Pub Date : 2023-11-30DOI: 10.18268/bsgm2023v75n3a091023
Paulina Cifuentes-Ruiz, Virginia Friedman, Joseph B. Lambert, George Mustoe, Alejandro Bugarin, Francisco J. Vega
The first biological inclusion in Cretaceous (Cenomanian) amber from Texas (USA) is here documented. Most of the Cretaceous ambers with biological inclusions are from Europe (Spain, France) and Myanmar (Asia). Although the coleopteran here reported is microscopic and incomplete, it preserves enough morphological details to be identified as a member of the Family Ptinidae Latreille, 1802. This antecedent is significative and reveals the potential of this Cretaceous amber to contain more diverse bioinclusions, since the paleoenvironment suggested by the sediments that contain the amber and the ecological affinity of recent representatives of the Ptinidae suggest a humid forest near an estuary, associated to deltaic plain deposits. Este hallazgo representa la inclusión biológica en ámbar más antigua en las Americas.
{"title":"First biological inclusion in Upper Cretaceous Texas amber, USA","authors":"Paulina Cifuentes-Ruiz, Virginia Friedman, Joseph B. Lambert, George Mustoe, Alejandro Bugarin, Francisco J. Vega","doi":"10.18268/bsgm2023v75n3a091023","DOIUrl":"https://doi.org/10.18268/bsgm2023v75n3a091023","url":null,"abstract":"The first biological inclusion in Cretaceous (Cenomanian) amber from Texas (USA) is here documented. Most of the Cretaceous ambers with biological inclusions are from Europe (Spain, France) and Myanmar (Asia). Although the coleopteran here reported is microscopic and incomplete, it preserves enough morphological details to be identified as a member of the Family Ptinidae Latreille, 1802. This antecedent is significative and reveals the potential of this Cretaceous amber to contain more diverse bioinclusions, since the paleoenvironment suggested by the sediments that contain the amber and the ecological affinity of recent representatives of the Ptinidae suggest a humid forest near an estuary, associated to deltaic plain deposits. Este hallazgo representa la inclusión biológica en ámbar más antigua en las Americas.","PeriodicalId":9315,"journal":{"name":"Boletín de la Sociedad Geológica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139198387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-30DOI: 10.18268/bsgm2023v75n3p131123
Joaquín A. Proenza
Ore microscopy, based on reflected light, is the most appropriate and widely used technique for the identification and characterisation of ‘opaque’ minerals in polished sections (blocks or thin sections). This methodology is essential in exploration, characterisation and evaluation of ore deposits. Moreover, it is helpful in petrographic studies of rocks containing opaque minerals and the characterisation of synthetic solids, as well as in mineral processing, metallurgical testing and environmental impact of mining exploitation.
{"title":"A practical guide to ore microscopy by Ricardo Castroviejo (Book review)","authors":"Joaquín A. Proenza","doi":"10.18268/bsgm2023v75n3p131123","DOIUrl":"https://doi.org/10.18268/bsgm2023v75n3p131123","url":null,"abstract":"Ore microscopy, based on reflected light, is the most appropriate and widely used technique for the identification and characterisation of ‘opaque’ minerals in polished sections (blocks or thin sections). This methodology is essential in exploration, characterisation and evaluation of ore deposits. Moreover, it is helpful in petrographic studies of rocks containing opaque minerals and the characterisation of synthetic solids, as well as in mineral processing, metallurgical testing and environmental impact of mining exploitation.","PeriodicalId":9315,"journal":{"name":"Boletín de la Sociedad Geológica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139200444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-30DOI: 10.18268/bsgm2023v75n3a301023
Samuel Eguiluz y de Antuñano, B. A. Than-Marchese, Luis Fernando Camacho Ortegón, R. López-Martínez, L. E. Gómez-Pérez
El Grupo Sierra Madre de Chiapas tiene informalidades en su nomenclatura estratigráfica que han sido transmitidas a través de la literatura geológica. Este trabajo describe las características de tres sucesiones litoestratigráficas que hacen comprensible la división tripartita del Grupo Sierra Madre. Una litología particular, que aquí se define sucesión El Chango, separa las sucesiones Cantelhá y Cintalapa para integrar a este grupo. Adicionalmente, la sucesión El Chango hace posible realizar una cartografía apropiada y su correlación permite interpretar la distribución regional de facies sedimentarias que presentan estas sucesiones. La epifluorescencia de rocas de la sucesión El Chango (Cenomaniano) exhibe compuestos orgánicos. Datos de pirólisis indican ⁓0.22% de carbón orgánico total en roca carbonatada, su reflectancia equivalente es 0.7 y 1.0, que ubica a la roca en la ventana de generación del aceite y gas metagénico, los valores de S2 menores de 0.2 mg HC/g hacen cuestionable el bajo potencial de expulsión de hidrocarburos, por lo que se requieren análisis adicionales. La porosidad impregnada con asfalto en rocas del Grupo Sierra Madre sugiere la existencia de roca almacén, cubierta regionalmente por rocas pelíticas como sello y los cambios de facies y deformación indica la existencia de trampas potenciales. Los datos de este trabajo proponen explorar un play hipotético petrolero en esta región.
{"title":"Estratigrafía del Grupo Sierra Madre en Chiapas y su hipotético potencial petrolero","authors":"Samuel Eguiluz y de Antuñano, B. A. Than-Marchese, Luis Fernando Camacho Ortegón, R. López-Martínez, L. E. Gómez-Pérez","doi":"10.18268/bsgm2023v75n3a301023","DOIUrl":"https://doi.org/10.18268/bsgm2023v75n3a301023","url":null,"abstract":"El Grupo Sierra Madre de Chiapas tiene informalidades en su nomenclatura estratigráfica que han sido transmitidas a través de la literatura geológica. Este trabajo describe las características de tres sucesiones litoestratigráficas que hacen comprensible la división tripartita del Grupo Sierra Madre. Una litología particular, que aquí se define sucesión El Chango, separa las sucesiones Cantelhá y Cintalapa para integrar a este grupo. Adicionalmente, la sucesión El Chango hace posible realizar una cartografía apropiada y su correlación permite interpretar la distribución regional de facies sedimentarias que presentan estas sucesiones. La epifluorescencia de rocas de la sucesión El Chango (Cenomaniano) exhibe compuestos orgánicos. Datos de pirólisis indican ⁓0.22% de carbón orgánico total en roca carbonatada, su reflectancia equivalente es 0.7 y 1.0, que ubica a la roca en la ventana de generación del aceite y gas metagénico, los valores de S2 menores de 0.2 mg HC/g hacen cuestionable el bajo potencial de expulsión de hidrocarburos, por lo que se requieren análisis adicionales. La porosidad impregnada con asfalto en rocas del Grupo Sierra Madre sugiere la existencia de roca almacén, cubierta regionalmente por rocas pelíticas como sello y los cambios de facies y deformación indica la existencia de trampas potenciales. Los datos de este trabajo proponen explorar un play hipotético petrolero en esta región.","PeriodicalId":9315,"journal":{"name":"Boletín de la Sociedad Geológica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139200619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-30DOI: 10.18268/bsgm2023v75n3a240823
Miguel Domínguez Acosta, Richard P. Langford, Thomas E. Gill
The Samalayuca Dunes (SMD) (Médanos de Samalayuca), Chihuahua, México, are one of México’s largest and least studied dune fields, now managed as a Protected Area for their ecological characteristics. We present a morphometric characterization of the dune field based on remote sensing and field studies, to advance understanding of its physical environment. SMD’s generally-fine sands originate from shoreline deposits of Paleolake Palomas, transported eastward (downwind) along an aeolian corridor, accumulating primarily as echo dunes upwind of the sierras of Samalayuca and Presidio. A complex wind regime, with northerly and southerly winds complementing regionally-prevailing southwesterlies, modified by topographic effects, shapes the SMD’s morphology. The sand sea covers ~139.7 km2, with ~113.8 km2 in the main eastern body and ~25.9 km2 in a northwestern subfield. We describe six major dune forms: north to south straight-crested dunes, east to west straight-crested dunes, star dunes, vegetated parabolic dunes, relict transverse dunes, and “megastar” (draa) dunes. Mean interdune centroid spacing is 76.5 m. The active dunes, previously described as an “aklé” pattern, are predominantly straight-crested dune sets oriented near-perpendicular to each other with general north-south and east-west crest orientations, 4-5 m high, spaced ~67 m apart for north-south trending crests and ~53 m for east-west trending crests, representing a nearly perpendicular interference pattern in some locations. The active dunes are superimposed in a compound and complex arrangement on relict remnants of much larger north-northwest trending transverse dune ridges fanning out from south to north-northwest, spaced approximately ~1 km apart and ~50 m high. The easternmost dune ridge contains an active set of at least 15 active megastar and reversing dunes up to 120 m tall, increasing in size and complexity from south to north. As a protected area with historical and ecological value, additional geologic investigations should be performed at the SMD, to help conserve this remarkable geologic feature.
{"title":"Morphometry of the Samalayuca dunes, northern Chihuahua, Mexico","authors":"Miguel Domínguez Acosta, Richard P. Langford, Thomas E. Gill","doi":"10.18268/bsgm2023v75n3a240823","DOIUrl":"https://doi.org/10.18268/bsgm2023v75n3a240823","url":null,"abstract":"The Samalayuca Dunes (SMD) (Médanos de Samalayuca), Chihuahua, México, are one of México’s largest and least studied dune fields, now managed as a Protected Area for their ecological characteristics. We present a morphometric characterization of the dune field based on remote sensing and field studies, to advance understanding of its physical environment. SMD’s generally-fine sands originate from shoreline deposits of Paleolake Palomas, transported eastward (downwind) along an aeolian corridor, accumulating primarily as echo dunes upwind of the sierras of Samalayuca and Presidio. A complex wind regime, with northerly and southerly winds complementing regionally-prevailing southwesterlies, modified by topographic effects, shapes the SMD’s morphology. The sand sea covers ~139.7 km2, with ~113.8 km2 in the main eastern body and ~25.9 km2 in a northwestern subfield. We describe six major dune forms: north to south straight-crested dunes, east to west straight-crested dunes, star dunes, vegetated parabolic dunes, relict transverse dunes, and “megastar” (draa) dunes. Mean interdune centroid spacing is 76.5 m. The active dunes, previously described as an “aklé” pattern, are predominantly straight-crested dune sets oriented near-perpendicular to each other with general north-south and east-west crest orientations, 4-5 m high, spaced ~67 m apart for north-south trending crests and ~53 m for east-west trending crests, representing a nearly perpendicular interference pattern in some locations. The active dunes are superimposed in a compound and complex arrangement on relict remnants of much larger north-northwest trending transverse dune ridges fanning out from south to north-northwest, spaced approximately ~1 km apart and ~50 m high. The easternmost dune ridge contains an active set of at least 15 active megastar and reversing dunes up to 120 m tall, increasing in size and complexity from south to north. As a protected area with historical and ecological value, additional geologic investigations should be performed at the SMD, to help conserve this remarkable geologic feature.","PeriodicalId":9315,"journal":{"name":"Boletín de la Sociedad Geológica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139202599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-30DOI: 10.18268/bsgm2023v75n3a061023
Jafar Sharifi, Y. Nasiri, Mahdi Badpa, Samira Taghdisi Nikbakht, Mehdi Hadi
The Miocene strata of the Qom Formation from the Ghalibaf section, Central Iran (NW Semnan) documented a high diversity of shallow-marine microfacies. These deposits in the Ghalibaf section, with a total thickness of 445 m, are characterized by twenty-one microfacies. The carbonate microfacies are deposited into five facies belts, including a lagoon, upper slope, lower slope, platform-margin sand shoals and margin facies. The presence of barrier reefs, intraclasts, oncoids, and grainstone aggregates, along with the absence of vast tidal flat areas, are distinguished. According to the aforementioned evidences, these sediments were deposited on a rimmed carbonate platform. In addition, the heterolithic calciturbidite deposits also show that the carbonate sequences were sedimented on a rimmed carbonate platform. Based on the available data of sequence stratigraphy analysis, seven third-order depositional sequences are bounded by type-1 and type-2 sequence boundaries. The relative sea-level changes between the upper and lower sequence boundaries in accord with the global sea-level curves reveal a reasonable correlation. However, some differences in other sequence boundaries might be due to local tectonic activities in the Qom Formation sedimentary basin, thereby leading to local sea-level changes. Moreover, biostratigraphic data based on the larger foraminifera index markers, including Praebullalveolina curdica, Borelis melo, Dendritina rangi, Meandropsina iranica, Elphidium sp. 14, Neorotalia viennoti, and Miogypsina sp. suggests the Miocene Shallow Benthic Zones, SBZ24-SBZ25 equivalent to the late Aquitanian-Burdigalian timespan.
{"title":"Depositional environment and sequence stratigraphy of the Qom Formation (Miocene) from the Ghalibaf section, Central Iran","authors":"Jafar Sharifi, Y. Nasiri, Mahdi Badpa, Samira Taghdisi Nikbakht, Mehdi Hadi","doi":"10.18268/bsgm2023v75n3a061023","DOIUrl":"https://doi.org/10.18268/bsgm2023v75n3a061023","url":null,"abstract":"The Miocene strata of the Qom Formation from the Ghalibaf section, Central Iran (NW Semnan) documented a high diversity of shallow-marine microfacies. These deposits in the Ghalibaf section, with a total thickness of 445 m, are characterized by twenty-one microfacies. The carbonate microfacies are deposited into five facies belts, including a lagoon, upper slope, lower slope, platform-margin sand shoals and margin facies. The presence of barrier reefs, intraclasts, oncoids, and grainstone aggregates, along with the absence of vast tidal flat areas, are distinguished. According to the aforementioned evidences, these sediments were deposited on a rimmed carbonate platform. In addition, the heterolithic calciturbidite deposits also show that the carbonate sequences were sedimented on a rimmed carbonate platform. Based on the available data of sequence stratigraphy analysis, seven third-order depositional sequences are bounded by type-1 and type-2 sequence boundaries. The relative sea-level changes between the upper and lower sequence boundaries in accord with the global sea-level curves reveal a reasonable correlation. However, some differences in other sequence boundaries might be due to local tectonic activities in the Qom Formation sedimentary basin, thereby leading to local sea-level changes. Moreover, biostratigraphic data based on the larger foraminifera index markers, including Praebullalveolina curdica, Borelis melo, Dendritina rangi, Meandropsina iranica, Elphidium sp. 14, Neorotalia viennoti, and Miogypsina sp. suggests the Miocene Shallow Benthic Zones, SBZ24-SBZ25 equivalent to the late Aquitanian-Burdigalian timespan.","PeriodicalId":9315,"journal":{"name":"Boletín de la Sociedad Geológica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139208094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-30DOI: 10.18268/bsgm2023v75n3a080923
J. Estrada-Álvarez, Carlo G. Sormani, Reinier Núñez-Bazán, Jorge A. Mata-González, Francisco J. Vega
Twelve pieces of amber containing the remains of cockroaches are used to form the basis of this paper. Gutierrezina vrsanskyi n. gen., n. sp., is described. Supella miocenica Cifuentes-Ruiz, Vidlička, Čiampor and Vega, 2011 is moved to the new genus Gutierrezina. Three new species are described for the genus Cariblatta Hebard, 1916: C. simojovelensis n. sp.; C. amfivola n. sp.; and C. uchbena n. sp. In addition, new information from Anaplecta vega Barna et al. 2019 and Latiblattella sp. is provided.
本文以 12 块含有蟑螂遗骸的琥珀为基础。描述了 Gutierrezina vrsanskyi n. gen.Supella miocenica Cifuentes-Ruiz, Vidlička, Čiampor and Vega, 2011 被归入新的 Gutierrezina 属。Cariblatta Hebard, 1916 属描述了三个新种：此外，还提供了 Anaplecta vega Barna 等人，2019 年和 Latiblattella sp.
{"title":"New taxa of cockroaches (Blattodea: Blattaria) from early Miocene amber of Chiapas, Mexico","authors":"J. Estrada-Álvarez, Carlo G. Sormani, Reinier Núñez-Bazán, Jorge A. Mata-González, Francisco J. Vega","doi":"10.18268/bsgm2023v75n3a080923","DOIUrl":"https://doi.org/10.18268/bsgm2023v75n3a080923","url":null,"abstract":"Twelve pieces of amber containing the remains of cockroaches are used to form the basis of this paper. Gutierrezina vrsanskyi n. gen., n. sp., is described. Supella miocenica Cifuentes-Ruiz, Vidlička, Čiampor and Vega, 2011 is moved to the new genus Gutierrezina. Three new species are described for the genus Cariblatta Hebard, 1916: C. simojovelensis n. sp.; C. amfivola n. sp.; and C. uchbena n. sp. In addition, new information from Anaplecta vega Barna et al. 2019 and Latiblattella sp. is provided.","PeriodicalId":9315,"journal":{"name":"Boletín de la Sociedad Geológica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139208694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-30DOI: 10.18268/bsgm2023v75n3a290623
Fernando Pérez-Villatoro, Sonia Dávila, Katy Juárez, R. M. Prol‐Ledesma
Deep-sea vents microorganisms have been well characterized with defined typical taxonomic groups, principally composed of archaea, while shallow hydrothermal vents are considered to host a different community with bacteria as predominant prokaryotes. This work focuses on two shallow basins in the northern Gulf of California: Wagner and Consag basins which show evidence of early stages of rifting processes and host numerous submarine vents with intense gas discharge. The exploratory study of archaea and bacteria in six sediment samples from the shallow vents in those basins (average depths of 100 m), demonstrate that similar archaea phyla inhabit these vents. The phylum Thermoproteota with Nitrosopumilus as the most abundant genera in five sites. However, in the sample with the highest temperature, the phylum Asgardarchaeota was predominant, and also the occurrence of archaeal lineages typical of deep sea vents like Nanoarchaeota, Thermoproteota, Euryarchaeota, and members from phylum Asgardarchaeota, were identified. This work is the first report of the presence of a typically deep vent community of archaea in this shallow vent environment.
{"title":"Archaeal communities at gas-venting shallow basins in the northern Gulf of California (Wagner and Consag basins)","authors":"Fernando Pérez-Villatoro, Sonia Dávila, Katy Juárez, R. M. Prol‐Ledesma","doi":"10.18268/bsgm2023v75n3a290623","DOIUrl":"https://doi.org/10.18268/bsgm2023v75n3a290623","url":null,"abstract":"Deep-sea vents microorganisms have been well characterized with defined typical taxonomic groups, principally composed of archaea, while shallow hydrothermal vents are considered to host a different community with bacteria as predominant prokaryotes. This work focuses on two shallow basins in the northern Gulf of California: Wagner and Consag basins which show evidence of early stages of rifting processes and host numerous submarine vents with intense gas discharge. The exploratory study of archaea and bacteria in six sediment samples from the shallow vents in those basins (average depths of 100 m), demonstrate that similar archaea phyla inhabit these vents. The phylum Thermoproteota with Nitrosopumilus as the most abundant genera in five sites. However, in the sample with the highest temperature, the phylum Asgardarchaeota was predominant, and also the occurrence of archaeal lineages typical of deep sea vents like Nanoarchaeota, Thermoproteota, Euryarchaeota, and members from phylum Asgardarchaeota, were identified. This work is the first report of the presence of a typically deep vent community of archaea in this shallow vent environment.","PeriodicalId":9315,"journal":{"name":"Boletín de la Sociedad Geológica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139205508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-30DOI: 10.18268/bsgm2023v75n3a011123
J. Lazcano, A. Camprubí, E. González-Partida, A. Iriondo, Daniel P. Miggins
El prospecto La Felipeña y otras manifestaciones minerales localizadas en el área periurbana de San Felipe (Baja California) consisten en vetas de cuarzo-carbonato con escasos sulfuros, mica blanca y turmalina, que muestran contenidos anómalos de Au. Las vetas se emplazaron en rocas metasedimentarias paleozoicas en facies de esquistos verdes y en diques cuarzo dioríticos que intruyen a las primeras. En este estudio, se presentan dos dataciones radiométricas que constriñen la edad de la mineralización en La Felipeña entre ~94 y 83 Ma. Una muestra de un dique encajonante arrojó una edad U-Pb en circones de 94.0 ± 0.8 Ma. El límite inferior corresponde a una edad 40Ar/39Ar en micas blancas hidrotermales de 82.73 ± 0.14 Ma. El estudio de inclusiones fluidas en cuarzo hidrotermal arroja temperaturas de atrapamiento entre ~400° y 530 °C, una presión de atrapamiento de ~210 MPa y salinidades de fluidos mineralizantes entre 5 y 14 wt.% NaCl equiv. La formación del depósito está asociada, en parte, a efervescencia. El depósito La Felipeña muestra características similares a los de tipo oro orogénico y es el primer caso documentado de este estilo de mineralización formado durante la transición entre la orogenia de las Sierras Peninsulares (~110−90 Ma), con la que culmina la construcción del batolito de las Sierras Peninsulares, y la orogenia Larámide sensu lato (~90−40 Ma), vinculada a un incremento de la tasa de convergencia entre las placas Farallón y Norteamérica. La mineralización aurífera del área de San Felipe prueba la continuidad espacio-temporal entre los cinturones de oro orogénico de las Sierras Peninsulares (~106−92 Ma) y Caborca (~77−36 Ma) en el extremo oriental del batolito de las Sierras Peninsulares.
{"title":"El depósito de oro supracretácico La Felipeña en el extremo oriental del batolito de las Sierras Peninsulares (Baja California, México): Estudio preliminar","authors":"J. Lazcano, A. Camprubí, E. González-Partida, A. Iriondo, Daniel P. Miggins","doi":"10.18268/bsgm2023v75n3a011123","DOIUrl":"https://doi.org/10.18268/bsgm2023v75n3a011123","url":null,"abstract":"El prospecto La Felipeña y otras manifestaciones minerales localizadas en el área periurbana de San Felipe (Baja California) consisten en vetas de cuarzo-carbonato con escasos sulfuros, mica blanca y turmalina, que muestran contenidos anómalos de Au. Las vetas se emplazaron en rocas metasedimentarias paleozoicas en facies de esquistos verdes y en diques cuarzo dioríticos que intruyen a las primeras. En este estudio, se presentan dos dataciones radiométricas que constriñen la edad de la mineralización en La Felipeña entre ~94 y 83 Ma. Una muestra de un dique encajonante arrojó una edad U-Pb en circones de 94.0 ± 0.8 Ma. El límite inferior corresponde a una edad 40Ar/39Ar en micas blancas hidrotermales de 82.73 ± 0.14 Ma. El estudio de inclusiones fluidas en cuarzo hidrotermal arroja temperaturas de atrapamiento entre ~400° y 530 °C, una presión de atrapamiento de ~210 MPa y salinidades de fluidos mineralizantes entre 5 y 14 wt.% NaCl equiv. La formación del depósito está asociada, en parte, a efervescencia. El depósito La Felipeña muestra características similares a los de tipo oro orogénico y es el primer caso documentado de este estilo de mineralización formado durante la transición entre la orogenia de las Sierras Peninsulares (~110−90 Ma), con la que culmina la construcción del batolito de las Sierras Peninsulares, y la orogenia Larámide sensu lato (~90−40 Ma), vinculada a un incremento de la tasa de convergencia entre las placas Farallón y Norteamérica. La mineralización aurífera del área de San Felipe prueba la continuidad espacio-temporal entre los cinturones de oro orogénico de las Sierras Peninsulares (~106−92 Ma) y Caborca (~77−36 Ma) en el extremo oriental del batolito de las Sierras Peninsulares.","PeriodicalId":9315,"journal":{"name":"Boletín de la Sociedad Geológica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139208700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-30DOI: 10.18268/bsgm2023v75n3a150823
Daniel López-Aguirre, Silvia Raquel García-Benítez, Rubén Nicolás-López, Enrique Coconi-Morales
En este trabajo se utilizan redes neuronales como una ventajosa herramienta para estimar parámetros petrofísicos de la columna estratigráfica atravesada por varios pozos. Los parámetros porosidad, volúmenes minerales y saturación de agua e hidrocarburos, se obtienen a partir de registros geofísicos de pozo básicos (rayos gamma, resistividad profunda, densidad volumétrica y tiempo de tránsito) y se infieren para otras zonas de la misma área geológica, en los que no se cuenta con este cuadro de información. Este análisis se realizó en secuencias siliciclásticas areno-arcillosas atravesadas por varios pozos perforados para alcanzar un yacimiento de hidrocarburos de baja permeabilidad. Se presentan estimaciones con modelos empíricos para enfrentarlas con las obtenidos con las redes neuronales de forma que se califique la actuación de la alternativa inteligente. Las leyes que rigen la dinámica de los parámetros, así como los detalles del contexto geológico quedan inmersos en los pesos de la red y la consistencia fenomenológica está definida a través de la congruencia de las entradas para conseguir las salidas elegidas. Se muestra la forma en la que el modelo neuronal habilita la propagación confiable de valores de propiedad y se convierte en un ventajoso auxiliar en el estudio de contextos geológicos muy complejos o escasamente parametrizados en los que las condiciones para la aplicación de correlaciones y métodos empíricos, así como el tiempo que se invierte en los procesos de ajuste y contextualización de registros, menguan la calidad y cantidad del conocimiento que se obtiene sobre el medio.
{"title":"Parametrización petrofísica de secuencias siliciclásticas areno-arcillosas con redes neuronales","authors":"Daniel López-Aguirre, Silvia Raquel García-Benítez, Rubén Nicolás-López, Enrique Coconi-Morales","doi":"10.18268/bsgm2023v75n3a150823","DOIUrl":"https://doi.org/10.18268/bsgm2023v75n3a150823","url":null,"abstract":"En este trabajo se utilizan redes neuronales como una ventajosa herramienta para estimar parámetros petrofísicos de la columna estratigráfica atravesada por varios pozos. Los parámetros porosidad, volúmenes minerales y saturación de agua e hidrocarburos, se obtienen a partir de registros geofísicos de pozo básicos (rayos gamma, resistividad profunda, densidad volumétrica y tiempo de tránsito) y se infieren para otras zonas de la misma área geológica, en los que no se cuenta con este cuadro de información. Este análisis se realizó en secuencias siliciclásticas areno-arcillosas atravesadas por varios pozos perforados para alcanzar un yacimiento de hidrocarburos de baja permeabilidad. Se presentan estimaciones con modelos empíricos para enfrentarlas con las obtenidos con las redes neuronales de forma que se califique la actuación de la alternativa inteligente. Las leyes que rigen la dinámica de los parámetros, así como los detalles del contexto geológico quedan inmersos en los pesos de la red y la consistencia fenomenológica está definida a través de la congruencia de las entradas para conseguir las salidas elegidas. Se muestra la forma en la que el modelo neuronal habilita la propagación confiable de valores de propiedad y se convierte en un ventajoso auxiliar en el estudio de contextos geológicos muy complejos o escasamente parametrizados en los que las condiciones para la aplicación de correlaciones y métodos empíricos, así como el tiempo que se invierte en los procesos de ajuste y contextualización de registros, menguan la calidad y cantidad del conocimiento que se obtiene sobre el medio.","PeriodicalId":9315,"journal":{"name":"Boletín de la Sociedad Geológica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139201274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-30DOI: 10.18268/bsgm2023v75n3a130923
E. Cañón‐Tapia
The spatial distribution of volcanic activity has been the subject of scientific enquiry for more than 350 years. Nevertheless, it has been only until recently that modern techniques of analysis started to be used to characterize such distribution. As a result, in the past 40 years many methods were devised, or adopted from other fields of study, aiming to achieve that purpose. Ironically, the plethora of now available methodologies has made problematic the selection of one method of study to characterize the spatial distribution of volcanic vents. In addition, given the diversity of methods, and their underlying assumptions, there are issues concerning the form in which the results of any specific method should be interpreted in a volcanic context. In this work I make emphasis on the relationship between the embedded assumptions of several common methods of study with the concept of a “natural partition”. Throughout this work it is remarked that 1) it is extremely important to gain conscience about the several assumptions implicit on each method of analysis, 2) never loose sight that not all volcanic systems are equal, and 3) that it is a myth that any quantitative method can provide reliable information about any system. The convenience of assessing more than one conceptual model to explain the formation of a cluster-subcluster structure is also mentioned. Overall, it is shown that the complexity of volcanic phenomena cannot be encapsulated by using a single method of study, or an automatized selection of parameters. Thus, given the complexity and diversity of volcanic phenomena, there is no particular method, nor set of methods, that can be recommended to be used on every situation of interest. Yet, as a golden rule, it is suggested that more than one method of analysis is used at every location of study, looking for congruency of results within a range of spatial scales.
{"title":"Geological significance of the spatial clustering and alignment of vents in zones of distributed volcanism: A critical review","authors":"E. Cañón‐Tapia","doi":"10.18268/bsgm2023v75n3a130923","DOIUrl":"https://doi.org/10.18268/bsgm2023v75n3a130923","url":null,"abstract":"The spatial distribution of volcanic activity has been the subject of scientific enquiry for more than 350 years. Nevertheless, it has been only until recently that modern techniques of analysis started to be used to characterize such distribution. As a result, in the past 40 years many methods were devised, or adopted from other fields of study, aiming to achieve that purpose. Ironically, the plethora of now available methodologies has made problematic the selection of one method of study to characterize the spatial distribution of volcanic vents. In addition, given the diversity of methods, and their underlying assumptions, there are issues concerning the form in which the results of any specific method should be interpreted in a volcanic context. In this work I make emphasis on the relationship between the embedded assumptions of several common methods of study with the concept of a “natural partition”. Throughout this work it is remarked that 1) it is extremely important to gain conscience about the several assumptions implicit on each method of analysis, 2) never loose sight that not all volcanic systems are equal, and 3) that it is a myth that any quantitative method can provide reliable information about any system. The convenience of assessing more than one conceptual model to explain the formation of a cluster-subcluster structure is also mentioned. Overall, it is shown that the complexity of volcanic phenomena cannot be encapsulated by using a single method of study, or an automatized selection of parameters. Thus, given the complexity and diversity of volcanic phenomena, there is no particular method, nor set of methods, that can be recommended to be used on every situation of interest. Yet, as a golden rule, it is suggested that more than one method of analysis is used at every location of study, looking for congruency of results within a range of spatial scales.","PeriodicalId":9315,"journal":{"name":"Boletín de la Sociedad Geológica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139205953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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