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At the moment, two freshwater bivalve species were described for the continental Jurassic of Patagonia: Diplodon simplex Morton and Diplodon matildensis Morton from La Matilde Formation of the Santa Cruz province. The Cañadón Asfalto... more
At the moment, two freshwater bivalve species were described for the continental Jurassic of Patagonia: Diplodon simplex Morton and Diplodon matildensis Morton from La Matilde Formation of the Santa Cruz province. The Cañadón Asfalto Formation located in Chubut province exhibits a high diverse invertebrate fossil fauna preserved mainly in lacustrine facies, which includes clam shrimps, bivalves, gastropods, ostracods and insects. However, few studies have been carried out on freshwater bivalve of this geological unit. In this work, a morphological description of bivalve assemblage and paleoenvironment analysis from the Cañadón Asfalto Formation was performed. Forty samples were collected from three stratigraphic levels at the Cañadón Asfalto locality. These levels are ash fall tuffs rich in glass particles accumulated in a lacustrine system with development of microbial activity. Morphological analyzes of outline and sizes were performed at each level. Our results showing the smalle...
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Research Interests: Geology, Paleontology, Biology, Palynology, Pollen, and 5 moreGenus, Paleogene, Reticulate, Annonaceae, and Macrofossil Analysis
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Abstract: Spinicaudatans are a diverse and geographically widespread group of small branchiopod crustaceans with an excellent fossil record. They inhabit ephemeral freshwater habitats with warm conditions and pH levels from neutral to... more
Abstract: Spinicaudatans are a diverse and geographically widespread group of small branchiopod crustaceans with an excellent fossil record. They inhabit ephemeral freshwater habitats with warm conditions and pH levels from neutral to alkaline. Many studies have been performed on the systematics of this group, also known as ‘conchostracans', although the paleoecology of these clam shrimp has not been widely analyzed. This paper examines some aspects of the relationship between spinicaudatans and their environments from the Upper Jurassic (Cañadón Asfalto Formation) of Argentina. We used sedimentological analysis to infer paleoenvironmental factors. Spinicaudatan features were also measured, including carapace size, growth band width, and growth lines. The results of this study reveal that the observed spinicaudatan species (Congestheriella rauhuti, Wolfestheria smekali, and Wolfestheria sp.) would have lived in carbonate lacustrine systems characterized by benthic microbial communities dominated by cyanobacteria. However, environmental factors such as oxygenation, pyroclastic deposits, and associated fauna (fish, ostracods, bivalves, and charophytes) were different at each locality. The spinicaudatan carapaces also show varying morphological features such as small or large carapace size, narrow or wide growth bands and low or high density of growth lines. These differences are related to abiotic (volcanic-oxygen) and biotic (fish and microbial) factors regarded as important agents for the development of the spinicaudatan populations.
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Palynologic assemblages from Middle and Upper Jurassic sediments of the Cañadón Asfalto Basin (central Chubut) and the Neuquén Basin are compared. The following localities are considered: Cañadón Lahuincó and Estancia Fossati (Chubut);... more
Palynologic assemblages from Middle and Upper Jurassic sediments of the Cañadón Asfalto Basin (central Chubut) and the Neuquén Basin are compared. The following localities are considered: Cañadón Lahuincó and Estancia Fossati (Chubut); Charahuilla, Arroyo Picún Leufú, and Portada Covunco (Neuquén). Palynostratigraphic and statistic studies show tendencies in diversity at species level and in suprageneric groups. Topographically elevated hinterlands with prevailing conifer vegetation (Araucariaceae and/or Podocarpaceae) can be inferred for the Jurassic. A very high representation of the thermophilous Cheirolepidiacean Classopollis pollen indicates warm, arid to semiarid climatic conditions in Chubut. A high representation of trilete spores suggests local humid conditions (deltaic swamps) in the studied Middle Jurassic areas of the Neuquén Basin, within a general semiarid climatic context. Low specific palynologic diversity in the lowermost part of the Cañadón Asfalto Formation (early Middle Jurassic) could be explained by the high frequency and intensity of the volcanic activity. In order to understand the regional paleoclimatic context, it is necessary to look northwards and southwards of the studied area. During the Late Jurassic, extremely arid conditions are indicated for nearly the whole extension of the Chaco-Paraná Basin and the Paraná Basin, which are the scenario of the largest paleodesert known so far from the geologic record worldwide ("Botucatú-paleodesert"). Along the Pacific coast, the paleoclimatic picture of an extremely arid region, at the same paleolatitudes mentioned, was completed by extensive Late Jurassic (Oxfordian) deposits of evaporites (anhydrite, gypsum), extending from Zapala (Neuquén Province) to the San Juan Province and continuing to southern Perú. Southwards of the studied area, in the Santa Cruz Province, previous records of arborescent ferns and coal deposits in the Middle to Late Jurassic La Matilde Formation suggest, at least locally, moist conditions.Sesiones libresFacultad de Ciencias Naturales y Muse
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Abstract The limestones of the Calabozo Formation of early Callovian age, crop out in the Neuquén Basin, southwestern Mendoza Province, Argentina. Facies/microfacies analysis at Arroyo El Plomo, west of Malargüe, shows that the limestones... more
Abstract The limestones of the Calabozo Formation of early Callovian age, crop out in the Neuquén Basin, southwestern Mendoza Province, Argentina. Facies/microfacies analysis at Arroyo El Plomo, west of Malargüe, shows that the limestones of the Calabozo Formation ...
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ABSTRACT Six facies associations are described for the Puesto Almada Member at the Cerro Bandera locality (Fossati sub-basin). They correspond to lacustrine, palustrine, and pedogenic deposits (limestones); and subordinated alluvial fan,... more
ABSTRACT Six facies associations are described for the Puesto Almada Member at the Cerro Bandera locality (Fossati sub-basin). They correspond to lacustrine, palustrine, and pedogenic deposits (limestones); and subordinated alluvial fan, fluvial, aeolian, and pyroclastic deposits. The lacustrine–palustrine depositional setting consisted of carbonate alkaline shallow lakes surrounded by flooded areas in a low-lying topography. The facies associations constitute four shallowing upward successions defined by local exposure surfaces: 1) a Lacustrine–Palustrine-pedogenic facies association with a ‘conchostracan’–ostracod association; 2) a Palustrine facies association representing a wetland subenvironment, and yielding ‘conchostracans’, body remains of insects, fish scales, ichnofossils, and palynomorphs (cheirolepidiacean species and ferns growing around water bodies, and other gymnosperms in more elevated areas); 3) an Alluvial fan facies association indicating the source of sediment supply; and 4) a Lacustrine facies association representing a second wetland episode, and yielding ‘conchostracans’, insect ichnofossils, and a palynoflora mainly consisting of planktonic green algae associated with hygrophile elements. The invertebrate fossil assemblage found contains the first record of fossil insect bodies (Insecta-Hemiptera and Coleoptera) for the Cañadón Asfalto Formation. The succession reflects a mainly climatic control over sedimentation. The sedimentary features of the Puesto Almada Member are in accordance with an arid climatic scenario across the Upper Jurassic, and they reflect a strong seasonality with periods of higher humidity represented by wetlands and lacustrine sediments.
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This file represent a complementary PCA anlysis between chemical data from fossil and mineral species. There are a paragraph about study description, one figure and three tables of analysis
Spinicaudatans (‘clam shrimps’) are small branchiopod crustaceans enclosed in a chitinous bivalved carapace that is often the only preserved element in the fossil record. However, few studies have analyzed the preservation of these... more
Spinicaudatans (‘clam shrimps’) are small branchiopod crustaceans enclosed in a chitinous bivalved carapace that is often the only preserved element in the fossil record. However, few studies have analyzed the preservation of these carapaces, which have been found in continental facies from the Devonian to the present. The aim of this study was to contribute to a better understanding of the chemical preservation of fossil spinicaudatan carapaces, and focused on spinicaudatan carapaces of the Cañadón Asfalto Formation from the Jurassic of Argentina. Semi-quantitative energy-dispersive X-ray spectrometry (EDS) analysis provided elemental composition data that were interpreted using principal component analysis (PCA). The results showed a complex chemical mode of preservation for spinicaudatan carapaces. In some parts, EDS spectra of the specimens exhibits peaks of calcium, phosphorous, aluminum and fluorine, representing the retention of original carapace material with some diagenetic recrystallization. Certain zones of the carapace show low intensity peaks of the elements mentioned above, while silicon and oxygen peaks (from the rock matrix) become the dominant spectral signals. These modes of preservation modify the interpretations and observations of the ornamentation of the carapace, which are used as taxonomic features. Our results suggest that specific diagenetic processes play a fundamental role in the preservation of spinicaudatans
This file correspond to tables from PCA analysis of main manuscript. There are three tables with captions
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Re-examination under a scanning electron microscope (SEM) of the type material of the species described by Tasch and Volkheimer (1970) and Vallati (1986) was applied, as well as, new materials collected from different localities of the... more
Re-examination under a scanning electron microscope (SEM) of the type material of the species described by Tasch and Volkheimer (1970) and Vallati (1986) was applied, as well as, new materials collected from different localities of the Las Chacritas Member from Cañadón Asfalto Formation (Argentina). Morphological description and new SEM images of the ornamentation pattern revealed features on carapaces that had not been recognized previously. These species are now referred to the family Eosestheriidae as Carapacestheria taschi (Vallati, 1986) and to the family Fushunograptidae as Wolfestheria patagoniensis (Tasch, in Tasch and Volkheimer, 1970). These records increase our knowledge about the Jurassic faunas from Argentina.
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Stratigraphy, facies analysis and paleoenvironments of the Cañadón Asfalto Formation, Jurassic Cerro Cóndor depocenter, Chubut province. The Cerro Cóndor depocenter represents the most complete stratigraphic sequence of the continental... more
Stratigraphy, facies analysis and paleoenvironments of the Cañadón Asfalto Formation, Jurassic Cerro Cóndor depocenter, Chubut province. The Cerro Cóndor depocenter represents the most complete stratigraphic sequence of the continental Jurassic of the Cañadón Asfalto basin and southern South America. It is situated in extraandean Patagonia, on both sides of the middle Chubut river valley. The sedimentation in this pull-apart basin begins early in the Middle Jurassic, accompanied by effusions of olivinic basalts. The prevailing lacustrine deposits are characterized by carbonatic and siliciclastic facies associations, interfingering with volcanic deposits grading from lavic in the base to predominantly pyroclastic towards the top. The facies evolution from north to south is described, embracing the sections of farm El Torito and the canyons of Los Loros, Las Chacritas, Carrizal, Asfalto and Lahuincó. The carbonatic facies/microfacies are represented by mudstones, wackestones, packston...
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Research Interests: Geology and Geochemistry
Las investigaciones interdisciplinarias que han comenzado recientemente en el Macrosistema Iberá buscan, entre otros aspectos, ampliar el conocimiento sobre la arqueología regional. En este artículo se dan a conocer los resultados de los... more
Las investigaciones interdisciplinarias que han comenzado recientemente en el Macrosistema Iberá buscan, entre otros aspectos, ampliar el conocimiento sobre la arqueología regional. En este artículo se dan a conocer los resultados de los análisis realizados sobre la colección de restos óseos humanos, faunísticos, líticos y cerámicos recuperados en el sitio Isla El Disparito. Sumado a esto se presentan los resultados sedimentológicos, paleobotánicos y mineralógicos del sitio, así como los fechados radiocarbónicos hasta ahora obtenidos. En los trabajos realizados se recuperaron fragmentos cerámicos alisados sin decoración, corrugados y decorados (por incisión y/o impresión), los que corresponderían a variados recipientes de contornos simples o complejos. A esto se suma un variado utillaje confeccionado tanto sobre hueso como sobre material lítico. Este último está elaborado principalmente sobre areniscas, conformado por puntas de proyectil con pedúnculo y aletas rectas o cóncavas; rae...
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Research Interests: Geology and Geophysics
Abstract Large carbonate microbialite build-ups are relatively uncommon in ancient fresh-water lacustrine basins as compared with those marine and saline environments. This paper discusses the formation of a large continental lacustrine... more
Abstract Large carbonate microbialite build-ups are relatively uncommon in ancient fresh-water lacustrine basins as compared with those marine and saline environments. This paper discusses the formation of a large continental lacustrine deposit, the Oligocene-Miocene Carinao Formation in Argentina, which contains large bioherms. The lacustrine formation occur in N-S corridor and is mostly composed by meter scale pinnacles and sheet-like carbonate beds that grade to detrital deposits towards the more subsident southern areas. The main facies are autochthonous and allochthonous limestones and detrital deposits. The autochthonous limestones include the carbonate pinnacles, which are about 4 m high and 0.5 m in diameter and coalesce laterally to form very continuous beds (several kms). The pinnacles are formed by plate-like, dome, vertically elongated and irregular horizontal bioherms, most of them with radial structure. The bioherms are boundstones of fibrous (fans and spherulites) and feather calcite crystals, micrite and inequigranular calcite mosaics. Both biogenic and abiogenic processes interfered in carbonate precipitation. Allochthonous limestones include peloidal, ostracod and intraclastic limestones, some containing coated grains. Polymictic conglomerates and cross-bedded hybrid arenites deposited in a fluvial-deltaic system located at the southwest of the basin. δ13C values vary between −0.4 and − 3.2‰ VPDB and δ18O are comprised between −5.7 and − 8.6‰ VPDB. The 87Sr/86Sr ratios range between 0.7061 and 0.7056. The Carinao Formation deposited in a fresh-water lake, sourced by meteoric and deep-groundwater. Tectonics was a main control determining the configuration of the lake system, the water supply and the alignment of some bioherms. The vertical succession or the different bioherms morphologies reflects well the lake level changes controlled by both tectonic and climate.
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Spinicaudatans (‘clam shrimps’) are small branchiopod crustaceans enclosed in a chitinous bivalved carapace that is often the only preserved element in the fossil record. However, few studies have analyzed the preservation of these... more
Spinicaudatans (‘clam shrimps’) are small branchiopod crustaceans enclosed in a chitinous bivalved carapace that is often the only preserved element in the fossil record. However, few studies have analyzed the preservation of these carapaces, which have been found in continental facies from the Devonian to the present. The aim of this study was to contribute to a better understanding of the chemical preservation of fossil spinicaudatan carapaces, and it focused on spinicaudatan carapaces of the Cañadón Asfalto Formation from the Jurassic of Argentina. Semiquantitative energy-dispersive X-ray spectrometry (EDS) analysis provided elemental composition data that were interpreted using principal component analysis (PCA). The results showed a complex chemical mode of preservation for spinicaudatan carapaces. In some parts, EDS spectra of the specimens exhibit peaks of calcium, phosphorous, aluminum, and fluorine, representing the retention of original carapace material with some diagenet...
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Research Interests: Geology and Geophysics
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The Upper Jurassic Cañadón Asfalto Formation (Cañadón Asfalto Basin, Patagonia Argentina), consists mainly of carbonate deposits accumulated in hydrologically closed lakes, which were especially sensitive to rainfall changes. The... more
The Upper Jurassic Cañadón Asfalto Formation (Cañadón Asfalto Basin, Patagonia Argentina), consists mainly of carbonate deposits accumulated in hydrologically closed lakes, which were especially sensitive to rainfall changes. The lacustrine carbonate sedimentation also interplayed with volcanic episodes recorded by tuffs and lavas, as observed in different basin sectors. These lakes probably underwent warm, alternating humid-subarid and arid conditions that resulted
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ABSTRACT Continental carbonates are rich in palaeoclimatic, palaeoenvironmental and palaeontological information. While carbonate accumulation mechanisms have been described for many types of continental environments, especially in... more
ABSTRACT Continental carbonates are rich in palaeoclimatic, palaeoenvironmental and palaeontological information. While carbonate accumulation mechanisms have been described for many types of continental environments, especially in extensional basins, there are still uncertainties that existing facies models fail to address. The Triassic Cerro de las Cabras and Cerro Puntudo formations are alluvial–fluvial–lacustrine sequences that represent a part of the sedimentary infill of two sub-basins of the Cuyana basin during the early stages of the Triassic rift in west-central Argentina. Previous work has provided absolute dates, confirming that these deposits are coeval (Anisian) allowing a comparative study of carbonate sedimentation in an extensional tectonic context. The description and origin of freshwater carbonate deposits and their surrounding siliciclastic sediments in specific areas of the Cuyana rift, gives insight into the major factors that control carbonate precipitation in all rift basins, including the characterization of the palaeohydrology and the importance of provenance. The Cerro de las Cabras Formation represents an ephemeral, playa-lake depositional system with subaerial exposure and pedogenesis. Its aggradational succession corresponds to the evaporative facies association lake type, diagnostic of underfilled lake basins where persistently closed surface hydrology can lead to thick evaporites. However, this formation lacks thick evaporites and has microbialitic limestones, pointing to an open groundwater supply. The Cerro Puntudo Formation represents an alkaline playa-lake system fed by groundwater and ephemeral surface-water input. The unit is an aggradational–minor progradational succession, pointing to a fluctuating profundal facies association, suggesting a balanced–filled lake type. These two synchronous, lacustrine depositional systems were influenced by tectonics and climate. Provenance and hydrology are key controls in carbonate accumulation in continental rift basins that must be included in future facies models for continental carbonates. Comparison with other rift basins suggests that application of lake type characterizations coupled with palaeohydrology and provenance patterns will aid in developing new sedimentation models for freshwater limestones in extensional settings.This article is protected by copyright. All rights reserved.
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The lower section of Canadon Asfalto Formation (Callovian-Oxfordian) is located at Las Chacritas, Cerro Condor area, on the middle course of Chubut River. It is represented by lacustrine carbonate faciès with interbedded volcanic layers... more
The lower section of Canadon Asfalto Formation (Callovian-Oxfordian) is located at Las Chacritas, Cerro Condor area, on the middle course of Chubut River. It is represented by lacustrine carbonate faciès with interbedded volcanic layers accumulated in the rift system of the Somuncura-Canadon Asfalto Basin. Eight microfacies (MF), defining the lake environments, and three biohermal faciès (MFB) corresponding to an extensive microbialitic belt overlying eulittoral sediments have been recognized: The microfacies are: MF1, mudstone with microbial lamination, related to supralittoral shallow ponds; MF2, biohermal intraclastic floatstone linked to storm episodes; culminating with evaporitic levels; MF3, mudstone with evidence of dessication formed in stagnant water; MF4, microbial-peloidal mudstone/wackestone with evidence of sporadic wave currents, in a eulittoral environment; MF5, intraclastic grainstone/rudstone with pedogenic alterations showing evidence of wave action in a eulittoral...
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The Cerro Cóndor depocenter represents the most complete stratigraphic sequence of the continental Jurassic of the Cañadón Asfalto basin and southern South America. It is situated in extraandean Patagonia, on both sides of the middle... more
The Cerro Cóndor depocenter represents the most complete stratigraphic sequence of the continental Jurassic of the Cañadón Asfalto basin and southern South America. It is situated in extraandean Patagonia, on both sides of the middle Chubut river valley. The sedimentation in this pull-apart basin begins early in the Middle Jurassic, accompanied by effusions of olivinic basalts. The prevailing lacustrine deposits are characterized by carbonatic and siliciclastic facies associations, interfingering with volcanic deposits grading from lavic in the base to predominantly pyroclastic towards the top. The facies evolution from north to south is described, embracing the sections of farm El Torito and the canyons of Los Loros, Las Chacritas, Carrizal, Asfalto and Lahuincó. The carbonatic facies/microfacies are represented by mudstones, wackestones, packstones, grainstones and microbialitic limestones, characteristic of littoral/marginal and palustrine environments. In the Cañadón Asfalto For...
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Research Interests: Geology and Geochemistry
Abstract: Patch reefs facies in the Picún Leufú Formation (Jurassic/Cretaceous boundary) in the Zapala region, Neuquén Basin, Argentina. In the locality of Cerrito Caracoles, situated in the nearby of Zapala city, in the western central... more
Abstract: Patch reefs facies in the Picún Leufú Formation (Jurassic/Cretaceous boundary) in the Zapala region, Neuquén Basin, Argentina. In the locality of Cerrito Caracoles, situated in the nearby of Zapala city, in the western central region of the Neuquén province, Argentina, the basal part of the Picún Leufú Formation (Jurassic/Cretaceous boundary) crops out. The facies and microfacies association analysis points out to an inner shelf margin environment, with development of well preserved patch reefs. The description of these bodies (coral and algae bafflestone, bryozoan bafflestone and algal boundstone), and of a low relief mound reef (skeletal algal packstone) are presented in this paper. The associated facies are represented by low energy deposits (mudstone), bar complexes (sandy skeletal packstone and skeletal packstone) and channels (skeletal intraclast floatstone and intraclast skeletal ooidal floatstone).
ABSTRACT The Las Chacritas Member is the lower part of the Cañadón Asfalto Formation (Jurassic). The unit is a completely continental limestone succession with volcanic contributions that were deposited during the development of the... more
ABSTRACT The Las Chacritas Member is the lower part of the Cañadón Asfalto Formation (Jurassic). The unit is a completely continental limestone succession with volcanic contributions that were deposited during the development of the Cañadón Asfalto Rift Basin (Chubut province, Patagonia, Argentina). A detailed sedimentological analysis was performed in the Fossati depocenter to determine the paleoenvironments that developed in the context of this rift. The Las Chacritas Member represents a carbonate paleolake system with ramp-shaped margins associated with wetlands that were eventually affected by subaerial exposure and pedogenesis. This process is represented by three main subenvironments: a) a lacustrine setting sensu stricto (lacustrine limestone facies association), represented by Mudstones/Wackestones containing porifera spicules (F1), Intraclastic packstones (F6) and Tabular stromatolites (F10) in which deposition and diagenesis were entirely subaqueous; b) a palustrine setting (palustrine limestone facies association) containing Microbial Mudstones (F2), Intraclastic sandy packstone with ostracode remains (F3), Oncolitic packstone (F5), Brecciated limestone (F7) and Nodular-Mottled limestone (F8) representing shallow marginal areas affected by groundwater fluctuations and minor subaerial exposure; and c) a pedogenic paleoenvironment (pedogenic limestone facies association) including Intraclastic limestone (F4) and Packstones containing Microcodium (F9) facies displaying the major features of subaerial exposure, pedogenic diagenesis and the development of paleosols. The fluvial–palustrine–lacustrine succession shows a general shallow upward trend in which contraction–expansion cycles are represented (delimited by exposure and surface erosion). The variations in the successive formations reflect the responses to fluctuations in a combination of two major controls, the tectonic and local climatic variables. The predominance of the palustrine facies associations was determined by its accommodation space as well as the local climate conditions. The variations in the lacustrine limestone facies associations reflect differential patterns of subsidence within the sub-basin. The diagnostic features of the palustrine limestone facies associations (organic matter (OM) content, microinvertebrate fauna, abundant mud cracks, brecciation, presence of evaporitic minerals) frame the sub-basin in a climatic context intermediate between arid and subhumid conditions.
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ABSTRACT The limestones of the Calabozo Formation of early Callovian age, crop out in the Neuquén Basin, southwestern Mendoza Province, Argentina. Facies/microfacies analysis at Arroyo El Plomo, west of Malargüe, shows that the limestones... more
ABSTRACT The limestones of the Calabozo Formation of early Callovian age, crop out in the Neuquén Basin, southwestern Mendoza Province, Argentina. Facies/microfacies analysis at Arroyo El Plomo, west of Malargüe, shows that the limestones of the Calabozo ...
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Research Interests: Geology and Geophysics
Page 1. Facies (2005) 51:350364 DOI 10.1007/s10347-004-0042-5 ORIGINAL ARTICLE Nora G. Cabaleri · Claudia Armella · Diego G. Silva Nieto Saline paleolake of the Caæadón Asfalto Formation (Middle-Upper Jurassic), Cerro Cóndor, Chubut... more
Page 1. Facies (2005) 51:350364 DOI 10.1007/s10347-004-0042-5 ORIGINAL ARTICLE Nora G. Cabaleri · Claudia Armella · Diego G. Silva Nieto Saline paleolake of the Caæadón Asfalto Formation (Middle-Upper Jurassic), Cerro Cóndor, Chubut province ...