Complex, time‐dependent, and asymmetric rift geometries are observed throughout the East African Rift System (EARS) and are well documented, for instance, in the Kenya Rift. To unravel asymmetric rifting processes in this region, we conduct 2D geodynamic models. We use the finite element software ASPECT employing visco‐plastic rheologies, mesh‐refinement, distributed random noise seeding, and a free

Ocean worlds have been identified as high‐priority astrobiology targets due to the link between life and liquid water. Young surface terrain on many icy bodies indicates they support active geophysical cycles that may facilitate ocean‐surface transport that could provide observables for upcoming missions. Accurately interpreting spacecraft observations requires constraining the relationship between

Cylindrical-shaped plugs can be tested using a Hoek-cell-like apparatus that allows for efficient and inexpensive measurements of a rock’s static elastic properties. However, when it comes to transverse isotropic material, this approach has a natural limitation due to the isotropic radial stresses; particular attention to the boundary conditions and the proper design of pressurization steps is warranted

Computation of traveltimes and raypaths is important for anisotropic tomography inversions. The eikonal-equation-based method outperforms traditional ray methods by producing more accurate results. However, most existing eikonal solvers are formulated on structured regular meshes, which are no longer accurate for models with the presence of irregular topography and subsurface interfaces. To solve the

Seismic imaging characteristics of a prototype electrically driven, linear synchronous motor-based, vertical-force seismic vibrator (“e-vib”) were evaluated at a site in the Netherlands. The system weighs 1.65 t and excites seismic signals with a peak force of 6.7 kN. Data were recorded along two collocated geophone-based nodal and landstreamer microelectromechanical system - MEMS-based sensor 2D seismic

Coastal freshwater forested wetlands are rapidly transitioning from forest to marsh, leaving behind many standing dead trees (snags) in areas often called ‘ghost forests’. Snags can act as conduits for soil produced greenhouse gases (GHG) and can also be sources as they decompose. Thus, snags have the potential to contribute GHGs to the atmosphere, but emissions are not well understood. We assessed

To study the fracture characteristics and fatigue damage of fractured rock masses, noncoplanar fractured rocklike specimens prepared using cement mortar were used for a graded cyclic loading–unloading test. The results showed that the two ends of the horizontal crack were the main stress concentration areas, and they inhibited crack initiation of the inclined fracture. With increasing crack inclination

In the process of coal mining, the surface subsidence under ultrathick loose layer is abnormal (subsidence coefficient greater than 1.0), which will cause great damage to the surface ecological environment. The fracture propagation and stress evolution of bedrock are of great significance to the prevention of surface subsidence. Taking the 1305 working face of a mine as the background, this paper study

It is very important to determine the seepage behaviour of fractured rock mass infilling to evaluate the stability of the surrounding rock. The joint transfixion rate is the ratio of the unpenetrated length to the penetration length of a joint in a sample. Samples of the fractured rock mass infilling using different transfixion rates were prepared, and a TCQT-III low-permeability coal-rock triaxial

The present study of field, petrological, exploration well, and seismic data describes backward-dipping duplexes comprised of phyllitic coal and bedding-parallel décollements and thrusts localized along lithological transitions in tectonically thickened Lower Devonian to lowermost Upper Devonian; uppermost Devonian–Mississippian; and uppermost Pennsylvanian–lowermost Permian sedimentary strata of the

We report techniques for measuring 41K/39K ratios using a Nu Instruments Sapphire double-focusing multi-collector ICPMS, equipped with a hexapole collision/reaction gas cell. Large Ar-hydride spectral interferences, as well as the 40Ar+ ion beam from the Ar-plasma, are effectively eliminated through a series of reactions with H2 gas in the collision/reaction cell. This allows the 39K+ and 41K+ ion

An integrated petrographic, fluid inclusion, noble gas, and stable isotope study was performed for the Late Oligocene, spatially associated Sukulu and Tororo carbonatite complexes in SE Uganda in order to understand their genesis and provide additional constraints on the evolution of the East African Rift System (EARS). Both carbonatite complexes comprise mainly ring-shaped calcio‑carbonatites with

Komatiites and sedimentary rocks sampled during the International Continental Drilling Program (BARB1-2–3-4–5) in the Barberton greenstone belt, South Africa, were analyzed for 146Sm-142Nd systematics. Resolved negative μ142Nd values (down to −7.7 ± 2.8) were identified in komatiites from the 3.48 Ga Komati Formation and this signature correlates with low Hf/Sm ratios measured in these samples. The

ABSTRACT Permo-Carboniferous felsic magmatic rocks are widely exposed on the northern half of the south-eastern Central Asian Orogenic Belt. However, their origin and spatiotemporal distribution are unknown. Herein, zircon U-Pb-Hf isotopic data, major and trace element compositions of the whole-rock, and Sr-Nd isotopic data derived for felsic volcanic rocks and granites of the Chaganaobao and Baiyinaobao

The present work is the first regional-scale reconnaissance of 11 brine springs located in the Zagros Fold and Thrust Belt (ZFTB). The springs represent a hypersaline character (Cl− ≥ 20000 mg/L) and emerge in evaporates, marl, and gypsum successions of the Lower Miocene Gachsaran Formation, which is considered as the most important cap-rock of Zagros oil reservoirs. Assessing the hydrochemical features

Litter decomposition produces labile and recalcitrant forms of dissolved organic matter (DOM) that significantly affect soil carbon (C) sequestration. Chemical analysis of this DOM can provide important knowledge for understanding soil DOM dynamics, but detailed molecular analyses on litter derived DOM are scarce. Here we use ultrahigh resolution mass spectrometry (FT-ICR MS) to characterize the molecular

The Nagssugtoqidian orogen (NO), which forms the northern margin of the North Atlantic craton in West Greenland, is largely comprised of ~2870 to 2720 Ma juvenile continental crust reworked during Paleoproterozoic orogenic events. Sparse evidence of components older than 3100 Ma in the area (U–Pb zircon ages and bulk-rock Sm–Nd isotopes) have hinted at a unit called the Qorlortoq gneiss but were not

We developed a modified topography prestack time migration (PSTM) scheme that can improve the imaging resolution by applying effective Q to topography migration. The computation of the traveltime at each imaging location in the migration is based on the floating datum smoothed by rugged topography. Unlike the common quality factor Q, the effective Q only determines the frequency-dependent amplitude

Least-squares reverse-time migration (RTM) works with an inverse operation, rather than an adjoint operation in a conventional RTM, and thus produces an image with a higher resolution and more balanced amplitude than the conventional RTM image. However, least-squares RTM introduces two side effects: sidelobes around reflectors and high-wavenumber migration artifacts. These side effects are caused mainly

Molybdenum isotopes are an established proxy for paleoredox conditions in low-temperature surface systems. However, the mechanisms behind demonstrated Mo isotope fractionation during igneous and hydrothermal processes at elevated temperatures are still controversial. This study focusses on a comprehensive dataset documenting the late stage magmatic-hydrothermal evolution of Mo isotope systematics in

Modelling the reservoirs and fluxes of Zn in Earth's crust and mantle requires data on the solubility of its mineral hosts and ores in coexisting fluids, as well as on the complexation of Zn in these fluids as a function of fluid composition, pressure, and temperature. However, due to experimental challenges, the availability of such data is limited to pressures below 1 GPa, which are only representative

Burial fluxes of organic carbon and biogenic silica were determined in 17 continental shelf sediment cores collected from the northern Weddell Sea, the Bransfield Strait, and the southern Drake Passage. Coring sites included open-shelf stations as well as slope and glacial trough environments, with water depths varying from 220 to 760 m. Apparent 210Pb accumulation rates from these cores ranged from

The Haughton Dome located on Devon Island, in the Canadian Archipelago represents a well-preserved, moderate-sized, complex impact crater. Previous age constraints for the 24 km-diameter impact structure have ranged from ca. 21 Ma to ca. 39 Ma. Herein, we present a coordinated microstructural and in situ U-Pb study of zircon and monazite coupled with 40Ar/39Ar laser step heating of shock-melted K-feldspar

The source of the mineralizing fluid in Archean greenstone-hosted orogenic gold deposits is widely debated, with the available geochemical and isotope data interpreted as reflecting the involvement of metamorphogenic fluid produced by devolatilization of greenstone belt metaigneous/metasedimentary rocks or granite-derived magmatic-hydrothermal fluids or both. Orogenic gold deposits form in complex

In order to elucidate the processes involved in iron and silicon isotopes partitioning during magmatic differentiation, it is essential to know the precise value of equilibrium fractionation factors between the main minerals present in the evolving silicic melts. In this study, we performed first-principles calculations based on the density functional theory to determine the equilibrium iron and silicon

We present the first results of a comprehensive investigation aimed at testing the hypothesis of chondrule-matrix complementarity and the four-component model for the compositions of the carbonaceous chondrites and their components. Combining point-counting with electron microprobe analyses, we have determined the bulk compositions of thin sections, as well as the average abundances and compositions

Rare earth elements (REEs) mobilize, fractionate, and are re-distributed during supergene processes, and thus provide a powerful tool with which to quantitatively reconstruct the effects of chemical weathering. Moreover, under certain conditions, the REEs can concentrate to levels in the regolith sufficient to form giant regolith-hosted REE deposits, that are now responsible for much of the World’s

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are microbial molecular fossils ubiquitous in natural environments. The correlation between the Methylation Index of brGDGTs (the MBT′5ME paleothermometer) and temperature offers an important tool for reconstructing past terrestrial temperatures. However, factors other than temperature could also affect the distribution of brGDGTs in lacustrine

Here we report a detailed archaeomagnetic and rock-magnetic study of a pottery kiln from Burgos (Spain) to reconstruct its burning conditions and date its last use and abandonment age. During the course of a rescue archaeological excavation carried out in 2015 in the center of Burgos city, a medieval pottery workshop was discovered. Two well-preserved kilns appeared and archaeomagnetic analyses were

Continental fold‐thrust belts display a variety of structural styles, ranging from thin‐skinned thrusts following weak lithologic contacts to thick‐skinned thrusts that deform mechanical basement. The common practice of splitting fold‐thrust belts into thin‐ and thick‐skinned map domains has not yielded a predictive model of the primary controls on structural style. Within the Mesozoic‐Paleogene Idaho‐Montana

Oil and gas operations in sedimentary basins have revealed the occurrence of significant temperature anomalies at depth, raising the possibility of major geothermal resource potential in the sedimentary sequences. The efficient development of such a resource may require enhancement by hydraulic stimulation. However, effective stimulation relies on an initial assessment of in situ mechanical properties

Fractures usually spread over various scales and strongly influence velocity and anisotropy. We investigate elastic velocity and anisotropy in rocks with fractures of different sizes. Based on synthetic rocks with controlled fracture geometries, we create a set of rocks with fracture diameter of 2, 3 and 4 mm and the fracture thickness is 0.06 mm. P‐ and S‐wave velocities are measured at 0.1 MHz, while

Organic matter (OM) loading drives benthic metabolism and controls nitrogen (N), phosphorus (P), and carbon (C) cycling in coastal sediments. To better understand the influence of OM on benthic metabolism, we conducted sediment core incubations in Long Island Sound, NY (USA), an estuary heavily influenced by anthropogenic nutrient loading. Cores were collected during the summer and winter at five stations

We present a morphotectonic study of the offshore northern Sumatra fore-arc high and fore-arc basin and an evolutionary model of the area based on high-resolution marine geophysical datasets. We show that the landward slope of the fore-arc high and the western edge of the Aceh fore-arc basin host a set of deeply-rooted, seaward-dipping backthrusts: main backthrust (MBT) and frontal backthrust (FBT)

Water inrush from coal seam floors is one major geological obstacle hindering safe and efficient production activities in mines. Determining the source of water inrush can facilitate its prediction and guide decisions regarding measures for prevention and control. The process of identifying the location of hidden hydraulic contact points in different confined aquifers forms the basis of hydrogeological

Blasting has been used extensively in deep underground excavation. In this paper, a numerical simulation LS-DYNA was carried out to investigate the influence of in situ stress and empty hole on rock fracture development. Based on the simulation process and existing laboratory data, the micromechanical properties of the Riedel-Hiermaier-Thoma (RHT) model were calibrated. By then, this model was used

The influence of groundwater on tunnel engineering is very complicated. Due to the complexity of water flow water pressure transfer and uncertain defects in the stratum, all of which are key factors with regard to the design of tunnel engineering. Therefore, the variation of surrounding rock during excavation and the deformation and failure of soft surrounding rock under different seepage paths of

Based on the engineering background, the 41051 working face of the 65th coal mine in Qitaihe Xinxing Mine was regarded as the engineering background, by using of the comprehensive research methods such as theoretical analysis and calculation, FLAC3D numerical simulation, physical parameters of coal and rock in laboratory, and the field industrial measurement, to research on the large drilling relieving

The Chang 7 interval of the Upper Triassic Yanchang Formation in the Ordos Basin represents a typical deep lacustrine depositional sequence. On the basis of field outcrops, cores, well logs, light/heavy mineral provenance analysis, and petrological studies, we evaluated the characteristics of deep-water gravity flow deposition of the Chang 7 interval and constructed a depositional model. The sediments

Brittleness index is an important mechanical index to evaluate the fracturability of conventional oil and gas reservoirs. However, the brittleness index of an organic coal reservoir is more complex. In this study, based on array sonic logging and density logging data, coal brittleness index is calculated using an elastic parameter method in the Mabidong coalbed methane (CBM) block in southern Qinshui

The Zagros suture zone in Iran is part of the Tethyan orogenic belt that records convergence between the Eurasian and Arabian plates during the Mesozoic-Cenozoic. Prior to collision, which may have initiated in the Late Eocene-Early Oligocene, much of the convergence was accommodated by the Late Triassic-Early Jurassic subduction of the Neotethys beneath the Iranian Cimmerides, terranes accreted on

The Teide-Pico Viejo (T-PV) stratovolcanoes constitute one of the most potentially active volcanic complexes in Europe. T-PV was traditionally considered as a non-explosive system, but recent studies have pointed out the explosive character of their phonolitic magmas, including plinian and subplinian eruptions and the generation of pyroclastic density currents, as is evidenced in the volcanological

LuHf geochronology is a powerful method to constrain the temporal evolution of geological systems. Traditional application of this dating method requires time-consuming chemical separation of the parent (176Lu) and daughter (176Hf) isotopes that is commonly accompanied by loss of textural context of the analysed minerals. In contrast, In-situ (laser-ablation based) LuHf geochronology offers a number

Rocks that make up the Mesoarchean (~3Ga) Buhwa greenstone belt (BGB) of the Zimbabwe craton divide into three associations: shelf, basinal, and transitional. Chert and iron formation exist within the three associations, allowing the unique opportunity to compare textural and geochemical attributes of iron- and silica-rich rocks from distinct positions within a single basin. We analyzed major-, trace-

The stable oxygen isotope composition (δ18O) of ammonites and belemnites is a common proxy for Jurassic and Cretaceous sea temperatures. The challenges and uncertainties associated with cephalopod δ18O and other proxy based paleotemperature reconstructions make cephalopods such as ammonites and belemnites a favourable target for carbonate clumped isotope paleothermometry. Our measurements of the clumped

The only known case of natural fission reactors is hosted by high-grade uranium (U) deposits at Oklo-Okelobondo and Bangombé in sandstones of the ~2.1 Ga Francevillian Group, Gabon. However, the geochemical influence of the depositional environment on this unique natural nuclear phenomenon has not been clearly established. Localized, unusually high vanadium (V) enrichments are thought to have prevented

Marine oxygen minimum zones play a crucial role in the global oceanic carbon, nitrogen, and sulfur cycles as they harbor microbial communities that are adapted to the water column chemistry and redox zonation, and in turn control the water column chemistry and greenhouse gas release. These micro‐organisms have metabolisms that rely on terminal electron acceptors other than O2 and often benefit from

Recent measurements on the dissolution rate of nano- and micron-scale rough calcite surfaces have shown lateral variations in dissolution rate, which can be quantified using rate spectra. This study uses numerical simulations to investigates the hydrodynamic processes during such experiments to explore whether hydrodynamic effects can explain the observed dissolution rate spectra. For this purpose

The varying nature and thickness of glacial sediments affect the characteristics of mineralized dispersal trains in the Amaruq gold deposit area in Nunavut, northern Canada. To help evaluate the deposit signature, glacial sediments were collected from frost boils along transects parallel to the main ice-flow direction. A complementary detailed geochemical drift exploration dataset and a new Quaternary

During rifting, pre‐existing penetrative basement fabrics can affect new faults in cover rocks by a mechanism that does not appear to involve reactivation. This subtle form of inheritance can significantly impact fault network architecture in rift basins above laterally variable basement domains with geomechanical anisotropies. Here we use multi‐layer, brittle‐ductile, crustal‐scale analogue experiments

Understanding how normal faults grow is key to determining the tectono‐stratigraphic evolution of rifts. According to recent studies, normal faults tend to grow in two temporally distinct stages: a lengthening stage, followed by a throw/displacement accumulation stage. However, this model is still debated and not widely supported by many additional studies. Relatively few studies have investigated