Eber A. Cristofolini, Matías Barzola, J. Otamendi, A. Tibaldi, Augusto Morosini, P. Armas, Giuliano Camilletti
This study presents a synthesis on the geology of the crystalline complex that constitute the Sierra de la Aguada, San Luis province, Argentine, from an approach based on field relations, petrologic and structural features and geochemical characteristic. This mountain range exposes a basement dominated by intermediate to mafic calcalkaline igneous rocks and peraluminous felsic granitoids, both emplaced in low to medium grade metamorphic rocks stabilized under low amphibolite facies. All this lithological terrane has been grouped in the El Carrizal-La Aguada Complex. Field relations, petrographic characterization and geochemical comparison of the plutonic rocks from the study area with those belonging to the Ordovician Famatinian suit exposed in the Sierra Grande de San Luis, suggest a genetic and temporal relation linked to the development of the Famatinian magmatic arc.
{"title":"Caracterización petrológica y geoquímica de las rocas plutónicas de la Sierra de La Aguada, Provincia de San Luis, Argentina: Implicaciones genéticas con el arco magmático Famatiniano","authors":"Eber A. Cristofolini, Matías Barzola, J. Otamendi, A. Tibaldi, Augusto Morosini, P. Armas, Giuliano Camilletti","doi":"10.3989/EGEOL.42711.440","DOIUrl":"https://doi.org/10.3989/EGEOL.42711.440","url":null,"abstract":"This study presents a synthesis on the geology of the crystalline complex that constitute the Sierra de la Aguada, San Luis province, Argentine, from an approach based on field relations, petrologic and structural features and geochemical characteristic. This mountain range exposes a basement dominated by intermediate to mafic calcalkaline igneous rocks and peraluminous felsic granitoids, both emplaced in low to medium grade metamorphic rocks stabilized under low amphibolite facies. All this lithological terrane has been grouped in the El Carrizal-La Aguada Complex. Field relations, petrographic characterization and geochemical comparison of the plutonic rocks from the study area with those belonging to the Ordovician Famatinian suit exposed in the Sierra Grande de San Luis, suggest a genetic and temporal relation linked to the development of the Famatinian magmatic arc.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"1 1","pages":"065"},"PeriodicalIF":0.7,"publicationDate":"2017-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76468135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work different types of chert from the Orinon Limestone Formation (upper Aptian-lower Albian) are studied. This formation outcrops in the eastern coast of Cantabria (Liendo-Castro Urdiales area) and includes outstanding and abundant cherty nodules, lenticular layers and crusts. The host rock is mainly a biocalcarenite (wackestone/packstone) of pellets, echinoids fragments, oysters, foraminifers and calcareous or calcified siliceous sponge spicules. The Orinon Limestone Formation was deposited in a marine open-shelf environment and preserves a hardground of regional extent with particular chert crusts. The silica source is associated to the dissolution of siliceous sponge spicules or to their calcification. Most of the chert is constituted by mosaics of micro-cryptocrystalline quartz and calcedonite, and it is generated by the selective silicification of biogenic structures, mainly dwelling trace fossils ( Thalassinoides isp.) because of the higher amount of organic matter and the higher porosity and permeability of the burrow infill. In the hardground , selective silicification affects body fossils such as belemnites, oysters and echinoids, and trace fossils (feeding burrows and borings) where in addition cherts is accumulated as an indeterminate crust. The silicification of the biogenic structures firstly occurred in form of opaline phases during the early diagenesis while the oxidation of the organic matter was active. Thus, Thalassinoides trace fossils affected by silicification preserve filaments and cocoids that might have had a microbial origin. Neoformation of dolomite and calcite occur only within the Thalassinoides trace fossils which indicates that diagenetic processes taking place within these burrows differed from those affecting the host rock and other biogenic structures. Dwelling trace fossils would have supposed a close micro-environment where the oxidation conditions changed from high to low rate.
{"title":"Silicificaciones selectivas en Thalassinoides y otras estructuras biogénicas asociadas a calizas de plataforma marina y hardground (Albiense inferior, Sonabia, Cantabria)","authors":"M. Bustillo, J. Elorza, D. Díez-Canseco","doi":"10.3989/EGEOL.42668.435","DOIUrl":"https://doi.org/10.3989/EGEOL.42668.435","url":null,"abstract":"In this work different types of chert from the Orinon Limestone Formation (upper Aptian-lower Albian) are studied. This formation outcrops in the eastern coast of Cantabria (Liendo-Castro Urdiales area) and includes outstanding and abundant cherty nodules, lenticular layers and crusts. The host rock is mainly a biocalcarenite (wackestone/packstone) of pellets, echinoids fragments, oysters, foraminifers and calcareous or calcified siliceous sponge spicules. The Orinon Limestone Formation was deposited in a marine open-shelf environment and preserves a hardground of regional extent with particular chert crusts. The silica source is associated to the dissolution of siliceous sponge spicules or to their calcification. \u0000Most of the chert is constituted by mosaics of micro-cryptocrystalline quartz and calcedonite, and it is generated by the selective silicification of biogenic structures, mainly dwelling trace fossils ( Thalassinoides isp.) because of the higher amount of organic matter and the higher porosity and permeability of the burrow infill. In the hardground , selective silicification affects body fossils such as belemnites, oysters and echinoids, and trace fossils (feeding burrows and borings) where in addition cherts is accumulated as an indeterminate crust. \u0000The silicification of the biogenic structures firstly occurred in form of opaline phases during the early diagenesis while the oxidation of the organic matter was active. Thus, Thalassinoides trace fossils affected by silicification preserve filaments and cocoids that might have had a microbial origin. \u0000Neoformation of dolomite and calcite occur only within the Thalassinoides trace fossils which indicates that diagenetic processes taking place within these burrows differed from those affecting the host rock and other biogenic structures. Dwelling trace fossils would have supposed a close micro-environment where the oxidation conditions changed from high to low rate.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"159 1","pages":"064"},"PeriodicalIF":0.7,"publicationDate":"2017-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86213770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
During the late Cenozoic the highest generic richness tended towards the loss of diversity, although three peaks were recognized with high rates of first records followed a high percentage of extinctions known as Rapid Turnover Fauna Episodes (RTE) (early Hemphillian, late Blancan and late Irvigntonian). However, these events define a pattern that fits the concept of Chronofauna of Olson (1952). The RTE episodes are considered in this structure as transition events between a Chonofauna and another. While the period of relative stability is equivalent to the Chronofauna, in which new ecomorphs are taking a dominant role, persisting around a series of intervals, is not the case in their taxonomic composition, which is altered by small events of low intensity extinctions. Under this pattern, we can deduce that in the last 9 million years, four different Chronofaunas can be recognized: Clarendoniano chronofauna (later section), Blancan chronofauna, Irvingtonian chronofauna and Holocene chronofauna (initial section).
{"title":"Dinámica de la estructura de comunidades del Cenozoico tardío de Norteamérica: Episodios de Recambio Rápido de Fauna (RTE) dentro del concepto de Cronofauna","authors":"R. H. Jasso","doi":"10.3989/EGEOL.42668.434","DOIUrl":"https://doi.org/10.3989/EGEOL.42668.434","url":null,"abstract":"During the late Cenozoic the highest generic richness tended towards the loss of diversity, although three peaks were recognized with high rates of first records followed a high percentage of extinctions known as Rapid Turnover Fauna Episodes (RTE) (early Hemphillian, late Blancan and late Irvigntonian). However, these events define a pattern that fits the concept of Chronofauna of Olson (1952). The RTE episodes are considered in this structure as transition events between a Chonofauna and another. While the period of relative stability is equivalent to the Chronofauna, in which new ecomorphs are taking a dominant role, persisting around a series of intervals, is not the case in their taxonomic composition, which is altered by small events of low intensity extinctions. \u0000Under this pattern, we can deduce that in the last 9 million years, four different Chronofaunas can be recognized: Clarendoniano chronofauna (later section), Blancan chronofauna, Irvingtonian chronofauna and Holocene chronofauna (initial section).","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"60 1","pages":"063"},"PeriodicalIF":0.7,"publicationDate":"2017-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82642050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This is a field-based work that describes the stratigraphy and sedimentology of the Andatza Conglomerate Formation. Based on facies analysis three facies associations of a coarse-grained turbidite system and the related slope have been identified: (1) an inner fan of a turbidite system (or canyon) and (2) a low- and (3) a high-gradient muddy slope respectively. The spatial distribution of the facies associations and the palaeocurrent analysis allow to interpret a depositional model for the Andatza Conglomerates consisting of an L-shaped, coarse-grained turbidite system, whose morphology was structurally controlled by synsedimentary basement-involved normal faults. The coarse-grained character of the turbidite system indicates the proximity of the source area, with the presence of a narrow shelf that fed the turbidite canyon from the north.
{"title":"El sistema turbidítico conglomerático de Andatza (Pirineos occidentales): Estratigrafía, sedimentología y control estructural","authors":"A. Bodego, L. M. Agirrezabala","doi":"10.3989/EGEOL.42535.422","DOIUrl":"https://doi.org/10.3989/EGEOL.42535.422","url":null,"abstract":"This is a field-based work that describes the stratigraphy and sedimentology of the Andatza Conglomerate Formation. Based on facies analysis three facies associations of a coarse-grained turbidite system and the related slope have been identified: (1) an inner fan of a turbidite system (or canyon) and (2) a low- and (3) a high-gradient muddy slope respectively. The spatial distribution of the facies associations and the palaeocurrent analysis allow to interpret a depositional model for the Andatza Conglomerates consisting of an L-shaped, coarse-grained turbidite system, whose morphology was structurally controlled by synsedimentary basement-involved normal faults. The coarse-grained character of the turbidite system indicates the proximity of the source area, with the presence of a narrow shelf that fed the turbidite canyon from the north.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"69 1","pages":"062"},"PeriodicalIF":0.7,"publicationDate":"2017-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85630409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
María Natalia Maffini, D. F. Ducart, S. Radice, J. Coniglio, F. D'Eramo, Manuel Demartis, Lucio P. Pinotti, A. M. Silva, C. Toledo
In the metamorphic basement of the Sierra de Comechingones, the southernmost extension of Sierras de Cordoba (Argentina), it is hosted a group of polymetallic Pb-Zn-Cu-Ag-Au veins associated with hydrothermal alteration zones, which are the result of a Late Paleozoic metallogenic period. In this paper, the application of spectral analysis in the SWIR (Short-Wave Infrared) region as well as magnetic techniques, unusual in Argentina for this style of mineralization, proved to be an effective tool in the study of altered areas and also useful to establish targets for mineral prospecting and/or exploration. A sericite-quartz assemblage is the main hydrothermal alteration product of the migmatic host rocks. It is developed into narrow but continuous altered zones which follow the main direction of the mineralized structures and can reach up to 5 meters to each side of the veins. Subordinately and locally, a carbonate siderite-calcite assemblage takes place as a result of altered amphibolites, which are interspersed within the metamorphic sequence. In the reflectance spectra, the wavelength position of the Al-OH absorption feature revealed compositional variations and cation substitutions in the hydrothermal white micas, ranging from potassic (wavelengths near 2200 nm) to micas with a lower octahedral Al content (wavelengths > 2210 nm) towards phengite. These variations and the spatial distribution within the altered areas are primarily controlled by three main factors: 1) hydrothermal fluid temperature, 2) pH and/or 3) Mg-Fe/Al ratio in the fluid-rock system. The crystallinity indexes (CI) calculated from the spectral data, indicate the predominance of high crystallinity illites with a slight increase of this parameter towards the proximal zones to the mineralized veins. The illite/smectite mix-layered clays indicate a fluid temperature decrease towards the distal zones and they can be used as vectors to mineralization. Both sericite-quartz and siderite-calcite hydrothermal assemblages are frequently affected by supergene oxidation processes that led to a conspicuous precipitation of hematite-goethite within the altered areas. The oxidation state of Fe +3 in these minerals is the main cause of the decrease of the magnetic susceptibility parameter in the host rocks. With a regional perspective, these hydrothermal alteration zones characterized by a high abundance of white micas of moderate to high crystallinity (CI=1,21-3,92 and IK=0,21-0,23), compositions ranging from potassic to phengitic (Al-OH wavelengths between 2200-2215 nm) and associated with hematization zones and low magnetic susceptibility values ( -3 SI), may be considered as potential targets for future prospecting and/or exploration of polymetallic veins hosted in the metamorphic environment of the Sierras Pampeanas.
{"title":"Estudio petrográfico, espectral y de susceptibilidad magnética de la alteración hidrotermal asociada con depósitos polimetálicos de Pb-Zn-Cu-Ag-Au, Sierra de Comechingones, Córdoba (Argentina)","authors":"María Natalia Maffini, D. F. Ducart, S. Radice, J. Coniglio, F. D'Eramo, Manuel Demartis, Lucio P. Pinotti, A. M. Silva, C. Toledo","doi":"10.3989/EGEOL.42408.403","DOIUrl":"https://doi.org/10.3989/EGEOL.42408.403","url":null,"abstract":"In the metamorphic basement of the Sierra de Comechingones, the southernmost extension of Sierras de Cordoba (Argentina), it is hosted a group of polymetallic Pb-Zn-Cu-Ag-Au veins associated with hydrothermal alteration zones, which are the result of a Late Paleozoic metallogenic period. In this paper, the application of spectral analysis in the SWIR (Short-Wave Infrared) region as well as magnetic techniques, unusual in Argentina for this style of mineralization, proved to be an effective tool in the study of altered areas and also useful to establish targets for mineral prospecting and/or exploration. A sericite-quartz assemblage is the main hydrothermal alteration product of the migmatic host rocks. It is developed into narrow but continuous altered zones which follow the main direction of the mineralized structures and can reach up to 5 meters to each side of the veins. Subordinately and locally, a carbonate siderite-calcite assemblage takes place as a result of altered amphibolites, which are interspersed within the metamorphic sequence. In the reflectance spectra, the wavelength position of the Al-OH absorption feature revealed compositional variations and cation substitutions in the hydrothermal white micas, ranging from potassic (wavelengths near 2200 nm) to micas with a lower octahedral Al content (wavelengths > 2210 nm) towards phengite. These variations and the spatial distribution within the altered areas are primarily controlled by three main factors: 1) hydrothermal fluid temperature, 2) pH and/or 3) Mg-Fe/Al ratio in the fluid-rock system. The crystallinity indexes (CI) calculated from the spectral data, indicate the predominance of high crystallinity illites with a slight increase of this parameter towards the proximal zones to the mineralized veins. The illite/smectite mix-layered clays indicate a fluid temperature decrease towards the distal zones and they can be used as vectors to mineralization. Both sericite-quartz and siderite-calcite hydrothermal assemblages are frequently affected by supergene oxidation processes that led to a conspicuous precipitation of hematite-goethite within the altered areas. The oxidation state of Fe +3 in these minerals is the main cause of the decrease of the magnetic susceptibility parameter in the host rocks. With a regional perspective, these hydrothermal alteration zones characterized by a high abundance of white micas of moderate to high crystallinity (CI=1,21-3,92 and IK=0,21-0,23), compositions ranging from potassic to phengitic (Al-OH wavelengths between 2200-2215 nm) and associated with hematization zones and low magnetic susceptibility values ( -3 SI), may be considered as potential targets for future prospecting and/or exploration of polymetallic veins hosted in the metamorphic environment of the Sierras Pampeanas.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"4 1","pages":"061"},"PeriodicalIF":0.7,"publicationDate":"2017-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86519326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
En este estudio se analizo el espectro de desgaste dental de los molares, superiores e inferiores, de individuos de las dos especies de roedores mas abundantes registradas en el yacimiento de Somosaguas Sur: Megacricetodon collongensis (Mein, 1958) y Democricetodon larteti (Schaub, 1925). Los resultados muestran gran abundancia de molares poco desgastados en ambas especies, lo que indica la existencia de una mortalidad fuertemente sesgada hacia los individuos juveniles. Este modelo de mortalidad refleja un suceso catastrofico de larga duracion y se asocia a periodos de sequia prolongados que produjeron la muerte temprana de los individuos durante generaciones. Esto es coherente con los datos obtenidos para los macromamiferos de Somosaguas donde tambien existe una mortalidad preferencial de los individuos juveniles asociada a eventos de gran aridez. A pesar de que todos los molares mostraron el mismo patron de mortalidad preferencial en individuos jovenes, ambas especies presentaron diferentes niveles de desgaste entre los distintos molares, lo cual sugiere que el proceso de masticacion pudo ser distinto entre ambas especies o que el inicio del desgaste de los molares anteriores pudo iniciarse durante la lactancia. Finalmente, el desgaste diferencial observado entre los M1 de M. collongensis y D. larteti podria deberse a la distinta morfologia de las cuspides y valles de sus molares, lo que provocaria que el desgaste no se produjese de la misma manera en las dos especies, o a ligeras diferencias dietarias.
{"title":"Mortalidad excepcional en los cricétidos (Rodentia) del Mioceno medio de Somosaguas (Pozuelo de Alarcón, Madrid)","authors":"Iris Menéndez, A. R. G. Cano, M. H. Fernández","doi":"10.3989/EGEOL.42347.397","DOIUrl":"https://doi.org/10.3989/EGEOL.42347.397","url":null,"abstract":"En este estudio se analizo el espectro de desgaste dental de los molares, superiores e inferiores, de individuos de las dos especies de roedores mas abundantes registradas en el yacimiento de Somosaguas Sur: Megacricetodon collongensis (Mein, 1958) y Democricetodon larteti (Schaub, 1925). Los resultados muestran gran abundancia de molares poco desgastados en ambas especies, lo que indica la existencia de una mortalidad fuertemente sesgada hacia los individuos juveniles. Este modelo de mortalidad refleja un suceso catastrofico de larga duracion y se asocia a periodos de sequia prolongados que produjeron la muerte temprana de los individuos durante generaciones. Esto es coherente con los datos obtenidos para los macromamiferos de Somosaguas donde tambien existe una mortalidad preferencial de los individuos juveniles asociada a eventos de gran aridez. A pesar de que todos los molares mostraron el mismo patron de mortalidad preferencial en individuos jovenes, ambas especies presentaron diferentes niveles de desgaste entre los distintos molares, lo cual sugiere que el proceso de masticacion pudo ser distinto entre ambas especies o que el inicio del desgaste de los molares anteriores pudo iniciarse durante la lactancia. Finalmente, el desgaste diferencial observado entre los M1 de M. collongensis y D. larteti podria deberse a la distinta morfologia de las cuspides y valles de sus molares, lo que provocaria que el desgaste no se produjese de la misma manera en las dos especies, o a ligeras diferencias dietarias.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"13 1","pages":"060"},"PeriodicalIF":0.7,"publicationDate":"2017-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89878548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the Sierra Arana area, dextral transcurrent faults form a set of long and narrow E-W tectonic bands, some of which are filled by Oligo-Aquitanian and Cretaceous sediments deeply squeezed among Jurassic carbonates. These bands form a “flower structure” which higher blocks, cut by the faults, fallen over Oligo-Aquitanian sediments, forming a tectonic melange. The crest zone of Sierra Arana indicates the position of a great reversed south verging anticlinal. The elements situated directly to the south of Sierra Arana, are attributed to a very internal Subbetic or to the Dorsal, and seem to correspond to the paleogeographic passage from the Subbetic to the Malaguide Complex.
{"title":"Transcurrencia y mélange tectónica en el área de Sierra Arana (Cordillera Bética, NE de Granada)","authors":"C. Galdeano, Á. Garrido","doi":"10.3989/EGEOL.42468.415","DOIUrl":"https://doi.org/10.3989/EGEOL.42468.415","url":null,"abstract":"In the Sierra Arana area, dextral transcurrent faults form a set of long and narrow E-W tectonic bands, some of which are filled by Oligo-Aquitanian and Cretaceous sediments deeply squeezed among Jurassic carbonates. These bands form a “flower structure” which higher blocks, cut by the faults, fallen over Oligo-Aquitanian sediments, forming a tectonic melange. The crest zone of Sierra Arana indicates the position of a great reversed south verging anticlinal. The elements situated directly to the south of Sierra Arana, are attributed to a very internal Subbetic or to the Dorsal, and seem to correspond to the paleogeographic passage from the Subbetic to the Malaguide Complex.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"28 1","pages":"055"},"PeriodicalIF":0.7,"publicationDate":"2016-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75260198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. E. A. E. Moujahid, Hassan Ibouh, A. Bachnou, M. A. Babram, A. E. Harti
The use of remote sensing, in this research, can be summarized in mapping and statistical studies of lineaments on the satellites images of the Jurassic outcrops in the Imilchil-Tounfite area, Central High Atlas of Morocco. This is to apply various manual techniques for extracting lineaments from Landsat TM image. Analytical techniques used in this work are: the principal component analysis (PCA) applied to selective bands of the visible and infrared, which allows creating new images with better visual interpretation. Directional filters N0°, N45°, N90°, and N135° with a 5.5 matrix were used to enhance lineaments in the corresponding perpendicular directions, and therefore to obtain a good discrimination of those structures. Preliminary results highlight a dominant geological fracturing trending ENE/WSW with 52% of the total lineaments, a second fracture trending is WNW/ESE at 23%, a third fracture series trending NE/SW with 20% and finally, a minor series of fractures trending NW/SE with 5% of the total lineaments. Distribution and statistical relationship, between fractures and the affected surface on the one hand and the fracture length on the other hand, shows a network of well-structured fractures. The final lineament map constitutes a contribution to complete the geology and assisting the mining and hydrogeological prospection, in the Imilchil-Tounfite area.
{"title":"Análisis de fracturas geológicas extraídas por teledetección en imágenes Landsat TM, ejemplo de la zona de Imilchil-Tounfite (Alto Atlas central, Marruecos)","authors":"H. E. A. E. Moujahid, Hassan Ibouh, A. Bachnou, M. A. Babram, A. E. Harti","doi":"10.3989/EGEOL.42328.394","DOIUrl":"https://doi.org/10.3989/EGEOL.42328.394","url":null,"abstract":"The use of remote sensing, in this research, can be summarized in mapping and statistical studies of lineaments on the satellites images of the Jurassic outcrops in the Imilchil-Tounfite area, Central High Atlas of Morocco. This is to apply various manual techniques for extracting lineaments from Landsat TM image. Analytical techniques used in this work are: the principal component analysis (PCA) applied to selective bands of the visible and infrared, which allows creating new images with better visual interpretation. Directional filters N0°, N45°, N90°, and N135° with a 5.5 matrix were used to enhance lineaments in the corresponding perpendicular directions, and therefore to obtain a good discrimination of those structures. Preliminary results highlight a dominant geological fracturing trending ENE/WSW with 52% of the total lineaments, a second fracture trending is WNW/ESE at 23%, a third fracture series trending NE/SW with 20% and finally, a minor series of fractures trending NW/SE with 5% of the total lineaments. Distribution and statistical relationship, between fractures and the affected surface on the one hand and the fracture length on the other hand, shows a network of well-structured fractures. The final lineament map constitutes a contribution to complete the geology and assisting the mining and hydrogeological prospection, in the Imilchil-Tounfite area.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"40 1","pages":"051"},"PeriodicalIF":0.7,"publicationDate":"2016-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77369369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Sesé, E. Soto, M. Santonja, A. Pérez-González, M. Domínguez-Rodrigo
The micromammal association established in this work is the following: Lagomorpha: Oryctolagus cuniculus; Eulipotyphla: Crocidura cf. russula, cf. Sorex sp., Neomys sp., Soricidae indet. and Talpa sp.; and Rodentia: Eliomys quercinus, Apodemus cf. sylvaticus, Cricetulus (Allocricetus) bursae, Arvicola aff. sapidus, Microtus (Iberomys) brecciensis and Microtus (Terricola) duodecimcostatus. This association is characteristic of the Middle Pleistocene. The morphological state of Cricetulus (A.) bursae, Arvicola aff. sapidus and Microtus (I.) brecciensis allows to place it in the advanced, but not final, Middle Pleistocene, which agrees with the numerical data of the site (243–337 ka) that places it in the MIS 8 or 9. The micromammals indicate the predominance of the open spaces with abundant vegetation mainly of herbaceous and bushes but also with some areas with trees. The climate would be of Mediterranean type, similar to the actual or perhaps a little milder and more humid.
{"title":"Los micromamíferos (Lagomorpha, Eulipotyphla y Rodentia) del yacimiento del Pleistoceno Medio de Cuesta de la Bajada (Teruel, España): Estudio sistemático y consideraciones paleoambientales","authors":"C. Sesé, E. Soto, M. Santonja, A. Pérez-González, M. Domínguez-Rodrigo","doi":"10.3989/EGEOL.42424.405","DOIUrl":"https://doi.org/10.3989/EGEOL.42424.405","url":null,"abstract":"The micromammal association established in this work is the following: Lagomorpha: Oryctolagus cuniculus; Eulipotyphla: Crocidura cf. russula, cf. Sorex sp., Neomys sp., Soricidae indet. and Talpa sp.; and Rodentia: Eliomys quercinus, Apodemus cf. sylvaticus, Cricetulus (Allocricetus) bursae, Arvicola aff. sapidus, Microtus (Iberomys) brecciensis and Microtus (Terricola) duodecimcostatus. This association is characteristic of the Middle Pleistocene. The morphological state of Cricetulus (A.) bursae, Arvicola aff. sapidus and Microtus (I.) brecciensis allows to place it in the advanced, but not final, Middle Pleistocene, which agrees with the numerical data of the site (243–337 ka) that places it in the MIS 8 or 9. The micromammals indicate the predominance of the open spaces with abundant vegetation mainly of herbaceous and bushes but also with some areas with trees. The climate would be of Mediterranean type, similar to the actual or perhaps a little milder and more humid.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"9 1","pages":"057"},"PeriodicalIF":0.7,"publicationDate":"2016-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84172426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Raúl Miranda-Avilés, María Jesús Puy-Alquiza, Lourdes Omaña, Isidro Loza-Aguirre
This article presents the results of the study on sedimentation, sedimentary environments, tectono-sedimentary and paleogeographic evolution of post-Laramide clastic deposits and pre-volcanism of the Sierra Madre Occidental in the Sierra de Guanajuato, central Mexico. The Eocene Duarte Conglomerate and Guanajuato Conglomerate were deposited in the middle and distal parts of alluvial fans. The studied rocks are composed of limestone clasts, granite, andesite, metasediments, diorite, and pyroxenite, indicating the erosion of uplifted blocks of the basal complex of the Sierra de Guanajuato (Arperos basin). The petrographic and compositional analysis of limestone shows a textural variation from basin limestones and shallow platform limestones. The shallow platform limestone contain bivalves, brachiopods, gastropods, echinoderms and benthic foraminifera from the Berriasian-Valanginian. The shallow-water limestone corresponds to the boundary of the Arperos basin whose original outcrops currently not outcrop in the Sierra de Guanajuato.
{"title":"Los depósitos clásticos pos-Laramide de la Sierra de Guanajuato: Implicaciones de su composición en la evolución tectono-sedimentaria y paleogeográfica","authors":"Raúl Miranda-Avilés, María Jesús Puy-Alquiza, Lourdes Omaña, Isidro Loza-Aguirre","doi":"10.3989/EGEOL.42480.417","DOIUrl":"https://doi.org/10.3989/EGEOL.42480.417","url":null,"abstract":"This article presents the results of the study on sedimentation, sedimentary environments, tectono-sedimentary and paleogeographic evolution of post-Laramide clastic deposits and pre-volcanism of the Sierra Madre Occidental in the Sierra de Guanajuato, central Mexico. \u0000The Eocene Duarte Conglomerate and Guanajuato Conglomerate were deposited in the middle and distal parts of alluvial fans. The studied rocks are composed of limestone clasts, granite, andesite, metasediments, diorite, and pyroxenite, indicating the erosion of uplifted blocks of the basal complex of the Sierra de Guanajuato (Arperos basin). The petrographic and compositional analysis of limestone shows a textural variation from basin limestones and shallow platform limestones. The shallow platform limestone contain bivalves, brachiopods, gastropods, echinoderms and benthic foraminifera from the Berriasian-Valanginian. The shallow-water limestone corresponds to the boundary of the Arperos basin whose original outcrops currently not outcrop in the Sierra de Guanajuato.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"162 ","pages":"058"},"PeriodicalIF":0.7,"publicationDate":"2016-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72504207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：