Petrology

Pyrite is widely distributed in lacustrine shales and has become a research focus in unconventional oil and gas exploration. Pyrite morphology is useful for identifying different types of organic matter and assessing shale oil enrichment in organic-rich shale. Abundant pyrite is developed in the source rocks from the Chang 7 Member of the Yanchang Formation in the Ordos Basin, NW China. However, the relationship between different pyrite types and the differential enrichment of shale oil still needs to be clarified...

In order to promote site screening for high-level radioactive waste (HLW) disposal purposes, the characteristics of argillaceous rock (potential host rock) from the Yingejing Sag of the Bayingebi Basin, Northwest China have been well discussed. Results show that (1) Unlike argillaceous host rocks in foreign countries, the argillaceous rock mainly consists of analcite, dolomite, and albite; the contents of clay minerals are only about 10%. Five typical structures could be categorized, dominating by the massive structure...

UNLABELLED: The unexpected discovery of felsic magma by the Iceland Deep Drilling Project-1 (IDDP-1) in the Krafla volcanic system (KVS) presents a unique opportunity to investigate pre-eruptive lithium (Li) dynamics and establish a more direct connection between magma reservoirs and volcanic deposits. Our study provides new insights into Li abundances and isotope compositions in bulk-rock, minerals, and groundmass glass from rhyolitic lavas at KVS, encompassing various stages of groundmass crystallisation...

CO2 capture and storage in geological reservoirs have the potential to significantly mitigate the effects of anthropogenic gas emissions on global climate. Here, we report the results of the first laboratory experiments of CO2 injection in continental flood basalts of South America. The results show that the analyzed basalts have a mineral assemblage, texture and composition that efficiently allows a fast carbonate precipitation that starts 72 h after injection. Based on the availability of calcium, chemical monitoring indicates an estimated CO2 storage of ~ 75%...

The forsterite zone of the Ubehebe Peak contact aureole, Death Valley, USA consists of an outer zone of tabular/jack-straw olivine and an inner zone of subequant polyhedral olivine. Subequant polyhedral forsterite crystals close to the intrusion are small and tabular forsterite crystals farther away are larger. To investigate the formation of the two morphologies, forsterite growth experiments were conducted in cold seal pressure vessels in the CaO-MgO-SiO2 -CO2 -H2 O system. Forsterite precipitation follows a disequilibrium reaction pathway made of three reactions: [1] tabular forsterite growth from quartz and dolomite, [2] forsterite growth from tremolite dissolution, and [3] subequant polyhedral forsterite growth from tabular forsterite dissolution...

UNLABELLED: The trace-element and isotope geochemistry of rutile are robust tools to determine metamorphic temperatures, age, and host-/source lithologies. The use of rutile as single grain indicator for pressure, temperature, time and composition (P-T-t-X) of the host rock, which is vital in the use of detrital rutile to trace plate-tectonic regimes throughout Earth's history, requires the identification of a pressure dependent trace element in rutile. We investigate the pressure dependence of hydrogen in rutile using polarized in-situ Fourier Transform Infrared (FTIR) spectroscopy...

To quantitatively characterize middle-high-ranked coal reservoirs, the physical characteristics of seven coal samples from the Huaibei Coalfield in northern China were investigated in detail based on experiments including proximate analysis, coal petrology, low-temperature nitrogen adsorption (LTNA), mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), and methane isothermal adsorption. The results show that coal maceral in the Huaibei Coalfield is dominated by vitrinite, with a large change in the maximum vitrinite reflectance ranging from 0...

The NASA Mars 2020 Perseverance rover is actively exploring Jezero crater to conduct analyses on igneous and sedimentary rock targets from outcrops located on the crater floor (Máaz and Séítah formations) and from the delta deposits, respectively. The rock samples collected during this mission will be recovered during the Mars Sample Return mission, which plans to bring samples back to Earth in the 2030s to conduct in-depth studies using sophisticated laboratory instrumentation. Some of these samples may contain traces of ancient martian life that may be particularly difficult to detect and characterize because of their morphological simplicity and subtle biogeochemical expressions...

Fluid inclusion microthermometry on olivines, clinopyroxenes, and amphiboles was used during a volcanic eruption, in combination with real-time seismic data and rapid petrographic observations, for petrological monitoring purposes. By applying this approach to the study of 18 volcanic samples collected during the eruption of Tajogaite volcano on La Palma Island (Canary Islands) in 2021, changes in the magma system were identified over time and space. Magma batches with distinct petrographic and geochemical characteristics emerged from source zones whose depth progressively increased from 27 to 31 kilometers...

The Nyainqentanglha Metallogenic Belt (NMB) is an economically important lead-zinc ore province located in the Central and Southern Lhasa subterrane, Tibet. The NMB consists mainly of skarn-type lead-zinc polymetallic deposits that form at the contact between Late Cretaceous-Eocene intrusive rocks and carbonatite/volcanic-sedimentary strata. These deposits are generally considered to be related to S-type granites formed by the Indo-Asian continental collision. However, the ε Hf (t) (ave. -1.6) of zircons from the mineralization-related granitoids indicates that it is crust-mantle mixing products...

The most crucial task of petroleum geology is to explore oil and gas reservoirs in the deep underground. As one of the analysis techniques in petroleum geological research, rock thin section identification method includes particle segmentation, which is one of the key steps. A conventional sandstone thin section image typically contains hundreds of mineral particles with blurred boundaries and complex microstructures inside the particles. Moreover, the complex lithology and low porosity of tight sandstone make traditional image segmentation methods unsuitable for solving the complex thin section segmentation problems...

Constraining the thermodynamic conditions within an impact structure during and after hypervelocity impacts is extremely challenging due to the transient thermal regimes. This work uses carbonate clumped-isotope thermometry to reconstruct absolute temperatures of impact lithologies within and close to the ∼66 Myr old Chicxulub crater (Yucatán, México). We present stable oxygen (δ18 O), carbon (δ13 C), and clumped-isotope (Δ47 ) data for carbonate-bearing impact breccias, impact melt rock, and target lithologies from four drill cores on a transect through the Chicxulub structure from the northern peak ring to the southern proximal ejecta blanket...

The Ediacaran Doushantuo phosphate deposit in Kaiyang, Guizhou Province, China, contains thick phosphate ores. Most of the ores are reconstituted phosphorite, and there have been few studies of the primary phosphorites, which has led to controversy regarding the origins and nature of mineralization of these phosphate-rich deposits. We identified high-grade primary phosphorites in the Kaiyang area and undertook a stratigraphic, petrological, sedimentological, geochemical, and isotopic study of these rocks. Moving up-section, the Longshui phosphate ore deposit comprises granular, micritic, stromatolitic, honeycomb, and sandy phosphorites...

The fourth member of the Sinian Dengying Formation in northern Sichuan was reformed by multistage diagenetic fluids. It is beneficial to systematically analyze the diagenetic evolution of the area to clarify the sedimentary evolution of the dolomite in the fourth member of the Dengying Formation and the fluid characteristics at different diagenetic stages. In this study, the petrological characteristics, vertical sedimentary evolution, diagenetic fluid stages, and diagenetic environment of Dengsi dolomite were analyzed by using carbon-oxygen strontium isotopes, rare-earth elements, major and trace elements, combined with the supporting thin section identification and cathodoluminescence techniques, and the source and properties of diagenetic fluid of Dengsi dolomite in different diagenetic environments were determined...

Lunar surface chemistry is essential for revealing petrological characteristics to understand the evolution of the Moon. Existing chemistry mapping from Apollo and Luna returned samples could only calibrate chemical features before 3.0 Gyr, missing the critical late period of the Moon. Here we present major oxides chemistry maps by adding distinctive 2.0 Gyr Chang'e-5 lunar soil samples in combination with a deep learning-based inversion model. The inferred chemical contents are more precise than the Lunar Prospector Gamma-Ray Spectrometer (GRS) maps and are closest to returned samples abundances compared to existing literature...

The detection of deep reflected S waves on Mars inferred a core size of 1,830 ± 40 km (ref. 1 ), requiring light-element contents that are incompatible with experimental petrological constraints. This estimate assumes a compositionally homogeneous Martian mantle, at odds with recent measurements of anomalously slow propagating P waves diffracted along the core-mantle boundary2 . An alternative hypothesis is that Mars's mantle is heterogeneous as a consequence of an early magma ocean that solidified to form a basal layer enriched in iron and heat-producing elements...

Shallow magmatic reservoirs that produce measurable volcanic surface deformation are often considered as discrete independent systems. However, petrological analyses of erupted products suggest that these may be the shallowest expression of extensive, heterogeneous magmatic systems that we show may be interconnected. We analyse time series of satellite-radar-measured displacements at Western Galápagos volcanoes from 2017 to 2022 and revisit historical displacements. We demonstrate that these volcanoes consistently experience correlated displacements during periods of heightened magma supply to the shallow crust...

The carbon dynamics of lacustrine deposits play an important role in controlling the atmospheric carbon cycle. However, the influences of various sedimentary factors on carbon accumulation in lacustrine deposits are rarely known. In this study, the petrological and geochemistry analyses of organic-rich (average total organic content = 24.22 wt%) lacustrine deposits and organic-poor (average total organic content = 2.48 wt%) lacustrine deposits buried under a peatland (the Zhibian peatland) in Northeast Asia are used to explore the above issues...

Petrological data of the recent alluvial sediments from the Ngaye River watershed in the Northern Cameroon were used in order to infer their origin with the probable source rocks as gneisses, amphibolites, and granites; and to investigate the occurrence of precious metals like Gold and Platinum Group Elements (Au-PGE). The Ngaye River watershed is located in the Adamawa plateau from the Adamawa-Yade Domain (AYD) in the Central Cameroon, Central Africa. This region is characterized by two contrasted seasons which induce a savanna vegetation cover with gallery forests along the rivers...

Secondary fluorescence (SF) is known to be a potential source of error in electron probe microanalysis (EPMA) when analyzing for a trace or minor element near a phase boundary. This often overlooked effect leads to a concentration enhancement whenever the neighboring phase contains a high concentration of the analyzed element. Here we show that SF may also lead to a concentration decrease, which can be mistakenly interpreted as a depletion. To examine this issue, we compare Ni profiles measured on well-characterized, homogeneous olivine [(Mg,Fe)2SiO4] grains embedded in basaltic glass, with semi-analytical calculations and numerical simulations of SF across phase boundaries...