Abstract
AbstractBuca dell’Onice di Monte Girello is a small cave located in the Alpi Apuane (central Italy). It preserves an exceptionally thick flowstone deposited intermittently during the Middle Pleistocene. Two main depositional cycles, separated by a physical discontinuity, have been recognised and described. This discontinuity and the top surface of the flowstone attest to two main phases of interrupted growth related to palaeoenvironmental and palaeoclimate changes. Pilot palynological investigations support the existence of such changes. Despite the high number of barren pollen samples and the overall very low concentration of pollen grains per gram of sediment, palynology furnishes some interesting insights especially regarding floral composition, vegetation cover and local to regional climate. The pollen record also contributes to the definition of the stratigraphic distribution of taxa no longer growing in this area (i.e. Carya and Picea). According to the pollen assemblage characteristic of arboreal vegetation cover, the flowstone was deposited predominantly during humid phases under both warm and cool climate conditions (interglacials/interstadials and at the end of interglacials). The warm and cool phases correspond, respectively, to increases of mixed thermophilous forest taxa and montane arboreal taxa. On the other hand, the pollen record does not show the major expansion of open vegetation associated with the coldest and driest conditions, which apparently fall at the main middle discontinuity and at the top interruption of the flowstone. Previous data permit changes in precipitation to be identified as one of the major limiting factors for the growth of this flowstone, probably in a period including MISs 13‐10. The more significant lithological features of the flowstone as well as the vegetal and climate signatures suggest that its development principally represents a response to global events including teleconnections active between the Mediterranean and the Atlantic circulation, with minor contribution from local factors.
Highlights
Non-marine carbonates are potential archives for recording natural environmental variations and anthropogenic impact, thanks to their sedimentological, petrographic, palaeontological and geochemical-isotopic features, which reflect the depositional environment including the chemical and physical properties of the waters from which they originate
Their analysis, especially on regular stalagmites fed from a point-source, has revealed a clear correlation of geochemical records with other climate proxies collected in distinct natural archives (e.g. marine oxygen isotope and terrestrial pollen records: Baker et al, 1993; Budsky et al, 2019; Moreno et al, 2014; Regattieri et al, 2012, 2016; Zanchetta et al, 2007, 2014)
The Alpi Apuane is a key area for the study of the late Quaternary as previously demonstrated by the many geochemical/isotopic studies performed in this area, as well as by numerous dates obtained from terrestrial carbonates, mainly speleothems
Summary
Non-marine carbonates are potential archives for recording natural environmental variations (climate, hydrology, tectonics) and anthropogenic impact, thanks to their sedimentological, petrographic, palaeontological and geochemical-isotopic features, which reflect the depositional environment including the chemical and physical properties of the waters from which they originate. Speleothems (stalagmites, stalactites and flowstones) are secondary carbonate deposits that form in caves from percolating waters rich in CaCO3 as calcite (or aragonite) precipitates, following CO2-outgassing (Ford & Williams, 2007) Their analysis, especially on regular stalagmites fed from a point-source (single drip site), has revealed a clear correlation of geochemical records with other climate proxies collected in distinct natural archives Flowstones are a common speleothem in caves, associated with calcite precipitation from seepage water in the form of well-layered deposits covering different surfaces (e.g. floors or gently dipping walls; White, 2004) Despite their complex morphology and growth dynamics compared to stalagmites (they originate from multiple drip sites or laminar flow of percolating waters; Baker & Smart, 1995), flowstones are potentially important as palaeoenvironmental archives (Baker et al, 1996; Demény et al, 2019; Drysdale et al, 2006). The potential of palynology in the study of Quaternary terrestrial carbonates is enhanced by the fact that they can be accurately dated radiometrically, producing a reliable geochronology for the climate proxy records they contain, including the geochemical ones
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
