Abstract The Peña Colorada mineralized area contains several iron oxide-apatite (IOA) deposits around the arguably richest known iron resource in Mexico. The Lower Cretaceous volcano-sedimentary host rock sequence has been subjected to several episodes of hydrothermal alteration, each accompanied by a distinct episode of faulting and intrusion (calc-alkaline to tholeiitic). Faulting is partly associated with the reactivation of cryptic structural corridors in basement rocks. High-resolution 40Ar/39Ar and apatite fission track (AFT) dating of this deposit and the adjacent Arrayanes prospect reveal the following sequence of events that range from the latest Cretaceous to the earliest Eocene: (1) intrusion of a 67.6 ± 3.5 Ma magnetite-bearing diorite with associated skarn/skarnoid metamorphism that was coeval or predated N-S to NNW-SSE faulting; (2) approximately 63.26 Ma syenite-like potassic alteration with disseminated magnetite, predated by N-S to NNW-SSE faulting and postdated by WNW-ESE faulting; (3) intrusion of 62.0 ± 2.5 Ma diorite and 59.39 ± 0.21 Ma andesite dikes that predate the main mineralization event at 55.72 to 54.84 Ma of large semi-stratabound massive and disseminated bodies; (4) intrusion of a 53.3 ± 3.0 Ma magnetite-bearing gabbro and 53 ± 2 Ma pegmatoid magnetite + fluorapatite veins at the Arrayanes prospect, which overlap the WNW-ESE faulting; (5) 50.70 to 48.18 Ma polymictic magnetite breccia as the last stage of mineralization in the area, predated by E-W faulting; and (6) reactivation of WNW-ESE faults and later NE-SW faults. Therefore, the total age span of the Peña Colorada deposit ranges between approximately 19 and 23 million years. The closeness in age between intrusions and mineralization in the Arrayanes prospect, their confinement between the WNW-ESE and E-W structural domains, and mingling or mixing structures between gabbro and diorite with an associated magmatic magnetite enrichment support the idea of a close genetic link between such intrusives and IOA hydrothermal mineralization. All mineralization events at Peña Colorada are associated with pervasive potassic to propylitic alteration, whereas at Arrayanes they are associated with dominant sodic alteration instead. Alteration features are suggestive of relatively shallow and deep formation of these deposits, respectively. Event 3 thermally reset fluorapatite in fragments of pegmatoid magnetite + fluorapatite + diopside associations (dated at 59 ± 2 Ma, AFT) within the polymictic breccia, which were sampled from a deep orebody (still to be found) and that would be likely associated with event 1 or 2. Consequently, exploration endeavors at depth at Peña Colorada may be considered promising. In this study, we use numerous geological and geochemical proxies to constrain the likeliest genetic model for the Peña Colorada and neighboring deposits: (a) the nearness in time and space between hydrothermal mineralization and magnetite-rich, tholeiitic, relatively oxidized intrusive rocks; (b) the occurrence of key mineral associations (i.e. magnetite + fluorapatite ± diopside veins); (c) the exclusive occurrence of fluorapatite in lieu of other apatites; (d) the composition in key major cations (Ca, Fe, Na, Mn) in fluorapatite; (e) the correlations between Ni/Cr vs. Ti values, between Ti+V vs. Ni/(Cr+Mn) values, between Ti+V vs. Al+Mn values, and Mg contents in magnetite; (f) pyroxene thermometry; (g) log f(O2) values calculated from Mn contents in fluorapatite; and (h) normalized REE patterns, and ΣLREE and ΣHREE contents in fluorapatite. These proxies indicate that IOA deposits in the Peña Colorada area have a hydrothermal origin with a strong magmatic influence (magmatic-hydrothermal iron oxide, or MHIO, deposits) that formed under high oxygen fugacities and “moderate” temperatures, and with a high geochemical affinity with IOCG and Kiruna-type deposits or the general IOCG “clan” (for both hydrothermal minerals and associated hypabyssal rocks). Relatively high Ti contents in magnetite, and high Ce and low Eu contents in fluorapatite in these deposits (with respect to typical compositions in IOCG “clan” deposits) are geochemical features still in need of further explanation. The correlation between regional and local structural domains and the geochronologic study in this paper constrain the possible ages of such domains as follows: (1) the N-S to NNW-SSE domain can be bracketed between 67.6 and 63.26 Ma, (2) the WNW-ESE domain between 63.26 and 59.39 Ma, (3) the E-W domain between 54.84 and 50.70 Ma, (4) the WNW-ESE to NW-SE domain is younger than 48.18 Ma, and (5) the NE-SW domain is still active. The structural analysis also shows that the massive orebody at Peña Colorada is partially stratabound but its emplacement was also controlled by low-angle Laramide faults, and that hydrothermal fluids were preferentially driven through volcano-sedimentary rocks. The latter characteristic is not only a matter of the stratigraphic distribution of relatively pervasive versus impervious rocks but also of the lateral distribution of such rocks due to N-S strike-slip faults. As additional results of this study, we determined that the conglomerates atop the host volcano-sedimentary sequence that were initially attributed to the Cerro de la Vieja Formation cannot be older than 67.6 Ma, and that the IOA deposits at Peña Colorada would be formed at depths of only a few hundred meters.

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La demanda mundial de aguacate Hass supera la oferta en más de un 50%. A pesar de los altos rendimientos de este cultivo en Colombia, la productividad se ve seriamente afectada por enfermedades como la pudrición de la raíz, causada por Phytophthora cinnamomi, y las pudriciones poscosecha causadas por Colletotrichum sp. y Phomopsis sp. En este trabajo se evaluó el potencial de 76 aislamientos bacterianos obtenidos de la rizósfera de plantas de aguacate, para la producción de metabolitos con actividad inhibitoria frente a patógenos del cultivo. El efecto antagonista de las rizobacterias frente a P. cinnamomi, Colletotrichum sp. y Phomopsis sp. fue probado a través de cultivos duales. El 36% de los aislamientos evaluados mostraron halos de inhibición frente a P. cinnamomi, 36% frente a Colletotrichum sp. y 67% frente a Phomopsis sp. Tres de los aislamientos más promisorios se fermentaron en diferentes medios de cultivo líquidos. Los extractos de los aislamientos ARP5.1 y AED06 a partir de medio mínimo mostraron actividad inhibitoria frente a los patógenos. Los medios suplementados con cloruro de cobre no incrementaron la actividad de los extractos. Estos resultados demostraron la viabilidad de utilizar extractos metabólicos microbianos como una alternativa para controlar in vitro los patógenos de aguacate.

The demand for Hass avocado in the global market exceeds the supply by over 50%. Colombia has a remarkable advantage as a producer in the region due to its high yields. However, the productivity of this crop can be seriously affected by diseases such as root rot, caused by Phytophthora cinnamomi, postharvest body rot and stem end rot, caused by Colletotrichum sp. and Phomopsis sp., respectively. The potential of 76 bacterial isolates obtained from avocado rhizosphere to produce inhibitory metabolites against avocado's pathogens was evaluated. The antagonistic effect of the rhizobacteria against P. cinnamomi, Colletotrichum sp. and Phomopsis sp. was tested through dual cultures. Thirty-six percent of the tested isolates presented inhibition halos against P. cinnamomi, 36% against Colletotrichum sp. and 67% against Phomopsis sp. Additionally, three isolates were selected for fermentation tests using different broth cultures. The extracts obtained from fermentations in the minimal medium of isolates ARP5.1 and AED06 showed inhibitory activity against the evaluated pathogens, but this effect was not observed with the AED26 extract. The media supplemented with copper chloride did not enhance activity of the extracts. These results suggest that using microbial metabolic extracts is a viable alternative for controlling avocado pathogens in vitro.

Objective: To describe variability in the cesarean ratio and indications for this procedure in women with and without a previous cesarean section. Methods: We conducted a cross-sectional study of 111 hospitals (year 2010) categorized in six levels. Ten groups of indications for cesarean section were developed. Measures of central tendency and diversity were used to determine variability and the Kruskal-Wallis test was used for comparisons among hospital levels. Results: The percentage of cesarean sections was 25.4%. In women without a previous cesarean section, the percentage was higher in private and public hospitals with a lower technological level (34.7% and 30.4% in private and 22.4% in lower level public hospitals). Among public hospital levels, no differences in the percentage of cesarean sections indicated were observed. Conclusions: Research on non-clinical factors could clarify the differences in the ratio of cesarean sections in private hospitals compared with public hospitals and among distinct levels of public hospitals.

Objetivo: Describir la variabilidad entre niveles hospitalarios del porcentaje de cesáreas y los motivos para realizarlas en mujeres sin y con cesárea previa. Métodos: Estudio transversal descriptivo de la actividad obstétrica de 111 hospitales (año 2010) clasificados en seis niveles. Se crearon 10 grupos de motivos de cesárea partiendo del diagnóstico principal. Se calcularon medidas descriptivas de tendencia central y de dispersión, y se utilizó el test de Kruskall-Wallis para la comparación entre niveles. Resultados: El porcentaje global de cesáreas fue del 25,4%. Los hospitales privados y públicos de menor nivel tecnológico presentaron mayores porcentajes de cesáreas en mujeres sin cesárea previa (34,7% y 30,4% en los privados y 22,4% en los públicos de menor nivel). Entre los niveles públicos no hubo diferencias en el porcentaje de cesáreas indicadas. Conclusiones: Investigaciones sobre factores no clínicos podrían aclarar las diferencias en los porcentajes de cesáreas entre los hospitales privados y los públicos, y entre los niveles de los públicos.

Objective: To describe variability in the cesarean ratio and indications for this procedure in women with and without a previous cesarean section. Methods: We conducted a cross-sectional study of 111 hospitals (year 2010) categorized in six levels. Ten groups of indications for cesarean section were developed. Measures of central tendency and diversity were used to determine variability and the Kruskal-Wallis test was used for comparisons among hospital levels. Results: The percentage of cesarean sections was 25.4%. In women without a previous cesarean section, the percentage was higher in private and public hospitals with a lower technological level (34.7% and 30.4% in private and 22.4% in lower level public hospitals). Among public hospital levels, no differences in the percentage of cesarean sections indicated were observed. Conclusions: Research on non-clinical factors could clarify the differences in the ratio of cesarean sections in private hospitals compared with public hospitals and among distinct levels of public hospitals.

Objetivo: Describir la variabilidad entre niveles hospitalarios del porcentaje de cesáreas y los motivos para realizarlas en mujeres sin y con cesárea previa. Métodos: Estudio transversal descriptivo de la actividad obstétrica de 111 hospitales (año 2010) clasificados en seis niveles. Se crearon 10 grupos de motivos de cesárea partiendo del diagnóstico principal. Se calcularon medidas descriptivas de tendencia central y de dispersión, y se utilizó el test de Kruskall-Wallis para la comparación entre niveles. Resultados: El porcentaje global de cesáreas fue del 25,4%. Los hospitales privados y públicos de menor nivel tecnológico presentaron mayores porcentajes de cesáreas en mujeres sin cesárea previa (34,7% y 30,4% en los privados y 22,4% en los públicos de menor nivel). Entre los niveles públicos no hubo diferencias en el porcentaje de cesáreas indicadas. Conclusiones: Investigaciones sobre factores no clínicos podrían aclarar las diferencias en los porcentajes de cesáreas entre los hospitales privados y los públicos, y entre los niveles de los públicos.