebrahimi
et al.
The Malek Chah Rouii granitoid pluton is exposed within the Deh-Salm metamorphic complex in the eastern margin of the Lut zone. The studied granitoid with peraluminous and calc-alkaline nature is composed of tonalite, granodiorite, and granite (monzo- and syenogranite). The predominant minerals are quartz, plagioclase, microcline, orthoclase, biotite, and muscovite with granular, myrmekite to poikiliitic textures. The similar trends of trace and REE on geochemical diagrams normalized to primary mantle and chondrite could be indicative of the common origin of the rocks under study. Furthermore, they are enriched in Rb, Th, U, K, Pb, Nd, La, Sm, Hf, Ce, and Pr and depleted in Nb, Sr, P, Ti, and Zr. These characteristics are the common features of the magmas formed in active continental subduction zones affected by continental crust. This pluton is a post-collision type originated in a normal to mature continental arc from a protolith with a poor clay metagreywacke composition involving biotite dehydration. The Al2O3+FeOt+MgO+TiO2vs. Al2O3/(FeOt+MgO+TiO2), SiO2 vs. p < sub>2O5, and. Zr as well as the Qtz-Ab-Or ternary diagram show that the Malek Chah Rouii granitoid formed at ≥5 kbarwater vapor pressure and an average temperature of 775℃. Key words:S-type granitoid, post-collision, source, Nehbandan, Lut Block
Abstract U-Th-Pb petrochronology is based on the incontrovertible fact that the diffusion of radiogenic Pb is negligibly small relative to retrograde reaction rates. Multi-element maps demonstrate that patchy textures tightly correspond to (U + Th)-Pb age variations, requiring that fluid-induced dissolution/ reprecipitation is the principal cause of Pb mobility. Attempts to model intracrystalline core-rim Pb zonations as diffusive transport are not legitimate unless genuine bell-shaped diffusion profiles in minerals can be documented, which happens only exceptionally. Monazite and zircon intra-grain age maps confirm that coupled dissolution-reprecipitation and retrogression reactions assisted by fluids control (Th + U)-Pb ages, not temperature. The chemical zonations observed in many (Th + U)-bearing mineral chronometers (e.g. monazite, allanite, xenotime, zircon) provide petrological constraints. Linking petrology with textures and the isotope record allows reconstructing entire segments of the P-T-A-X-D-t history of a rock and its geodynamic environment. The dearth of mathematically sound diffusion profiles equally applies to the isotope records of micas and feldspars. The tight link between petrology, microtextures, chemical composition and geochronology also pertains to Rb-Sr and K-Ar. Overdetermined multi-mineral Rb-Sr isochrons with excess scatter, and spatially resolved/stepwise release 39Ar-40Ar results, demonstrate ubiquitous correspondence between relict phases and isotopic inheritance. Many rock-forming minerals are highly retentive of Sr and Ar, unless they are obliterated by retrograde reactions. The rates of dissolution in fluid-controlled reactions are several orders of magnitude faster at upper and mid-crustal levels than diffusive reequilibration rates. Thus, as a rule Rb-Sr and K-Ar chronometers date their own formation. Accurately establishing P-T paths of monometamorphic rocks requires assessing petrologic equilibrium using multivariate thermodynamic software. Dating complex parageneses of polymetamorphic, unequilibrated rocks requires labor-intensive disentangling by: (i) qualitative identification of relicts, retrogression reactions, and chemically open systems by imaging techniques (e.g. cathodoluminescence, element maps, etc.); (ii) microchemical analyses at the μm-scale quantifying heterochemical disequilibrium phases and assigning them to a P-T-A-X segment; (iii) spatially resolved/stepwise release, relating the chemical signature of the analyzed mineral to its age. K-Ar and Rb-Sr usually provide a different perspective on the P-T evolution of a rock than does (Th + U)-Pb, as K + Rb-rich minerals (phyllosilicates and especially feldspars) mostly form later and react/dissolve faster in the retrograde path than U-rich accessory phases. The present paper reviews these general principles by means of well-understood examples, both successful and unsuccessful in matching the independently known external constraints.
Abstract Estimation of fluid and rock properties of a hydrocarbon reservoir is always a challenging matter; especially, it is true for heterogeneous carbonate reservoirs. Petrophysical logs and laboratory activities are common methods for characterizing a hydrocarbon reservoir. This method in conjunction with geostatistical methods is applied to relatively homogeneous sandstone reservoirs or matrix media of dual-porosity heterogeneous carbonate reservoirs. To estimate properties of fracture system of a dual-media carbonate reservoir, outcrop properties, electrical borehole scans, fractal discrete fracture network and analogy with other reservoirs are common methods. Results which obtained from these methods describe the reservoir in a static way and could be relied on them for very small portion of the reservoir. In this paper, a dynamic procedure for describing reservoir features is proposed in order to enhance the conventional reservoir characterization methods. This method utilizes the reported production data for a specific period of time in conjunction with rock and fluid properties to estimate drainage radius of the well and matrix block height, porosity and width of fracture in the estimated drainage radius. The presented method is elaborated through its application in a real case. By this method, one can generate maps of matrix block size and fracture width and porosity throughout the reservoir. Also, it could be a powerful tool for estimation of effectiveness of acid/hydraulic fracturing activity.
Formation of the first continents belongs to fundamental questions regarding the evolution of the Earth. Though the growth of early crust is often debated, role of the mantle lithosphere that represents the biggest volume of continents is often overlooked, particularly in geologic interpretations of tectonic processes. This is mainly due to difficulties in its imaging and uncertainty in its rheology. Investigation of seismic anisotropy from propagation of teleseismic P and S waves in three dimensions (3D), i.e., with no limitation imposed on the symmetry axis orientation into the horizontal or vertical directions, provides a unique constraint on tectonic fabrics and character of past and present-day deformations of the continental lithosphere. In this paper, we collect independent findings from seismology, petrology and geochemistry to support our 3D anisotropic model of mantle lithosphere with tilted symmetry axes, derived from data of passive seismic experiments organised in tectonically different domains of Archean, Proterozoic and Phanerozoic provinces of Europe.Olivine preferred orientation, formed by mantle convection in the oceanic mantle lithosphere due to its spreading on both sides of the mid-ocean ridges, is a prerequisite for the tilted anisotropies that we model in the continents. We have explained the systematically oriented dipping fabrics in the continental mantle lithosphere by successive subductions of ancient oceanic plates and their accretions enlarging primordial continent cores. Consequent continental break-ups and assemblages of wandering micro-plates preserve “frozen” anisotropic fabrics and create patchwork structures of the present-day continents. Supporting arguments for such model arise from petrological and geochemical studies indicating that continental mantle peridotites formed in oceanic environments and became “continental” after significant thickening or underthrusting. Combining seismological, petrologic and geochemical findings can help to bridge the gulf between the different viewpoints and evoke further discussions on possible growth mechanisms of the continental lithosphere. Keywords: Continental growth, Mantle lithosphere, Seismic anisotropy, Subduction cycles, Dipping olivine fabrics, Relict oceanic subductions
A set of organic-rich black rocks (23.8 m), mainly consisting of siliceous rocks, shale and limestones, outcrops between carbonate rocks of the Maokou and Wujiaping formations in the Xibeixiang section, northwestern Sichuan Basin, at the margin of the Upper Yangtze Platform. Detailed conodont stratigraphy, organic petrology and organic geochemistry studies were performed on samples from the Xibeixiang section. The conodonts found in the study area were Jinogondolella prexuanhanensis, J. xuanhanensis and Clarkina posbitteri hongshuiensis. All of them lived at the end of Guadalupian, confirming that the black rocks in the section were deposited during the late period of the Maokou Formation indicating that the Guangyuan-Wangchang Marine Trough began to develop in the late Guadalupian stage on the Upper Yangtze Platform. The detailed study of organic petrology reveals that benthic algae is the main contributor for hydrocarbon in the black rock series, with a small amount of macroplanktonic algae, and the organic matter is type Ⅱ. The organic geochemical analyses of the black rocks show that the TOC content ranges 1.04% to 32.58% and the chloroform bitumen "A" content ranges 0.03% to 1.05%, indicating favorable source rocks. Thermal parameters, such as the vitrinite reflectance (Ro) value ranges 1.0% to 1.4%, the Tmax value ranges 440 to 460℃, the conodont color index (CAI) ranges 1.5 to 2.5, the Ts/Tm ratio ranges 0.35 to 1.43, the moretane/hopane ratio ranges 0.05 to 0.39, the C2920S/(20S+20R) ranges 0.39 to 0.65, and the C29αββ/(αββ+ααα) ranges 0.26 to 0.58, which indicate that these black rocks are mature to highly mature. The integrated study of lithology, hydrocarbon-forming organisms, conodonts and biomarkers indicate that these black rocks were deposited in a relatively reductive deep-water environment with a high salinity.
Júlia Farré-de-Pablo, J. Proenza, J. González-Jiménez
et al.
Department of Mineralogy, Petrology and Applied Geology, University of Barcelona, Marti i Franques s/n, 08028 Barcelona, Spain 2 Department of Mineralogy and Petrology, Faculty of Sciences, University of Granada, Avenida Fuentenueva s/n, 18002 Granada, Spain 3 Andalusian Earth Science Institute (IACT), Spanish Research Council (CSIC)–University of Granada, Avenida de las Palmeras, 4, 18100 Armilla, Granada, Spain 4 Institute of Geology, National Autonomous University of Mexico, Ciudad Universitaria, 04510 Coyoacan, CDMX, Mexico
Abstract Carbonated water injection (CWI) might be an efficient alternate to CO2 injection technique. In CWI, CO2 exists as a dissolved phase and not as a free phase; thus, it eliminates some challenges encountered in CO2 injection such as poor sweep efficiency and gravity segregation. In CWI, the density and viscosity of water become higher than normal due to the CO2 dissolution, thereby reducing the gravity segregation and channeling effect. This article is a comprehensive review on how carbonated water flooding has evolved over the time and captured salient features on the mechanisms involved in its role in enhanced oil recovery. The aspects reviewed in this article include a brief comparison of conventional CO2 injection and carbonated water injection and the benefits thereof. Solubility of CO2 in water, brine and oil phases is discussed in detail with valid correlations. A brief history of the development of CWI in the laboratory and field information is captured from 1905s to the present followed by the possible mechanisms and principle of CWI reported by various authors. This article also captured the latest findings on the beneficial effect of hybridizing CWI with smart water technologies.
Reza Monazzami Bagherzadeh, Mohammad Hassan Karimpour, G. Lang Farmer
et al.
Introduction
The study area is located in the northeast of Iran (the Khorasan Razavi province) and 28 km northwest of Bardaskan city and in position of 57˚ 46΄ to 57˚ 52΄ latitude and 35˚ 21΄ to 35˚ 24΄ longitude. The study area is a part of Taknar zone. The Taknar geological-structural zone is situated in the north Central Iranian microcontinental and it is a part of Lut block (Fig.1). Taknar plutonic complex that is situated in the Taknar structural zone is located in the northern part of Iranian microcontinent.
Materials and methods
Chemical analysis of REE and minor elements of samples of the Bornaward diorites and gabbro’s took place in the ACME Lab. in Vancouver, Canada, by the ICP-MS method (Table. 1). For the Bornaward diorite dating by the U-Pb method, zircon grains of material remaining in the sieve, Bromoform were isolated from light minerals by cleaning and were isolated with a minimum size of 25 microns, and then studies took place in the Crohn's Laser Lab Arizona (Gehrels et al., 2008). Measurement of Rb, Sr, Sm and Nd isotopes and (143Nd/144Nd)i , (87Sr/86Sr)i ratios and ƐNd (T=552), ƐNd (T=0), ƐSr (T=552) and ƐSr (T=0) took place in radioisotope Laboratory, University of Aveiro in Portugal.
Discussion
Geology of study area
The study area forms the central part of the Bornaward plutonic complex. This complex is a granitoid assemblage including granite, granodiorite, tonalite and granophyre.tscentral part has been formed by intermediate and basic intrusive rocks such as diorite, quartz diorite and gabbro units (Fig. 2). From the genetic point of view, the intermediate and mafic rocks of the Taknar plutonic complex does not have any relationship with granitoid rocks of this assemblage, and they are related to a similar magmatic phase but are separated from this granitoid assemblage. However, these mafic and intermediate units are older than granitic units at the rim of the complex that are called Bornaward granite.
Petrography
The main minerals in the diorite and quartz diorite rocks are plagioclase and hornblende and we can see biotite in the quartz dioritic rocks. Quartz exist as tiny grains and anhedral and in the matrix rock. The amount of Quartz in the quartz diorites is 5 to 20%. Plagioclases usually have normal zoning and are highly altered to sericite. Most of the plagioclases were saussuritized. Altered minerals resulted from plagioclase and hornblende are sericite, epidote, chlorite, zoisite and clinozoisite.
The main minerals in the gabbro are pyroxene, hornblende, and fine grains plagioclase. Minor minerals in the rocks are apatite, magnetite and other opaque.
The main texture of intermediate and mafic rocks in this assemblage is medium granular to coarse grain and especially in the intermediate rocks and gabbro rocks, we can see scattered poikilitic, intersertal, sub-ophitic and porphyroid texture.
Geochemistry
The area diorite and gabbro is located locate in Tholeiitic and Calc-alkaline series (Fig. 9). Shand index (Al2O3/(CaO+Na2O+K2O)) is obtained under 1.1, in Metaluminous field (Fig. 7) and I-type granite field (Chappell and White, 2001). Based on the TAS diagram (Middlemost, 1985), all the diorite and gabbro samples are located in diorite, gabbro-diorite and gabbro-norite groups (Fig. 6). The diorite and gabbro’s show enrichment LREE and low ascending pattern ((La/Yb)N =1.40-6.12 and LaN =12.26-75.81).
U-Pb zircon geochronology
Measurement of U-Th-Pb isotopes of the Bornaward diorite zircons of BKCh-03 sample (Table 2) show that its age is related to 551.96±4.32 Ma ago (Upper Precambrian (Neoproterozoic) (Ediacaran) (Fig. 14).
Sr-Nd isotopes
The (87Sr/86Sr)i and (143Nd/144Nd)i content of Bornaward diorite and gabbro rocks is located in the range of 0.7038 to 0.7135 and 0.51203 to 0.51214, respectively (Tables 3 and 4). It shows that the diorite and gabbro rocks can be affected by hydrothermal alteration because their (87Sr/86Sr)i is above (Fig. 16). The numeral amounts of ƐNd(T=552) of Bornaward diorite and gabbro are 2.0 to 4.0.
Petrogenesis
The Bornaward diorite and gabbro rocks show a widespread enriched pattern of Rb, U, K, Pb, La and Th elements than chondrite, while Ba, Ti, Ta, Sr and Nb elements show reduction as a result of fractional crystallization (Fig. 11). The rocks of this complex are formed at the continental margin and VAG environment (Fig. 18) which is related to the subduction of the oceanic crust that exists between the Iranian microcontinent and the Afghan Block.
Results
This assemblage with age of Late Neoproterozoic is the result of extensive magmatism in the northern part of the Iranian microcontinent due to Katangahi orogeny event. The similar magmatism in the northern part of the Iranian microcontinent is existing as Khaf-Kashmar-Bardeskan volcano-plutonic belt.
Based on the geochemical investigations, the magmatism of these rocks has been tholeiitic and calk-alkaline and have formed the coexistent rocks with I-type granites. Alumina saturation index for intermediate and mafic rocks of Bornaward complex is metalumina. These are medium-K rocks and enriched in the LILE such as Rb, Pb, U and Th while depleted of the Nb, Ti, Ta, Sr and Ba. Therefore, it shows that these rocks have resulted from the mixing by the lower crust.
The low (87Sr/86Sr)i Bornaward diorite and gabbro rocks and the numeral amounts of Ɛ0Nd(present) of these rocks from -0.2 to 4.0 show that production of such intrusive masses can be attributed to the source of upper mantle or contaminated lower continental crust. Environment of formation of the intermediate and basic rocks of the Bornaward plutonic complex is active continental margin and
volcanic arc environment.
References
Chappell, B.W. and White, A.J.R., 2001. Two contrasting granite types: 25 years later. Australian Journal of Earth Sciences, 48(4): 489–499.
Gehrels, G.E., Valencia, V.A. and Ruiz, J., 2008. Enhanced precision, accuracy, efficiency, and spatial resolution of U–Pb ages by laser ablation– multicollector– inductively coupled plasma-mass spectrometry. Geochemistry, Geophysics, Geosystems, 9(3): 1–13.
Middlemost, E.A.K., 1985. Magmas and Magmatic Rocks. An Introduction to Igneous Petrology. Longman, London, New York, 266 pp.
Machine-learning methods are evaluated to study the intriguing and debated topic of discrimination among different tectonic environments using geochemical and isotopic data. Volcanic rocks characterized by a whole geochemical signature of major elements (SiO2, TiO2, Al2O3, Fe2O3T, CaO, MgO, Na2O, K2O), selected trace elements (Sr, Ba, Rb, Zr, Nb, La, Ce, Nd, Hf, Sm, Gd, Y, Yb, Lu, Ta, Th) and isotopes (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 87Sr/86Sr and 143Nd/144Nd) have been extracted from open-access and comprehensive petrological databases (i.e., PetDB and GEOROC). The obtained dataset has been analyzed using support vector machines, a set of supervised machine-learning methods, which are considered particularly powerful in classification problems. Results from the application of the machine-learning methods show that the combined use of major, trace elements and isotopes allows associating the geochemical composition of rocks to the relative tectonic setting with high classification scores (93 %, on average). The lowest scores are recorded from volcanic rocks deriving from back-arc basins (65 %). All the other tectonic settings display higher classification scores, with oceanic islands reaching values up to 99 %. Results of this study could have a significant impact in other petrological studies potentially opening new perspectives for petrologists and geochemists. Other examples of applications include the development of more robust geothermometers and geobarometers and the recognition of volcanic sources for tephra layers in tephro-chronological studies.
The data presented in this article are related to research to the research article entitled ‘Petrology and Geochemistry Data of the Precambrian granitoids from the Hyderabad part of Eastern Dharwar Craton, Telangana state, India’. The granitoids from the Hyderabad area of the Telangana State are confined to the Precambrian gneissic complex of the northern-eastern part of Eastern Dharwar Craton. They cover 7760 Sq. km of the study area and fall between latitudes 16° 52′–17°42′ N and between East longitudes 77° 21′–77° 51′ E. The granitoids are mainly classified into grey and pink granites, granodiorites and aplites. The field studies are understood they occasionally contain older mafic enclaves in the form of lensoid bodies and thin bands and cut by younger dolerite dykes, pegmatite and quartz veins and laboratory investigations resolved the classification of the granitods and their chemical histories. Keywords: Precambrian gneisses, Granitoids, Mafic enclave, Dolerite dykes and chemical histories
Computer applications to medicine. Medical informatics, Science (General)