Main Lithological Units Research Articles

Updating Geological Information about the Metallogenesis of the Iberian Pyrite Belt

The Iberian Pyrite Belt (IPB) represents one of the largest districts of volcanogenic massive sulfide (VMS) deposits in the world, and is a critical source of base metals (Cu, Pb, and Zn) for Europe. Confirmed resources exceed 1700 Mt of massive sulfides with grades of around 1.2% Cu, 1% Pb, and 3% Zn as well as more than 300 Mt of stockwork-type copper mineralization. Significant resources of Sn, precious metals (Au and Ag), and critical metals (Co, Bi, Sb, In, and Se) have also been evaluated. The genesis of these deposits is related to a complex geological evolution during the late Devonian and Mississippian periods. The geological record of such evolution is represented by three main lithological units: Phyllite–Quartzite Group, the volcano–sedimentary Complex (VSC), and the so-called Culm Group. The sulfide deposits are located in the VSC, associated with felsic volcanic rocks or sedimentary rocks such as black shales. The massive sulfide deposits occur as tabular bodies and replacement masses associated with both volcanic and sedimentary rocks. Their mineralogical composition is relatively simple, dominated by pyrite, chalcopyrite, sphalerite, and galena. Their origin is related to three evolutionary stages at increasing temperatures, and a subsequent stage associated with the Variscan deformation. The present paper summarizes the latest developments in the IPB and revises research areas requiring further investigation.

Cryogenian-Ediacaran crustal growth and evolution of the active margin of the Dahomeyide belt, Ghana

AbstractThe study presents detailed petrographical, geophysical, structural and geochemical data of the internal nappes zone to establish the deformational history, origin and tectonic setting and constrain the crustal growth and evolution of the active margin of the Dahomeyide belt. Two main lithological units, (i) deformed meta-granitoids (migmatites and gneisses) and (ii) undeformed granitoids, dominate the internal nappes zone. The granitoids are generally I-type, metaluminous to weakly peraluminous, low-K tholeiite to high-K calc-alkaline and of tonalite, granodiorite and granite affinity. The overall trace element patterns of the studied granitoids characterized by the enriched LILE and depleted HFS, with negative peaks of Nb-Ta, Sr, P and Ti, are indications of arc-related magmatism. Structural analysis reveals four deformation phases (D1-D4). D1 represents Northwest-Southeast (NW-SE) Pan African shortening associated with a continent-continent collision, resulting in westward nappe stacking. Progressive NW-SE shortening resulted in D2 and D3 top-to-the-NW dextral and sinistral thrusting events during the Pan-African orogeny. D4 is an extensional event likely associated with the orogenic collapse phase. The gneisses and migmatites, with dominant axial planar foliations, point to their formation in a collisional setting or influence by the Pan-African collisional processes. Continental-arc signatures in these rocks imply continental subduction during their protolith formation. The intrusive granitoid and pegmatite are undeformed, meaning late- to post-orogenic emplacement. These findings suggest that the internal nappes zone archived the subduction-collision and post-collisional phase of the Pan-African orogeny and recorded large-scale migmatization and granitoid emplacement due to partial melting of thickened lower crust between Mid-Cryogenian and late Ediacaran.

Environmental and Human Impact on Gully Erosion Recorded in Fan Sediments: A Case Study of the Vilnius area, Lithuania

Abstract Geomorphological and sedimentological research carried out in the vicinity of Vilnius (SW Lithuania) aimed to determine the age and stages of development of gullies in relation to climatic conditions and human activity. Two gullies located on the northern slope of the Vilnia river valley were examined in detail. The sedimentological features of the sediments which form fans at the mouths of the gullies were analysed. Three main lithological units were distinguished. On the basis of radiocarbon datings, the beginning of gully erosion was determined to be in the Middle Ages. This process began with intensive settlement in this area. Further stages of a cutting which were distinguished include early modern times and the period from the seventeenth century to the present day.

Geological and energy potential analysis of Küplüce-Gökçesu basin rich in coal and other potential energy resources

The Küplüce-Gökçesu Basin, located in northwestern Anatolia, is an Eocene-aged shallow marine basin known for its rich carbonaceous sediments. The basin is underlined by Paleozoic metamorphic rocks, granites from the Sakarya Massif, and Jurassic-Upper Cretaceous turbiditic and carbonate rocks. The sedimentary deposits in the basin consist of two main lithological units, namely, the Tokmaklar and Sazlar Formations. The Tokmaklar Formation comprises marl, bituminous marl, clayey bituminous limestone, Nummulite limestone, and marl-clay-sandstone successions. Economic coal formations are found at the base of the Tokmaklar Formation, along with bituminous limestone and marl. The Sazlar Formation is composed of thick layered sandy limestones and marls, deposited in reefal conditions. Previous studies conducted in the 1980 s estimated the coal reserves in the Küplüce-Gökçesu Basin to be around 40 million tons. However, this study reveals the discovery of a new coal seam that was not previously identified, with a potential thickness of approximately 11 m. This discovery suggests that the coal reserves in the region could be significantly larger than previously known, potentially 5-6 times greater. The quality of the Küplüce-Gökçesu coals is classified as semi-bituminous hard coal of the lower bituminous coal group, based on chemical analysis results. This study contributes to the understanding of the geology and coal potential of Eocene basins in Anatolia and provides valuable information for future exploration and exploitation activities.

Lithology mapping with satellite images, fieldwork-based spectral data, and machine learning algorithms: The case study of Beiras Group (Central Portugal)

Geological remote sensing has been an invaluable means to obtain data to perform geological mapping objectively and with high accuracy. However, there is a significant gap in geological cartography information at 1:50 000 scale throughout the territory in mainland Portugal. The lack of geological mapping is reflected in the geological resources and land management information. This investigation’s main objective was to assess the viability of using remote sensing, machine learning and geochemical techniques as proof of concept for the Portuguese context using the Beiras Group (mainland Portugal) as a case study area of 341 km2. Multispectral analysis was carried out in two Landsat-8 images of 2015, one in the winter and the other in the summer. Hyperspectral data were obtained using a 400–1000 nm spectroradiometer applied to 23 rock samples collected in two field campaigns – the first in January and the second in April 2019. Spectral differences were found distinguishing the two main lithological units, where the granites (Granito de Coentral and Granito de Vila Nova) had an increasing wavelength spectra shape throughout the whole VNIR measurements. Geochemical data was carried out using X-ray Fluorescence, where the average quantity of major elements such as Na2O [2.15 %] and CaO [0.41 %] was higher in granites than metasediments: 0.38 % and 0.11 %, respectively. The J48 machine learning algorithm was performed using as input Landsat-8 reflectance data which showed a high success rate in both confusion matrixes (83,72 % and 94,08 %).

Lithostratigraphy, Origin, and Geodynamic Setting of Iron Formations and Host Rocks of the Anyouzok Region, Congo Craton, Southwestern Cameroon

In Cameroon, most of the iron formation occurrences reported are found within the Nyong and Ntem Complexes. The Anyouzok iron deposit is located in the Nyong Complex greenstone belts, which represent the NW margin of this Congo craton. The main lithological units comprise the iron formations (IFs) unit, consisting of banded IFs (BIFs) and sheared BIFs (SBIFs), and the associated metavolcanic rocks unit consisting of mafic granulite, garnet amphibolite, and biotite gneiss. Within the Anyouzok area, BIFs are rare, while SBIFs are ubiquitous. This study reports the petrography, mineralogy, and whole rock geochemistry of IFs and interbedded metavolcanic rocks of the Anyouzok iron deposit. The abundance of cavities, higher Fe contents (49.60–55.20 wt%), and strong Eu anomalies (Eu/Eu* = 2.14–3.17) within the SBIFs compared to the BIFs suggest that SBIFs were upgraded through post-depositional hydrothermal alteration activities. REE signatures indicate the contribution of both seawater and hydrothermal fluids during BIFs precipitation. Mafic granulite and garnet amphibolite protoliths were derived from the partial melting of a metasomatized spinel lherzolite depleted mantle source. The overall compositional variations of the Anyouzok IFs and interbedded metavolcanic rocks endorse an Algoma-type formation deposited in the back-arc basin under suboxic to anoxic conditions.

Numerical Groundwater Flow Modeling of the Megech River Catchment, Tana Sub Basin, North Western Ethiopia

The study area is found in Amhara Regional State, North Gondar Administrative Zone, Gondar town and surrounding Keble of river catchment. It’s total area coverage is 785 km 2 with main lithologic units of lacustrine deposit, Middle Basalt (Aiba) and Upper basalt (Alajie).Numerical Groundwater Flow Modeling of the Megech River Catchment, Tana Sub Basin is conducted with the objective of simulating the groundwater flow system of the area and to evaluate the response of the hydrogeological system under different stress, so that the resulting consequence on the system can be estimated.The calibrated statistics of the model area with Mean Error (ME) of 4.8, Absolute Mean Error (AME) of 4.9, and Root Mean Square Error value of 6.8 (RMSE), which is an indicator of good calibration. The sensitive parameter of the model was identified during calibration process. Based on this, hydraulic conductivity and recharge is sensitive in RMSE than River Conductance values. The simulated water budget at steady state condition of Megech river catchment is analyzed. The simulated inflow of the model is 1.0703551E+06 m 3 /day which is equal to simulated outflow 1.0703559E+06 m 3 /day with difference -7.9617882E-01(-0.79617882) m 3 /day. The groundwater system of Megech Catchment total withdrawals of the well is 1.78853E+04m3/day. Scenario analysis was conduct in recharge decreasing and increasing of withdrawals rate. Keywords: calibration, water budget, simulation, Scenario, steady state, numerical groundwater flow modeling, sensitive, Tana sub basin, Megech River, groundwater withdrawal. DOI: 10.7176/JEES/12-6-01 Publication date: June 30 th 2022

Geology and Structural Studies of Precambrian Basement Rocks Around Mahuta, Zuru Schist Belt, Northwestern Nigeria

The study of geology and structures in part of Zuru schist belt northwestern Nigeria was aimed at understanding the rock units, mineralogy, structural configuration, distribution and deformation. This was achieved through lineament analysis, petrographic study and structural analysis (geometric, kinematic and dynamic). Lineament analysis revealed the distribution, relative abundance and orientations of linear-curvilinear features. Three (3) main lithologic units were revealed; medium-grained granite, quartz-mica schist, and quartzite while minor ones are quartz vein, quartzofeldspathic pegmatite and aplitic dyke; this was arrived at because of minerals assemblages like quartz, feldspars, biotite, and muscovite. Structural analysis revealed the presence of normal fault, strike-slip fault and systematic joint (orthogonal). The joints trend is dominantly NE-SW, N-S, E-W. The normal faults reveal maximum principal stress (σ1) orientation in 087, the intermediate stress (σ2) was oriented in 222 while the minimum stress (σ3) was oriented in 312 directions. The kinematic axes revealed from the fault data are P-axis (Compressional) is 87/087; B-axis (Tensional) is 02/222 while T-axis (Transpressional) is 02/312. The component of deformation of the normal fault is elongated by 10-30 cm, while the vertical deformation effect is neutral. The area experienced multiple phases of deformation. The study will aid in mineral exploration.

Microfacies analysis and reservoir discrimination of channelized carbonate platform systems: An example from the Turonian Wata Formation, Gulf of Suez, Egypt

The channelized carbonate reservoirs played important role in the global hydrocarbon production. This study presents a new contribution to the carbonate platform system of the Turonian sediments in the Gulf of Suez. The siliciclastic fluvial channelized system incised the carbonate platform in October Field to deposit excellent reservoir unit. Also, the study interprets the facies change, depositional environment, and petrophysical characteristics of the Turonian Wata sequence, to figure out the fluvial channel reservoir distribution and discrimination using surface outcrops in addition to five cored wells. The petrographic analysis and depositional settings interpretations were conducted to the subsurface and outcrop samples. Then, the conventional core analysis measurements were combined with borehole logs for optimum reservoir discrimination, rock typing, and flow units interpretation. Besides, we studied the reservoir heterogeneity and predict permeability and reservoir rock typing in the un-cored intervals. Our finding revealed that the Wata Formation is subdivided into three main lithological units characterized by 16 microfacies. The lower and upper ones are carbonate dominated, composed of wackestones, packstones, and grainstones which is deposited in platform setting belong to lower/middle shelf and mid/outer shelf to outer ramp setting respectively. The middle unit is classified into lower and upper zones, where the lower clastic zone is composed of vari-sized sandstones, siltstone, and mudstone with some plant remains deposited in a point bar of fluvial channel and flood plains. The upper zone is composed of clastic/carbonate intercalations deposited in intertidal/shelf settings. The integration between the petrography and petrophysics enables discriminating the Wata sandstone reservoir into four static rock types (PSRT 1–4), which are controlling its reservoir quality and heterogeneity. The PSRT1 and PSRT2 have the best reservoir quality in the channelized unit and are recommended to be tracked along with October Field. The HFU2 and HFU3 are the main flow capacity in the Wata reservoir, composed of PSRT1 and PSRT2, and represented by the calcareous and ferruginous quartz arenite microfacies. This study presented a secondary dolomitized microfacies with 85% oil potentiality resulted from the incision of the fluvial channel above the aerially exposed carbonate lower unit. The research addressed the optimized petrophysical properties and reservoir heterogeneity of the channelized Wata sequences. In addition, it highlights a guidelines for further exploration and production of these reservoirs in the basin.

Geology and mineralogy of sapphire-rich metasomatites (sapphirites) deposit at the Portezuelo de Pajas Blancas, northern Chile: Genetic implications for unusual metasomatic processes in the Central Andes

The Portezuelo de Pajas Blancas deposit, located in northern Chile, represents a unique opportunity to constrain unusual geological processes involved in the genesis of sapphire-rich metasomatites in the central Andes. For this purpose, geological mapping was combined with conventional and high-resolution petrographic and mineralogical analysis (light microscope, SEM-EDS and automated mineralogy). Results demonstrate that this uncommon occurrence is genetically related to eight main lithological units that host variable proportions of corundum (sapphire), sillimanite, andalusite, diaspore, böhmite, dravite, magnesiofoitite, olenite, alunite, and calcite. Microtextural relationships between mineralogical assemblages demonstrate that the origin of this deposit was associated with two main genetic stages. The early stage is linked to the initial crystallisation of abundant sapphire, promoted by an extreme desilication during high-temperature prograde metasomatic processes due to the intrusion of a Cretaceous granodioritic magma body (Si-Al-rich) into basaltic rocks from the La Negra Formation (Al-rich Si-poor) through the Atacama Fault System. The late-stage corresponds to hydrothermal alteration of sapphires to böhmite and diaspore in the deep and shallow zones, respectively, where dravite and alunite were precipitated directly from these fluids. The formation of this late hydrothermal assemblage can be interpreted as an overprinting of a metasomatic retrograde system. This study demonstrates that the sapphire-bearing rocks at Portezuelo de Pajas Blancas correspond to primary metasomatic sapphirites related to middle- to high-temperature contact metasomatism at estimated pressures of ∼ 2 kbar.

PGE distribution in Merensky wide-reef facies of the Bushveld Complex, South Africa: Evidence for localized hydromagmatic control

ABSTRACT The wide-reef facies of the Merensky Reef in the eastern part of the western lobe of the Bushveld Complex was sampled in order to better resolve otherwise spatially constrained variation in highly siderophile elements across this geological unit. The platinum group element mineralogy and whole-rock highly siderophile element concentrations were measured across two vertical sections in close proximity. In one section, the Merensky Reef unit was bound by top and bottom platinum group elements-enriched horizons (reefs) with a well-developed pegmatoidal phase in the top third of the intrareef pyroxenite, but with neither a top nor a bottom chromitite present. The other drill core section featured a thin (<1 cm thick) chromitite layer associated with the highest platinum group element concentrations of any rock in this study as the bottom reef, but with a chromitite-absent top reef, and very poor development of the pegmatoid. Primitive mantle-normalized profiles of the main lithological units show relatively flat, primitive mantle-like highly siderophile element abundances (Cr, V, Co, Ni, platinum group elements, Au and Cu) in the Merensky pyroxenite, with modest depletion in Ir-affiliated platinum group elements. The platinum group element-rich top and bottom reefs, and the pegmatoidal upper pyroxenites, display characteristic enrichment in the Pt-affiliated platinum group elements and undepleted Ir-affiliated platinum group elements. The leuconoritic hanging wall and footwall rocks show comparable highly siderophile element profiles, distinguished from one another by relative depletion in the Pt-affiliated platinum group elements of the footwall samples. The vertical variation in highly siderophile element abundances through both sections is characterized by low platinum group element abundances through the lower reef pyroxenite, with platinum group element, Au, and Cu ± Ni concentrations increasing through the upper pegmatoidal pyroxenite, and main enrichment peaks at the top and bottom reefs. Significant localized (centimeter-scale) zones of chalcophile metal depletion are present immediately above the top reef and below the bottom reef. In addition, a wider zone of Pt-affiliated platinum group elements (with Pd more depleted than Pt)-depletion was identified within the pegmatoidal pyroxenite around one meter below the top reef. The platinum group element mineralogy of the bottom reef consists mainly of platinum group element sulfides, with minor arsenides and antimonides. In contrast, the platinum group element mineralogy of the top reef, and the small amount of data from the intrareef pyroxenite, mainly consist of Pt-affiliated platinum group elements-Bi-tellurides. The Pt-sulfides are mainly equant, relatively coarse crystals (many grains between 50 to 100 μm2 area), contrasting with the Pt-affiliated platinum group elements-Sb-As and -Bi-Te minerals that tend be high aspect-ratio grains, occurring in veinlets or as rims on earlier-forming platinum group element phases. These Te-As-Bi-Sb compounds are closely associated with chlorite, actinolite, quartz, and chalcopyrite, consistent with secondary deposition at lower temperatures and association with aqueous fluids. A model is proposed involving the emplacement of the Merensky unit as a magma pulse into at least semi-crystallized host rock, followed by aqueous fluid saturation and local migration, combined with concentration of late magmatic fluids around the top and bottom contacts of the magma pulse. Late remobilization of Pt-affiliated platinum group elements from the zones immediately (centimeter-scale) above the top reef, and from the underlying meter or two of pyroxenite, and from the centimeters underlying the bottom reef, have added additional platinum group elements to the reefs as late platinum group elements-Te-As-Bi-Sb minerals, independent of whether or not chromite is present in the reef initially.

Crustal Structure of the Seismogenic Volume of the 2010–2014 Pollino (Italy) Seismic Sequence From 3D P- and S-Wave Tomographic Images

A tomographic analysis of Mt. Pollino area (Italy) has been performed using earthquakes recorded in the area during an intense seismic sequence that occurred between 2010 and 2014. 870 local earthquakes with magnitude ranging from 1.8 to 5.0 were selected considering the number of recording stations, the signal quality, and the hypocenter distribution. P- and S-wave arrival times were manually picked and used to compute 3D velocity models through tomographic seismic inversion. The resulting 3D distributions of VP and VS are characterized by high resolution in the central part of the investigated area and from surface to about 10 km below sea level. The aim of the work is to obtain high-quality tomographic images to correlate with the main lithological units that characterize the study area. The results will be important to enhance the seismic hazard assessment of this complex tectonic region. These images show the ductile Apennine platform (VP = 5.3 km/s) overlaying the brittle Apulian platform (VP = 6.0 km/s) at depth of around 5 km. The central sector of the area shows a clear fold and thrust interface. Along this structure, most of the seismicity occurred, including the strongest event of the sequence (MW 5.0). High VP (>6.8 km/s) and high VP/VS (>1.9) patterns, intersecting the southern edge of this western seismogenic volume, have been interpreted as water saturated rocks, in agreement with similar geological context in the Apennines. These fluids could have played a role in nucleation and development of the seismic sequence. A recent study revealed the occurrence of clusters of earthquakes with similar waveforms along the same seismogenic volume. The hypocenters of these cluster events have been compared with the events re-located in this work. Jointly, they depict a 10 km × 4 km fault plane, NW-SE oriented, deepening towards SW with a dip angle of 40–45°. Instead, the volume of seismicity responsible for the ML 4.3 earthquake developed as a mainshock-aftershock sequence, occurring entirely within the average-to-low VP/VS Apennine platform. Our results agree with other independent geophysical analyses carried out in this area, and they could significantly improve the actual knowledge of the main lithologic units of this complex tectonic area.

Petrology and Geochemistry of Rocks of Ishiagu and Environs Southeastern Nigeria Using Ed-Xrf Method

Geochemistry of rocks of Ishiagu area was carried out using Energy Dispersive X-Ray fluorescence (ED-XRF) method. Twelve samples were analyzed and their geochemical properties determined using Excel-Software. Geological mapping reveals that basalts, dolerites and diorites emplaced in shale and mudrock country hosts are the main lithological units occurring in the area. They have silica content of 40.4–49.2wt.%, indicating they are basic-ultrabasic in character. The dolerite and diorite contain average plagioclase (An70-17.4vol.%), hematite 26.29vol.%, showing enrichment in ferromagnesian minerals and depletion in quartz. The Na2O and K2O averaged 1.22wt.% and 1.46wt.% respectively, indicating depletion in alkali, thus corroborating their basic–ultrabasic property. The TiO2 value is 3.6wt. %, indicating oceanic magma derivation. The industrial metals Pb, Cu, Ni and Zn were relatively similar with average values of 37.13, 23.96, 23.69, and 20.08ppm respectively, showing common protolith. The diorite and dolerite are enriched in trace elements Zr, Sr, with average concentration of 172.49, 109.73ppm, and relatively depleted in As and Au with values of 0.04 and 0.03ppm respectively. Petrogenetic analyses using ternary diagram TiO2–K2O–P2O5 for discriminating magma type, the dolerites and diorites all plot in continental basaltic field. In the AFM, and P2O5 versus Zr plots all the dolerites and diorites fall in the tholeiitic field, corroborating that they originated from tholeiitic basaltic magma, probably derived from lower crust/upper mantle. In the Na2O/Al2O3 versus K2O/Al2O3 diagram the dolerites and diorites all plot in the igneous field, the shale plot in metasedimentary field, while the ironstone fall on the boundary between igneous and metasedimentary fields indicating hybrid provenance.

Optical (visual) Kerogen assessment of Enugu Shale, Anambra Basin, Southeastern Nigeria: Implications for source rock potential and thermal maturation

Palynological analysis was carried out on Ten (10) samples from outcrops of the Campanian Enugu Formation, a component lithostratigraphic unit of the Anambra Basin, using the acid maceration techniques for recovering acidinsoluble organic-walled microfossils. Two main lithological units were encountered, which include: carbonaceous shale and siltstone. Result from kerogen laboratory examination reveals two (2) main groups of palynofacies association namely; palynofacies (A and B), based on the change in particulate organic matter constituents of organic residue extract. Palynofacies A is characterized by abundant opaques debris with common terrestrial phytoclasts, which occupy the southwestern and northwestern parts of the studied area, whereas palynofacies B dominates in the northeastern part, characterised by abundant phytoclasts followed by frequent opaques debris. Kerogen type III with gas-prone material is suggested for both palynofacies. The examined exine of spore/ pollen grain are pale yellow – yellow, with Thermal Alteration Index TAI of 1+ to 2- and Vitrinite Reflectane (R o) (0.3 % - 0.4 %) in palynofacies A, and yellow – yellow brown, with Thermal Alteration Index TAI of 2- to 2, and Vitrinite Reflectane (R o) of 0.3% - 0.5% in palynofacies B. These revealed source rock that is thermally immature to slightly mature but has potential to generate mainly gas. The kerogen data generated using transmitted light microscopy correlated well with geochemical data obtained using rock-eval pyrolysis method, and this shows the method a reliable tool for assessing petroleum potential in any given sedimentary basins.

Occurrence of some campanian-maastrichtian organic-walled microfossils from Enugu Shale, Anambra Basin, Southeastern nigeria: Implications for age and paleoenvironments

Detailed geological field mapping and sampling of the Enugu Formation in the Anambra Basin has been carried out in order to re-examine the age of sediments and reconstruct their paleoenvironments of deposition. A total of ten (10) outcrop samples of shale were subjected to palynological laboratory examination, using conventional method of acid demineralization and maceration techniques for recovering acid-insoluble organic-walled microfossils from sediments. Two main lithological units were distinguished: - carbonaceous fissile shale and siltstone. A late Campanian - Earliest Maastrichtian age was assigned based on index palynomorphs marker taxa Longapertites marginatus (overwhelming abundance), Monocolpites marginatus, Zlivisporis blanensis, and Echitriporites trianguliformis. The age designation was strengthened by the occurrence of a well-known stratigraphic age-diagnostic organic-walled microplankton Coronifera tubulosa, Senegalinium spp. and Andalusiella polymorpha. Palynomorphs of environmental value include Cyathidites minor, (a tree fern of wet, forested, tropical to temperate regions, usually most developed in mountainous / highland terrains under moist and equable climate); Spinizonocolpites baculatus/echinatus, Longapertites marginatus, Mauritidites crassibaculatus and Moncolpites marginatus, which are palm pollen that inhabit similar brackish water as the mangrove. A non-marine to marginal marine depositional setting has therefore been proposed for the Enugu Formation.

MAPPING LITHOLOGICAL AND MINERALOGICAL UNITS USING HYPERSPECTRAL IMAGERY

 Hyperspectral images such as the Earth Observer-1 (EO-1) provides an efficient method of mapping surface mineralogy because it can measures the energy in narrower bands compared with multispectral sensors. The Kirkuk anticline northern Iraq is one of the most petroleum-rich provinces. It is characterized, that is an asymmetrical, cylindrical anticline, with a fold axis trend towards North West- East, South East. The study’s primary goal is to apply satellite processing and techniques on the Eo-1 imagery for identifying lithological and mineral units at a part of Kirkuk anticline northern Iraq. The EO-1 image was corrected at the beginning of atmospheric impacts using the FLAASH module in ENVI software. Processing of (Minimum Noise Fraction- MNF) processing was applied and then it reduced the dimensionality of data, as well as, the processing of (PPI) pixel purity index was applied to spatial reduction. This study tested the potential of (spectral angle mapper supervised classification-SAM) classification for mapping the lithological and mineral units using the Hyperion imagery. three different sources of endmembers or spectra are used for SAM classifications. The one:  is done by Analytical Spectral Devices (ASD) Spectrometer. The second: reference spectra have been taken from the spectral library of USGS. Third: extracting endmembers from the purest pixels of the hyperion image, which was done by applying (MNF and PPI). The endmembers were provided, generated as the training area for SAM classification.  The present results demonstrated the great potential of data used to map the distribution of alteration of minerals and lithological units in a part of Kirkuk anticline. The classified Hyperion image shows that Jarosite and illite are the most dominant altered minerals, as well as, the main lithological units of the upper member of Fatha formation are revealed in the core of the Kirkuk anticline with scattered and small outcrops towards the flanks.

Accretion tectonics in Western Gondwana highlighted by the aeromagnetic signature of the Sergipano Belt, NE Brazil

Identification of suture zones in Precambrian orogens can be a major problem due to later reworking and/or erosion. Interpretation of aerogeophysical data is a useful tool to the understanding of the structure and evolution of old fold belts. In this study, we use aeromagnetic data to identify domain boundaries in the Sergipano Belt (SB), a Neoproterozoic orogen developed on the northern border of the São Francisco Craton (SFC), NE Brazil. The SB was formed due to convergence between the SFC and the Pernambuco-Alagoas Superterrane during the Brasiliano Orogeny, culminating in the assembly of West Gondwana. Total Magnetic Intensity (TMI) and tilt derivative maps provided the delimitation of magnetic domains corresponding to main lithological units of the Sergipano Belt and its basement and the definition of first to fourth order lineaments. Matched filter and Euler deconvolution results allowed to observe the magnetic behavior of both domains and lineaments in depth. The data suggest that the Marancó and Poço Redondo domains are two distinct lithotectonic units and that the Jirau do Ponciano dome, extreme NE of the Sergipano Belt, is likely a structural window of the São Francisco paleoplate reworked basement. Interpretation of these results combined with existent geological data allowed to highlight at least two possible terrane boundaries in the northern margin of the São Francisco Craton, represented by the São Miguel do Aleixo and Belo Monte-Jeremoabo shear zones, and the definition of the High-Intensity Magnetic Zone, which comprises a ca. 10 km wide and 140 km long corridor of mafic and ultramafic rocks, and represents the main suture zone within the SB. The data imply that the Sergipano Belt evolved as an accretionary orogen during West Gondwana assembly.

Paleoenvironment and source-rock potential of the Cenomanian-Turonian Eagle Ford Formation in the Sabinas basin, northeast Mexico

The Cenomanian-Turonian Eagle Ford Formation is a widespread organic-rich mudrock in Texas and northern Mexico. The economic significance of this unit for oil and gas production in USA has led to numerous investigations documenting its lithological and geochemical variability. Comparatively little is known about facies distribution and source rock potential of this unit in Mexico. Here, we studied a section of the Eagle Ford Formation in the central part of the Sabinas basin. In order to evaluate the lateral continuity of the Eagle Ford Formation, and more specifically to gain understanding of the paleoenvironmental drivers of organic matter deposition and the hydrocarbon source source rock potential of this unit, we combined lithological, gamma-ray spectrometric, petrographic and organic geochemical data.Vertical distribution of main lithologic units and gamma-ray signal of the Eagle Ford Formation of the studied section match those documented in several sites from Texas, with the shale-dominated, bentonite-rich succession of the lower Eagle Ford showing the higher gamma-ray values, and the limestone-dominated succession of the upper Eagle Ford exhibiting moderate-high gamma ray values. Th/K and U/Th ratios suggest that the organic-rich lower Eagle Ford was deposited mainly during a warmer and more humid period, probably related to a sub-humid regional climate phase during the Cenomanian-Turonian global warming event, and under anoxic/dysoxic marine environments. Furthermore, a higher abundance of radiolarians indicates its deposition under nutrient-rich surface water conditions induced by upwelling currents. In contrast, these ratios support a less humid climate and oxic/dysoxic conditions during the accumulation of the upper Eagle Ford. Nevertheless, fluctuations of bottom water oxygen are evidenced by the occurrence of high TOC contents and bioturbated levels. Although TOC values throughout the Eagle Ford Formation point to a poor to very good source rock potential, both equivalent vitrinite reflectance (%VReq) and Tmax values indicate that the organic matter is overmature and has an exhausted hydrocarbon generation capability.

Introduction to the cartographic and sedimentological study of the coverage of the TAHANAOUT BASIN (HIGH ATLAS, MOROCCO)

This study is carried out on the northern edge of the High Atlas of the MARRAKECH basin. The TAHNAOUT DOUAR SOUR basin belongs to the Atlasic domain which is structured by the Hercynian orogeny, taken up and elevated by the Alpine orogeny, our main goal in this studying is to map the TAHNAOUT DOUAR SOUR basin and to characterize all these geological formations, For this purpose we analysed sedimentary tectonic structures ,made lithostratigraphic sections with description and draw a geological map at scale 1/25000 on a topographic background by used MapInfo platform. As final results, our studying of the TAHANOUT basin consists of two main lithological units: the basement formed by conglomeratic and turbidite deposits (alternating sandstone and pelites), and the lithological unit that forms the cover of the TAHNAOUT basin formed by a red detrital material and, carbonate deposits in some cases depending on the deposition environment, The TAHNAOUT basin is also affected by tectonic activity at the basement and Meso-Cenozoic cover levels [1-2]. Magmatic activity is absent and no trace has been recorded.

Origin of Neoproterozoic metamorphic suites along the Western Segment of Allaqi Shear Zone, Southern Egyptian Nubian Shield

The Neoproterozoic basement complex of the western segment of the Allaqi Shear Zone (ASZ) in the extreme southern part of the Egyptian Nubian Shield comprises four main lithologic units: gneisses, amphibolites, island arc metasediments, and intrusives. In the present study, these units investigated at the outcrop scale, as well as petrographically and geochemically. Gneisses are subdivided into three types: hornblende, muscovite, and biotite gneisses. The hornblende and muscovite gneisses have para-gneissic origin, while the biotite gneiss has igneous protolith. Amphibolites have intermediate andesitic to basaltic andesite composition, with igneous origin, and were formed in island-arc environments. The metagabbros are subalkaline and have within-plate geochemical characteristics. The metasediments involve graphite-muscovite, albite, chlorite, biotite-muscovite, carbonate, and tremolite-actinolite schists, in addition to metagreywackes. The bulk chemistry of metasedimentary succession revealed their formation within active continental margin setting with pelitic to semi-pelitic and psammitic precursor. The previously mentioned lithologic units are poly deformed and intensively affected by shearing and thrusting. These structures strike in various direction: WNW-ESE, NNE-SSW, NW-SE, NW-SE, and E-W, which are consistent with the automatic and manual principal component analyses (PCA) lineament extraction.