El Geoparc Mundial de la UNESCO "Comarca Minera, Hidalgo": Un resultat de la cooperació científica entre Mèxic i Catalunya

La Comarca Minera de l'Estat d'Hidalgo, a la zona centreoriental de Mèxic, va rebre la designació de Geoparc Mundial de la UNESCO el 5 de maig de 2017. Aquest reconeixement va culminar un projecte transdisciplinari de tres anys, el qual va implicar una intensa cooperació entre diverses institucions de recerca mexicanes i catalanes. El projecte, encapçalat per la Universidad Nacional Autónoma de México (UNAM), va reunir un grup nombrós d'especialistes en ciències de la Terra, i també en d'altres disciplines totalment alienes a la geologia, i va fomentar la participació d'organitzacions agràries (ejidos) i civils, a més de la col·laboració d'estudiants i voluntaris. Actualment la Comarca Minera es un dels sis únics geoparcs d'Amèrica (i un dels dos que hi ha a Mèxic), i conté un geopatrimoni excepcional, l'eix del qual es la mineria del districte argentífer històric de Pachuca-Real del Monte. A més dels excepcionals dipòsits de tipus epitermal, que es compten entre els més grans del món, el geoparc presenta els següents elements geològics de rellevància mundial: (a) la localitat tipus de la cristobalita i de la tridimita, (b) els basalts amb disjunció columnar de Huasca de Ocampo, descrits pel naturalista prussià Alexander von Humboldt l'any 1803, i (c) l'obsidiana del Cerro de Las Navajas, explotada ininterrompudament des d'abans del Virregnat i que fou estratègica pel comerç de diverses cultures de Mesoamèrica.The Comarca Minera, Hidalgo UNESCO Global Geopark (Mexico) was formally designated on May 5th, 2017. This achievement was the result of a transdisciplinary, three-year project, for which there has been close cooperation among Mexican and Catalan universities, as well as Hidalgo's government institutions. The project was leaded by the National Autonomous University of Mexico (UNAM in its Spanish acronym) and brought together geoscientists of all disciplines, as well as specialists outside geology. It also prompted the collaboration of agrarian (ejidos) and civil organizations, as well as of students and volunteers. At present Comarca Minera is one of the six geoparks in America, treasuring an outstanding geoheritage around the silver mining of the historical district of Pachuca-Real del Monte. In addition, the geoheritage includes the follow highlights: (a) the type locality of cristobalite and tridymite, (b) the columnar jointed basalts of Huasca de Ocampo, described for the first time by the Prussian naturalist Alexander von Humboldt in 1803, and (c) Cerro de Las Navajas, which was one of the most important obsidian deposits for Mesoamerican cultures.El Geoparque Mundial de la UNESCO Comarca Minera, Hidalgo (México) fue designado oficialmente el 5 de mayo de 2017, culminando de esta manera un proyecto transdisciplinario de tres años, periodo durante el cual se mantuvo una intensa cooperación entre instituciones de educación superior y gubernamentales mexicanas y universidades catalanas. El proyecto, liderado por la Universidad Nacional Autónoma de México (UNAM), aglutinó un nutrido grupo de especialistas en geociencias y en disciplinas totalmente ajenas a estas, y promovió la participación de organizaciones campesinas (ejidos) y de la sociedad civil, así como de voluntarios y estudiantes de diversas licenciaturas

Mineralogical characterization of Sn deposits from the Santa Fe District, Bolivia

The Sn-Zn-Pb-Ag Japo-Santa Fe-Morococala ore deposit is located in the Central Andean Belt province. The ore mineralization is hosted in a Paleozoic metasedimentary sequence and porphyritic Oligocene-Miocene igneous rocks. Ore minerals occur in veins and disseminations. Two types of ore mineralization are distinghished: (1) An early Sn mineralization and (2) a late Sn and Zn-Pb-Ag mineralization. Mineral association consists mainly of quartz, pyrite, cassiterite, other sulfides and sulfosalts. Cassiterite, up to 0.25 wt% In, constitutes the earliest mineralization. Galena and sphalerite are the main sulphide minerals. Sphalerite shows up 0.24 wt% In. Stannite group is represented by stannoidite, kësterite, and sulfides of the Sn-Cu-Zn-Fe-S system. Sulfosalts include sakuraiite, potosiite, franckeite, freibergite, tetrahedrite, myargyrite, boulangerite, jamesonite, zinckenite, cylindrite and andorite. In this deposit, after an epigenetic magmatic stage, a long greisen-hydrothermal event took place with several episodes of metal deposition.Peer ReviewedPostprint (published version

Bioevents and redox conditions around the Cenomanian-Turonian anoxic event in Central Mexico

The Xilitla section of central Mexico (western margin of the proto-North Atlantic) is characterized by pelagic sediments enriched in marine organic matter. Using biostratigraphic and radiometric data, it was dated at the latest Cenomanian-earliest Turonian transition. We identified an interval coeval with the faunal turnover associated with the Oceanic Anoxic Event 2 (OAE 2), recording the Heterohelix shift and thePeer ReviewedPreprin

Mineral chemistry of In-bearing minerals in the Santa Fe mining district, Bolivia

The Santa Fe mining district is located in the Central Andean tin belt of Bolivia and contains several SnZn-Pb-Ag deposits. From the economic point of view, the most important deposits of the district are Japo, Santa Fe and Morococala. Beyond the traditional metal commodities, the Central Andean Tin Belt could become an exploration target for indium, owing to the potential of the ore-bearing paragenesis with high concentrations of this technology-critical element. In the Santa Fe mining district, the ore occurs as two main types: (a) Sn-rich cassiterite-quartz veins, and (b) Zn-Pb-Ag veins with sphalerite, galena and stannite mineral phases. The In content in igneous rocks is between 1.5 and 2.5 ppm, whereas in the ore concentrate it attains up to 200 ppm. The 1,000×In/Zn ratio in concentrate ranges from 25 up to 4,000. Exceptionally high In values were found in sakuraiite from Morococala deposit (2.03 wt%). Sakuraiite in this deposit shows evidences for a link between stannite and kësterite trend of solid solutions. There is a noteworthy exploration potential for strategic metals in this district and even in similar deposits elsewhere in the Central Andean tin belt.Peer ReviewedPostprint (published version

Mineral chemistry of In-bearing minerals in the Santa Fe mining district, Bolivia

[eng] The Santa Fe mining district is located in the Central Andean tin belt of Bolivia and contains several Sn-Zn-Pb-Ag deposits. From the economic point of view, the most important deposits of the district are Japo, Santa Fe and Morococala. Beyond the traditional metal commodities, the Central Andean Tin Belt could become an exploration target for indium, owing to the potential of the ore-bearing paragenesis with high concentrations of this technology-critical element. In the Santa Fe mining district, the ore occurs as two main types: (a) Sn-rich cassiterite-quartz veins, and (b) Zn-Pb-Ag veins with sphalerite, galena and stannite mineral phases. The In content in igneous rocks is between 1.5 and 2.5 ppm, whereas in the ore concentrate it attains up to 200 ppm. The 1,000×In/Zn ratio in concentrate ranges from 25 up to 4,000. Exceptionally high In values were found in sakuraiite from Morococala deposit (2.03 wt%). Sakuraiite in this deposit shows evidences for a link between stannite and kësterite trend of solid solutions. There is a noteworthy exploration potential for strategic metals in this district and even in similar deposits elsewhere in the Central Andean tin belt.[spa] El distrito minero Santa Fe se encuentra ubicado en la Faja Estannífera de la cordillera Central Andina de Bolivia, que aloja diversos depósitos de Sn-Zn-Pb-Ag. Desde el punto de vista económico, los depósitos más importantes en este distrito son los de Japo, Santa Fe y Morococala. Más allá de los productos metálicos tradicionales, la Faja Estannífera podría convertirse en un blanco de exploración para elementos como el indio, por el potencial de su paragénesis mineral con altas concentraciones de este elemento, crítico para el desarrollo de tecnología. Los yacimientos minerales del distrito de Santa Fe se presentan en dos tipos principales: (a) depósitos ricos en Sn, constituidos por vetas de cuarzo con casiterita, y (b) depósitos diseminados de Zn-Pb-Ag, con esfalerita, galena y estannita. El contenido de In en las rocas ígneas del distrito, varía entre 1,5 y 2,5 ppm, mientras que en el concentrado de los minerales de mena alcanza hasta 200 ppm de In. Asimismo, la razón 1.000×In/Zn en concentrados de mineral oscila entre 25 y 4.000. Fases de sakuraiíta del yacimiento de Morococala contienen valores excepcionales de In (hasta 2.03% en peso). La sakuraiíta en el distrito minero de Santa Fe muestra evidencia de ser el vínculo mineralógico entre la tendencia general de las soluciones sólidas de estannita y kësterita. Existe un potencial de exploración obvio para metales estratégicos en este distrito e incluso en depósitos similares en otras zonas de la Faja Estannífera en la cordillera Central Andina

Primeros datos de inclusiones fluidas e isótopos de azufre del depósito VMS de Tizapa, México

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Mineralogía del depósito de Sn del distrito de Santa Fe, Bolivia

El depósito de Sn-Zn-Pb-Ag de Japo-Santa Fe-Morococala se encuentra en la provincia metalogenética del cinturón Central Andino. La mineralización se encuentra encajada en una secuencia metasedimentaria paleozoica y rocas ígneas porfídicas del Oligoceno-Mioceno. Las menas se encuentran en vetas y diseminaciones. Se distinguen dos tipos de mineralización: (1) una mineralización temprana de Sn y (2) una mineralización tardía de Sn y Zn-Pb-Ag. La asociación mineral consiste principalmente en cuarzo, pirita, casiterita, sulfuros y sulfosales. La casiterita, hasta 0,25% en peso de In, constituye la mineralización más temprana. La galena y la esfalerita son los principales sulfuros. La esfalerita presenta 0,24% de In. Los minerales del grupo de la estannita están representados por estannoidita, kersterita y sulfuros del sistema Sn-Cu-ZnFe-S. Las sulfosales incluyen sakuraiita, potosiita, franckeita, freibergita, tetrahedrita, myargyrita, boulangerita, jamesonita, zinckenita, cylindrita y andorita. En este depósito, después de una etapa magmática epigenética, se produjo un largo evento greisen-hidrotermal con varios episodios de deposición de metales.Peer ReviewedPostprint (published version

Carbonate-hosted Zn-Pb-Cu-Ba (-Ag) mineralization in the Mehdiabad deposit, Iran: new insights, new discoveries

The Mehdiabad deposit in the Yazd-Anarak metallogenic belt (YAMB), central Iran, is the largest car-bonate-hosted Zn-Pb-Ba-Cu (-Ag) deposit in the world, with a reserve of 630 Mt sulphide and non-sulphide ore. It was formed during the Early Cretaceous by the replacement of barite and hydrothermally dolomitized breccia bod-ies of the Taft and Abkuh formations. This deposit consists of different ore zones, including the feeder zone, massive ore (including sulphide-oxide parts), massive barite ore, and copper-rich sulphide-barite ore, formed in an exten-sional environment related to the Naein-Baft back-arc basin. The deposit is stratabound and comprises a wedge-shaped sulphide-barite orebody with complex replacement textures of sulphides and barite. The primary sulphide ore, including a copper-rich core (with a reserve of more than 50 Mt of copper ore), developed in a barite sheath and characterized by the replacement of barite and pyrite by an assemblage of chalcopyrite, bornite, sphalerite and galena. Several stages of barite and sulphide deposition in the Mehdiabad deposit are similar to those reported in other Irish-type and barite-replacement sediment-hosted Zn-Pb deposits worldwide (e.g., Red Dog deposit, Alaska, USA).Peer ReviewedPostprint (published version

Geological setting and genesis of stratabound barite deposits at Múzquiz, Coahuila in northeastern Mexico

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Biogenic vs geochemical precipitation of minerals in the submarine hydrothermal vents of Punta Mita, Mexico

The submarine hydrothermal vents located in the vicinity of Punta Mita contain abundant deposition of calcite, pyrite. Also present are barite, carbonate hydroxyl-apatite, cinnabar and T1-sulfide.Textures indicate direct deposition for calcite and pyrite; however, pyrite also replaces magnetite in the host rock. Thermal water was filtered and microscopic analysis of the particles fiom the filters shows that the shape of the crystals varies euhedral crystals of pyrite to globular aggregates that may be interpreted as a mixture of chemical and biogenic precipitation. Isotopic signature of sulfur in pyrite and carbón in calcite indicates that biogenic deposition is an important phenomenon in this hydrothermal systemPeer ReviewedPostprint (published version