Petrology

Middle Permian Qixia Formation in the southwestern region of Sichuan (SW China) has experienced multiphase fluidisation, resulting in an unclear understanding of the reservoir reconstruction effect. In this study, a systematic analysis of the Qi2 member in Wulong Town was carried out by combining field outcrop petrology and geochemistry. The results demonstrated that multiple sets of crystalline dolomite-bioclastic limestone cycles were stacked vertically in the Qi2 member, accompanied by the development of fractures and karst channels...

The Chamdo Basin is a secondary basin in the eastern part of Tibet China and is one of the most promising of petroliferous basins for new petroleum exploration. The Qamdo Basin records a complex burial history from the Mesozoic to the Cenozoic; however, the poorly constrained sedimentology of Cenozoic strata in this basin has severely obscured the overall profile and impeded further explorations of oil and gas resources. Here, we conduct whole-rock geochemical analyses of major, trace, and rare earth elements in fine-grained clastic rocks of the Paleocene Gongjue Formation, Qamdo Basin to reveal depositional environments, provenance, and tectonic setting...

To understand variations in geochemistry, organic petrology, and chemical composition of crude oil and byproducts, an immature sample from the Cretaceous Qingshankou Formation in the Songliao Basin, China, was analyzed by anhydrous and hydrous pyrolysis (AHP/HP) at a wide range of temperatures ranging from 300 °C to 450 °C. The geochemical parameters: TOC, S2 , HI, and Tmax obtained from Rock-Eval pyrolysis showed both a decrease and an increase as thermal maturity progressed under HP and AHP conditions...

Tourmaline has two different [6]-coordinated sites, the Y site and the Z site. Vacancies were reported from both sites. Based on high-quality chemical and single-crystal structural data it usually needs increasing proportions of short-range order configurations Na(Al2 □ )Al6 (BO3 )3 [Si6 O18 ]V (OH)3 W (OH) or Na(Al2 □ )Al6 (BO3 )3 [Si6 O18 ]V (OH)3 W F in order to produce Y-site vacancies (with □ being the symbol for a vacant site). Less commonly, the short-range configuration Ca(Al2 □ )Al6 (BO3 )3 [Si5 T3+ O18 ]V (OH)3 W (OH) could occur in Al-rich tourmalines with a Si deficiency, where T3+  = B, Al...

"Multi-method-approach" has now been for many years the buzzword in marble provenance analysis. Nevertheless a true combination of the results of different analytical methods is rarely applied in the sense of the combined simultaneous use of a large number of analytically obtained numerical variables. It is demonstrated here that the combination of data from isotope analysis, chemical data, and data from the chemical analysis of inclusion fluids of an artefact and of course in combination with a corresponding database enhances substantially the accuracy of marble provenance analysis...

The Kesem-Megezez Section is located on the western escarpment of the main Ethiopian rift, central Ethiopia, part of the northwestern Ethiopia plateau, and hosts both flood basalts (Kesem Oligocene basalts) and shield volcano basalts (Megezez Miocene basalts) separated by an Oligo-Miocene silicic pyroclastic formation. Petrography, whole-rock trace, and major element data are presented for the Kesem Oligocene and Megezez Miocene basalts to assess their petrogenetic characteristics and the processes involved in their evolution...

An estimate of the radiogenic heat production (RHP) across the different petrologic units of northeastern, Nigeria was previously not performed. Hence, their geothermal potentials are not widely known. However, an airborne radiometric data of equivalent uranium, (eU), equivalent thorium (eTh,) and percentage potassium (% K) acquired by Nigerian geological survey agency (NGSA) in the year 2009 was deployed in the evaluation of the RHP across the major petrologic outcrops of northeastern, Nigeria. The objective of this study is to estimate the quantity of RHP across the 13 petrologic units of the northeastern Nigerian terrain via the use of an empirical equation (<mml:math xmlns:mml="https://www...

The shale of the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation in the Xichang Basin is the main replacement horizon for the shale gas exploration being conducted in the Sichuan Province, except for the Sichuan Basin. The fine identification and classification of the types of shale facies are important for shale gas exploration and development evaluation. However, the lack of systematic experimental studies on rock physical characteristics and micro-pore structures leads to a lack of physical evidence for the comprehensive prediction of shale sweet spots...

This study presents the first report of plastics in the geological record (rocks and formations composed of plastics) along the central Caribbean Coast of Colombia, northern coast of South America. These novel records of pollution include two rock types (plastiglomerates and quartz plastisandstones), two altered plastic types (pyroplastics and plasticrusts), two soil types (plasticlasts and anthrosols), and a series of artifacts (fossils) found near human settlements. All of them were analyzed using Fourier Transform Infrared (FTIR) spectroscopy...

UNLABELLED: The South-East Crater (SEC) at Mt. Etna started a period of lava fountaining in December 2020, producing over 60 paroxysms until February 2022. The activity had an intense sequence from February 16 to April 1, 2021, totaling 17 paroxysmal events separated by repose times varying from 1 to 7 days. The eruptive sequence was extensively monitored, providing a unique opportunity to relate the chemistry and texture of the erupted products to eruption dynamics. We investigate the temporal evolution of the magmatic system through this eruptive sequence by quantifying variations in the composition and texture of clinopyroxene...

Volcanic rocks were among the most sought-after materials to produce grinding tools in antiquity because lavas lithologies, either mafic or felsic, ensured good wear resistance and grinding capacity with respect to many other kinds of rocks. The interest in findings made of vesciculated lavas, referable to parts of querns, mortars, and/or pestles of the Final Bronze Age site of Monte Croce Guardia (Arcevia) lies in the fact that this settlement was built upon limestones belonging to the sedimentary sequence of the Marche-Umbria Apennines (central Italy) and far away from potential raw materials of volcanic rocks...

The petrophysical and petrothermal characterization of the sedimentary succession of the Oliana anticline in the Southern Pyrenees has been performed on the basis of mineral density, connected porosity, permeability, P-wave velocity and thermal conductivity measurements of rock samples distributed along this anticline. This dataset was used to explain: (I) the variability of petrophysical rock properties along the Oliana anticline, (II) the distribution of thermal conductivity along the sedimentary units of the anticline, (III) the relationships between the fold and petrology concerning the mineral density, connected porosity, permeability, P-wave velocity and thermal conductivity of rocks and (IV) the tectonic and diagenetic controls underlying the observed relationships, as described in the research article: "Petrological, petrophysical and petrothermal study of a folded sedimentary succession: the Oliana anticline (Southern Pyrenees), outcrop analogue of a geothermal reservoir - Global and Planetary Change Journal (2023)"...

High conductivity anomalies in the shallow mantle are frequently attributed to minor partial melt (basalt or carbonatite) in the olivine-dominated peridotites. Conductivity of a melt-mineral mixture depends on the configuration of melt that could be affected by grain size of the constitutive mineral(s), but this has rarely been explored. Here, we provide experimental evidence using a conductive carbonatite analog and olivine that the bulk conductivity decreases systematically with increasing olivine grain size...

UNLABELLED: The petrogenesis of extra-large flake graphite is enigmatic. The Bissett Creek graphite deposit, consisting of flake graphite hosted in upper-amphibolite facies quartzofeldspathic gneisses and rare aluminous gneisses, provides an analogue for graphite exploration. In the Bissett Creek gneisses, graphite is homogeneously distributed and composes 2-10 vol. % of the rocks. Disseminated graphite flakes (~ 1 to 6 mm in size) are interleaved with biotite and are petrologically associated with upper-amphibolite facies metamorphic mineral assemblages...

Chagan Sag is one of the most significant tectonic unit in the Yin'e Basin. The special component of the organic macerals and biomarkers in the Chagan sag suggests great difference of its hydrocarbon generation process. In this paper, forty samples of source rocks are subjected to carry out on the geochemical characteristics by methods of rock-eval analysis, organic petrology and gas chromatography mass spectrometry (GC-MS) to reveal the origin, depositional environment and maturity of organic matter in Chagan Sag, Yin'e Basin of Inner Mongolia...

Knowledge of the exact composition of building materials (aggregate, binder, air voids, etc.) is essential for the further development of more resistant and sustainable building materials. In numerous scientific studies, the material behavior of asphalt is tested using mechanical methods. Here, the overall material behavior is determined (bitumen, air voids, aggregate). With the advent of imaging techniques, it is becoming possible to determine the individual constituents separately and perform a more detailed analysis of their location, shape and composition...

Because of the steep subduction of a highly concave slab, researchers have characterized megathrusts under the Marianas as among the coldest and curviest plate coupling interfaces in various circum-Pacific subduction zones. Seismic tomography indicates that the heterogeneous underlying plate varies markedly in its subduction angle, velocity, and flexure along the strike and dip, while their effects on the thermal structure and intraslab earthquake occurrence remain enigmatic. By incorporating the 3-D MORVEL velocity and state-of-the-art slab geometry into thermomechanical modeling, we estimated the 3-D subduction thermal state and hydrothermal regime below the Marianas...

The 2021 volcanic eruption at La Palma, Canary Islands, was the island's most voluminous historical eruption. Little is known about this volcano's feeding system. During the eruption, seismicity was distributed in two clusters at ~10-14 km and ~33-39 km depth, separated by an aseismic zone. This gap coincides with the location of weak seismic swarms in 2017-2021 and where petrological data have implied pre-eruptive magma storage. Here we use seismological methods to understand the seismic response to magma transfer, with 8,488 hypocentral relocations resolving small-scale seismogenic structures, and 156 moment tensors identifying stress heterogeneities and principal axes flips...

Methane (CH4 ) is a critical but overlooked component in the study of the deep carbon cycle. Abiotic CH4 produced by serpentinization of ultramafic rocks has received extensive attention, but its formation and flux in mafic rocks during subduction remain poorly understood. Here, we report massive CH4 -rich fluid inclusions in well-zoned garnet from eclogites in Western Tianshan, China. Petrological characteristics and carbon-hydrogen isotopic compositions confirm the abiotic origin of this CH4 . Reconstructed P-T- f O2 -fluid trajectories and Deep Earth Water modeling imply that massive abiotic CH4 was generated during cold subduction at depths of 50-120 km, whereas CO2 was produced during exhumation...

The parameters of coal petrology and methane adsorption are significant to exploit coal and coalbed methane (CBM). Based on borehole core sampling, a new method using the P-wave velocity to predict coal maceral, coal face index, and Langmuir parameter of high-volatile bituminous coals was proposed. The results showed that the P-wave velocity correlated positively with coal skeletal density, apparent density, and ash yield with fitting coefficients ( R 2 ) of 0.55, 0.57, and 0.57, respectively, but it negatively correlated with coal porosity and moisture content with R 2 of 0...