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The Puyo-Tena roadway is prone to landslides due to the geodynamics, geomorphology, and geological materials of the area (unstable outcrops and strata). In recent years, this problem has persistently caused the road to be partially or completely disabled on numerous occasions. The objective of the research was to generate a cartographic model of landslides susceptibility based on variables such as slope, geological formations, land cover and land use, as well as distances to faults, road, and rivers. The degree of landslides incidence was estimated as the linear combination of the weighted variables using the analytic hierarchy process. The importance of this semi-quantitative method lies in its ability to break down a complex decision problem into a simpler and more coherent decision model. The resulting cartographic model was classified into five susceptibility categories: very low, low, moderate, high, and very high. The results showed that 17 km out of the 80 km of the Puyo-Tena roadway have a high probability of landslides, which is equivalent to 21.25% of the road. Furthermore, within this percentage, it was determined that there are fifteen regions with a high probability of landslides due to their location in areas with steep slopes, porous and permeable lithology, a large number of rivers, and agricultural soils. The area under the curve (AUC) of the receiver operating characteristic (ROC) was used for model verification. The verification results showed that the cartographic model for the study area has an accuracy value of 83.7%. The cartographic model of landslide susceptibility will enable relevant decisions to be made to mitigate potential hazards that may endanger transporters, material goods, and residents of the area. [ABSTRACT FROM AUTHOR]

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The article discusses the health problems that Charles Darwin experienced throughout his life, including gastrointestinal, dermatological, and cardiac issues. During his expedition on the HMS Beagle, Darwin made numerous observations of flora, fauna, and geological formations that contributed to the development of his theory of evolution. Although there is no consensus on his specific ailments, the possibility of him suffering from Chagas disease is raised, although it has not been able to be confirmed due to the refusal to exhume his remains. Despite his health problems, Darwin managed to make important scientific contributions. [Extracted from the article]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Siho is an archaeological site located in the Northern Maya Lowlands, where a number of grinding tools have been documented, mostly metates made with local limestone that has petrological characteristics (physical and chemical) which may indicate a particular geological origin. The statistical treatment of data extracted by X-ray fluorescence allows us to discern limestone materials from different geological formations, based on the quantity of silicon (Si) and/or calcium (Ca) in the sample. This data shows a link between the limestone of the Sihó metates and the rocks from the geological formation known as Carrillo Puerto located in the Yucatan peninsula. Furthermore, the comparison by mean thin sections between geological and archaeological materials has been useful to characterise and identify lithic materials used to fabricate the metates. The complementarity between both archaeometrical techniques, together with ethnographic, historical and archaeological documentation, provide us with information that suggests an immediate exploitation of the limestone rocks used to make the metates and brings us closer to a better understanding of the quarrying strategies practiced by the ancient Mayans of Sihó. [ABSTRACT FROM AUTHOR]

The paper analyses how Neuquen's state policies configured territorial knots in the area where the mapuce community Campo Maripe is located, in northern Añelo, the core of the Vaca Muerta geological formation. It is argued that these policies designed spaces boosting certain economic activities and their associated territorialities and brought indigenous deterritorialization as a consequence. The Mapuce community Campo Maripe, whose territory currently partially overlaps with the Loma Campana oil field -one of the three most important fields in the extraction of hydrocarbons by non-conventional methods-, has been selected as a case study due to how notorious its resistance strategies have become over the last few years. Written documents and oral testimonies are used to characterize the complex scenario of territorial overlapping caused by state policies and the development of specific interactions between the different actors within the territorial knots. [ABSTRACT FROM AUTHOR]

Copyright of H-Industria: Revista de Historia de la Industria Argentina y Latinoamericana is the property of H-Industria, Revista de Historia de la Industria Argentina y Latinoamericana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This text reflects about Vaca Muerta megaproject, a geological formation rich in unconventional hydrocarbons that came as a public hope in Argentina both in the second government of Cristina Fernández de Kirchner, and in the government of Mauricio Macri, in a geopolitical context and in a particular phase of the capitalist accumulation mode characterized by the production of extreme energy. Based on a qualitative orientation research and a socio-political approach to social inquiry, this paper aims to analyze the following dimensions: 1) the importance of Vaca Muerta in the government agenda and the public expectation for its development 2) the questions about the privileged technique for its exploitation, fracking 3) the existing questions regarding the economic and productive viability of the megaproject, as well as regarding its environmental and territorial effects, 4) the social resistances that arose around this activity. The paper contributes to a critical reflection on the different dimensions, levels and actors that, in an asymmetrical network of power, dispute, value and adopt opposing positions around a resource of substantive relevance in the present: energy. [ABSTRACT FROM AUTHOR]

During the Upper Cretaceous the northwestern margin of South America was characterized by a complex tectonic environment represented by the accretion of multiple terranes and the generation of varied magmatic events. The Sabanalarga quartz-diorite and the Santa Fe Gabbro previously described as a single body called Sabanalarga Batholith, present multiple differences among themselves and today are considered two independent plutons, representing two of the upper Cretaceous magmatics events. Both plutons intrude crusts of different affinity; The Santa Fe Gabbro intrudes a Plateau-type and island arc crust while the Sabanalarga quartz-diorite intrude into continental crust. The carried total rock chemical analysis showed anomalies of Nb-Ti, patterns of HFSE and REE in the multielemental diagrams indicatives of rocks generated in subduction environments. The Santa Fe Gabbro presents adakitic characteristics that are not present in the Sabanalarga quartz-diorite. The low Zr content and relations (La / Yb) n vs Sr / Y < 10 suggest that the Santa Fe Gabbro magma was formed in an oceanic environment, contrary to the Sabanalarga quartz-diorite with high Zr and relationships (La / Yb) n vs Sr / Y> 10 who suggest an origin in a continental environment for this magma. U-Pb LA ICPMs were analyzed for both intrusives: Santa Fe Gabbro showed ages between 78.4 and 81.8 Ma and Sabanalarga quartz-diorite ages between 71.5 and 76.7 Ma. Due to the new geochemical and geochronological data, it is suggested that Santa Fe Gabbro and Sabanalarga quartz-diorite are two different bodies with no temporal relationship and whose spatial relationship is still debatable. Is suggested for the geological setting of formation for these plutons a double subduction model type Molucca. [ABSTRACT FROM AUTHOR]

Argentine geology exposes lithogenetic belts and favorable environments for the generation of deposits of minerals and rocks strongly required by agriculture, both sources of nutrient elements as corrective applications or amendments (gypsum, calcium and magnesium carbonates, potassium salts, phosphoric rocks and borates, among the main ones). Geological environments of formation of gypsum deposits in Argentina are five: in the Neuquén basin, deposits mainly corresponding to the lithogenetic belt of Cretaceous- Tertiary marine and coastal deposits and Jurassic-Cretaceous marine deposits; in the Pampean region deposits belong to quaternary evaporitic deposits in salt flats and endorheic basins; in the west and center-west of Argentina they correspond to the girdle of neogene basin deposits and cretaceous continental deposits, while in the south-west of Mesopotamia they belong to the lithogenetic belt of pleistocene palustre-lacustrine basin deposits. Potassium resources belong to endorheic basins of the Puna with Li - K - B brines, and saline horizons with silvite in the Huitrín Formation forming part of the evaporitic sequence of the Neuquén basin. Geological environments for the formation of limestone and dolomite deposits in Argentina are seven: in the central region of the country deposits belong to two lithogenetic belts, the Precambrian-Cambrian basement (Ca and Ca-Mg) and to a lesser extent the deposits of neogene basins (Ca); in the Precordillera they correspond to Cambrian-Ordovician carbonate platform, while in Buenos Aires to upper Precambrian - Ordovician marine deposits. In the Neuquen Basin deposits belong to the lithogenetic belt of Jurassic- Cretaceous marine deposits. In the Neuquen Basin and the Central region, deposits of carbonate rocks (Ca and Ca-Mg) were also developed in the belt of cretaceous-tertiary marine and coastal deposits. In the province of Entre Rios (southern Mesopotamia, Argentina), they are linked to the lithogenetic belt of Miocene-Holocene coastal deposits. Phosphoric or slightly phosphoric rocks developed at the cretaceous and tertiary marine levels in Patagonia; in the Ordovician sediments of northwestern Argentina, mainly the eastern flank of the Eastern Cordillera with full record of Tremadocian age, and to a lesser extent in the Sub-Andean Sierras; and in phosphate limestones and phosphate sandstones of the lower Cretaceous of the Neuquen Basin. Borate deposits are located in the Puna and correspond to evaporitic facies of tertiary synogenic deposits and quaternary salt deposits. [ABSTRACT FROM AUTHOR]

Copyright of Boletin de Geologia is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this study is to contribute to the petrophysical generalization performance of Bahía Honda region for mineral exploration purposes. For this purpose, the lithotypes present in the region were characterized, based on the existing magnetic, gravimetric and radiometric surveys, at a scale of 1: 100,000, as well as the values of density, magnetic susceptibility and gamma intensity measured in a significant number of pits. Statistical processing of aforementioned physical properties assisted the Petrophysical characterization. Linking physical properties with existing geophysical surveys allowed obtaining maps of spatial performance of these properties, not only for the lithotypes described, but also in the geological formations present in the area, which constitutes an important tool for mapping work, geological and mining prospecting carried out in the region. [ABSTRACT FROM AUTHOR]

There are several organic matter-rich shale geologic formations in Mexico that could be considered non-conventional potential oil reservoirs; one of those formations is the Eagle Ford Formation (Late Cenomanian - Turonian), aim of this study. The Eagle Ford Formation is located within the Sabinas paleobasin and along the Burros-Peyote paleoplatform, in the Coahuila State. This formation has been previously described as a transgression system deposited in a shallow marine environment with a total organic carbon between 0.5 to 8% with type II organic matter. For these reasons, it could be considered a potential source for non-conventional hydrocarbons. Therefore, it is considered that a reservoir of shale gas must have certain requirements, such as: 1) high total organic carbon (> 2% of COT), 2) presence of types II and III kerogen, 3) vitrinite reflectance values greater than 1.2% Ro (0.7% for shale oil), 4) thickness greater than 30 m and large extension, 5) fracturability (<40% clays or absence of expandable clays) or the presence of a microcracking system, 6) overpressure, 7) adequate depth, 8) heterogeneity, and others. A systematic sampling was carried on outcrops of Coahuila State with the goal to determine the thermal maturity degree of the Eagle Ford Formation using a detailed stratigraphic analysis of three columns (CSI, CSII and CSV) and micro-thermometric of fluid inclusions. Our results indicate that the Eagle Ford Formation is a sedimentary sequence rich in organic matter, locally composed of carbonaceous carbonate shale in laminar stratification alternating with shaly limestone (mudstone- wackestone) and clastic o bioclastic limestone (packstone-grainstone). Regarding the diagenetic alteration, primary porosity is affected by compaction and cementation processes. However, it was also observed a secondary micro-porosity development due to neomorphism, dolomitization, fracturing and stylolitization processes. Measured homogenization temperatures (Th) in fluid inclusions are between 65 °C and 125 °C, reaching the temperature window to generate oil and humid gas. The thermal evolution through its facies changes in the basin is not homogeneous. Our results indicate that the Eagle Ford Formation is a sedimentary sequence rich in organic matter, locally composed of carbonaceous carbonate shale in laminar stratification alternating with shaly limestone (mudstone- wackestone) and clastic o bioclastic limestone (packstone-grainstone). [ABSTRACT FROM AUTHOR]

The landscape of Deseado Massif in Santa Cruz province, is dominated by Jurassic volcanic geologic formations. In this geologic framework, good quality lithic raw material has a great availability and variability. Regional archaeological record presents a long human occupation sequence starting in late Pleistocene. In this paper, neutron activation analysis is implemented to characterize geochemical variability in Cantera del Rojo (CDR) and other lithic quarries within the study area. In turn, the technique is applied on archaeological artifacts from Cueva Maripe site to evaluate raw material sources. Neutron activation analysis has been frequently used on obsidian, but very rarely on other kind of rocks. Thus, this paper constitutes the first application of this methodology to identify provisioning sources of different silica rocks. Results indicate statistically significant associations between one of the quarries (CDR), which allow us to establish a geochemical identity. The Cueva Maripe site artifacts analyzed were manufactured on raw materials sourced from D9 quarry and from another unknown source. This is the first application of neutron activation analysis to the study of silica rocks to resolve archaeological problems, so it represents a landmark on the raw material provenance studies in Argentina. [ABSTRACT FROM AUTHOR]

In this paper we analyze some dimensions related to the implications of the production of extreme energy in the geological formation of Vaca Muerta, in particular in the Province of Neuquén, through the use of the fracking technique. For this, we start from a general intellection budget: the energy issue can be analyzed as a system where the different actors are in constant tension and dispute for a resource that is vital for economic production and to satisfy the welfare conditions of the population, but it is appropriate asymmetrically. Likewise, the extraction and production of energy takes place in different territories and the socio-environmental, political and economic impacts are distributed unevenly and problematically. With this purpose we will organize the writing from two levels of inquiry: 1) "from above", the conception of the Vaca Muerta megaproject as a public policy of government, centrally from 2012 onwards, warning continuities and ruptures in the proposals, programs and official conceptions regarding their exploitation and 2) "from below", giving an account of the attributes and particularities of the collective actors and of the social conflicts that have arisen around this extractive process. [ABSTRACT FROM AUTHOR]

Here we report stable isotope analyses performed on the remains of Peruvian soldier excavated in the archaeological site of Alto de la Alianza, a battle site where the conflict Guerra del Pacífico (1879-1884) took place, near Tacna in southern Peru. These analyses were conducted to glean data on dietary habits and approximate the origin of the individual tested. Our data suggests three important stages in the life of this soldier: one between 9 and 12 years of age, 12-20, and 20- 30 years. The acquired values of δ13C y δ15N suggest a diet acquired from the inner valley or a mountainous ecosystem. The δ18O values suggest these areas were of medium elevation, and the 87Sr/86Sr, an area of old geological formations. Our results, from the standpoint of forensic archaeology, serve as guide evidence for the identification of individuals that can be corroborated with archive documents. [ABSTRACT FROM AUTHOR]

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Copyright of Revista del Museo de Antropología is the property of Museo de Antropologia - IDACOR and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Boletin de Geologia is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this study is to develop electrical resistivity models in geological formations of greater interest for geological engineering in the southern area of the East of Cuba. A procedure for the generalization of the geo-electrical database was prepared to generate the referred geo-electrical models. A total of 38 works with 895 vertical electrical surveys, of which 317 (35.4%) located near (parametrical) drills. Three models for the Paso Real formation and one for the Capdevila, the most distributed in the region under investigation were defined. The surface quartz sands from the municipality of Sandino were identified to have higher electrical resistivity averages (1241 Ω•m), while they do not exceed 86 Ω•m in the lower horizons to resolve basic tasks of the geological engineering investigations. The assessment of the cover clayey sandy soils was satisfactory in both geological formations while the determination of the water table depth was unfavorable. The remaining tasks varied between relatively favorable to unfavorable according to the geological formations. [ABSTRACT FROM AUTHOR]

The article is about the amendments to Annexes II and III of the Convention for the Protection of the Marine Environment of the North-East Atlantic, related to the storage of carbon dioxide flows in geological structures (OSPAR). These amendments were adopted in Ostend, Belgium, on June 29, 2007. The objective of these amendments is to allow the storage of CO2 in geological formations in the seabed. Spain, along with other contracting parties, adopted these modifications in 2007. These amendments entered into force on July 23, 2011. [Extracted from the article]

The alternation and competition between the parasynthetic structures within the same conceptual field have been present in the Spanish system of word formation since the beginning of the language itself. So, while a parasynthetic model is operating at a particular time, it is replaced by a different one in the next period, without excluding the possibility of parallel existence and variation in use. We note this variation —although reduced— also in the nineteenth century. New parasynthetic formations are generated, that are actually alternations of pre-existing ones, with which they continue to coexist. Firstly, this study aims to show the reason for the new creation, subjecting the doublets of [a- + X + -ar] and [en- + X + -ar] structures to a lexical-syntactic examination with the intent to reflect the differences between corradical parasynthetic couples in a contextual use, and secondly, it examines the possible influence of related languages on the formation of the analysed voices. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

El artículo discurre sobre varias formaciones geológicas utilizadas en ceremonias rituales mayas en la antigua ciudad de Palenque en México. Se describen los mitos de la civilización maya en cuanto a la creación del mundo. El autor comenta sobre los objetos geológicos y los fósiles marinos del sitio arqueológico que demuestran una creencia del antiguo mundo cubierto en aguas primordiales. También examina tableros y otras esculturas que presentan escenas de los mitos de la creación del mundo.

Copyright of Instituto Superior de Correlacion Geologica, Serie Correlacion Geologica is the property of Instituto Superior de Correlacion Geologica (INSUGEO-CONICET) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Instituto Superior de Correlacion Geologica, Serie Correlacion Geologica is the property of Instituto Superior de Correlacion Geologica (INSUGEO-CONICET) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Boletin de Geologia is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Bisbee Group is the most important lithostratigraphic unit that identifies the Lower Cretaceous in southeastern Arizona and northeastern Sonora. In the sierra Basómari, this group is characterized by outcrops of the Morita, Mural and Cintura formations, which are strongly affected by folds of kilometric dimensions locally overturned, normal faults of Mesozoic age, and a Cenozoic normal faulting. These lithostratigraphic units are overlain by Tertiary volcanic and sedimentary rocks. In the study area the Morita Formation is constituted by thin- to medium-bedded fine-grained sandstone, with some horizons with fossil wood, intercalated with fossiliferous and marly thin- to medium- bedded limestone. The Mural Limestone is characterized by thin- to massive-bedded fossiliferous limestone, intercalated with thin- to medium-bedded sandstone and clayish sandstone beds. The Cintura Formation is mainly made up of thin- to massive-bedded sandstone intercalated with laminar to thin-bedded mudstone. The Bisbee Group rocks in the area of the sierra Basómari represent shallow- marine sedimentary environments: intertidal inner neritic, middle neritic with development of lagoonal and ooidal bank conditions, outer neritic (open marine platform) and pelagic. [ABSTRACT FROM AUTHOR]

The term knickpoint is commonly used in geomorphology to distinguish any abrupt change in the channel slope observed along a longitudinal stream profile. Knickpoints are an expression of disequilibrium in a fluvial system and occur in both alluvial and bedrock rivers. Advances in fluvial geomorphology and landscape evolution indicate that knickpoint formation is related to tectonic, climatic and geomorphic processes. Nonetheless, at present there is no formal definition for the term. Present usage of the term knickpoint does not provide information about its triggering factors. Thus, the word knickpoint describes only a morphological property of channels. The term needs to be formally defined in Spanish, since it has been used on a casual basis. In this paper the term knickpoint is reviewed and a genetic classification is developed. Five different types of knickpoints are distinguished: glacial, lithologic, tectonic, eustatic and glacio-isostatic. It is proposed here that the term knickpoint be adopted into the geomorphic and geologic Spanish lexicon by including the genesis as an adjective attached to the noun. [ABSTRACT FROM AUTHOR]

The Yegua Formation (Eocene) in the Burgos Basin is divided into three units. The lower Yegua is sandstone deposited in a near shore environment of a highstand systems tract (HST), whose top is truncated by a prominent unconformity and regional sequence boundary at around 39.5 Ma. The middle Yegua is a complex facies, which consists of basin-floor fan sandstones, channels, and unconformities corresponding to a lowstand systems tract and prograding wedge, but also includes a transgressive systems tract . The upper Yegua represents a HST, which underlies the maximum flood surface that constitutes the base of the Jackson Formation. The Yegua Formation possibly reflects the final sediment influx towards the ancestral Gulf of Mexico resulting from Laramide age uplift and orogenic deformation in Northeastern Mexico. [ABSTRACT FROM AUTHOR]

We report the results of a magnetostratigraphic study of the San Marcos Formation in central Coahuila, at two localities along the San Marcos Fault. These localities are characterized by outcrops of a sequence of conglomerates, immature sandstone and red mudstone, cemented by hematite; the sequence was deposited in a continental environment, and has been assigned to the Early Cretaceous. All specimens, from a total of 35 paleomagnetic sites, were subjected to alternating field and thermal demagnetization, the latter being the most effective in isolating the (high temperature) characteristic magnetization. The characteristic component is unblocked between 625° and 660 °C. Both normal and reverse polarity magnetizations are represented, and the overall mean is of Dec = 352.7 °, Inc = 55.5 °, N = 3 localities (18 sites), k = 27.07, α95 = 6.8 °. This result suggests a small clockwise rotation with respect to the expected reference direction for the Cretaceous, estimated from the apparent polar wandering curve for cratonic North America. However, the data suggest that there was relative rotation between localities, and the observed rotations are more likely explained as local vertical-axis rotations. The magnetic polarity zonation in the San Marcos Formation suggests that this unit represents the Early Barremian through Early Aptian. The correlation to global magnetic polarity timescale suggests that this unit is correlative with Cupido Formation, and that the transgressive littoral facies of the Las Uvas Formation, as well as flooding of Coahuila paleo-island at Potrero Colorado, occurred in the Early Aptian. The best correlation with the global magnetic polarity time scale corresponds to the interval from M5n (normal) to M0r (inverse) approximately between 131-125 Ma. The sedimentation rate indicated by this correlation, assuming a constant rate, is relatively low (∼30-50 m/Ma) for an active tectonic environment and is more consistent with a region where accommodation is achieved by isostatic adjustment between crustal blocks (Coahuila Block and Sabinas Basin). [ABSTRACT FROM AUTHOR]

It is proposed in this note that the oldest terrigenous rocks cropping out in the Tolimán region in the state of Querétaro belong to two different units: El Chilar complex and the San Juan de la Rosa Formation. The first consists of highly deformed siliciclastic turbidites and the second is a volcano-sedimentary succession deposited in marine conditions. The volcanism of the San Juan de la Rosa Formation is felsic in composition and Late Jurassic-Early Cretaceous in age. We postulate as a working hypothesis that the felsic magmatism of the San Juan de la Rosa Formation are part of the Jurassic volcanic arc in central Mexico that migrated in time and space towards the south.? [ABSTRACT FROM AUTHOR]

The Cretaceous Zimapan basin was affected by compressive Laramide deformation, which gave place to tectonic uplift in the area. After regional uplift of the rocks, erosion began to fill several continental intermontane basins with an orientation parallel to the alignment of the major folded structures. The "El Morro Formation" represents the alluvial and fluvial filling of the intermontane basins. El Morro Formation type locality has a stratigraphic thickness of 64 meters and is composed of four lithofacies with different source rocks. The earliest stratigraphic work in Zimapan area described a stratigraphic thickness that varies from several meters to 400 meters with drastic lateral changes. Sedimentation of the El Morro Formation was interrupted by the accumulation of a succession of andesitic breccias of Las Espinas Formation. Both formations are locally interfingered by a few meters and the top of El Morro Formation includes andesitic clasts, which gave a K/Ar age of 38.1±1.4 Ma. An age of 62 Ma was obtained in diagenetic illite fromthe Jiliapan-El Volantin thrust fault, located 25 km north of Zimapan, which constrains the end of active compressive deformation to the earliest Paleocene. The age of the El Morro Formation ranges from at least the middle Paleocene to middle Eocene by the K/Ar isotopic age of the overlying volcanic rocks and the diagenetic illite formed during the movement of the Jiliapan-El Volantin thrust faults. The palynological assemblages indicate a tropical climate with abundant precipitation and confirm the fluvial regimen that prevailed during the deposition of El Morro Formation. [ABSTRACT FROM AUTHOR]

The Sierra Los Chinos is located in east-central Sonora, where three stratigraphic sequences whose ages that vary from Lower Cretaceous to Tertiary are exposed. The Lower Cretaceous succession is composed of the Agua Salada, Lampazos and Los Picachos Formations. A second sequence of Upper Cretaceous strata is constituted by volcanosedimentary rocks; while a third sequence of the Tertiary rocks is comprised by volcanic and intrusive rocks and by the sedimentary Báucarit Formation. The Lower Cretaceous rocks are strongly folded and faulted, the outstanding structures are the anticlines and synclines oriented NW-SE, with vergencies either to the northeast or to the southwest faulting in the area is mainly normal and trust faults. The Alamo section is separated into 5 informal units (A, B, C, and D), which correspond to the Los Picachos Formation. The Los Picachos Formation exposed in The Alamo range has a thickness of 560 m. and is constituted by 4 lithics packages, the presence of rudist inside the clasts that constitute a package of conglomerates near the base, as well as the rudist Coalcomana sp. in the unit A and of orbitolinids and calcispheres (Pithonella ovalis) near the top, allow us to assigne it to the middle to upper Albian. The textural characteristics of the limestone beds, as well as its faunal content indicate that these sediments were deposited in a shallow water outer-neritic marine environment with local development of ooidal banks and rudist bioherms. [ABSTRACT FROM AUTHOR]

The structural analysis of La Trocha Fault Zone at a regional scale was carried out, following the interpretation of a great volume of geological and geophysical information, which was classified as: morphometric, gravimetric, superficial and underground geology. A digital elevation model (DEM) was obtained, starting with the digitalization of 24 parts of the Topographical Map of the Republic of Cuba 1:50000, published by the Geodesy and Cartography Cuban Institute in 1977. The processing of the DEM allowed obtaining the main existing alignments in the region. The information of the gravimetrical mapping of the Central Basin at a scale of 1:100000 was processed. The maps of anomalies of Bouguer, ascending analytic continuations and gravimetric gradients were constructed. The geological information of the surface was taken from the Geologic Map of the Republic of Cuba 1:100000, published by the Geology and Palaeontology Institute in 2001, while the underground geological information was obtained from the wells perforated during the oil activity in the Central Basin. The processing of the geological and geophysical information was carried out digitally. The combined interpretation of the geological and geophysical information allowed an approach to the geometric characteristics of the La Trocha Fault Zone. The predominant directions were established in the zone of main displacement and the possible evolution of the tectonic efforts. An evolution model was proposed for the region, considering the existence of a flower structure, which adjusts the existing characteristics and explains the simultaneous development of a tensional basin, the Central Basin company. [ABSTRACT FROM AUTHOR]

El artículo caracteriza fisiográficamente la península de Yucatán, México y describe el origen de sus pozos naturales--llamados cenotes. Indica cómo se formó la península, discurre sobre los procesos geomorfológicos que resultaron en la formación de los cenotes y comenta sobre su clasificación según sus características hidrobiogeoquímicas.

The basic algorithm of a rheologic model of continuos deformation is presented (DERECO, Version 1.91) structurally based considering folding as infinitesimal or finite amplitude elements. Aspects related with folds shape, energy dissipation phenomena, time discretization and the structure of the stress field are also discussed. Model has been validated with the folded concentric (simple and chevron) mesostructures of the San Cayetano Lower (?) -- Upper Jurassic) formation, folded continental basement formation of the Sierra del Rosario, western Cuba, outcropping at Cinco Pesos. [ABSTRACT FROM AUTHOR]

The recompilation of geologist-geochemical information preliminary existing on the Metalogenic District Dora-Francisco, has served of base for the recognition projects accomplished by Economic Asociation Holmer Gold Mines Limited-Geominera S.A. during the period 1994-1998. With the objective of clarifying the fundamental features that characterize the location of hydrothermals deposits in this region and, in this way, offer a true geochemical prognosis, is proposed a methodology where are combined the classification techniques with learning (expert programs) and the multivariate statistic (principal components analysis). The results of processing of the available geochemical data are show as standards geochemical maps to the prognosis of sulfurous mineralization (cupriferous and polimetalics). The overlapping of geochemicals maps with the geological map make possible to appreciate relationships between the complex lithogeochemical anomalies uncovereded and given lithological sequences of the formation San Cayetano, something which contributes favorably to corroborate the geochemical specialization of the Methalogenic District Dora-Francisco. As a result final are proposed exploration sectors with differentiated priority orders that answer to the integration of the prospectives categories assigned, the correspondence with sequences of the San Cayetano formation favorable to host sulfurous mineralization and the spatial continuity of the different Units of Basic Information defined. [ABSTRACT FROM AUTHOR]