Cenozoic Sedimentary Rocks Research Articles

Vilyui and Priverkhoyansk Composite Tectono-Sedimentary Elements, Northeastern East Siberia

A vast region of the Northeastern Siberia west of the Verkhoyansk Range includes two large sedimentary basins, Vilyui and Priverkhoyansk. Combined, these basins constitute the Lena-Vilyui Petroleum Province, which contains the largest gas reserves in the northeastern Asia. Both basins have a long and complex geological history that resulted in the accumulation of over 14 km-thick succession of Upper Proterozoic, Paleozoic, Mesozoic and Cenozoic sedimentary rocks. According to the volume's terminology, we subdivide this sedimentary body into two composite tectono-sedimentary elements (CTSE), the Vilyui and Priverkhoyansk (VI CTSE and PV CTSE), which closely correspond to the same-named basins. The CTSEs consist of ten distinct tectono-sedimentary elements (TSEs), each representing a distinct tectonic setting. This region has been studied very irregularly. In total, more than 400 deep wells have been drilled, mostly within the VI CTSE and only a few tens - in the PV CTSE. Eleven gas and gas condensate accumulations have been discovered in the VI CTSE. The PV CTSE remains poorly explored with only two commercial discoveries made as of the present-day.

Linking Taiwan to the Cathaysia Block during the Cenozoic: Evidence from Pb isotopes in detrital K-feldspar

The Cenozoic sedimentary rocks on the island of Taiwan hold significant implications for understanding tectonic and drainage evolutions in SE China, but the provenance of these rocks remains controversial. Here we derived Pb isotopes in detrital K-feldspars from the drainage systems in western Taiwan to evaluate the provenance of sediments and reveal the evolution of Cenozoic sedimentary. Our findings indicate that the fluvial sediments eroded from the Cenozoic sedimentary rocks were primarily derived from the eastern Cathaysia Block (91%), with minor contributions from the Yangtze River catchment. Spatially, the northern part of Taiwan contains more sediments derived from the Yangtze River catchment than the southern part. The Cathaysia Block has been crucial in supplying detritus to Taiwan since the Eocene, whereas the contribution of the Yangtze Block varies greatly at different sedimentary periods. Two major shifts in provenance occur at the boundaries between Eocene, Oligocene, and Miocene, which may be related to the changes in drainage systems and landscapes in eastern China.

Tracing uplift and erosion in orogenic settings using quartz luminescence sensitivity: Insights from the Northern Andes uplift

The optically stimulated luminescence (OSL) sensitivity of the fast component in quartz has been increasingly used in provenance analysis of Quaternary sediments. Quartz OSL natural sensitization is thought to be mainly controlled by the formation conditions of the source bedrock and surface processes occurring mainly in sediment source areas. Thus, quartz OSL sensitivity can be linked to distinct sediment source regions, based on their tectonic setting and erosion conditions. In this way, changes in quartz OSL sensitivity within siliciclastic successions would track variations in sediment provenance. So far, few works evaluated how the OSL sensitivity of quartz sand grains varies in sedimentary successions that experienced long-term cycles of deep burial, exhumation, and erosion. Therefore, this work aims to characterize the sensitivity of the fast OSL component of quartz sand grains retrieved from the Cenozoic sedimentary rocks of the Northern Andes basins and assess its spatiotemporal changes. We found that quartz grains with the lowest OSL sensitivity are sourced by crystalline and volcanic rocks related to the Andean Continental Arc emplaced in the Colombian Central Cordillera, reflecting the onset of denudation in orogenic sources during the Paleocene. Subsequently, increasing trends in OSL sensitivity are related to the sedimentary recycling during the Andean orogeny, reaching maximum values as a result of the progressive unroofing of Cretaceous rocks in the Colombian Eastern Cordillera, originally sourced from the low-relief Amazon Craton. Changes in quartz OSL sensitivity measured in the Cenozoic sedimentary basin-fill sequences of the Northern Andes vary according to the shifts in sediment provenance related to the orogenic construction and sediment recycling of the Andean range.

Fracture analysis and low-temperature thermochronology of faulted Jurassic igneous rocks in the Southern Colombian Andes: Reservoir and tectonic implications

Fractured basement hydrocarbon reservoirs are widely distributed worldwide in more than 30 basins, where volcanic and plutonic rocks have produced significant quantities of oil and gas. The Upper Magdalena Valley Basin (UMVB) is a mature and productive hydrocarbon basin located in the Colombian Andes. In this basin, plutonic and volcaniclastic Jurassic rocks are thrusted on top of Cretaceous to Cenozoic sedimentary rocks, which constitute the petroleum system. Multi-scale fracture analysis together with petrography, petrophysics, and low-temperature thermochronology were conducted in and outcrop analogue of this basement to assess the structural evolution and investigate the main factors controlling the development of fracture properties in igneous basements. Thermochronological data indicate the occurrence of three exhumation events between the Early Cretaceous and Miocene, suggesting that most of the fracture networks within the Agrado-Betania hanging-wall were likely formed before hydrocarbon migration. Structural analysis has identified a fault damage zone with a width of approximately 746 m. Volcanic breccias and ash tuffs exhibit slightly higher areal fracture intensities (P21 > 30 m/m2) compared to plutonic and clastic rocks (P21 < 20 m/m2). Furthermore, the fracture networks exhibit good connectivity, with connection per branch (CB) values exceeding the 1.5 percolation threshold. Petrophysical calculations of matrix-fracture properties indicate high permeabilities (ranging from 1000mD to 10000000mD) and low porosities (<10%). The structural position and the diagenetic transformation of the volcanic rocks are the primary factors controlling fracture intensity in the igneous rocks within the Agrado-Betania fault. Results from this outcrop analogue also show that polyphasic structural histories and the burial history positively influence the quality of fractured basement reservoirs.

The transition from backarc extension to Andean growth: Insights from geochronologic, sedimentologic, and structural studies of Mesozoic and Cenozoic sedimentary and volcanic rocks in south-central Chile (36°S)

Many studies propose a significant shift in the tectonic and paleogeographic evolution of the Andes in south-central Chile and Argentina during the Late Cretaceous. It has been proposed that the preceding Jurassic-Early Cretaceous extensional regime that resulted in a low-relief volcanic arc and the backarc Neuquén basin came to an end, giving way to shortening and Andean growth from the Late Cretaceous onward. Nevertheless, there are disagreements regarding the timing and nature of this transition to Andean orogenesis. To address these issues, we conducted geochronologic (U–Pb and 40Ar/39Ar), sedimentologic, and structural studies on Mesozoic-Cenozoic sedimentary and volcanic rocks in the Río Maule area (Principal Cordillera, Chile, 36°S). From our findings and prior analyses, we propose the following tectono-stratigraphic evolution of the region. (1) Marine deposition of the Tithonian-Hauterivian Baños del Flaco Formation took place in an extensional backarc basin. (2) After a ∼ 40 Myr hiatus, fluvial deposits of the Colimapu Formation and volcanic rocks of the Plan de los Yeuques Formation accumulated during the Cenomanian-Danian. Whereas the Colimapu Formation displays evidence of syndepositional shortening, the Plan de los Yeuques Formation exhibits synextensional growth strata. Contrary to other studies, our results suggest that the Chilean part of the Principal Cordillera was largely a zone of active deposition rather than an elevated fold-thrust belt during the Late Cretaceous. We propose that sedimentation occurred within a series of relatively stable intermontane subbasins generated by shortening, followed by extension. (3) After a ∼ 20 Myr hiatus, middle Eocene to early Miocene (Lutetian-Aquitanian) accumulation of a thick succession of andesitic lavas and minor clastic sediments of the Abanico Formation occurred in an intraarc extensional basin. (4) Finally, major shortening and uplift of previously deposited Mesozoic-Cenozoic rocks took place throughout the Neogene. This phase constituted the primary contractional deformation in the Andes of south-central Chile and Argentina. In terms of the transition to early Andean deformation, we propose that structural deformation did not generate a major, regional-scale fold-thrust belt during the late Albian-Santonian. Modest extension, tectonic quiescence, or low-magnitude shortening seem to have dominated during the early to middle Cenozoic.

Coastal Cliffs of the Rio Grande do Norte State: Geoheritage Characterization and Valorization in Northeast Brazil

The Rio Grande do Norte state, Northeast Brazil, has 410 km of coastal extension, being 107 km approximately composed of cliffs excavated in Cenozoic sedimentary rocks. In the last three decades, these cliffs are passing for transformations due the human occupation, tourism activity and climatic changes. To inventory the geoheritage present in these cliffs is essential to support management plans that include investment to conserving part of this Earth’s natural history. This paper aims to inventory, classify, assess and value the Potiguar cliffs as geological sites. From 46 outcrops that Saraiva Junior (2021) studied to describe the cliffs’ geomorphology, 20 geological sites were selected, these are used in national and international publications and divided in three frameworks: Miocene-Pliocene sedimentation, Pleistocene sedimentation and Cenozoic tectonics. These 20 cliffs were inventoried using the Brilha (2016) methodology in order to qualify and quantify the scientific value, potential educational and touristic uses and degradation risk. The Ponta do Mel, Barra de Tabatinga, Ponta dos Três Irmãos, Barreira do Inferno, Ponta do Reduto and Morro do Chapéu were defined as the most valuable cliffs on the scientific aspect. We proposed monitoring planning based on the cliff’s baselines, protection measures based on the specific threats and three geotouristic routes based on the geographic distribution of the sites and the frameworks.

Investigating the Formation of Hot-Dry Rock in Gonghe Basin, Qinghai, China

The Gonghe Basin, Qinghai Province, China, has rich geothermal and hot-dry rock resources. Through a magnetotelluric survey line with 400 points, combined with regional geology data, the deep geoelectrical structural background and thermal source mechanisms of the Gonghe Basin were explored. The results showed that (1) a deep structure with high conductivity may exist at a depth of 15 km in the basin, and could be compared to the layer-shaped, low-velocity, high-conductivity structure in the eastern part of the Qinghai–Tibet Plateau; (2) the rushing reverse fault played a crucial role in heat control and conduction from the hot field; and (3) high-temperature heat storage existed, including four layers of geothermal resources. This study proposed a triple-polymorphism model of hot-dry rock in the area; that is, the high-conductivity layer in the Middle–Late Cenozoic crust was the principal heat source; the Middle–Late Triassic granite was the essential heat-storing body, as well as a parent rock to the hot-dry rock; and the Cenozoic sedimentary rock was the effective caprock. This model is critical to understanding geothermal causes, predicting geothermal resources, and planning, on the Qinghai–Tibet Plateau.

Structural lineament mapping using remote sensing in the aures massif (ne algeria)

The Aures massif is located in the eastern part of the Atlasic Domain and formed by Mesozoic and Cenozoic sedimentary rocks. The main objective of this study is to map the structural lineaments and geologically analyze their different geometric aspects, like orientation and distribution, using remote sensing data. Another important aim is to track the extent of lineaments, understand how they integrate into the regional structure and trace the main tectonic events responsible for the Aures' structuration. Both manual and automatic approaches were employed to achieve the study's objectives. More than twelve thousand lineaments were identified, and grouped into four direction families: NW-SE, NE-SW, E-W, and N-S. Two main factors control the orientation: density and distribution of the lineaments, and topographic and geologic factors. A good correspondence was found between literature and techniques employed in this work regarding structural lineament analysis showing that the Aures lineaments result from the succession of Alpine orogeny tectonic phases. Mainly two phases were responsible on its structuration: the major Atlasic event, which occurred during the Lutetitian stage with NW-SE trending, and the Alpine which happened in late Miocene with N-S compression.

Burial and thermal history of the eastern transform boundary of the central western carpathians based on 1D basin modeling

This paper represents the first data on the thermal and burial history of Mesozoic and Cenozoic sedimentary rocks in the Maruszyna IG-1 deep borehole from the transpressional shear zone of the Western Carpathians. Representative, organic-rich mudstone and claystone samples were selected to determine thermal maturity using mean random vitrinite reflectance (Ro) and thermal alteration index (TAI) data. The reconstruction of the thermal history of fold-and-thrust units was carried out using 1D modeling. This study uniquely distinguishes various thermal maturity levels in the deep profile determined by strata repetition, different absorption of clay and carbonate mineral settings and structural thermal changes in humic particles and palynomorphs. Reflectance of autochthonous vitrinite varies from 0.77 to 1.95% indicating thermally mature to overmature organic matter. Different subsidence-uplift models were tested during modeling in order to find a plausible scenario of tectonic development and heat flow history. The thermal maturity of the individual thrust sheets was modeled separately allowing their individual thermal histories to be investigated before and after the main and final thrusting phase. The best-calibrated scenario assumes a low paleo heat flow ranging from 45 to 54 mW.m-2, affecting the eastern part of the Western Carpathians. The maximum temperature which lead to maturation of the organic matter seems to be related to its successive burial during Cretaceous due to compressional deformation. Individual thrust sheets reached thermal maturity prior to the final thrusting phase. The overthrust was accompanied by 3000–4000 m burial/erosion resulting in different thermal pathways during wedge growth.

Geology of giant quartz veins and their host rocks from the Eastern Pyrenees (Southwest Europe)

ABSTRACT Giant Quartz Veins (GQVs) are ubiquitous in different tectonic settings and, besides being often related to hydrothermal ore deposits, also represent large-scale fingerprints of the structural and geochemical history of the rocks in which they are hosted. Here we present detailed geological maps and interpretations of three key areas of the Eastern Pyrenees where GQVs are well exposed. The studied rocks record different styles of deformation and are representative of common settings of the Pyrenees where GQVs are present: pre-Variscan metasedimentary and metavolcanic rocks, late Variscan granitoids, and Mesozoic and Cenozoic sedimentary rocks. GQVs in the study areas formed along pre-existing brittle and ductile structures or at locations with lithological heterogeneities, and have alteration haloes of silicified host rocks. The geological maps and interpretations presented here contribute to gain insights into the formation mechanisms of GQVs and into the structural constraints on fluid flow and mineral reactions at different depths of the Earth’s crust.

New Insights on Subsurface Geology and the San Andreas Fault at Loma Prieta, Central California

ABSTRACT The 1989 Mw 6.9 Loma Prieta earthquake is the first major event to occur along the San Andreas fault (SAF) zone in central California since the 1906 M 7.9 San Francisco earthquake. Given the complexity of this event, uncertainty has persisted as to whether this earthquake ruptured the SAF itself or a secondary fault. Recent work on the SAF in the Coachella Valley in southern California has revealed similar complexity, arising from a nonplanar, nonvertical fault geometry, and has led us to reexamine the Loma Prieta event. We have compiled data sets and data analyses in the vicinity of the Loma Prieta earthquake, including the 3D seismic velocity model and aftershock relocations of Lin and Thurber (2012), potential field data collected by the U.S. Geological Survey following the earthquake, and seismic refraction and reflection data from the 1991 profile of Catchings et al. (2004). The velocity model and aftershock relocations of Lin and Thurber (2012) reveal a geometry for the SAF that appears similar to that in the Coachella Valley (although rotated 180°): at Loma Prieta the fault dips steeply near the surface and curves with depth to join the moderately southwest-dipping main rupture below 6 km depth, itself also nonplanar. The SAF is a clear velocity boundary, with higher velocities on the northeast, attributable to Mesozoic accretionary and other rocks, and lower velocities on the southwest, attributable to Cenozoic sedimentary and volcanic rocks of the La Honda block. Rocks of the La Honda block have been offset right-laterally hundreds of kilometers from similar rocks in the southern San Joaquin Valley and vicinity, providing evidence that the curved northeast fault boundary of this block is the plate boundary. Thus, we interpret that the Loma Prieta earthquake occurred on the SAF and not on a secondary fault.

Cenozoic deposits of western Kotel’nyi Island (New Siberian Islands): key insights into the tectonic evolution of the Laptev Sea

ABSTRACT The Arctic sedimentary basins are still poorly studied in comparison with other regions. The lack of deep wells across the eastern Russian Arctic has resulted in numerous contrasting geodynamic models for the geological evolution and age of sedimentary successions within this frontier region, where a modern mid-ocean ridge breaks through the continental crust in the Laptev Sea. The only onshore evidence of rifting processes is a number of small graben-like depressions exposed on the New Siberian Islands and along the Laptev Sea coast. We present U-Pb detrital zircon provenance and palynology study results of the Cenozoic sedimentary rocks filling graben-like depressions across western Kotel’nyi Island. Palynological data indicate that these sedimentary rocks are Early Eocene to Pleistocene in age. Based on U-Pb detrital zircon dating, Early Eocene and Late Oligocene clastic sediments were sourced from underlying deformed Palaeozoic rocks as well as by reworking of Upper Mesozoic rocks outcropping elsewhere on Kotel’nyi Island, which bear Siberian signature. Plio-Pleistocene clastic sediments were not derived from the erosion of deformed Palaeozoic rocks, suggesting the cessation of active uplift by this time and the development of a regional peneplain. Therefore, by extrapolating our onshore observations to the neighbouring offshore, we propose that graben structures imaged by seismic profiles along the eastern flank of the Laptev Rift System are likely to host Eocene and Oligocene sediments. Thus, it implies the Cenozoic extension led to formation of grabens on- and offshore in the eastern portion of Laptev Sea as early as Eocene. Further studies are necessary to evaluate the age of graben-related basins in the central and western part of the Laptev Sea.

An overview of the engineering properties of Cenozoic sedimentary rocks in Oman

An overview of the engineering properties of Cenozoic sedimentary rocks in Oman

Multistage Gold Mineralization at The Wanagon Gold Prospect, Ertsberg District, Mimika Regency, Papua Province, Indonesia

DOI:10.17014/ijog.9.3.279-290The Wanagon Gold prospect area located in the Ertsberg District, Papua Province, the eastern part of Indonesia, is predominantly underlain by Upper Mesozoic to Cenozoic sedimentary rocks intruded by the Wanagon Sill monzodiorite-diorite and andesite intrusion (Wanagon Dike). The study by previous researchers at Wanagon Gold prospect was based on pre-2005 exploration data and did not contain extensive additional drillings in 2007-2011. This paper aims to elucidate the genesis of the Wanagon Gold deposits based on the latest exploration data. The mineralogy was determined by using thin section and polish section analyses, a scanning electron microscope with an energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), and Near-Infrared spectroscopy (NIR). The chemical composition of the rock was identified using an X-ray fluorescence spectrometer (XRF). Gold mineralization is associated with pyrite, of which there are three types of gold-bearing pyrite: (1) massive pyrite, (2) disseminated pyrite, and (3) fine-grained pyrite associated with clay minerals. Only massive pyrite contains visible gold-bearing minerals such as native gold, electrum, and gold-telluride minerals, while in nonmassive pyrite, gold is only detected by the assay. The deposit is interpreted as structurally controlled distal gold skarn. Instead, its local association of gold with arsenic also indicates a minor component of more-distal sediment-hosted type gold mineralization.

Fluvial evolution in a growing thrust-fold range of the Yumu Shan, NE Tibetan Plateau

In an active thrust-fold belt, the drainage evolution, such as the alternation between transverse and longitudinal rivers, will influence the surface erosion within the range and the sedimentary sequence in the foreland basin. However, knowledge of the controls of changes in transverse or longitudinal drainage patterns in an uplifting range is limited. The Yumu Shan, on the northeastern margin of the Tibetan Plateau, is an example for a young and active thrust-fold range that shows evidence for drainage reversals since ∼3 Ma. The materials we used are the late Cenozoic depositional sequences around the Yumu Shan. Analyses of the lithology, grain size, roundness, and clast orientation of gravel deposits on the northern and southern flanks, combined with the results of cosmogenic nuclide burial dating, reveal that a transverse river, the Liyuan River, crossed the Yumu Shan range during 3.0–1.8 Ma by eroding weak Cenozoic sedimentary rocks. After 1.8 Ma, however, this transverse river was deflected and flowed along the edge of the range, and a longitudinal river developed along the back flank of the range. This process was synchronous with the exposure of resistant Paleozoic rocks by the continuous uplift of the range. After comparison with other potential controlling factors for drainage reversals, such as variations in rock uplift, climate or upstream aggradation, we find that the change in bedrock resistance was the most likely control on the change from a transverse to a longitudinal drainage pattern in this relatively young thrust-fold belt. Furthermore, through comparison with a series of active fold-thrust belts worldwide, we propose a simple conceptual model for the drainage evolution of active fold-thrust belts. In the earlier stage of the uplift, the exposed soft sedimentary rocks will cause transverse (antecedent) rivers to cross the range. After the continuous uplift of the range, resistant rocks cause the deflection of a transverse river and its change to a longitudinal river along the back flank of the range. In the final stage, after the several million years to around ten million years of uplift, with the development of a mature range, the local base level of the foreland will greatly fall, promoting a return to a transverse drainage pattern by headward erosion and capture of longitudinal rivers.

Tectonic domains in the NW Amazonian Craton from geophysical and geological data

The Amazonian Craton is one of the largest cratonic areas in the world. In Colombia, a major portion of the Craton is covered by Paleozoic to Cenozoic sedimentary rocks and recent deposits. This, in addition to the difficulty of access and dense tropical rainforest, have made the geology of this area to remain relatively unexplored to this date. Most accepted models for the Proterozoic evolution of the Amazonian Craton indicate that it evolved via successive accretion of orogenic belts and crustal terranes around an ancient nucleus, and that tectonic provinces identified in the southern half of the craton, the Guaporé Shield, extend underneath the Amazon River Basin onto its northern exposure, the Guiana Shield. Nevertheless, recent geologic studies in the W Guiana Shield indicate that its evolution may have been different from the W Guaporé Shield, where these accretionary models were formulated. In this work, we used airborne gravity/magnetic geophysical datasets covering the NW portion of the Amazonian Craton, to better elucidate its structure and tectonic evolution. We apply a multiscale edge detection and 3D modeling to identify and delineate major crustal discontinuities and other geological features. Using this approach, we identified six primary geophysical lineaments that are interpreted as possible crustal boundaries. By combining our geophysical interpretation with all the geological, geochronologic and isotopic information available for the region, we propose the presence of the following tectonic domains: Ventuari-Tapajós, Rio Negro-Juruena (which we further subdivide into Atabapo and Vaupés Belts), Apaporis Graben, and Putumayo. Furthermore, a new U-Pb zircon crystallization age of 1227 ± 8/13 Ma obtained from volcanic rocks of the Piraparaná Formation indicates that extensional tectonics along the Apaporis Graben began at least in the late-Mesoproterozoic. This is significantly older than previously thought, and thus entirely transforms the tectonic significance of the Apaporis Graben structures. Our interpretation of structural limits is in excellent agreement with and provides a more accurate location for previously suggested boundaries, which were until now only loosely constrained by the sparse geological and geochronologic information available. This work provides the first regional reconstruction of crustal-scale features of NW South America, improving the understanding of the regional tectonic architecture of NW Amazonian Craton using geophysical methods.

Exploring Causal Relationships for Geoheritage Interpretation \u2014 Variable Effects of Cenozoic Volcanism in Central European Sedimentary Tablelands

Modern conceptual approach to geointerpretation and geoeducation emphasizes the holistic understanding of the environment and attends to linkages between various abiotic, biotic, and cultural components. In this paper, we highlight multiple relationships between Cenozoic volcanism and host sedimentary rocks, mainly sandstones of Cretaceous age, which can be explored in the context of geotourism and geoeducation in several Central European geoparks (Bohemian Paradise UNESCO Global Geopark, Land of Extinct Volcanoes Aspiring Geopark, Ralsko National Geopark) and their surroundings. These include the effects of magmatism on sandstones, with further consequences for landform development at different spatial scales, the origin of mineral resources, underpinning of biological diversity, and specific land use contrasts. Existing interpretation provisions are reviewed, and a three-tiered framework to show these different linkages is proposed. It is argued that different, but complementary themes can be addressed at the landscape, landform, and individual outcrop (geosite) level.

Petrography and reservoir quality controls in shallow transitional marine Cretaceous-Paleogene deposits in the Dahomey Basin, Nigeria

Upper Mesozoic and Early Cenozoic sedimentary rocks are of great significance to the petroleum geology of the Eastern Dahomey Basin as they are valuable prospects for hydrocarbon reservoirs. Diagenesis and reservoir quality (porosity and permeability) controls are deduced from core samples recovered from six shallow exploration wells in the onshore area of the Eastern Dahomey Basin using petrographic, petrophysical and mineralogical tools. The studied lithostratigraphic intervals consist of limestone, calcareous siliciclastic sandstone (Ewekoro and Araromi Formations), quartz arenite and clay-matrix supported sandstone (Afowo Formation) which were deposited within a shallow marine depositional environment.Siliciclastic samples of the Ewekoro Formation consist predominantly of calcareous sandstone and limestone, which are classified as packstone and wackestone. The porosity values in the sandstones range from 5 to 36% whereas permeability ranges from 0.006 to 109 mD. Ewekoro Limestone porosity ranges from 7 to 32% and permeability ranges from 0.003 to 13 mD. Samples of the Araromi Formation exhibit a porosity of 4 to 45% with permeability between <0.001 and 1764 mD in sandstones whereas a single limestone sample has 8% porosity and permeability of 0.03 mD. Porosity in quartz arenitic sandstones of the Afowo Formation ranges from 15 to 47% with permeability of 0.05 to >10,000 mD, while in the clay-matrix supported sandstones, the values range from 18 to 42% and 0.05 to 5 mD for porosity and permeability, respectively. The main pore-occluding authigenic minerals are carbonate cements (Fe-dolomite, Fe-calcite, siderite and dolomite), iron oxide, kaolinite, and illite-smectite mixed layer clays. The best reservoir quality is observed in the quartz arenitic sandstones of the Araromi and Afowo Formations, except for the low permeability, clay-matrix supported sandstone facies.The most significant controlling factors in sandstones are clay mineral matrix contents and the presence of carbonate cements. Fe-calcite, Fe-dolomite and kaolinite formation occurs during early diagenesis in the studied lithologies and has helped to reduce the effect of compaction. The results of this study indicate fair to good reservoir quality in the shallow marine sedimentary rocks of the Eastern Dahomey Basin, which could be targeted in further exploration campaigns in the region.

한반도 남부의 지질 유형별 지형 기복과 삭박 저항력

This study tried to reveal relative surface denudation resistance and ranking by geologic types in the Southern Korean Peninsula using an 1:250,000 digital geologic map and ASTER GDEM. Among rock types such as igneous, sedimentary and metamorphic rocks, metamorphic rock showed the greatest resistance to surface denudation. The most resistant rock to surface denudation by geologic periods (e.g., the Precambrian, Paleozoic, Mesozoic and Cenozoic) was found from the Precambrian. Among the major tectonic settings in the Southern Korean Peninsula such as the Gyeonggi massif, Okcheon belt, Yeongnam massif, Gyeongsang basin and Pohang basin, the Okcheon belt indicated the greatest resistance. The most and least resistant rocks from the representative nine rocks in the Southern Korean Peninsula were Paleozoic limestone, and Cretaceous sedimentary rock and Cenozoic sedimentary rock, respectively. This study suggests that Paleozoic limestone, Cretaceous volcanic rock, Paleozoic sedimentary rock and Precambrian gneiss can be regarded as hard rocks with high elevation, steep slope and complicated relief, while soft rocks with low elevation, gentle slope and simple relief are Jurassic granite, Cretaceous sedimentary rock and Cenozoic sedimentary rock.

Evaluation of Typologies, Use Values, Degradation Risk, and Relevance of the Seridó Aspiring UNESCO Geopark Geosites, Northeast Brazil

The Serido, an interstate region of the northeastern hinterlands of Brazil, which encompasses several municipalities between the states of Rio Grande do Norte and Paraiba, has a geological heritage resultant from a series of natural processes over geological time, with a remarkable petrologic, structural, stratigraphic, and geomorphologic variety. The region is characterized by Paleoproterozoic gneisses, Neoproterozoic metasupracrustal rocks, magmatisms ranging from the Paleoproterozoic to Meso-Cenozoic, and Cenozoic sedimentary rocks. Taking into consideration the uniqueness of this Geological Heritage, it was developed since 2010 a proposal to create the Serido Geopark, which has been under development and in 2019 the territory was officially accepted as an aspiring geopark. With the geopark proposal also becomes necessary to develop geoconservation strategies. This paper aims to conduct different assessments of 21 geosites of Serido Aspiring UNESCO Geopark regarding scientific value, educational and touristic uses, and the associated degradation risk. The work is completed with a classification of the types of interest, visualization scale, and relevance of geosites. This work provides solid information, including tables, graphs, maps, and statistic for decision makers to establish priorities for action in order to promote the geosites protection.