Solid Earth Sciences最新文献

Water utilization for different human activities is universally crucial, but it is not readily available for consumption in some areas, such as the central parts of Lagos State, Nigeria. Moreover, there are many groundwater controlling factors (GWCFs) spanning geological, geophysical, and hydrological factors that contribute to this scenario, coupled with uncertainties that necessitate their careful selection using appropriate modelling techniques. In this study, the Dempster–Shafer Theory of Evidential Belief Function (DST-EBF) model (a coupling approach) was deployed to produce a groundwater prospectivity zonation (GWPZ) map for the study areas. The choice of the selected locations was informed by the continued dearth of water supplies, necessitating the need to discover new locations or re-appraise the existing ones for groundwater resource development. Furthermore, remote sensing, geological, field geophysical, and hydrological datasets that constituted GWCFs were integrated into a Geographic Information System (GIS) environment. Next, the computed values for the evidence of the mass functions (i.e., belief, disbelief, uncertainty, and plausibility) were combined using the Dempster–Shafer combination rule and then interpolated using the Inverse Distance Weighted (IDW) method. Subsequently, the GWPZ map was generated and classified into five zones, ranging from very low to high prospectivity zones. The GWPZ map was validated using cross-validation to estimate statistical errors, the receiver operating characteristic (ROC) curve, and the use of inverted resistivity models from the 2D electrical resistivity imaging surveys. All the metrics used for the validation provided good account for the classified GWPZ map. The north-eastern and the south-central parts are the most promising regions for groundwater, which could be harnessed for sustainable development through borehole drilling. Thus, the integration of the DST-EBF model and GIS for effective groundwater resources and uncertainty mapping was quite successful and impressively reliable.

The polyphase deformation features and detachment faults on the northern (Gumusler) and southern (Camardı) borders of the Nigde Massif rocks, as well as the structures developed as a result of these faults, are investigated in this paper. The Nigde Massif in the studied areas is basement Palaeozoic–Mesozoic metamorphic units. The Late Cretaceous Uckapılı granodiorite and Sineksizyayla meta-gabbro introduced the Nigde massif. These units are overlain unconformably by Late Cretaceous-Quaternary rocks. The metamorphic rocks on the massif's southern edge underwent 5-phase ductile deformation, whereas the metamorphic rocks on the northern margin underwent 3-phase folding. Both the northern and southern edges include post-Middle Eocene extensional detachment features. These are most likely extensional detachment faults related to the massif's uplift. Central Anatolia is still under an extensional tectonic regime today. Therefore, detachment fault activity and occurrence continue. A large portion of the low-angle normal faults shows an extensional detachment feature. The detachment faults identified north and south of the study area are also active today.

The scarcity of the early Precambrian geological record limits our comprehension of crucial information concerning interactions between the crust and mantle, mechanisms involved in subduction zone arc-continental collisions, as well as patterns of mantle enrichment and crustal growth during this epoch. The Dengfeng terrane in the North China Craton provides significant data on Precambrian crustal evolution, particularly within the Neoarchean magmatic suites. Our study focuses on a variety of basic rocks across several locations in this region. Basic rocks from Huishansi and Sanhuangzhai (2558–2525 Ma) exhibit characteristics such as low SiO₂ (45.44–56.54 wt%), K₂O (0.77–2.7 wt%), Na₂O (1.66–4.51 wt%), and high MgO (4.66–11.22 wt%) and FeO_T (8.17–13.77 wt%). Similarly, basic rocks from Shipaihe and Guojiayao (2480 Ma) also display low SiO₂ (46.16–52.48 wt%), K₂O (0.24–1.28 wt%), and Na₂O (1.87–3.75 wt%), with FeO_T (1.07–2.31 wt%), but feature higher content of MgO (5.33–8.83 wt%) and Mg^# (44–62, averaging 53). Both sets exhibit relatively flat REE patterns and weak negative anomalies in Nb, Ta, and Ti, corresponding to a tholeiitic basalt composition for the protoliths. Analyzing low (Hf/Sm)_N, (Nb/La)_N, and Th/Yb ratios, coupled with depleted HFSE, suggests potential crustal contamination in the rocks from Huishansi and Sanhuangzhai. Further, based on low V/Sc ratios (5.38–10.27, average 7.02) and depleted zircon Ɛ_Hf(t) values, our proposition is that the magma was sourced through partial melting of a depleted and relatively reduced mantle source. These findings offer valuable insights into the tectonic evolution of the Dengfeng terrane, spanning from subduction to post-collisional extension.

In the southern part of the Siberian platform, a new genetic type of lithium mineralization was discovered in the Lower Cambrian halogen-carbonate formation of the Angara-Lena marginal trough, which arose as a result of the introduction of a fluid-saturated solution into the sedimentary cover of the platform. Focal hydrothermal development of halogen-carbonate deposits along deep faults led to the formation of lithium-bearing mineralization. A gradual reduction in tectonic activity within the Angara-Lena marginal trough was accompanied by the subsidence of hydrothermal-sedimentary deposits. In this case, the precipitated substance was dispersed and later transformed into layers. It has been established that the main lithium minerals are hectorite and lithiophorite. The results of a study of lithological and geochemical associations of rare earth elements in sections of Early Cambrian deposits of the studied lithium mineralization are presented.

Litho-stratigraphic characterization within hydrogeological units of a major aquifer system in Southern Nigeria was carried out using Electrical Resistivity (ER), Stratigraphic Modified Lorenz Plots (SMLP), and Flow Zone Indicator (FZI) algorithms. The aim of integrating these technologies was to generate hydraulic flow units (HFU) that would describe the speed of flow and efficiency within the aquifer's stratigraphic units. Electrical Resistivity technology delineated four geoelectric layers within the study area: motley topsoil, coarse sand, fine sand, and sandy clay, with the aquiferous formation being the third layer. Via measures obtained from geo-electrical data, major geo-hydraulic parameters were estimated. The hydraulic conductivity ranged from 3.1 x 10⁻⁵ to 9.3 x 10⁻⁵ m/s, effective porosity ranged from 0.33 to 0.54, permeability ranged from 4362.9 to 13143.4 mD, tortuosity ranged from 0.85 to 0.97, Aquifer Quality Index (AQI) values ranged from 3.57 to 4.88 and Flow Zone Indicator values ranged from 4.11 to 7.00. The Stratigraphic Modified Lorenz Plots delineated the presence of three hydraulic flow units within the region. The first hydraulic flow zone was a superconductor with good efficiency ranking; the second and third flow zones were conductors having fair efficiency rankings. Results obtained from measures of Aquifer Quality Index (AQI) were employed to generate Discrete Rock Typing (DRT) results which indicated the presence of two distinct aquifer rock matrix types. The Dykstra-Parson co-efficient, employed in evaluation of aquifer heterogeneity, gave a value of unity, indicating perfect heterogeneity of the aquifer.

The formation of continental red beds is generally considered to be related to an arid climate. Heating experiments (performed by L.J. and G.C.) using dried black mud sediment also demonstrate that the reddening may be caused by the transformation of goethite to haematite that begins at approximately 150 °C under anhydrous conditions, and increasing the temperature to 450 °C is positively correlated with the red colour and peak value of haematite. If this process applies to continental red beds, it implies a thermal origin of red beds as a result of high diagenetic temperatures rather than as the cause of their deposition under an arid climate. Namely, subsiding red-bed basins are heated from below rather than warmed from above. Here, we further strengthen this idea by new evidence from borehole cores drilled from red beds in SE China, showing a clear geological section from the surface soil to red beds to bottom granite. The data reveal that the continental red beds formed at least at a temperature within 150–400 °C, and the underlying granite usually formed at temperatures greater than 600 °C. Our results imply a possible relationship between continental red bed events and Earth's thermal cycles.

The sediments from the Mayo Oulo intracontinental Basin, along the N–S cross section between the Gadavou and Lombel localities in central part of the basin, were investigated through major and trace elements geochemistry associated with palynological analysis to determine their condition of sedimentation, paleoclimate evolution and metallogenic implication along the Cretaceous sequence from the N–S cross section of the central part of this basin. From bottom to top of this sequence there are various types of facies with various concentrations of carbonate. Based on their major oxides compositions, the sediments were classified as Shales associated with Fe-shales, Fe-sands, Wacke and Litharenite. The CIX (Chemical Index of Alteration, 62.65 to 98.14) and PIX (Plagioclase Index of Alteration, 65.00 to 99.13) sediments underwent a various chemical weathering; little chemical weathering in the middle to the upper part of the sequence and moderate to high chemical weathering in the lower part. The discriminant function-based multidimensional tectonic diagrams indicate mainly and respectively arc-collisional and Island arc-active continental margin settings which are consistent with the Precambrian geological history of the study area. The SiO₂ vs. Al₂O₃+K₂O + Na₂O, C-values, associated with trace elements plots such as Sr/Ba, and Rb/Sr, and palynological content (continental or terrestrial species exclusively, dominated by Gymnosperm pollens such as. Inaperturopollenites sp., Araucariacites sp. and Classopollis sp, associated with spores such as Cicatricosisporites sp) indicate mainly arid to semi-arid climate with periodic humid to semi-humid conditions. The Sr/Ba values ranging from 0.084 to 6.408 suggest a fluctuating and sometimes high salinity (Hypersaline milieu). The rare earth elements data show high LREE/HREE ratios (2.86–13.31); high negative and positive Eu anomaly (Eu/Eu∗ = 0.33 to 1.38) and no Ce anomaly (Ce/Ce∗ = 0.94 to 1.02); these features, together with mixed major and trace element ratios and plots such as, Al₂O₃/TiO₂ ratios (14.31–54.26); Th/Co ratios (0.30–14.58); Ce vs La/Yb, Zr vs TiO₂ and La/Sc vs Th/Co plots, indicate that the sediments are derived mainly from felsic to intermediate or mafic rock composition. Ni/Co (1.86–3.59) and U/Th (0.03–0.76) ratios are consistent with oxic conditions from bottom to top of the sequence. The Al/Si ratio shows positive correlation with CIA, Th, Zr, Hf, Na, K and negative correlation with Ca and Mg. The positive correlation with K, Hf, Na, Zr, and Th from detrital origin and negative correlation with Ca and Mg from chemical origin could suggest the geochemical composition control of grain size. According to the ternary Al–Fe–Mn diagram metallogenic classification, the studied samples are essentially terrigenous and partially weakly metalliferous, clos