Pub Date : 2021-04-01DOI: 10.18268/BSGM2021V73N1A140920
Ehsan Zamaniyan, M. Khanehbad, R. Moussavi-Harami, A. Mahboubi
Qadir Member of Nayband Formation, located in East of Central Iran, has developed to a great extent. Investigation of the lithofacies and sedimentary environment, resulted in identification of the deltaic and marine deposits. Based on field evidence and facies features, Qadir Member consists of two lithofacies, including carbonate and siliciclastic facies. The siliciclastic facies were identified as having four sandstone facies including Sr, Sh, Sp, St, three fine-grained lithofacies, including FI, Fm, Fl (Sr) / Sr (FI) and one coal facies. Also, regarding the field, laboratory studies, and identification of lithofacies, the coastal plain, deltaic (including deltaic plain, proximal delta front, distal delta front, and prodelta) and open marine environments were identified for Qadir Member which is is under the impact of tidal currents. The chemical weathering index (71%) indicated semi-arid to semi-humid conditions and plotting the geochemical data showed the provenance of re-cycling and active continental margin and because of Chemical Index of Alteration, the weathering rate was found to be rather medium to high. The geochemical diagrams also showed a probable source of the intermediate igneous and sedimentary rocks. The active continental margin conditions for this deposit could suggest the Neotethys subduction under Iran’s plate and volcanic activity at the end of Triassic, which coincided with the early Cimmerian orogeny in Alborz and Central East Iranian Microcontinent.
{"title":"Sedimentary environment and provenance of sandstones from the Qadir member in the Nayband Formation, Tabas block, east-central Iran","authors":"Ehsan Zamaniyan, M. Khanehbad, R. Moussavi-Harami, A. Mahboubi","doi":"10.18268/BSGM2021V73N1A140920","DOIUrl":"https://doi.org/10.18268/BSGM2021V73N1A140920","url":null,"abstract":"Qadir Member of Nayband Formation, located in East of Central Iran, has developed to a great extent. Investigation of the lithofacies and sedimentary environment, resulted in identification of the deltaic and marine deposits. Based on field evidence and facies features, Qadir Member consists of two lithofacies, including carbonate and siliciclastic facies. The siliciclastic facies were identified as having four sandstone facies including Sr, Sh, Sp, St, three fine-grained lithofacies, including FI, Fm, Fl (Sr) / Sr (FI) and one coal facies. Also, regarding the field, laboratory studies, and identification of lithofacies, the coastal plain, deltaic (including deltaic plain, proximal delta front, distal delta front, and prodelta) and open marine environments were identified for Qadir Member which is is under the impact of tidal currents. The chemical weathering index (71%) indicated semi-arid to semi-humid conditions and plotting the geochemical data showed the provenance of re-cycling and active continental margin and because of Chemical Index of Alteration, the weathering rate was found to be rather medium to high. The geochemical diagrams also showed a probable source of the intermediate igneous and sedimentary rocks. The active continental margin conditions for this deposit could suggest the Neotethys subduction under Iran’s plate and volcanic activity at the end of Triassic, which coincided with the early Cimmerian orogeny in Alborz and Central East Iranian Microcontinent.","PeriodicalId":48849,"journal":{"name":"Boletin De La Sociedad Geologica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41872409","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}
Pub Date : 2021-04-01DOI: 10.18268/BSGM2021V73N1A080620
María Sánchez-González, I. I. Alcántara, J. Morales, Avto Goguitchaichvili
El graben de Chapala-Acambay se caracteriza por el registro de yacimientos de diatomitas del Cuaternario con espesores variables, donde domina flora indicativa de lagos profundos. El depósito de diatomita de 6.70 m de espesor de la cuenca de represamiento de Agostitlán contiene un registro paleoambiental que marca la transición de condiciones menos frías de hace ca. 37,000 años cal aP hasta el inicio del Glacial tardío ca. 25,000 años cal aP. En el inicio de la formación del represamiento se desarrolló un cuerpo de agua profundo con dominio de Stephanodiscus niagarae, con escaso aporte de material detrítico dominando las facies arcillosas. Los valores de susceptibilidad magnética en este primer episodio del lago son bajos, con un par de notorios incrementos en la susceptibilidad magnética y asociados a periodos de erosión de las sierras altas que limitan la cuenca. Sucesivamente, hacia las condiciones del lago se vuelven fluctuantes; las facies sedimentarias son más detríticas, alternando con episodios de sedimentación fina, disminuyen las agrupaciones de Stephanodiscus spp y aumentan los porcentajes de Aulacoseira ambigua y Fragilaria spp, lo que sugiere condiciones más frías y alcalinas. La cima de la sucesión se caracteriza por un aumento en la concentración de los minerales magnéticos, así como por un descenso significativo de las especies planctónicas y ticoplanctónicas que vienen sustituidas por formas bentónicas y perifíticas, lo cual se interpreta como una respuesta al incremento de la aridez en esta zona, previo al inicio del Último Máximo Glacial.
{"title":"Evolución paleoambiental de la diatomita de Agostitlán, Michoacán, durante la transición Pleistoceno-Holoceno","authors":"María Sánchez-González, I. I. Alcántara, J. Morales, Avto Goguitchaichvili","doi":"10.18268/BSGM2021V73N1A080620","DOIUrl":"https://doi.org/10.18268/BSGM2021V73N1A080620","url":null,"abstract":"El graben de Chapala-Acambay se caracteriza por el registro de yacimientos de diatomitas del Cuaternario con espesores variables, donde domina flora indicativa de lagos profundos. El depósito de diatomita de 6.70 m de espesor de la cuenca de represamiento de Agostitlán contiene un registro paleoambiental que marca la transición de condiciones menos frías de hace ca. 37,000 años cal aP hasta el inicio del Glacial tardío ca. 25,000 años cal aP. En el inicio de la formación del represamiento se desarrolló un cuerpo de agua profundo con dominio de Stephanodiscus niagarae, con escaso aporte de material detrítico dominando las facies arcillosas. Los valores de susceptibilidad magnética en este primer episodio del lago son bajos, con un par de notorios incrementos en la susceptibilidad magnética y asociados a periodos de erosión de las sierras altas que limitan la cuenca. Sucesivamente, hacia las condiciones del lago se vuelven fluctuantes; las facies sedimentarias son más detríticas, alternando con episodios de sedimentación fina, disminuyen las agrupaciones de Stephanodiscus spp y aumentan los porcentajes de Aulacoseira ambigua y Fragilaria spp, lo que sugiere condiciones más frías y alcalinas. La cima de la sucesión se caracteriza por un aumento en la concentración de los minerales magnéticos, así como por un descenso significativo de las especies planctónicas y ticoplanctónicas que vienen sustituidas por formas bentónicas y perifíticas, lo cual se interpreta como una respuesta al incremento de la aridez en esta zona, previo al inicio del Último Máximo Glacial.","PeriodicalId":48849,"journal":{"name":"Boletin De La Sociedad Geologica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45540537","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}
Pub Date : 2021-04-01DOI: 10.18268/BSGM2021V73N1A121220
I. Corral
The Cerro Quema Au-Cu deposit is hosted by a dacite dome complex of the Río Quema Formation, a Late Campanian-Maastrichtian volcano-sedimentary sequence of the Panamanian magmatic arc. Its formational age is constrained at ~49 Ma by field evidences, crosscutting relationships and 40Ar/39Ar geochronology (Corral et al., 2016, Corral, 2021). The recent molybdenite Re-Os dates by Perelló et al. (2020) claim that ore is spatially and temporally related to the host volcanic domes at ~71 Ma. After a thorough review of the geologic, geochemical and geochronological data from the Cerro Quema area, it is concluded that the Re-Os dates of Perelló et al. (2020) are not representative of the Cerro Quema formational age. Their proposed formational age at ~71 Ma is significantly older than the age of the host rock (~67 Ma). Furthermore, they invoke a previously unrecognized regional-scale magmatic event solely based on their molybdenite Re-Os dates. Instead, the Cerro Quema genetic model discussed here, in which magmatic-hydrothermal fluids derived from porphyry copper-like intrusions associated with the Valle Rico batholith produced the Au-Cu mineralization at ~49 Ma, is consistent with the geology, geochemistry and geochronology of the Azuero Peninsula.
Cerro Quema Au Cu矿床由Río Quema组的英安岩圆顶杂岩托管，该组是巴拿马岩浆弧的晚Campanian Maastrichtian火山沉积序列。其形成年龄受现场证据、横切关系和40Ar/39Ar地质年代限制在~49 Ma（Corral et al.，2016，Corral，2021）。Perelló等人最近的辉钼矿Re-Os日期。（2020）声称，矿石在空间和时间上与约71 Ma的主火山穹丘有关。在彻底审查了Cerro-Qema地区的地质、地球化学和地质年代数据后，得出结论，Pereló等人的Re-Os日期（2020）不能代表Cerro-Qima地层时代。它们提出的~71 Ma的形成年龄明显大于主岩的年龄（~67 Ma）。此外，他们仅根据辉钼矿Re-Os日期，就援引了以前未被识别的区域规模岩浆事件。相反，这里讨论的Cerro-Qema成因模型与阿祖罗半岛的地质、地球化学和地质年代一致，其中源自与Valle Rico岩基相关的斑岩类铜侵入体的岩浆热液在~49 Ma产生了Au-Cu矿化。
{"title":"Comment to \"Porphyry-related high-sulfidation mineralization early in Central American Arc Development: Cerro Quema deposit, Azuero Peninsula, Panama\" by Perelló et al., (2020)","authors":"I. Corral","doi":"10.18268/BSGM2021V73N1A121220","DOIUrl":"https://doi.org/10.18268/BSGM2021V73N1A121220","url":null,"abstract":"The Cerro Quema Au-Cu deposit is hosted by a dacite dome complex of the Río Quema Formation, a Late Campanian-Maastrichtian volcano-sedimentary sequence of the Panamanian magmatic arc. Its formational age is constrained at ~49 Ma by field evidences, crosscutting relationships and 40Ar/39Ar geochronology (Corral et al., 2016, Corral, 2021). The recent molybdenite Re-Os dates by Perelló et al. (2020) claim that ore is spatially and temporally related to the host volcanic domes at ~71 Ma. After a thorough review of the geologic, geochemical and geochronological data from the Cerro Quema area, it is concluded that the Re-Os dates of Perelló et al. (2020) are not representative of the Cerro Quema formational age. Their proposed formational age at ~71 Ma is significantly older than the age of the host rock (~67 Ma). Furthermore, they invoke a previously unrecognized regional-scale magmatic event solely based on their molybdenite Re-Os dates. Instead, the Cerro Quema genetic model discussed here, in which magmatic-hydrothermal fluids derived from porphyry copper-like intrusions associated with the Valle Rico batholith produced the Au-Cu mineralization at ~49 Ma, is consistent with the geology, geochemistry and geochronology of the Azuero Peninsula.","PeriodicalId":48849,"journal":{"name":"Boletin De La Sociedad Geologica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47010846","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}
Pub Date : 2021-04-01DOI: 10.18268/BSGM2021V73N1A270820
Anaid Fragoso-Irineo, J. Lazcano, Roberto S. Molina-Garza, A. Iriondo
En este estudio se implementa la inversión 3D de datos gravimétricos satelitales mediante el programa 3DINVER.M para modelar el grosor de la corteza en el rift del Golfo de California. Este rift oblicuo separa dextralmente la península de Baja California del continente de Norteamérica desde el Mioceno, periodo en el que se produjo el cambio desde un régimen tectónico fundamentalmente extensional al transtensional presente. A lo largo de su eje, el rift del Golfo de California se encuentra en una fase de oceanización incipiente en varias cuencas de su mitad meridional, mientras que al norte la presencia de corteza oceánica es controvertida. A consecuencia de esta particularidad, la corteza de la cuenca marina del Golfo y la de regiones terrestres adyacentes presentan importantes diferencias de densidad y grosor, siendo ambos parámetros fundamentales del método empleado, y, por ello, se realiza un modelo específico para cada dominio. Los modelos de grosor cortical generados se compararon con las estimaciones puntuales previas basadas en métodos sísmicos, obteniéndose que el 98% de los puntos confrontados del modelo marino y el 87% del terrestre se ajustan a un rango de ±6 km de diferencia, con diferencias promedio absolutas de 1.5 km y de 3.5 km respectivamente. La cuenca del Golfo en los modelos evoluciona a lo largo de su eje y desde el sur al norte desde una corteza híper-adelgazada (~8−12 km), característica de corteza oceánica a transicional, hasta una corteza continental moderadamente adelgazada (~12−18 km). En al área extendida circundante, que completa la denominada como Provincia Extensional del Golfo, la corteza continental varía habitualmente entre ~15 y ~28 km, mientras que en sus flancos la corteza llega a alcanzar los ~35−40 km en los dominios más engrosados (Sierra Madre Occidental y Meseta del Colorado). Asimismo, con base en las estimaciones del grosor cortical y la geología regional, se propone una nueva demarcación para la Provincia Extensional del Golfo.
{"title":"Estimación gravimétrica del grosor cortical en el Golfo de California","authors":"Anaid Fragoso-Irineo, J. Lazcano, Roberto S. Molina-Garza, A. Iriondo","doi":"10.18268/BSGM2021V73N1A270820","DOIUrl":"https://doi.org/10.18268/BSGM2021V73N1A270820","url":null,"abstract":"En este estudio se implementa la inversión 3D de datos gravimétricos satelitales mediante el programa 3DINVER.M para modelar el grosor de la corteza en el rift del Golfo de California. Este rift oblicuo separa dextralmente la península de Baja California del continente de Norteamérica desde el Mioceno, periodo en el que se produjo el cambio desde un régimen tectónico fundamentalmente extensional al transtensional presente. A lo largo de su eje, el rift del Golfo de California se encuentra en una fase de oceanización incipiente en varias cuencas de su mitad meridional, mientras que al norte la presencia de corteza oceánica es controvertida. A consecuencia de esta particularidad, la corteza de la cuenca marina del Golfo y la de regiones terrestres adyacentes presentan importantes diferencias de densidad y grosor, siendo ambos parámetros fundamentales del método empleado, y, por ello, se realiza un modelo específico para cada dominio. Los modelos de grosor cortical generados se compararon con las estimaciones puntuales previas basadas en métodos sísmicos, obteniéndose que el 98% de los puntos confrontados del modelo marino y el 87% del terrestre se ajustan a un rango de ±6 km de diferencia, con diferencias promedio absolutas de 1.5 km y de 3.5 km respectivamente. La cuenca del Golfo en los modelos evoluciona a lo largo de su eje y desde el sur al norte desde una corteza híper-adelgazada (~8−12 km), característica de corteza oceánica a transicional, hasta una corteza continental moderadamente adelgazada (~12−18 km). En al área extendida circundante, que completa la denominada como Provincia Extensional del Golfo, la corteza continental varía habitualmente entre ~15 y ~28 km, mientras que en sus flancos la corteza llega a alcanzar los ~35−40 km en los dominios más engrosados (Sierra Madre Occidental y Meseta del Colorado). Asimismo, con base en las estimaciones del grosor cortical y la geología regional, se propone una nueva demarcación para la Provincia Extensional del Golfo.","PeriodicalId":48849,"journal":{"name":"Boletin De La Sociedad Geologica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43312717","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}
Pub Date : 2021-04-01DOI: 10.18268/BSGM2021V73N1A220620
F. Vega, C. R. Borges-Sellén, Javier Aguilar-Pérez, Alberto F. Arano-Ruiz, Lázaro W. Viñola-López, Torrey Nyborg
Icriobranchiocarcinus rodas Vega n. sp., is recorded from lower Maastrichtian (Upper Cretaceous) Arroyo Grande Formation near the town of Rodas (Central Cuba). I. rodas Vega n. sp. represents additional evidence of paleobiogeographic affinities between Chiapas (SE Mexico) and Cuba, during the Late Cretaceous. The genus Icriobranchiocarcinus Vega, 2018 in Vega et al., 2018 was erected from the type species Icriobranchiocarcinus tzutzu Vega, 2018 from the lower Maastrichtian Ocozocoautla Forma-tion (Chiapas). I. rodas Vega, n. sp. preserves details of ventral morphology as well as more details of chelipeds not reported in I. tzutzu, adding to the morphology of the genus. Icriobranchiocarcinus belong to a family (Lythophylacidae Van Straelen, 1936) that became extinct worldwide during the K/Pg event.
Icriobranchiocarcinus rodas Vega n.sp.，记录自罗德里格斯镇附近的下马斯特里赫特阶（上白垩纪）阿罗约-格兰德组。I.rodas Vega n.sp.代表了晚白垩纪恰帕斯州（墨西哥东南部）和古巴之间古生物地理学亲缘关系的额外证据。Vega et al.，2018中的Icriobranchiocarcinus Vega属，2018是由模式种Icriobranchioccarcinus tzutzu Vega，2018从下马斯特里赫特阶Ocozocoautla Forma tion（恰帕斯州）建立的。I.rodas Vega，n.sp.保留了腹侧形态的细节，以及I.tzutzu中未报道的螯足类的更多细节，增加了该属的形态。Icriobranchiocarcinus属于一个在K/Pg事件期间在全球范围内灭绝的科（Lythophylacidae Van Straelen，1936）。
{"title":"A new lithophylacid crab (Crustacea, Decapoda, Portunoidea) from the Late Cretaceous (early Maastrichtian) of Cuba","authors":"F. Vega, C. R. Borges-Sellén, Javier Aguilar-Pérez, Alberto F. Arano-Ruiz, Lázaro W. Viñola-López, Torrey Nyborg","doi":"10.18268/BSGM2021V73N1A220620","DOIUrl":"https://doi.org/10.18268/BSGM2021V73N1A220620","url":null,"abstract":"Icriobranchiocarcinus rodas Vega n. sp., is recorded from lower Maastrichtian (Upper Cretaceous) Arroyo Grande Formation near the town of Rodas (Central Cuba). I. rodas Vega n. sp. represents additional evidence of paleobiogeographic affinities between Chiapas (SE Mexico) and Cuba, during the Late Cretaceous. The genus Icriobranchiocarcinus Vega, 2018 in Vega et al., 2018 was erected from the type species Icriobranchiocarcinus tzutzu Vega, 2018 from the lower Maastrichtian Ocozocoautla Forma-tion (Chiapas). I. rodas Vega, n. sp. preserves details of ventral morphology as well as more details of chelipeds not reported in I. tzutzu, adding to the morphology of the genus. Icriobranchiocarcinus belong to a family (Lythophylacidae Van Straelen, 1936) that became extinct worldwide during the K/Pg event.","PeriodicalId":48849,"journal":{"name":"Boletin De La Sociedad Geologica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49109588","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}
Pub Date : 2021-04-01DOI: 10.18268/BSGM2021V73N1A021020
R. Leal-Bautista, E. Perry, Jesús Alvarado-Flores, Liliana Alzate-Gavira, J. Domínguez-Maldonado, R. Tapia-Tussell
El repentino colapso del lago Chakanbacán (también conocido como Om o Chakambacab) ocurrió de forma natural y sin previo aviso entre el 19 y el 21 de agosto de 2018. El Lago Chakanbacán, situado al sur de Quintana Roo, 16.5 Km WNW de Nicolás Bravo, Quintana Roo es parte del borde occidental del polje Morocoy-Nuevo Becak. El desplome asociado con el drenaje del lago ha abierto fracturas en la orilla oeste del lago, exponiendo el yeso de la Formación Icaiche. Esta ocurrencia establece la orilla occidental del lago como el afloramiento más oriental conocido del yeso de Icaiche en la zona. El drenaje del lago Chakanbacán parece ser parte de un proceso kárstico que ocurre por rápida disolución y eliminación selectiva de capas de yeso de la Formación Icaiche bajo el lecho del lago. Por lo tanto, el colapso del lago en agosto de 2018 puede demostrar, en tiempo real, un importante proceso de karstificación continuo responsable de una característica geomórologica regional: las numerosas depresiones kársticas drenadas internamente (poljes) de hasta >100 km de largo en Campeche y el sur de Quintana Roo. Se ha propuesto que estos poljes son característicos de colapso resultantes de la eliminación en la solución de yeso de la Formación Icaiche. Estos se producen tanto dentro como adyacentes a una gran área donde la Formación Icaiche se extiende, y, en particular, sobre un estimado de 10000 km2 o más dentro de esa formación donde hay enormes lechos de yeso en la superficie o debajo de una fina capa protectora de roca resistente a la intemperie química.
{"title":"Karst drainage of lake Chakanbacán and its relation to Icaiche Formation","authors":"R. Leal-Bautista, E. Perry, Jesús Alvarado-Flores, Liliana Alzate-Gavira, J. Domínguez-Maldonado, R. Tapia-Tussell","doi":"10.18268/BSGM2021V73N1A021020","DOIUrl":"https://doi.org/10.18268/BSGM2021V73N1A021020","url":null,"abstract":"El repentino colapso del lago Chakanbacán (también conocido como Om o Chakambacab) ocurrió de forma natural y sin previo aviso entre el 19 y el 21 de agosto de 2018. El Lago Chakanbacán, situado al sur de Quintana Roo, 16.5 Km WNW de Nicolás Bravo, Quintana Roo es parte del borde occidental del polje Morocoy-Nuevo Becak. El desplome asociado con el drenaje del lago ha abierto fracturas en la orilla oeste del lago, exponiendo el yeso de la Formación Icaiche. Esta ocurrencia establece la orilla occidental del lago como el afloramiento más oriental conocido del yeso de Icaiche en la zona. El drenaje del lago Chakanbacán parece ser parte de un proceso kárstico que ocurre por rápida disolución y eliminación selectiva de capas de yeso de la Formación Icaiche bajo el lecho del lago. Por lo tanto, el colapso del lago en agosto de 2018 puede demostrar, en tiempo real, un importante proceso de karstificación continuo responsable de una característica geomórologica regional: las numerosas depresiones kársticas drenadas internamente (poljes) de hasta >100 km de largo en Campeche y el sur de Quintana Roo. Se ha propuesto que estos poljes son característicos de colapso resultantes de la eliminación en la solución de yeso de la Formación Icaiche. Estos se producen tanto dentro como adyacentes a una gran área donde la Formación Icaiche se extiende, y, en particular, sobre un estimado de 10000 km2 o más dentro de esa formación donde hay enormes lechos de yeso en la superficie o debajo de una fina capa protectora de roca resistente a la intemperie química.","PeriodicalId":48849,"journal":{"name":"Boletin De La Sociedad Geologica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67929939","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}
Pub Date : 2021-04-01DOI: 10.18268/BSGM2021V73N1A040820
Rafael Villanueva-Olea, Sara A. Quiroz-Barroso, Jesús Quiroz-Barragán, Miguel A. Torres-Martínez, Francisco Sour-Tovar
Thirteen parataxa of crinoid plates from two localities of the lower-middle Permian of the Las Delicias Formation are described. Both zones are situated in Sierra de las Delicias, to southwestern Coahuila state. The parataxa Pentagonopternix coahuilensis n. sp., Cyclocaudex typicus, C. insaturatus, C. cf. insaturatus, Cyclocaudex sp., Floricyclus diminuta n. sp., Floricyclus sp. Preptopremnum rugosum, P. laeve, Preptopremnum sp., Heterostelechus keithi, Cyclocaudiculus regularis and Epicrinus torreonense new genus and species were found in Las Difuntas locality of the middle Permian (Wordian–Capitanian) whereas Cyclocaudex typicus, C. sp., Preptopremnum laeve and Epicrinus torreonense were also found in Las Sardinas locality whose strata have been dated as early Permian (Kungurian-Roadian). The occurrence of all parataxa in strata from the middle Permian of the Las Delicias Formation allowed extending their stratigraphic range until the Wordian–Capitanian. Most species described have been associated to the Grandian Paleoprovince, nonetheless, the presence of Floricyclus and Pentagonopternix parataxa in the Permian of Coahuila proves the cosmopolitan nature of both genera.
本文描述了Las Delicias组中下二叠统两个地区的13个海百合类板块副群。这两个地区都位于科阿韦拉州西南部的德拉斯德利西亚斯。在中二叠纪(世界- capitian)的Las Difuntas地区发现了副类群Pentagonopternix coahuilensis n. sp.， typicus, C. insaturatus, C. cfinsaturatus, cyococaux sp.， Floricyclus diminuta .， Floricyclus sp.， pretopremum rugosum, P. laeve, pretopremum sp.， Heterostelechus keithi, Cyclocaudiculus regularis和Epicrinus torreonense。在Las Sardinas地区还发现了早二叠世(Kungurian-Roadian)地层的pretopremum lave和Epicrinus torreonense。所有副类群在Las Delicias组中二叠世地层中的出现，使它们的地层范围扩大到世界- capitanian。大多数被描述的物种都与格兰底古省有关，尽管如此，在科阿威拉的二叠纪中出现的Floricyclus和Pentagonopternix parataxa证明了这两个属的世界性。
{"title":"Placas columnares de crinoideos de la Formación Las Delicias, Pérmico inferior y medio de Coahuila, México","authors":"Rafael Villanueva-Olea, Sara A. Quiroz-Barroso, Jesús Quiroz-Barragán, Miguel A. Torres-Martínez, Francisco Sour-Tovar","doi":"10.18268/BSGM2021V73N1A040820","DOIUrl":"https://doi.org/10.18268/BSGM2021V73N1A040820","url":null,"abstract":"Thirteen parataxa of crinoid plates from two localities of the lower-middle Permian of the Las Delicias Formation are described. Both zones are situated in Sierra de las Delicias, to southwestern Coahuila state. The parataxa Pentagonopternix coahuilensis n. sp., Cyclocaudex typicus, C. insaturatus, C. cf. insaturatus, Cyclocaudex sp., Floricyclus diminuta n. sp., Floricyclus sp. Preptopremnum rugosum, P. laeve, Preptopremnum sp., Heterostelechus keithi, Cyclocaudiculus regularis and Epicrinus torreonense new genus and species were found in Las Difuntas locality of the middle Permian (Wordian–Capitanian) whereas Cyclocaudex typicus, C. sp., Preptopremnum laeve and Epicrinus torreonense were also found in Las Sardinas locality whose strata have been dated as early Permian (Kungurian-Roadian). The occurrence of all parataxa in strata from the middle Permian of the Las Delicias Formation allowed extending their stratigraphic range until the Wordian–Capitanian. Most species described have been associated to the Grandian Paleoprovince, nonetheless, the presence of Floricyclus and Pentagonopternix parataxa in the Permian of Coahuila proves the cosmopolitan nature of both genera.","PeriodicalId":48849,"journal":{"name":"Boletin De La Sociedad Geologica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47948868","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}
Pub Date : 2021-04-01DOI: 10.18268/BSGM2021V73N1A171220
G. Olivares-Casillas, A. Correa-Metrio, E. Zawisza, Marta Wojewódka-Przybył, M. Blaauw, F. J. Romero
The last three millennia have been characterized by global temperature oscillations of around one Celsius degree, and high frequency variability on precipitation. Two main temperature anomalies have been reported worldwide, the Medieval Warm Period (MWP) and the Little Ice Age (LIA), characterized by higher and lower than average temperatures, respectively. Precipitation variability has been mostly associated with El Niño anomalies in the Equatorial Pacific. These global variability modes have been modulated by regional factors such as sea surface temperatures and their interaction with continental landmasses. Understanding regional responses to these anomalies would shed light on ecosystem response to environmental variability, a paramount tool for conservation purposes on the light of modern climate change. Here we present a 3,000-year sedimentary record from Lake Metztitlán, located in a Biosphere Reserve under the rain shadow of the Sierra Madre Oriental. Cladoceran and geochemical analyses were used to reconstruct lacustrine dynamics through the time period encompassed by the record. Our record points to highly dynamic lacustrine systems, coupled with global and regional climatic variability. In Metztitlán, the MWP was associated with low lake levels and a high torrentiality of the precipitation reflected in high-frequency peaks of detrital material. The LIA was associated with an enlarged water body, probably as a result of lower evapotranspiration. Overall, global climatic variability resulted in high variability of regional precipitation and detrital input in the Metztitlán region, in turn associated with changes in lake morphometry and depth. Our record highlights the vulnerability of the area to changes in sea surface temperature of the Gulf of Mexico, and to changes in the frequency of El Niño events. Although the effects of global climate change in the region are inescapable, our results emphasize the importance of controlling anthropogenic activities as an additional source of pressure on the regional ecosystems.
过去三千年的特点是全球温度波动约一摄氏度，降水量变化频率高。据报道，世界范围内有两个主要的温度异常，即中世纪暖期（MWP）和小冰期（LIA），其特征分别是高于和低于平均温度。降水变化主要与赤道太平洋的厄尔尼诺异常有关。这些全球变化模式受到区域因素的调节，如海面温度及其与大陆陆地的相互作用。了解区域对这些异常现象的反应将有助于了解生态系统对环境变化的反应，这是根据现代气候变化进行保护的重要工具。在这里，我们展示了Metztitlán湖3000年的沉积记录，该湖位于马德雷山脉（Sierra Madre Oriental）雨影下的生物圈保护区。枝角类和地球化学分析用于重建记录所涵盖的整个时期的湖泊动力学。我们的记录表明，湖泊系统高度动态，加上全球和区域气候变化。在Metztitlán，MWP与低湖水位和碎屑物质高频峰所反映的高降水量有关。LIA与水体增大有关，可能是蒸散量降低的结果。总体而言，全球气候变化导致Metztitlán地区的区域降水和碎屑输入具有高度可变性，进而与湖泊形态计量和深度的变化有关。我们的记录突出表明，该地区易受墨西哥湾海面温度变化和厄尔尼诺事件频率变化的影响。尽管全球气候变化对该地区的影响是不可避免的，但我们的研究结果强调了控制人为活动的重要性，这是对该地区生态系统造成额外压力的来源。
{"title":"Environmental variability during the last three millennia in the rain shadows of central Mexico","authors":"G. Olivares-Casillas, A. Correa-Metrio, E. Zawisza, Marta Wojewódka-Przybył, M. Blaauw, F. J. Romero","doi":"10.18268/BSGM2021V73N1A171220","DOIUrl":"https://doi.org/10.18268/BSGM2021V73N1A171220","url":null,"abstract":"The last three millennia have been characterized by global temperature oscillations of around one Celsius degree, and high frequency variability on precipitation. Two main temperature anomalies have been reported worldwide, the Medieval Warm Period (MWP) and the Little Ice Age (LIA), characterized by higher and lower than average temperatures, respectively. Precipitation variability has been mostly associated with El Niño anomalies in the Equatorial Pacific. These global variability modes have been modulated by regional factors such as sea surface temperatures and their interaction with continental landmasses. Understanding regional responses to these anomalies would shed light on ecosystem response to environmental variability, a paramount tool for conservation purposes on the light of modern climate change. Here we present a 3,000-year sedimentary record from Lake Metztitlán, located in a Biosphere Reserve under the rain shadow of the Sierra Madre Oriental. Cladoceran and geochemical analyses were used to reconstruct lacustrine dynamics through the time period encompassed by the record. Our record points to highly dynamic lacustrine systems, coupled with global and regional climatic variability. In Metztitlán, the MWP was associated with low lake levels and a high torrentiality of the precipitation reflected in high-frequency peaks of detrital material. The LIA was associated with an enlarged water body, probably as a result of lower evapotranspiration. Overall, global climatic variability resulted in high variability of regional precipitation and detrital input in the Metztitlán region, in turn associated with changes in lake morphometry and depth. Our record highlights the vulnerability of the area to changes in sea surface temperature of the Gulf of Mexico, and to changes in the frequency of El Niño events. Although the effects of global climate change in the region are inescapable, our results emphasize the importance of controlling anthropogenic activities as an additional source of pressure on the regional ecosystems.","PeriodicalId":48849,"journal":{"name":"Boletin De La Sociedad Geologica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45300402","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}
Pub Date : 2021-04-01DOI: 10.18268/BSGM2021V73N1A011020
E. Perry, R. Leal-Bautista, G. Velazquez-Oliman, J. Sánchez-Sánchez, Nikklas Wagner
This paper explores strong indirect evidence for existence of a previously unrecognized deep groundwater aquifer in southern Quintana Roo, adjacent parts of Campeche, and (probably) northern Belize. The region contains rocks of Cretaceous-to-Holocene age, including: 1) an up-thrust block of the late Cretaceous carbonate known in Belize as the Barton Creek Formation, which is the oldest formation exposed in the Mexican Yucatán Peninsula, 2) the Cretaceous/Paleogene Albion Formation consisting of weakly consolidated Chicxulub impact air-fall deposits, 3) the Paleocene-Eocene Icaiche Formation, containing a massive 25-35 m thick gypsum member that crops out over an estimated area of more than 10,000 km2 in the elevated interior region of the northern lowlands, and 4) younger rocks of relatively low permeability that flank the region on the east. Hydrogeology is dominated by groundwater and surface flow in and adjacent to the Rio Hondo Fault Zone (RHFZ) and by recharge in the elevated interior region. Groundwater in the elevated region has a high sulfate concentration and is approximately saturated with gypsum dissolved from the Icaiche Formation. High-sulfate groundwater and river water with a slightly lower gypsum saturation index than in the elevated region also occurs in the RHFZ, but no water of comparably high sulfate content is present elsewhere in the study area. This suggests that the elevated region is a recharge zone for high-sulfate groundwater carried eastward beneath a 50 km gap by a deep, previously unrecognized aquifer and then discharged into the RHFZ. Based on chemistry of chloride, sulfate and other ions it is proposed here that a deep aquifer comprising the strongly weathered upper surface of the Barton Creek Formation plus the overlying weakly consolidated Albion Formation connects the elevated recharge area with the RHFZ discharge area. If this composite permeable zone does extend westward beneath the elevated recharge zone, it is probably an excellent aquifer.
{"title":"Aspects of the Hydrogeology of southern Campeche and Quintana Roo, Mexico","authors":"E. Perry, R. Leal-Bautista, G. Velazquez-Oliman, J. Sánchez-Sánchez, Nikklas Wagner","doi":"10.18268/BSGM2021V73N1A011020","DOIUrl":"https://doi.org/10.18268/BSGM2021V73N1A011020","url":null,"abstract":"This paper explores strong indirect evidence for existence of a previously unrecognized deep groundwater aquifer in southern Quintana Roo, adjacent parts of Campeche, and (probably) northern Belize. The region contains rocks of Cretaceous-to-Holocene age, including: 1) an up-thrust block of the late Cretaceous carbonate known in Belize as the Barton Creek Formation, which is the oldest formation exposed in the Mexican Yucatán Peninsula, 2) the Cretaceous/Paleogene Albion Formation consisting of weakly consolidated Chicxulub impact air-fall deposits, 3) the Paleocene-Eocene Icaiche Formation, containing a massive 25-35 m thick gypsum member that crops out over an estimated area of more than 10,000 km2 in the elevated interior region of the northern lowlands, and 4) younger rocks of relatively low permeability that flank the region on the east. Hydrogeology is dominated by groundwater and surface flow in and adjacent to the Rio Hondo Fault Zone (RHFZ) and by recharge in the elevated interior region. Groundwater in the elevated region has a high sulfate concentration and is approximately saturated with gypsum dissolved from the Icaiche Formation. High-sulfate groundwater and river water with a slightly lower gypsum saturation index than in the elevated region also occurs in the RHFZ, but no water of comparably high sulfate content is present elsewhere in the study area. This suggests that the elevated region is a recharge zone for high-sulfate groundwater carried eastward beneath a 50 km gap by a deep, previously unrecognized aquifer and then discharged into the RHFZ. Based on chemistry of chloride, sulfate and other ions it is proposed here that a deep aquifer comprising the strongly weathered upper surface of the Barton Creek Formation plus the overlying weakly consolidated Albion Formation connects the elevated recharge area with the RHFZ discharge area. If this composite permeable zone does extend westward beneath the elevated recharge zone, it is probably an excellent aquifer.","PeriodicalId":48849,"journal":{"name":"Boletin De La Sociedad Geologica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48341767","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}
Pub Date : 2020-11-28DOI: 10.18268/bsgm2020v72n3a250820
J. Proenza, L. Torró, C. E. Nelson
The region that encompasses Latin America and the Caribbean is a preferential destination for mining and mineral exploration, according to the Mineral Commodity Summaries 2020 of the US Geological Survey (https://www.usgs.gov/centers/nmic/). The region contains important resources of copper, gold, silver, nickel, cobalt, iron, niobium, aluminum, zinc, lead, tin, lithium, chromium, and other metals. For example, Chile is the world’s largest copper producer and the second largest lithium producer. Brazil is the world’s leading niobium producer, the second largest producer of iron ore, and the third-ranked producer of tantalum. Cuba contains some of the largest reserves of nickel and cobalt in the world, associated with lateritic Ni-Co deposits. Mexico is traditionally the largest silver producer and contains the two largest mines in this commodity and, along with Peru, Chile, Bolivia and Argentina, accounts for more than half of the total amount of global silver production. The region also hosts several world-class gold mines (e.g., Pueblo Viejo in the Dominican Republic, Paracotu in Brazil, Veladero in Argentina, and Yanacocha in Peru). Also, Bolivia and Brazil are among the world’s leading producers of tin. The region hosts a variety of deposit types, among which the most outstanding are porphyry copper and epithermal precious metal, bauxite and lateritic nickel, lateritic iron ore from banded iron-formation, iron-oxide-copper-gold (IOCG), sulfide skarn, volcanogenic massive sulfide (VMS), Mississippi Valley type (MVT), primary and weathering-related Nb-bearing minerals associated with alkaline–carbonatite complexes, tin–antimony polymetallic veins, and ophiolitic chromite. This special issue on Mineral Deposits of Latin America and the Caribbean in the Boletín de la Sociedad Geológica Mexicana contains nineteen papers. Contributions describe mineral deposits from Mexico, Panama, Cuba, Dominican Republic, Colombia, Venezuela, Ecuador, Chile, and Argentina. This volume of papers covers four mineral systems (mafic-ultramafic orthomagmatic mineral systems, porphyry-skarn-epithermal mineral systems, iron oxide copper-gold mineral systems, and surficial mineral systems). This special issue also includes papers on industrial minerals, techniques for ore discovery (predictive modelling of mineral exploration using GIS), regional metallogeny and mining history.
{"title":"Mineral deposits of Latin America and the Caribbean. Preface","authors":"J. Proenza, L. Torró, C. E. Nelson","doi":"10.18268/bsgm2020v72n3a250820","DOIUrl":"https://doi.org/10.18268/bsgm2020v72n3a250820","url":null,"abstract":"The region that encompasses Latin America and the Caribbean is a preferential destination for mining and mineral exploration, according to the Mineral Commodity Summaries 2020 of the US Geological Survey (https://www.usgs.gov/centers/nmic/). The region contains important resources of copper, gold, silver, nickel, cobalt, iron, niobium, aluminum, zinc, lead, tin, lithium, chromium, and other metals. For example, Chile is the world’s largest copper producer and the second largest lithium producer. Brazil is the world’s leading niobium producer, the second largest producer of iron ore, and the third-ranked producer of tantalum. Cuba contains some of the largest reserves of nickel and cobalt in the world, associated with lateritic Ni-Co deposits. Mexico is traditionally the largest silver producer and contains the two largest mines in this commodity and, along with Peru, Chile, Bolivia and Argentina, accounts for more than half of the total amount of global silver production. The region also hosts several world-class gold mines (e.g., Pueblo Viejo in the Dominican Republic, Paracotu in Brazil, Veladero in Argentina, and Yanacocha in Peru). Also, Bolivia and Brazil are among the world’s leading producers of tin. The region hosts a variety of deposit types, among which the most outstanding are porphyry copper and epithermal precious metal, bauxite and lateritic nickel, lateritic iron ore from banded iron-formation, iron-oxide-copper-gold (IOCG), sulfide skarn, volcanogenic massive sulfide (VMS), Mississippi Valley type (MVT), primary and weathering-related Nb-bearing minerals associated with alkaline–carbonatite complexes, tin–antimony polymetallic veins, and ophiolitic chromite. This special issue on Mineral Deposits of Latin America and the Caribbean in the Boletín de la Sociedad Geológica Mexicana contains nineteen papers. Contributions describe mineral deposits from Mexico, Panama, Cuba, Dominican Republic, Colombia, Venezuela, Ecuador, Chile, and Argentina. This volume of papers covers four mineral systems (mafic-ultramafic orthomagmatic mineral systems, porphyry-skarn-epithermal mineral systems, iron oxide copper-gold mineral systems, and surficial mineral systems). This special issue also includes papers on industrial minerals, techniques for ore discovery (predictive modelling of mineral exploration using GIS), regional metallogeny and mining history.","PeriodicalId":48849,"journal":{"name":"Boletin De La Sociedad Geologica Mexicana","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2020-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49383516","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}
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