Diego Guido - Profile on Academia.edu (original) (raw)

Papers by Diego Guido

Andean Geology, Sep 28, 2023

sulfuración hospedado en rocas volcánicas del Grupo Choiyoi, donde se destacan los sectores Merca... more sulfuración hospedado en rocas volcánicas del Grupo Choiyoi, donde se destacan los sectores Mercado-Kamila y Julieta, los cuales concentran los mayores recursos del distrito. El sector Julieta es un sistema vetiforme auroargentífero de cuarzo-calcita, con texturas bandeadas coloformes, brechosas y reemplazos tipo lattice bladed. En este estudio, a partir del análisis detallado de la mineralogía y textura de las vetas del sector Julieta (denominadas en este trabajo simplemente como veta Julieta), se discriminaron 9 pulsos que fueron agrupados en 4 eventos principales, 3 de ellos de naturaleza hidrotermal y 1 del tipo tectónico-hidrotermal. Los pulsos P1, P2 y P3 son estériles y de naturaleza carbonática, mientras que P4 y P5A son de composición calcedónica y con textura bandeada coloforme. Este último posee bandas color crema con adularia y bandas negras tipo ginguro bands, a las cuales se asocian máximos valores de 5,5 g/t Au y 52 g/t Ag. El pulso P5B también es silíceo, aunque de textura brechosa, mientras que el pulso P6 es de naturaleza silíceo-carbonática. La evolución de los pulsos migra hacia composiciones carbonáticas, representada por los pulsos P7 y P8, ambos de textura brechosa. El último evento consiste en un pulso silíceo-ferruginoso del tipo tectónico-hidrotermal (P9). La veta Julieta posee un rumbo definido NO-SE, con subestructuras menores de orientación E-O y N-S, y puede dividirse en 3 segmentos según su morfología: norte, central y sur. Tanto los mayores espesores, como las mayores inclinaciones y los altos valores de metales preciosos se asocian a inflexiones generadas entre los 3 segmentos. Respecto a la geometría de los clavos mineralizados, la veta posee un clavo principal subhorizontal, el que respondería a un control del tipo litológico, en tanto que clavos secundarios subverticales obedecerían a un control del tipo estructural. Por otro lado, diferencias en la

Revista de la …, 2004

Revista de la Asociación Geológica Argentina, Jun 30, 2019

Detección de indio a partir de espectrometría Raman en esfaleritas del depósito epitermal polimet... more Detección de indio a partir de espectrometría Raman en esfaleritas del depósito epitermal polimetálico Pingüino, Macizo del Deseado, Patagonia RESUMEN El indio (In), considerado como un metal crítico, está presente en diferentes minerales, pero la esfalerita es la principal fuente y el mineral portador más importante de este metal. En la Patagonia argentina, el depósito Pingüino presenta un sistema de vetas polimetálicas con importantes anomalías de In relacionadas al sulfuro de Zn. Estas vetas contienen pulsos con sulfuros masivos donde se depositaron tres generaciones de esfalerita. El pulso más importante, debido al volumen de esfalerita y el contenido de indio, es la esfalerita del segundo pulso (Sph II), con hasta 2,56% en peso de In, alta concentración de Fe y moderada concentración de Cu y Cd. La introducción de In y Cd en la red del sulfuro de Zn produce modificaciones identificables en los espectros de Raman, a partir del pico de 325-335 cm-1, asignado a los enlaces In-S. La espectroscopía Raman representa una técnica alternativa y novedosa en la caracterización de minerales permitiendo determinar rápidamente la presencia de cationes sustitutos como el In y otros elementos en su estructura cristalina.

Intrusive bodies associated with the polymetallic mineralization of the Cerro León deposit, area of Cerro Tranquilo anticline, Santa Cruz: Geophysical evidence

A new middle-late Jurassic compression flora associated with the San Agustín hot-spring deposit, southern Patagonia, Argentina

ABSTRACT We describe a new Middle-Late Jurassic flora from the La Matilde Formation (Bahia Laura ... more ABSTRACT We describe a new Middle-Late Jurassic flora from the La Matilde Formation (Bahia Laura Group) associated with the San Agustín hot-spring deposit, western Deseado Massif, Southern Patagonia, Argentina. The 7 genera and 14 morphospecies, preserved as impressions, record a relatively diverse woodland plant community dominated by conifers and bennettitaleans growing adjacent to herbaceous lake margin communities.

E Quisetum Thermale Sp. Nov. (Equisetales) from the Jurassic San Agust N Hot Spring Deposit, Patag

American Journal of Botany, 2011

Filamentous cyanobacteria and associated microorganisms, structurally preserved in a Late Jurassic chert from Patagonia, Argentina

Journal of South American Earth Sciences, Apr 1, 2021

Abstract A new cyanobacterium, Patagonifilum jurassicum nov. gen. et sp., is structurally preserv... more Abstract A new cyanobacterium, Patagonifilum jurassicum nov. gen. et sp., is structurally preserved in Late Jurassic hydrothermally influenced siliceous chert from the Deseado Massif, Patagonia, Argentina. The cyanobacterium occurs in the form of loosely to densely spaced, heteropolar filaments (up to 4.5 μm wide) that form turf-like stands, or spherical to hemispherical colonies on different substrates, usually degraded plant stems. Filaments consist of barrel-shaped cells enveloped in a non-stratified sheath, and basal cells that are distinct. The fossil is similar to certain present-day members of the Oscillatoriales (e.g., Homoeothrix), Synechococcales (e.g., Tapinothrix), and Nostocales (e.g., Rivularia, Gloeotrichia). Associated with the cyanobacteria are spheroidal to ovoid vesicles, up to 45 μm in diameter, which occur singly or clustered, mostly near the base of the filaments. They resemble certain present-day zoosporic fungi, and algae, coccoid cyanobacteria, and possibly certain arthropod eggs; however, their systematic affinities remain unresolved. This discovery is nevertheless important because it suggests that the cyanobacterial overgrowths from the Patagonian Jurassic cherts were not monospecific, but rather comprised different organisms that perhaps even interacted with each other.

RESUMEN. Se presentan nuevos afloramientos de cuerpos subvolcánicos correlacionables con la Forma... more RESUMEN. Se presentan nuevos afloramientos de cuerpos subvolcánicos correlacionables con la Formación Cerro León en el sector oriental del Macizo del Deseado. Esta unidad aflora en dos sectores, en el bajo Leonardo y en el afloramiento Bahía Laura del Complejo Río Deseado. El primer sector presenta trece diques y un filón capa intruyendo a las sedimentitas pérmicas de la Formación La Golondrina y el segundo sector comprende tres diques que intruyen a rocas del basamento. Se trata de rocas de color gris a negro, frecuentemente alteradas, con textura microgranuda a porfírica, con fenocristales de plagioclasa, diópsido (En 42 Fs 11 Wo 47) y en menor medida de hornblendas ricas en Mg (magnesio hastingsita), en una matriz holocristalina de textura intergranular. Son rocas subalcalinas de composiciones basalto-andesita y con afinidades calcoalcalinas. La edad Ar/Ar obtenida en una de estas muestras (180,1±1,5 Ma) representa la primer determinación realizada en esta unidad y es coherente con las relaciones estratigráficas observadas para esta formación. La comparación con rocas ígneas jurásicas de la provincia geológica Macizo del Deseado, favorece la vinculación temporal y genética con el evento volcánico-piroclástico del Jurásico medio a superior (Formación Bajo Pobre y Grupo Bahía Laura). Sin embargo, la diferencia en las edades Ar/Ar, sugieren una interrupción entre el evento subvolcánico (180 Ma) y el volcanismo Jurásico medio a superior (177 a 150 Ma). Se considera, preliminarmente, que los cuerpos subvolcánicos de la Formación Cerro León representarían las primeras evidencias magmáticas del rift jurásico en el Macizo del Deseado.

Journal of South American Earth Sciences, Jun 1, 2020

A Middle-Late Jurassic fossil plant assemblage is described from the Bahía Laura Complex at the L... more A Middle-Late Jurassic fossil plant assemblage is described from the Bahía Laura Complex at the Laguna Flecha Negra locality, Santa Cruz Province. The fossil assemblage is autochthonous, preserved in volcaniclastic sediments in the fringes of a geothermal landscape. Taxonomic study of the palaeoflora revealed 17 taxa. The recognized species have been previously described in Jurassic localities of Gondwana and illustrate the diversity of plant communities that lived in a volcanic setting. The dominant elements of this flora are microphyllous conifers of the families Araucariaceae and Cheirolepidiaceae. Fossil leaves of Cycadeoidales co-dominate the community. There is a low diversity and abundance of ferns. Composition of the plant community is compared to coetaneous floras of the Bahía Laura Complex to analyse geographical variations in the diversity of Middle-Late Jurassic assemblages of Santa Cruz Province, and a relative uniformity is recognized. Forest landscapes were dominated by conifer trees, with cycadeoids as small trees or shrubs. The herbaceous understory was dominated by fern communities with low species diversity; Equisetales and Isoetales appeared as subordinated elements. Microphyllous conifers and cycadophytes, as well as a low diversity of ferns, are indicative of relatively dry weather. THE PROVINCE of Santa Cruz in Argentina hosts extensive Mesozoic deposits with plant remains in different modes of preservation (Archangelsky and Archangelsky, 2002). In this province, fossil assemblages are known from all three periods of the Mesozoic. Fossil bearing Triassic rocks are known from the El Tranquilo Group, and palaeofloristic studies have been carried out at El Tranquilo (e.g. Azcuy

International Journal of Plant Sciences, Feb 1, 2020

Premise of the Research: Despite their ecological significance in modern terrestrial ecosystems, ... more Premise of the Research: Despite their ecological significance in modern terrestrial ecosystems, knowledge about the evolution of arbuscular mycorrhizae based on the fossil record is still scarce, especially concerning the case of root nodules harboring arbuscular mycorrhizal fungi as in some extant gymnosperms and angiosperms. Exceptionally preserved conifer nodular roots were found in the Jurassic fossil-bearing chert deposits of the Deseado Massif (Santa Cruz, Argentina), raising the possibility to study them in association with arbuscular Manuscript Click here to access/download;Manuscript;Nunes et al. 2019 Revised version-ca.docx

Palaeogeography, Palaeoclimatology, Palaeoecology, 2019

which comprises periderm to the secondary xylem, shows evidence of interactions with xylophagous ... more which comprises periderm to the secondary xylem, shows evidence of interactions with xylophagous borers, fungi, actinomycetes and other fungal-like microorganisms. In the secondary phloem, it displays rows of traumatic resin ducts, which host abundant mycelium comprising very thin hyphae differentiated into spore-producing structures comparable to actinomycete bacteria and spherical fungal-like resting structures. In the cortical and phloem regions, there are cell groups with structural changes, which appear variably degraded by fungi.. The secondary xylem displays decay of cellulose and lignified components, at various spatial scales, comparable with fungal decay patterns in modern wood. Further septate fungal filaments, sometimes bearing clamp connections are associated with decayed regions. The degraded secondary xylem shows circular to oval borings filled with frass containing degraded tracheids, comparable to those bored by different wood boring beetles. Development of traumatic resin ducts in the phloem could have been triggered by penetration of the living stem by these xylophagous arthropods. The association of the different components present suggests pathogenic and saprotrophic interactions promoting decomposition of the stem, and represents a rarely-documented example of multitrophic biological interactions involving several different biological groups in Jurassic terrestrial palaeoecosystems.

La Marciana Jurassic sinter—implications for exploration for epithermal precious-metal deposits in Deseado Massif, southern Patagonia, Argentina

Transactions, Aug 1, 2002

Abstract A well-preserved Jurassic siliceous sinter has been identified at La Marciana farm in so... more Abstract A well-preserved Jurassic siliceous sinter has been identified at La Marciana farm in southern Patagonia, Argentina. Fossil sinters are a rare occurrence and this example bridges the gap between Devonian/Carboniferous examples and more abundant Tertiary sinters. Its presence is significant in the context of exploration for epithermal precious-metal deposits in the Deseado Massif geological province of southern Patagonia. Field and textural characteristics of the La Marciana siliceous deposit provide unequivocal evidence of its origin. It is located in an appropriate volcanic and epithermal environment and it displays a strongly developed non-planar depositional lamination, elongate cavities parallel to this lamination, small-scale stromatolitic columnar structures, moulds of stems and roots of plants and desiccation cracks. Geochemical and oxygen isotope studies provide additional information compatible with a sinter origin. The content of precious-metal elements—apart from in anomalous hydrothermal breccia—is low, and the average Au, Ag, As and Sb concentrations are similar to those of most known fossil sinters. The 18O SMOW values obtained on La Marciana sinter range from 7.3 to 16‰ and could indicate a lower temperature of formation when compared with quartz-vein isotope data from the Cerro Vanguardia area—the best-known example of an epithermal precious-metal deposit in the Deseado Massif. Hydrothermal alteration of the volcanic rocks and the presence of quartz veinlets and hydrothermal breccias with Au and Ag anomalies in the La Marciana area are indicative of gold- and silver-rich hydrothermal activity. Taken in conjunction with the presence of the La Marciana sinter, which is further evidence of Jurassic hot-spring deposits in the western border of the Deseado Massif, this suggests that exploration in the area should focus on locating epithermal quartz vein systems that may be preserved at depth.

Goldschmidt2022 abstracts, 2022

Modelado Geológico y Geoquímico Tridimensional De La Veta Marta Norte, Depósito Pingüino, Macizo Del Deseado

Revista de la Asociación Geológica Argentina, Jul 25, 2020

Tracing Hot-Spring Facies and thier Geothermally Silicified Microbial Textures into the Geologic Record: Relevance for Mars Biosignature Recognition

Geologica Acta, 2014

The Patagonian basement rocks are dominated by Precambrian to Early Paleozoic metamorphic rocks i... more The Patagonian basement rocks are dominated by Precambrian to Early Paleozoic metamorphic rocks intruded by Paleozoic granitoids. Recently discovered basement rocks in the Cerro Negro District are characterized mainly by quartz-muscovite-chlorite schists; the metamorphic grade reaches greenschist facies (biotite-garnet grade) with a regional S 1 schistosity subparallel to the original sedimentary structure S 0 and a secondary nonpenetrative S 2 foliation. New detrital zircon U-Pb geochronology shows that maximum depositional ages for detrital zircons are Devonian, ages of 379 ± 4Ma. These results suggest that the Cerro Negro basement rocks are the youngest basement in the Deseado Massif, overlapping some detrital zircon ages in the eastern Andean Metamorphic Complex in the Andean region. Most of detrital zircons are igneous in origin with a major peak around ~396Ma, provably sourced from the Devonian granitoids of the Río Deseado Complex (El Laurel and Bahía Laura granites) and equivalent northern Patagonia granitoids (e.g. Colan Conhué and Lago Lolog granites). Secondary peaks correspond to Ordovician to Silurian ages, being the Río Deseado Complex and La Modesta Formation (and their igneous contributors) the possible sources of the zircons. The minor oldest peaks yield Cambrian-Neoproterozoic; Mesoproterozoic and Paleoproterozoic-Archean ages, evidencing a common source from the interior of Gondwana. The results provide new insights about the relationships between the pre-Permian metasedimentary rocks of the extra-Andean and Andean region during Mid-Paleozoic ages.

Exceptional molecular preservation in the Late Jurassic Claudia palaeo-geothermal field (Deseado Massif, Patagonia, Argentina)

Organic Geochemistry

Gas chromatography-mass spectrometry was applied to samples collected from an exceptionally well-... more Gas chromatography-mass spectrometry was applied to samples collected from an exceptionally well-preserved Late Jurassic (~150 Ma) sinter complex of the Claudia palaeo-geothermal field, Deseado Massif geological province, Argentinean Patagonia, which, despite its age, has never been deeply buried. Results indicate that the distal sinter apron has a much higher preservation potential for indigenous organic matter (OM) than the more proximal (vent area) facies of this palaeo-geothermal field. Specifically, homohopane ratios show that the OM of the proximal apron is of mixed thermal maturities and is in low abundance. In contrast, the OM extracted from the distal apron contains highly abundant, thermally immature biomarkers, the presence of which are consistent with the lower original fluid temperatures of the distal spring facies. Moreover, despite indications of the presence of some thermally mature aromatic compounds, hopane and sterane ratios confirm that the distal apron samples are extremely thermally immature and thereby constitute an area of exceptional molecular preservation. From an astrobiological viewpoint, these results suggest that silica sinter can preserve abundant organics over millions of years in palaeoenvironmentally conducive settings, and that sample-site selection within a hot spring facies-model framework may be critical in the successful search for ancient extra-terrestrial life.

Detection and Preservation of Biosignatures in Mars Analogs Hot Spring Deposits from the Taupo Volcanic Zone, New Zealand

EPSC-DPS Joint Meeting 2019, Sep 1, 2019

Journal of South American Earth Sciences, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.