Browsing by Author "Orellana, Hector"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Spatial analysis of paleoclimate variations based on proxy records in the south-central Andes (18°-35° S) from 32 to 4 ka
    (2023) Orellana, Hector; Latorre, Claudio; Garcia, Juan-Luis; Lambert, Fabrice
    The long-term climate dynamics of the central Andes are part of an ongoing international research effort to reconstruct past climatic variations and sensitivity to different regional and global drivers during the last 50,000 years. The large number of diverse records, however, makes it difficult to compare results without an integrated spatial analysis that considers the nature of the record and whether they are integrating environmental conditions across a large basin (i.e., a lake record) or at a very local scale (such as a rodent midden). We compiled 92 records from the southern sector of the central Andes (SCA, 18 & DEG;- 35 & DEG;S). Recalibrated records were further compared by converting the original author's interpretation into a scale of relative moisture anomalies (compared to the present) that ranges from -2 (very dry) to very wet (+2). Moisture anomaly maps were generated for intervals at 4, 6, 9.5,14, 17, 21 and 32 ka BP (103 calibrated 14C years before present) using records within a 5% age uncertainty. Our compilations show a surprising degree of agreement in the extent and magnitude of past climate changes during late Pleis-tocene, but less spatial agreement during the Holocene. The TRACE21 transient climate model shows similar results, with better agreement during the Pleistocene compared to the Holocene. Our analyses not only reveal discrepancies between proxy record interpretations at sites from the same region but show which regions in the SCA require more study. & COPY; 2023 Elsevier Ltd. All rights reserved.
  • Thumbnail Image
    Item
    The alluvium of August 9, 2015 in Alto Patache, Tarapaca region, Atacama Desert
    (PONTIFICA UNIV CATOLICA CHILE, INST GEOGRAFIA, 2017) Orellana, Hector; Garcia, Juan Luis; Ramirez, Carla; Zanetta, Nicolas
    During the 09 August 2015 (strong El Nino year) heavy rains fell in the coastal Atacama Desert, including our Research Station Atacama UC_Alto Patache (cordillera de la Costa, Tarapaca Region). In this study we provide a detailed analysis of the meteorology and hydrogeomorphic response to the 51,6 mm in 6 hours of rain recorded in Alto Patache. In our control basin (7.2 Ha) we estimated a maximum erosion of similar to 1070 m(3), which were partially stored in the distal alluvial fan, where we quantified 637 m3 of material. We estimated a mean water discharge of 11 m(3) s(-1) at the lower basin. The comparison between the meteorological and morphostratigraphical data allows us to define three phases that best characterize the anatomy of the 9A: Initial, Peak and End. We conclude that Alto Patache embraces an overall geomorphic stability that is interrupted recurrently by debris flows linkable to ENSO variability.