ISSN: 2310-2799
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546,196 artículos
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Año:
2019
ISSN:
2007-2902, 1026-8774
Applegate, Shelton P.
Universidad Nacional Autónoma de México
Resumen
A hitherto unknown fossil fish is described from the middle Cretaceous beds near the town of Tepexi de Rodríguez, State of Puebla. The new genus is related to Ophiopsis and Macrepistius and therefore is placed in the family Ophiopsidae. The fossil fish is from the Tlayua quarry and is known from two specimens.
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Año:
2019
ISSN:
2007-2902, 1026-8774
Rozo-Vera, Gloria A.; Carreño, Ana Luisa
Universidad Nacional Autónoma de México
Resumen
A study of planktonic foraminifera from 47 surface sediment samples from the Gulf of California yielded distributional data of 48 species and subspecies. Globigerina pachyderma incompta, G. bulloides and Globigerinita glutinata constitute the most abundant and widely distributed taxa. Distinctly different faunal assemblages are thought to reflect predominant surface water masses in the gulf and, in turn, differences in temperature and salinity.
In addition, distributional patterns of some species appear to mark upwelling zones and oceanic fronts, as well as areas influenced by Eastern Equatorial Pacific Ocean water. In general terms, this study demonstrates that the Gulf of California contains eurythermal planktonic foraminiferal assemblages.
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Año:
2019
ISSN:
2007-2902, 1026-8774
Vassallo, Luis Fernando
Universidad Nacional Autónoma de México
Resumen
A study was undertaken in the mining district of Guanajuato to determine the mineralogy of the Veta Madre vein. The stages of mineralization were determined and the elemental content of each mineral was analyzed.
The stages of mineralization are: (1) early stage with sulphides of Cu-Pb-Zn, (2) metallic stage with Ag-Au with white quartz, (3) metallic stage with Ag-Au with transparent quartz and calcite, and (4) post-metallic stage with calcite.
The system acanthite-aguilarite-naumannite shows continuity with respect to the contents of selenium and sulfur and does not show exsolution textures. The content of sulfur ranges from 13.29 to 2.19%, the content of selenium from 1.53 to 19.46 %, and the content of silver from 85.28 to 78.35% respectively, between the minerals acanthite and naumannite.
Some other economically important minerals are electrum, native silver, polybasite, chalcopyrite, sphalerite and galena.
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Año:
2019
ISSN:
2007-2902, 1026-8774
Martínez-Reyes, Juventino; Nieto-Samaniego, Ángel Francisco
Universidad Nacional Autónoma de México
Resumen
Studies of faults in the central part of the Transmexican Volcanic Zone were initiated after the intense earthquakes that shook the country in September, 1985. The studied area extends between Mexico City and Guadalajara, following the 20°N parallel.
Review of literature and maps as well as field work allowed the elaboration of maps with different scales, using topographic maps, scale 1:50,000; from CETENAL as base maps.
Volcanic rocks of intermediate composition predominate in a sequence of Oligocene to Recent ages; Pliocene-Quaternary volcanism is particularly abundant… In order to continue, download the full text in PDF.
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Año:
2019
ISSN:
2007-2902, 1026-8774
de Pablo-Galán, Liberto
Universidad Nacional Autónoma de México
Resumen
1,214 renal calculi, which had been espontaneously expelled or surgically removed from 825 male and 389 female patients, were characterized mineralogically. The calculi are classified as per their mineralogy in those composed of: (1) weddellite, (2) whewellite, (3) weddellite- whewellite, (4) weddellite - whewellite - apatite, (5) apatite - struvite, (6) struvite and (7) uricite. Mixing among some of these types can be observed. Of the trace elements Fe, Zn, Pb, Mn, Cu, and Sr, the contents of Fe and Zn are respectively 297 and 214 ppm for weddellite, 766 and 255 for whewellite, 1,297 and 703 for apatite, 248 and 264 for struvite, and 1,218 and 320 for uricite. Download full text.
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Año:
2019
ISSN:
2007-2902, 1026-8774
Aranda-Gómez, José Jorge; Aranda-Gómez, José Manuel; Nieto-Samaniego, Angel Francisco
Universidad Nacional Autónoma de México
Resumen
The Sierra de Guanajuato is a mountain range that extends over a distance greater than 100 km with a N45ªW trend… In order to continue, download the full paper in PDF.
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Año:
2019
ISSN:
2007-2902, 1026-8774
Aranda-Gómez, José J.; Pérez-Venzor, José A.
Universidad Nacional Autónoma de México
Resumen
The mapped area is located in the immediate vicinity of La Paz, State of Baja California Sur. The rocks that crop out range in age from middle Cretaceous to Holocene (?). In the eastern portion, the basement is exposed and it is composed of foliated tonalite and granodiorite, calcareous metasediments, an apparently undeformed but tilted layered gabbroic intrusion and a large granitic (sensu lato) batholith. The NW portion of the mapped area is covered by Cenozoic rocks which were informally divided into three groups named pre-volcanic, volcano-sedimentary and postvolcanic, as volcanism is one of the most prominent geologic events in the study area. The pre-volcanic rocks are arkosic sandstones of continental (eolian?) origin and unknown age... In order to continue, download the full paper in PDF.
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Año:
2019
ISSN:
2007-2902, 1026-8774
Vega-Vera, Francisco Javier; Perrilliat, María del Carmen
Universidad Nacional Autónoma de México
Resumen
The stratigraphic range of the Difunta Group is extended to the Eocene in the La Popa Basin. The exposed areas of the Adjuntas and Viento formations are revised… In order to continue, download the full paper in PDF.
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Año:
2019
ISSN:
2007-2902, 1026-8774
Roldán-Quintana, Jaime; Lozano-Santa Cruz, Rufino; Arrazolo-Reyna, Sonia
Universidad Nacional Autónoma de México
Resumen
The Baviácora área is located 90 km to the northeast of Hermosillo, the state capital of Sonora. The pegmatites reported here are located in the central and souther parts of the Baviácora 1:50,000 topographic sheet (H12-D23), of INEGI… In order to continue, download the full paper in PDF.
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Año:
2019
ISSN:
2007-2902, 1026-8774
Almazán-Vázquez, Emilio
Universidad Nacional Autónoma de México
Resumen
A sequence consisting of 950 m of Middle and Upper Cambrian and 475 m of Lower Ordovician sedimentary rocks crops out near the Sierra Madre Occidental in the east-central portion of Sonora, southwest of the town of Arivechi… In order to continue, download the full paper in PDF.
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