9 research outputs found

    Late Quaternary evolution of alluvial fans in the Playa, El Fresnal region, northern Chihuahua desert, Mexico: Palaeoclimatic implications

    Get PDF
    The Playa El Fresnal area is a tilted terrane characteristic of an extensional basin. It is a half graben/tilted-block system with a playa-lake on the basin floor flanked by piedmonts covered by alluvial fans. Structural heterogeneities within normal fault zones influenced the geomorphic expression of the uplifted footwall blocks of associated volcanism, and the downdropped hanging wall. The footwall area is the main sediment source, but the hanging wall-derived sediments are more extensive. The ancient alluvial fans are in the distal part, whereas the hanging-wall sediments are located in the apex area. A geomorphic analysis of the relative topographic position of the alluvial fans, degree of dissection of the original surfaces, general sedimentology (facies description), and stream channel network type, highlights the importance of climatic change in interpreting alluvial-fan surfaces. Three generations of alluvial fans were identified on the footwall and hanging wall slopes. They were formed during the late Quaternary climatic shift, consistent with the main climatic changes recorded in the paleolake stratig-raphy of northern Mexico and the American Southwest. These alluvial fans consist mainly of debris-flow deposits from flash floods, probably triggered by a change from relatively moist to arid conditions. They contrast with the typically lower-flow-regime of thick-bedded, cross-bedded, and lenticular channel facies, and associated floodplain sequences of rivers

    Late Quaternary evolution of alluvial fans in the Playa, El Fresnal region, northern Chihuahua desert, Mexico: Palaeoclimatic implications

    Get PDF
    The Playa El Fresnal area is a tilted terrane characteristic of an extensional basin. It is a half graben/tilted-block system with a playa-lake on the basin floor flanked by piedmonts covered by alluvial fans. Structural heterogeneities within normal fault zones influenced the geomorphic expression of the uplifted footwall blocks of associated volcanism, and the downdropped hanging wall. The footwall area is the main sediment source, but the hanging wall-derived sediments are more extensive. The ancient alluvial fans are in the distal part, whereas the hanging-wall sediments are located in the apex area. A geomorphic analysis of the relative topographic position of the alluvial fans, degree of dissection of the original surfaces, general sedimentology (facies description), and stream channel network type, highlights the importance of climatic change in interpreting alluvial-fan surfaces. Three generations of alluvial fans were identified on the footwall and hanging wall slopes. They were formed during the late Quaternary climatic shift, consistent with the main climatic changes recorded in the paleolake stratig-raphy of northern Mexico and the American Southwest. These alluvial fans consist mainly of debris-flow deposits from flash floods, probably triggered by a change from relatively moist to arid conditions. They contrast with the typically lower-flow-regime of thick-bedded, cross-bedded, and lenticular channel facies, and associated floodplain sequences of rivers

    Cost-effective enrichment hybridization capture of chloroplast genomes at deep multiplexing levels for population genetics and phylogeography studies

    No full text
    Biodiversity, phylogeography and population genetic studies will be revolutionized by access to large data sets thanks to next-generation sequencing methods. In this study, we develop an easy and cost-effective protocol for in-solution enrichment hybridization capture of complete chloroplast genomes applicable at deep-multiplexed levels. The protocol uses cheap in-house species-specific probes developed via long-range PCR of the entire chloroplast. Barcoded libraries are constructed, and in-solution enrichment of the chloroplasts is carried out using the probes. This protocol was tested and validated on six economically important West African crop species, namely African rice, pearl millet, three African yam species and fonio. For pearl millet, we also demonstrate the effectiveness of this protocol to retrieve 95% of the sequence of the whole chloroplast on 95 multiplexed individuals in a single MiSeq run at a success rate of 95%. This new protocol allows whole chloroplast genomes to be retrieved at a modest cost and will allow unprecedented resolution for closely related species in phylogeography studies using plastomes

    Discovery of 2-arylbenzoxazoles as upregulators of utrophin production for the treatment of Duchenne muscular dystrophy.

    No full text
    A series of novel 2-arylbenzoxazoles that upregulate the production of utrophin in murine H2K cells, as assessed using a luciferase reporter linked assay, have been identified. This compound class appears to hold considerable promise as a potential treatment for Duchenne muscular dystrophy. Following the delineation of structure-activity relationships in the series, a number of potent upregulators were identified, and preliminary ADME evaluation is described. These studies have resulted in the identification of 1, a compound that has been progressed to clinical trials

    Mémoire du sol, espace des hommes

    No full text
    corecore