Search results for "speleothems"
showing 8 items of 8 documents
Persistent link between Caribbean precipitation and Atlantic Ocean circulation during the Last Glacial revealed by a speleothem record from Puerto Ri…
2020
The sensitivity of tropical Atlantic precipitation patterns to the mean position of the Intertropical Convergence Zone (ITCZ) at different time scales is well‐known. However, recent research suggests a more complex behavior of the northern hemispheric tropical rain belt related to the ITCZ in the western tropical Atlantic. Here we present a precisely dated speleothem multi‐proxy record from a well‐monitored cave in Puerto Rico, covering the period between 46.2 and 15.3 ka. The stable isotope and trace element records document a pronounced response of regional rainfall to abrupt climatic excursions in the North Atlantic across the Last Glacial such as Heinrich stadials and Dansgaard/Oeschger…
Geoconservation in Sicily (Italy): the Example of the Isola delle Femmine (Palermo)
2022
Abstract The Regional Administration of Sicily recently erected Isola delle Femmine—a small island of the Tyrrhenian Sea, close to Palermo—as a geosite. A detailed geological survey has been carried out in order to define the most important geological features of the island together with the development of a new geological map based on topographic data and a digital model at 1:2.000 scale specially processed. Finally, a geological pathway through the island has been traced and illustrated. The geological substrate of Isola delle Femmine consists of a Mesozoic carbonate succession belonging to the Panormide Carbonate Platform. Two lithostratigraphic units have been differentiated. The lowest…
A stalactite record of four relative sea-level highstands during the Middle Pleistocene Transition
2017
International audience; Ice-sheet and sea-level fluctuations during the Early and Middle Pleistocene are as yet poorly understood. A stalactite from a karst cave in North West Sicily (Italy) provides the first evidence of four marine inundations that correspond to relative sea-level highstands at the time of the Middle Pleistocene Transition. The speleothem is located ∼97 m above mean sea level as result of Quaternary uplift. Its section reveals three marine hiatuses and a coral overgrowth that fixes the age of final marine ingression at 1.124 ± 0.2, thus making this speleothem the oldest stalactite with marine hiatuses ever studied to date. Scleractinian coral species witness light-limited…
Late Quaternary Variations in the South American Monsoon System as Inferred by Speleothems—New Perspectives using the SISAL Database
2019
Here we present an overview of speleothem δ18O records from South America, most of which are available in the Speleothem Isotopes Synthesis and Analysis (SISAL_v1) database. South American tropical and subtropical speleothem δ18O time series are primarily interpreted to reflect changes in precipitation amount, the amount effect, and consequently history of convection intensity variability of convergence zones such as the Intertropical Convergence Zone (ITCZ) and the South America Monsoon System (SAMS). We investigate past hydroclimate scenarios in South America related to the South American Monsoon System in three different time periods: Late Pleistocene, Holocene, and the last tw…
The SISAL database: a global resource to document oxygen and carbon isotope records from speleothems
2018
Stable isotope records from speleothems provide information on past climate changes, most particularly information that can be used to reconstruct past changes in precipitation and atmospheric circulation. These records are increasingly being used to provide “out-of-sample” evaluations of isotope-enabled climate models. SISAL (Speleothem Isotope Synthesis and Analysis) is an international working group of the Past Global Changes (PAGES) project. The working group aims to provide a comprehensive compilation of speleothem isotope records for climate reconstruction and model evaluation. The SISAL database contains data for individual speleothems, grouped by cave system. Stable isotopes of oxyg…
Textural features and isotope geochemistry of the Scillato travertine (north-central Sicily): genetic implications.
2015
The travertine deposit, outcropping near the Scillato town (north-central Sicily), was originated by precipitation of calcium carbonate from the Scillato springs, documented as bicarbonate-enriched waters due to dissolution of the Madonie mountains carbonate rocks. This deposit is today well represented by the Travertine Cave, essentially constituted by stalactites and stalagmites in which travertine typically appears laminated with alternation of light and dark laminae. Mineralogical analysis have revealed the almost exclusive presence of calcite and observation under the polarized-light microscope showed different textural features, like presence of debris and porous portions, micritic po…
Secondary minerals from halite caves in the Atacama Desert (Chile)
2017
In the past 15 years several expeditions by French, American and especially Italian cavers have surveyed over 15 km of salt cave passages in the Cordillera de la Sal, close to San Pedro de Atacama village (Atacama Desert, Northern Chile). Over 50 caves have been explored up to now at an elevation around 2,500 m asl. These karst systems are characterized by in-cave temperature of around 17 °C and a relative humidity always very low, with a maximum of 15%. This extreme aridity is due to the severe conditions of the area with only a couple millimeters annual rainfall and several years without rain. Currently the rare precipitation events are enough to allow the dissolution of the salt rock and…
Scripts for Quality Control of SISAL workbooks
2020
Files needed for Quality Control checks of the SISALworkbook_v12 (Comas-Bru and Harrison, 2019). This includes a Python script (wb_check_v12_compatible.py) for automatic checks and an R script (plot_agemodels_hiatus_v12) for manual checks. Instructions on how to run these scripts are provided in a README_instructions.txt file. See supplementary material of Comas-Bru et al (2020, https://doi.org/10.5194/essd-2020-39) for further information on the checks.