Geochemistry and geochronlogy of granite rocks.

The construction of the beach bar sandstone in the saline lake basin is defined by four factors, water salinity, clastic input, geomorphy, and monsoon.

Clockwise P-T-t paths for Khetri (westernmost; marked by red rectangle) and Alwar sub-basins (eastern; marked by black rectangle) indicating a Grenvillian age (~1.1–0.9 Ga) orogeny were identified from the North Delhi Fold Belt. The prograde path is inferred to be high-pressure type.

The Sciadopityaceae are today a monotypic and relict family of the Coniferales, restricted to Japan with an endemic species of Sciadopitys verticillata Sieb. et Zucc., known as umbrella pine. Megafossil remains assigned to the Sciadopityaceae have been reported from various parts of the boreal hemisphere. However, structurally preserved fossil wood of the Sciadopityaceae is poorly documented. Here we present an anatomically preserved fossil wood of the Sciadopityaceae from the Jurassic of East Asia. A new fossil wood Zhangoxylon yanliaoense gen. et sp. nov. is proposed for the specimens, which are anatomically characterized by a heterogeneous pith, endarch primary xylem and special secondary xylem. The anatomical structures of the new genus are similar to those of the living Sciadopitys except for the type of radial pitting. The present specimen has an araucarian radial pitting, while that of the living Sciadopitys is abietinean. Therefore, Zhangoxylon gen. nov. from the Middle to Late Jurassic (Callovian to Kimmeridgian) in western Liaoning may represent the Sciadopitys-like petrified wood which bears pith and primary xylem. This new fossil, so far, the best-known fossil wood of the family Sciadopityaceae, sheds light on the early evolutionary history of the family Sciadopityaceae, and contributes to a better understanding of the palaeoenvironment of the Jurassic Yanliao Biota in East Asia.

The precursor limestones were tight, and the hydrothermal silicification significantly enhanced the reservoir properties of the deep carbonates and not inherited from precursor carbonates.

The image is fault-sealing evolution, which was evaluated by the structural deformation and hydrocarbon accumulation experiment. The soybean oil injection was performed at the last minute, but the injection can be performed in any fault-sealing stage. So, the image theoretically inverts the coupling relationship between fault-sealing capacity and hydrocarbon accumulation in time and space.

Magmatic activity from the Neoproterozoic through the Oligocene created dense metasomes in the lower lithosphere (green veins in the first box model). Faulting in the Mid-Miocene facilitated the creation and release of dense lithospheric drips, which then sank into the underlying mantle and began melting. This process has manifested itself on the surface via cinder cones across the YTVL, lithospheric exhumation following the release of the dense drips, and river incision through the uplifted landscape.

The Pushi area of South-west China features a large area of purple soil that formed by the weathering of Cretaceous terrigenous clastic rocks. The overall chemical weathering intensity of argillaceous rocks was slightly higher than that of sandstone, and the four profiles generally reflected medium to strong chemical weathering. The chemical weathering characteristics varied for the four profiles with different pedogenic parent rocks, which could be mainly attributed to internal factors such as the lithology of the pedogenic parent rock and external topographic factors such as altitude.

The remote affection of north-eastward extrusion of the Tibetan Plateau first arrived at the south-west of the arcuate tectonic belt during the Miocene and then spread from south-west to north-east across the arcuate tectonic belt.

Xiqianluzi Pb–Zn polymetallic deposit underwent two types of mineralization, first the Mesoproterozoic sedimentary exhalative Pb–Zn mineralization and second the Late Permian–Early Triassic magmatic hydrothermal Au mineralization.

This study provides new constraints on the dynamic setting of the Sichuan Basin during the Cambrian–Silurian using a fine interpretation of seismic profiles and strata thickness analysis. The facts that the Leshan–Longnvsi palaeo-uplift was an extensional structure and basement faults were normal faults suggest that the Sichuan Basin was in an extensional setting during the Cambrian–Silurian. Seven basement faults controlled the extensional process during the Cambrian–Silurian in the Sichuan Basin.

The Feidong Segment of the TLFZ had experienced strong sinistral strike–slip movement at the beginning of the Early Cretaceous (~143 Ma), intense extensional activity during the Early Cretaceous (135–102 Ma), and weak sinistral strike–slip at the end of the Early Cretaceous (~100 Ma).

This study concentrates on the Middle–Late Eocene ostracods from Fayoum area, Egypt. It represents an attempt to use the multivariate analyses to detect the similarity between the Egyptian ostracods and those from the southern Tethys and western Africa. The results of Principal Compenent Analysis (PCA) and Q-mode cluster analysis construct three provinces, North Africa, the Middle East, and West Africa. The strong similarity between these provinces supports the migration of ostracods along the southern Tethys during Eocene age.

Integrating the new zircon U–Pb ages of gneissic granites, published geochronological data and Nd isotopic compositions of igneous rocks from the northern Alxa Block and its vicinity, we propose that the ZHTZ, Hanshan Block, Tsaggan Uul terrane, and the Hutag Uul terrane may share a common Precambrian crystalline basement, which may constitute the Late Riphean South Gobi microcontinent.

Precambrian–Cambrian unconformity exists between the Luoquan and Xinji formations. The former comprises glacial to deglaciation deposits, and the latter is composed of shallow to coastal deposits. The provenance area of the Luoquan Formation is the North China Craton (NCC), and the provenance areas of the Xinji Formation are the NCC and the Qinling Terrane.

Foraminiferal, nannoplankton, geochemical, and sedimentological studies on the Cenozoic sediments of Kachchh Basin, India, reveals deposition within a humid, tropical, localized periodic oxic-dysoxic environment. Signals of global events like Eocene Thermal Maximum-2, Middle Eocene Climatic Optimum, and Mid Miocene Climatic Optimum are inferred and presented with facies development models.

Voyage of Ramgarh Crater.

The transition from Early to Middle Jurassic is marked by an increase in dolomitization and bioturbation but intensity decreases on the N-S transect. The pore occluding cements of the Middle Jurassic carbonates are Fe deficient, have low Sr and Mn levels as compared to the Lower Jurassic carbonates. The redox potential suggests majority of the grain supported carbonates represent early cementation under oxic-dysoxic conditions.

Based on U–Pb zircon and monazite geochronology, petrography, and fieldwork, we define a Palaeoproterozoic Khondalite Belt in NE Brazil. This belt was metamorphosed in the Orosirian and reworked in the Neoproterozoic Brasiliano-Panafrican orogeny.

Provenance of the Mesozoic-Cenozoic sediments from southern Junggar Basin were the North Tianshan and Yili-Central Tianshan regions based on detrital zircon U-Pb ages and Hf isotopes. Carboniferous–Permian intermediate-felsic rocks may be the primary uranium sources.

The present study targets the evaluation of mid-late Cretaceous rock units in the Abu Gharadig Field employing geochemical characterization data as well as generation modeling. Here, cuttings from 4 wells were assessed using TOC%, Rock-Eval pyrolysis, and vitrinite reflectance (Ro%) analyses. Also, 1D basin models were constructed for these wells to identify different stages and timing of hydrocarbon generation. Our results showed that each of Kharita and Bahariya formations have poor to fair organic richness of mainly type III kerogen that is mainly gas-prone. Moreover, Abu Roash (A/R) E, F, and G members exhibit poor to very good organic richness of mixed type II-III and type III kerogens with mainly gas and minor oil generative potential. Noteworthy, A/R B, C, and D members are non-source rocks, based on their poor organic richness and poor generation potential. The Khoman B member has poor to fair organic richness of mainly kerogen type II-III that is mainly oil- and gas-prone. On the other hand, the Khoman A has poor to good organic richness of type III, mixed type II-III, and type II kerogens with both oil- and gas generative potential. Vitrinite and Rock-Eval (T_max and Production Index) thermal maturity parameters are all indicating that the mid-late Cretaceous source rocks are mostly mature and entered the oil generation window. The burial history models demonstrated the predominance of high rates of subsidence during the Cretaceous time followed by the Syrian arc folding event during Santonian-Tertiary time forming the main trapping style in the area. The maturity and generation models implied that the A/R G source rock came into the peak of the oil generation window at a time since ~23 to ~4 m.y. Moreover, the A/R F source rock has reached the peak of the oil window since ~22 to ~7 m.y. Instead, the Khoman B source rock has entered only the early generation stage since ~28 to ~18 m.y. The transformation ratio (TR%) of these source rocks indicates that at least limited hydrocarbon expulsion (TR >25%) took place, but hydrocarbon migration to a nearby prospect is still rather unlikely due to the <50% TR. On a basin scale, our synthesis using spatial and temporal Rock-Eval data of the studied mid-late Cretaceous rock units across the Abu Gharadig basin demonstrated a spatiotemporal heterogeneity in the organic matter type and maturity. The heterogeneity can be attributed likely to changes in bioproductivity, paleo-oxygenation, water column conditions, riverine input, and sedimentation rates. These constraints were manipulated mainly by variations in paleoclimate, eustatic sea-level, and basin tectonics.

Closure model of the southern splay of the Palaeo-Tethys at the Carboniferous, Permian, Middle Triassic, and Late Triassic time. Top row: Geological evidence of the local depositional environment at each geological time. Bottom row: Palaeogeography models based on local geological evidence at each geological time. The actual palaeo-latitudes are not applied in this model to ease the explanation and understanding. The palaeo-latitudes of the Sibumasu and Indochina blocks from the Late Carboniferous to Triassic times and plate reconstruction of Late Permian (~260 Ma) served as the references.

Middle to Late Holocene palaeoenvironment reconstruction of Great Rann of Kachchh integrates ichnology, sedimentology, and geochemistry for deducing marine to brackish environment transition in the Rann sediments.

Stable C and O isotopic values derived from Molar tooth of 56 ka old Elephas namadicus fossil and 51 ka old bovids suggest the prevalence of C₄ type of vegetation in Marginal Ganga Plain during ~56–51 ka BP. This was the time when Indian Summer Monsoon was relatively weak.

The study area contains several gold-bearing quartz veins associated with hydrothermally altered zones rich in sulphides, muscovite/sericite, iron oxides, and hydrous silica. Despite the mining potential of the area, several zones remain unexplored. In this study, Aster 07XT, Landsat 8, and aeromagnetic data were integrated to detect potential zones associated with gold mineralizations in Northern Cameroon. For this purpose, the relative band absorption depth, band ratioing, and analytic signal (AS) techniques were applied to enhance, identify and map hydrothermal alteration minerals, that is, hydroxyl-bearing, iron oxide/hydroxide. Besides, a semi-automatic approach was applied to extract remotely sensed and aeromagnetic lineaments from PCI Geomatica and Centre for Exploration Targeting Grid Analysis respectively. Hence, several potential mining targets were delineated from the processing of both remote sensing and aeromagnetic data. The intersection of all region of interest pixel points from argillic (314 942), phyllic (304 740), and propylitic (327 377) alteration minerals allowed the enhancement of 1077 pixel points which represent areas where argillic, phyllic, and propylitic alteration coincide. Hence, the 1077-pixel points computed were considered potential mining sites. The extracted lineaments and 1077 potential ore deposits were superimposed on both the AS anomaly map (in purple) and the band ratio 4/2 image (iron oxides better enhanced in red with 20% transparency). We could denote that most of the 1077 potential mining sites fall either on the purple signal (representing high magnetic susceptibility areas due to magnetite, ilmenite, etc.) or on the red signal which is linked to iron-bearing minerals such as haematite, goethite, jarosite, etc. Thus, there exists a positive correlation between the 1077 potential sites and iron oxide minerals. Besides, the structural features extracted from both remote sensing and magnetic data show a positive correlation with most of the 1077 potential sites enhanced. The target hydrothermal alteration zones were proved to be spatially associated with known mining areas and gold occurrences in the study area. Consequently, new prospective mining areas have been designated. This study confirmed the reliability and applicability of the processing of satellite imagery in mineral exploration in Northern Cameroon. It is suggested that the dataset used in this study provides a suitable tool for mapping hydrothermal alteration minerals linked to gold deposits and can be applied in other provinces with similar geological settings.