ABSTRACT The objective of this work is to discuss the paleoenvironment and age of the Los Monos Formation, in outcrop and subsurface, along a regional transect (west-east) in the southern sector of the Tarija basin. The lithofacies and ichnofacies of the Alarache, Angosto del Pescado and Balapuca outcrops and core-intervals of the Aguas Blancas xp-13, Ramos x-12, Tartagal x-1 and Tonono x-1 boreholes were analyzed. The definition of lithofacies and ichnofacies allowed us to interpret a shallow to outer shelf paleoenvironment (from the offshore-transition, offshore and shelf). Towards the top of the Tonono Formation, the equivalent of the Los Monos Formation in the Chaco-Salteño was defined as a brackish-waters marginal-marine paleoenvironment. The mineralogy of the mentioned sections plus the Vespucio x-1 borehole was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), thus the majority elements in clay minerals were also determined from EDAX. Authigenic and detrital clays from SEM-EDAX were recognized. Four clay mineral assemblages were defined (I+Ch; Ch+I; I+K; K+I), where I+K and K+I assemblages characterize the transgressive events within the basin. The palynofacies of the Balapuca, Alarache and Angosto del Pescado outcrops and samples from the Ramos xp-1002, Ramos xp-1011 and Ramos xp- 1012 boreholes were defined, the dominance of terrestrial palynomorphs was identified with variable participation of marine palynomorphs, according to a shallow marine paleoenvironment with shoreline shifts. Two transgressive events were recognized during the late Eifelian-early Givetian and the late Givetian-early Frasnian, which are characterized by an increase in marine components and clay assemblages of I+K and K+I. The palynological associations point to a late Eifelian-early to middle Givetian age for the Los Monos Formation in the study area. The analysis of illite crystallinity and expansive layers in the mixed-layer IS indicated advanced diagenesis for the unit, from late mesodiagenesis (Tonono x-1 and Vespucio x-1) to telodiagenesis (Balapuca and Ramos), according to the final stage of oil generation window to gas generation window, respectively. Finally, based on the mineral composition with a predominance of quartz (>70% in average) and low content of clays (<20% in average), thermal maturity in oil and gas window, the important thickness in the subsurface (700-1000 meters) and significant lateral continuity (>100 km2), the unit has some of the attributes to be considered as a potential shale-type unconventional reservoir.

Abstract Geological studies in the northern sector of the Chaco foreland Basin, Bolivia, yielded new fossils coming from late Oligocene-late Miocene of the Petaca Formation. Few fossil mammals were known from the Subandean Region of Bolivia. We report a partially complete mandible of a hegetotheriid Hegetotheriinae (Notoungulata, Typotheria) from Abapó (Río Grande River). The specimen (YPFB-LIT-PAL-005) is very close in size and dental morphology to the late Oligocene (Deseadan South American Land Mammal Age, SALMA) — Santacrucian (early Miocene) Prohegetotherium schiaffinoi (Kraglievich 1932) from Fray Bentos (Uruguay and Argentina), Salla (Bolivia), Divisadero Largo-Potrerillos and Quebrada Fiera (Argentina). However, mandibular characteristics, as the shape with a marked change in height along its length, increasing towards the back, a prominent masseteric crest, a deep mandibular groove, and a remarkable thickening of the ventral rim of the mandible, indicate differences between this specimen and Prohegetotherium schiaffinoi and the other Hegetotheriinae. The affinity of YPFB-LIT-PAL-005 with P. schiaffinoi suggests a late Oligocene to early Miocene for the upper bearing horizon of the Petaca Formation (in Abapó), an older age than previously assigned to the top of this unit (late Miocene), and confirms the taxon distribution between ∼ 36 ° to ∼ 17 ° south latitude.

A description and interpretation of geological structures in different structural positions (flanks, hinge) of the Tin Tin anticline, a basement-cored fold formed during Cenozoic Andean contraction in the southwest sector of the Eastern Cordillera (northwestern Argentina), is presented. The majority of the structures are west-transported thrust fault-related folds which affect the Salta Group, producing the thickening of the sedimentary cover. The kinematic of these structures is synthetic with the Tin Tin anticline (west-vergence) and generally have the same NNE-SSW-strike. Minor strike-slip faults oblique to the anticlinal orientation were observed. The geometric relationship between the sedimentary cover and the basement suggests an initial event of thin-skinned deformation prior to the basement core uplift (thick-skinned deformation). In other words, the initial Cenozoic contraction began with the sedimentary cover shortening prior to the main activity of basement faults. Overall, the total deformation displayed in the anticlinal Tin Tin was generated by the combination of buckling and bending processes.

Se presenta una descripción e interpretación de las estructuras de deformación en las diferentes posiciones estructurales (flanco, charnela) del anticlinal Tin Tin, un pliegue con núcleo de basamento formado durante la contracción cenozoica andina en el sector suroeste de la Cordillera Oriental del noroeste argentino. La gran mayoría de las estructuras son pliegues asociados a fallas inversas de bajo ángulo con transporte occidental que en conjunto afectan a todas las unidades del Grupo Salta, y producen un engrosamiento de la cobertura sedimentaria. La cinemática de las estructuras coincide con la del anticlinal principal (vergencia y transporte occidental) y en general presentan su misma orientación NNE-SSO. En menor medida se encuentran fallas de rumbo con alta inclinación y orientación oblicua a la del anticlinal. Las relaciones geométricas entre las estructuras en la cobertura sedimentaria indican una cronología que sugiere una deformación de piel fina relativamente previa al ascenso principal del núcleo de basamento (deformación de piel gruesa). Dicho de otra forma, la contracción inicial cenozoica comenzó con el acortamiento de la cobertura sedimentaría en forma previa a la actividad principal de las fallas del basamento. En términos generales, la deformación total representada en el anticlinal Tin Tin fue generada por la combinación de los procesos de buckling y bending.

The Yacoraite Formation lithology is mainly composed by carbonate rocks of gray whitish-yellowish colors and also by marls, siltstones, sandstones and claystones of middle gray, pale green or reddish-purple color. The interbeded black claystones are the hydrocarbon source rock and the carbonates are the reservoir. It is deposited in the Cretaceous/Tertiary basin of the northwestern Argentina inside the Balbuena Subgroup which involves also the underlying Lecho Formation originated during an episode of thermal subsidence. A previously rifting period occured and was deposited the Pirgua Subgroup. Both subgroups are the base of Salta Group (Neocomian-Eocene). The Caimancito oil field is located east of Calilegua hills, in sub-Andean foothill, at the Jujuy province, Argentina. The main reservoir is composed by fractured dolomites and limestones of the Yacoraite Formation with an average porosity of 5.7 % and permeability from 0.1 mD to 8.1 mD and some values up to 250 mD. The fractures observed in borehole images and dip-meter are high dipping angle with three different main trends: E-W and NW-SE (Type I) interpreted as open and N-S (Type II) as closed. The sets fracture intersections produce rectangular blocks varying in size according to the lithology and stratigraphy. The fractures tend to be located in carbonates rather than in silicicoclastics. The fracture intensity increases as the bed thinning. The trends of the reverse faults are N-S parallel to the Andean hills and the normal faults are E-W trend.

La Formación Yacoraite está constituida por rocas carbonáticas de color gris blanquecino-amarillento y en menor proporción también por margas y areniscas color gris medio, limolitas color verde claro a rojo violado y arcilitas negras. Las intercalaciones pelíticas negras constituyen la roca madre de hidrocarburos y los carbonatos conforman el reservorio. Se encuentra depositada en la cuenca Cretácico/Terciaria del noroeste argentino dentro del Subgrupo Balbuena que involucra también a la infrayacente Formación Lecho, depositadas durante un episodio de subsidencia termal. Previamente existió un período de rifting donde se depositó el Subgrupo Pirgua. Ambos subgrupos conforman la base del Grupo Salta (Neocomiano-Eoceno). El Yacimiento Caimancito se ubica al este de la serranía de Calilegua, provincia de Jujuy y su principal reservorio lo constituyen dolomías y calizas naturalmente fracturadas de la Formación Yacoraite, con porosidad de 5,7 % y permeabilidad primaria de 0,1 mD a 8,1 mD con valores que ascienden hasta 250 mD. Las fracturas observadas en subsuelo, en imágenes y dip-meter de pozo, son de alto ángulo dispuestas en tres sistemas principales: dos con rumbos E-O y NO-SE interpretadas como abiertas (Tipo I) y otro N-S (Tipo II) cerradas. La intersección de ambos sistemas de fractura, fragmentan bloques rectangulares de variados tamaños. La mayor cantidad de fracturas se produce en los carbonatos. La intensidad de fracturación aumenta a medida que disminuye el espesor de los estratos calcáreos. La orientación de las fallas inversas es de rumbo N-S paralelo a las serranías andinas y el de las fallas directas es de rumbo E-O.

OBJETIVO: Verificar a sensibilidade diagnóstica da análise bacteriológica do escarro induzido (EI) para o diagnóstico de tuberculose (TB) pulmonar e identificar as variáveis clínicas associadas com o diagnóstico confirmado. Além disso, avaliar o rendimento diagnóstico da broncoscopia realizada se a pesquisa de BAAR for negativa no EI. MÉTODOS: Estudo transversal e retrospectivo de pacientes com suspeita de TB pulmonar ativa, encaminhados ao serviço para a indução de escarro. Foram revisados consecutivamente os registros laboratoriais de todos os pacientes submetidos à indução de escarro entre junho de 2003 e janeiro de 2006, assim como o prontuário eletrônico de cada caso. Também foram revisados os resultados bacteriológicos das amostras broncoscópicas coletadas dos pacientes cujos resultados de BAAR em EI foram negativos. RESULTADOS: Dos 417 pacientes estudados, 83 (19,9%) tiveram resultados positivos (BAAR e/ou cultura) no EI. Na análise de regressão logística, os achados radiológicos de cavitação pulmonar (OR = 3,8; IC95%: 1,9-7,6) e de infiltrado de padrão miliar (OR = 3,7; IC95%: 1,6-8,6) associaram-se mais significativamente com o diagnóstico de TB pulmonar. A broncoscopia foi realizada, após resultado de BAAR negativo no EI, em 134 pacientes e acrescentou 25 (64,1%) diagnósticos confirmados de TB pulmonar. CONCLUSÕES: Na prática clínica, a frequência de diagnósticos confirmados de TB pulmonar por EI (19,9%) foi menor do que aquela previamente relatada em ensaios controlados. Cavitação e infiltrado miliar aumentam a probabilidade diagnóstica de TB pulmonar no EI. O uso de broncoscopia quando EI é negativo para BAAR melhora significativamente a sensibilidade para o diagnóstico de TB.

OBJECTIVE: To determine the diagnostic sensitivity of bacteriological analyses in induced sputum (IS) for the diagnosis of pulmonary tuberculosis (TB) and to identify the clinical characteristics associated with the confirmed diagnosis, as well as to determine the diagnostic yield of bronchoscopy carried out when IS tests negative for AFB in smear microscopy. METHODS: A retrospective, cross-sectional study of patients suspected of having active pulmonary TB and referred to our clinic for sputum induction. We consecutively reviewed the laboratory data of all patients submitted to sputum induction between June of 2003 and January of 2006, as well as their electronic medical records. In addition, the results of the bacteriological analysis of bronchoscopic specimens collected from the patients whose AFB tests were negative in IS were reviewed. RESULTS: Of the 417 patients included in the study, 83 (19.9%) presented IS samples that tested positive for TB (smear microscopy or culture). In the logistic regression analysis, radiological findings of cavitation (OR = 3.8; 95% CI: 1.9-7.6) and of miliary infiltrate (OR = 3.7; 95% CI: 1.6-8.6) showed the strongest association with the diagnosis of pulmonary TB. In 134 patients, bronchoscopy was carried out after negative AFB results in IS and added 25 (64.1%) confirmed diagnoses of pulmonary TB. CONCLUSIONS: In our clinical practice, the frequency of confirmed diagnosis of pulmonary TB using IS (19.9%) was lower than that previously reported in controlled trials. Cavitation and miliary infiltrate increase the diagnostic probability of pulmonary TB using IS. The use of bronchoscopy when IS tests negative for AFB significantly increases sensitivity in the diagnosis of pulmonary TB.