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This article investigates how, where, and to what extent the mineralogical and chemical composition of sand-sized sediments is modified by extreme weathering in modern equatorial settings, with the ultimate goal of learning to read climate from the sedimentary record. To single out the weathering effect, we studied the compositional trends of fluvial sands along the western branch of the East African Rift between 5°S and 5°N. The relative durability of different detrital components, as well as potential hydraulic-sorting and grain-size effects, were assessed by comparing samples with similar provenances in different climatic and environmental conditions or of different size classes within the same sample. Sands of equatorial central Africa at the headwaters of the Congo and Nile basins display the full spectrum of petrologic suites characterizing rift-shoulder and volcanic rift provenances. Unlike in arid Arabia, quartzose sands are not restricted to areas where detritus is recycled from prerift sedimentary covers. In a hot humid climate, weathering can effectively obliterate the fingerprint of parent rock lithology and produce a nearly pure quartz residue even where midcrustal basement rocks are being actively uplifted and widely unroofed. In such settings garnet is destroyed faster than hornblende, and zircon faster than quartz. Weathering control on detrital modes is minor only in the rain shadow of the highest mountains or volcanoes, where amphibole-dominated quartzofelicdspathic metamorphiclastic sands (Rwenzori Province) or clinopyroxene-dominated feldspatholithic volcaniclastic sands (Virunga Province) are generated. Our detailed study of the Kagera basin emphasizes the importance of weathering in soils at the source rather than of progressive maturation in temporary storage sites during stepwise transport and shows that the transformation of diverse parent rocks into a quartzose \"white sand\" may be completed in one sedimentary cycle in hydromorphic soils of subequatorial lowlands. Micas and heavy minerals, which are less effectively diluted by recycling than main framework components, offer the best key to identify the original source-rock imprint. The different behavior of chemical indexes such as the CIA (a truer indicator of weathering) and the WIP (markedly affected by quartz dilution) helps us to distinguish strongly weathered first-cycle versus polycyclic quartz sands.

Provenance of pre‐obduction Eocene turbidites from New Caledonia is used to better constrain their geodynamic context and inform debate on subduction polarity. Chemical compositions of detrital clinopyroxenes in arenites are compared against potential sources. Basaltic source modeling using cpx/rock partition coefficients confirms E‐MORB origins from the allochthonous Poya Terrane. Detrital zircon populations in the Bourail Flysch are similar to those of the autochthonous Upper Cretaceous sedimentary cover. In contrast, a predominance of early Eocene zircons in the Nepoui‐Koumac Flysch suggests derivation from the supra‐subduction dyke system of the Peridotite Nappe. Results were compared with other arenite components (bioclasts, oxides, sulfides, zircon) and whole‐rock compositions of rock fragments and blocks of the breccia/olistostrome in the upper part of the turbidites. Together, the data set allows identification of multiple successive sources and processes. A syntectonic character for the flysch basins is inferred from the pre‐turbidite unconformity and provenance evolution. An abundance of shallow‐water bioclasts throughout the succession indicates the formation and continuous destruction of a rimming carbonate platform. The existence of two previously identified types of turbidite basins is confirmed by the characteristics of the Bourail (foreland) and the Nepoui‐Koumac (wedge‐top) flysch successions. These basins were located on the northern Norfolk Ridge (lower plate) and ultramafic allochthon (accretionary wedge), respectively, representing elements of a foreland basin. These observations are inconsistent with a hypothesized connection between New Caledonia and a continent‐directed Pacific subduction zone. Together with all available geologic data, the results of this investigation confirm the model of northeast‐ or east‐dipping pre‐obduction subduction.

Petrography, scanning electron microscopy, X-ray diffraction, and both conventional and special core analyses are applied to precisely reservoir characterize the Lower Cretaceous Bentiu and Abu Gabra Formations of the Muglad Basin, which is among the largest hydrocarbon reservoirs in South Kordofan, SW North Sudan. Based on this integrated study, the Abu Gabra–Bentiu sequence comprises four petrographical microfacies, which consist of two reservoir rock types (RRTs). RRT1 is composed of quartz arenites and RRT2 is composed of quartz wackes. The greatest storage, flow capacities, and reservoir quality are assigned for RRT1 due to its good-to-excellent porosity (average ∅ = 26.7%), permeability (average k = 1365 md), reservoir quality index (RQI, average = 1.43 μm), flow zone indicator (FZI, average = 3.66 μm) and discrete rock type (DRT, average = 13). The relatively low-to-fair reservoir quality of the Abu Gabra Formation (average ∅ = 13.2%, average k = 14.7 md, average RQI = 0.17 μm, average FZI = 1.05 μm, and average DRT = 10) is due to authigenic kaolinite and siderite content, compaction and cementation by silica and clay patches.

Carbonate rocks encompass about 15% of the exposed sedimentary sequences on the Earth. The Lesser and the Tethyan Himalayan units are sedimentary sequences in the Himalayan region that comprise carbonates along with pelites and arenites. It is critical to understand these carbonate rocks because of the impending large-scale infrastructure developments in the Himalayas. In this study, the petrographic traits and physico-mechanical properties of carbonate rock samples from the Deoban Formation, Lesser Garhwal Himalaya, India, have been attempted. The physico-mechanical behavior of carbonate rocks is governed by a variety of petrographic characteristics, such as grain size, grain shape, mineralogy, and the existence of microcracks and veins in the rock. It is also apparent that petrographical indices have a significant impact on the engineering attributes of the rocks. The association of the Uniaxial Compressive Strength (UCS), Brazilian Tensile Strength (BTS), and dry density with acoustic wave velocities (V p and V s ) is markedly positive. In contrast to UCS with porosity, correlations between porosity and acoustic wave velocities, and porosity and tensile strength are weakly negative. The impact of grain size on UCS is more significant than that of other textural characteristics like form factor and aspect ratio. The study showed no strong correlations between acoustic wave velocities and aspect ratio, but it did uncover weak positive correlations between acoustic wave speeds and form factor, and weak negative correlations between acoustic wave velocities and grain size.

The first arrival of sedimentary material from Asia onto the Indian continental margin provides a minimum constraint on the timing of initial India-Asia collision. A combination of petrology, detrital Cr-spinel geochemistry, and zircon U-Pb dating of the Upper Cretaceous to Eocene deep-water succession at the Sangdanlin section, southern Tibet, provides evidence for major provenance change within the strata. The Upper Cretaceous-Paleocene Denggang Formation quartzarenites contain zircons with dominant Proterozoic-Ordovician U-Pb ages, with an additional age peak of Early Cretaceous, which we interpret to be derived from the northern Indian margin. By contrast, the lithic sandstones of the Early to Middle Eocene Sangdanlin and Zheya formations are dominated by zircons younger than 200 Ma, showing one major peak at ∼80-125 Ma and two subdominant peaks at ∼54-70 and ∼180-196 Ma, comparable to those from the Gangdese magmatic arc. Cr-spinels in the Sangdanlin and Zheya formations are abundant and characterized by extremely low TiO2 wt%, indicating an ophiolitic source. We consider the Sangdanlin and Zheya formations syncollisional, deposited in a foredeep basin, with the provenance being the Gangdese arc and the Yarlung Zangbo suture zone. The abrupt sedimentary provenance change between the Denggang and Sangdanlin formations denotes the onset of India-Asia continental collision occurring before the late Ypresian (∼50 Ma). Comparison of our data with those from coeval strata along the Himalaya suggests limited diachroneity in the India-Asia continental collision process.

The Marnoso-arenacea basin (MaB) of the Northern Apennines represents one of the most significant lower–middle Miocene foredeep turbidite systems in the Mediterranean region. While the northern part of the basin (Emilia-Romagna Region) has been extensively investigated, the Umbrian portion remains less understood, particularly concerning high-resolution stratigraphic and structural frameworks. This study integrates detailed field mapping, physical stratigraphy, biostratigraphic data from calcareous nannofossils, and petrographic analyses of arenites and calcarenites to reconstruct the tectono-stratigraphic evolution of the MaB in the Umbrian portion of the basin. The basin is divided into three main tectono-stratigraphic units: Afra-Mt. Verde, Pietralunga–Gubbio–Valtopina and Mt. Vicino. The middle unit is detailed by means of stratigraphic architecture and sedimentary characteristics, which allow us to identify two distinct sub-units. Several carbonate and hybrid turbidite beds, including the Contessa megabed, serve as regional key markers, enabling robust stratigraphic correlations. Two mass-transport complexes (MTDs) have been identified and dated, revealing close relationships between sedimentation patterns and thrust propagation. Modal petrographic data indicate a mixed provenance, from the Alpine and Apennine regions, changing over time in response to tectonic segmentation. These findings enhance our understanding of the internal organization of the MaB and provide new insights into the foredeep’s paleogeography and tectono-sedimentary evolution during the Langhian–Serravallian stages.

Twenty-one sandstone samples belonging to the intermediate part of Gorgoglione Flysch (GF) dated Middle-Miocene, cropping out in the Southern Apennines (Italy), have been studied to highlight the detritus provenance. Petrographic and chemical composition indicates that the successions consist of feldspatho-quartzose and litho-feldspatho-quartzose arenites interbedded with pelitic and calciclastic layers and reveals a provenance from a basement formed by low- to medium-grade metamorphic rocks with abundant granitoids covered by sedimentary rocks in which a volcanic component was also present. In the Mediterranean area, basements with these characteristics are widespread both in western and southwestern domains. The supply provenance of Gorgoglione Flysch has been better detailed utilizing U–Pb detrital zircon ages recording the geological history of the source rocks. Fifty-eight crystals from six samples of coarse- and fine-grained sandstones have been analysed using the U–Pb isotopic systematic (LA-ICP-MS). They produce 70 concordant zircon ages forming three defined clusters at 672 ± 28 Ma, 458 ± 9 Ma and 297 ± 8 Ma, and four zircon ages corresponding to 24 ± 1 Ma. An evaluation of the entire collected data suggests that the provenance area is better identified in northwestern sectors of the Mediterranean area in which the Sardinia–Corsica (pro-part) block plays a fundamental role.

During the early Bajocian, a conspicuous coal-bearing siliciclastic succession was deposited in the northern Tabas Bock, which is important for understanding the regional geodynamics of the Central-East Iranian Microcontinent (CEIM) as well as for the Jurassic coal genesis in this part of Laurasia. Sedimentary facies analysis in a well-exposed section of the lower Bajocian Hojedk Formation (Kalshaneh area, northern Tabas Block) led to the recognition of ten characteristic sedimentary facies and three facies associations, representing channels with point bars and floodplains of a Bajocian meandering river system. Modal analysis indicates that the mature quartz arenites and quartzo-lithic sandstones of the Hojedk Formation originated from the erosion and recycling of older, supracrustal sedimentary rocks on the Yazd Block to the west. The coal petrography and maturity show an advanced maturation stage, whereas the great thickness of these continental strata points to a pronounced extension-related subsidence in the northern Tabas Block. The rapid rate of differential subsidence can be explained by accelerated normal block-faulting in the back-arc extensional basin of the CEIM, facing the Neotethys to the south. Compared to the thick Jurassic, the post-Jurassic strata are relatively thin and played a limited role in the thermal history of the coal in the northern Tabas Block. A relatively high geothermal gradient in the tectonically highly mobile area of the northern Tabas Block and/or heating by regionally widespread Palaeogene intrusions were most probably the key drivers of the thermal maturation of the Middle Jurassic coals.

The Durness Group of NW Scotland records deposition on the Laurentian margin from the basal Miaolingian (Cambrian, 509 Ma) to the Dapingian–Darriwilian boundary interval (Middle Ordovician, 470.3–468.9 Ma). The 930 m thick succession of peritidal and subtidal carbonates was deposited on the Scottish promontory, a nearly 120° deflection in the Palaeozoic continental margin between the Appalachian and Greenland sectors. These sediments were deposited as part of the Great American Carbonate Bank, a non-uniformitarian, continent-scale carbonate platform developed on the peneplaned craton. Measurement and description of a bed-by-bed composite section through the Durness Group provide a high-resolution reference framework that integrates conodont biostratigraphy, chemostratigraphy and sequence stratigraphy, including correlation with the Sauk megasequence and its subdivisions. The Sauk II–Sauk III sequence boundary marks the base of the group. The top of the group is faulted against rocks of the Moine thrust zone, generated by the Scandian orogeny, but sedimentation was probably terminated by the earlier Grampian arc–continent collision at 470–469 Ma. The highly mature quartz arenites of the underlying Ardvreck Group (Cambrian Series 2) indicate that there was no source-to-sink depositional continuity from the Hebridean foreland to the Dalradian Supergroup, which has coeval clastic sedimentary rocks of contrasting composition.

The early Cretaceous sand intervals of Lower Goru Formation (LGF) are significant reservoir for hydrocarbons and are situated in study area of Sawan gas field, Middle Indus Basin, Pakistan. This integrated study focuses on the development of stratigraphic traps and reservoir geometries in paleo-depositional environment through sequence stratigraphic and diagenetic analysis of productive Lower Goru sandstone. The datasets of well-logs from five wells (Sawan-1, Sawan-2, Sawan-3, Judge-1, and Nara-1), core samples from two wells (Sawan-1 and Sawan-2) and 2D seismic section (line: PSM96-133) are used in this study. The key system tracts including lowstand, transgressive, and highstand system tracts are identified with several progradational and retrogradational parasequences. The bounding stratigraphic surfaces are identified as sets of onlaps and downlaps unveiling different episodes of rise and fall in sea level with different sedimentation conditions. A depositional model is generated to map the paleo-environment of the reservoir by integrating the results of stratigraphic analysis. The log trends and seismic stratigraphic analysis showed the thickening trend of productive C-sand interval towards the eastern direction followed by gradual thinning in the middle part and shale-out trend towards the south and west part of the area. This indicates that the paleo-depositional direction was from east to west in shallow marine settings. The petrography and diagenesis results reveal that reservoir sands are iron chlorite-cemented sublitharenites to lithic arenites. The porosity and permeability of the reservoir is preserved due to a high amount of early diagenetic pore-lining iron chlorite, which commonly coats the surface of the quartz grains. The facies depositional environment is a wave dominated lowstand shelf edge delta system in which proximal delta front sands constitute the best reservoir. The outcomes of this research hold significant promise for advancing the comprehension of diagenetic processes and their influence on reservoir properties within the Lower Goru sandstone and its surrounding regions.