AMUSED: A MUltidisciplinary Study of past global climatE changes from continental and marine archives in the MeDiterranean region. The Castiglione maar drilling (central Italy)

The current “global warming” has been widely attributed to a human-induced greenhouse effect however, until the natural variability of climate is totally understood, it is extremely difficult disentangle the natural and human-induced climatic signal and the resulting effects in a short and long period. In order to understand the role that each component plays in the climate processes it becomes essential to acquire considerably longer records than the time it takes for them to undergo significant changes. The wealth of paleoclimatic information, and the improvement of our knowledge, relies on high-quality and high-resolution data availability, provided that these are anchored to accurate age models.

AMUSED (https://progetti.ingv.it/index.php/it/amused) is a project funded by the Istituto Nazionale di Geofisica e Vulcanologia aimed at reconstruct the climate variability in the central Mediterranean region during the middle-late Quaternary, with focus to the Holocene, by integrating paleoclimate multi-proxies data acquired from different paleoenvironmental settings. In detail, the project investigates lacustrine, speleothem and marine successions in central Italy at different temporal scales and resolution (i.e., from orbital to sub-millennial scale). Additionally, the project aims at the evaluation and reduction of the natural CO₂ emission trough plantation of CO₂-absorbing flora in the Colli Albani volcanic district.

The lacustrine sedimentary succession of the Castiglione maar (Colli Albani Volcano) that based on low-resolution previous studies should account for the last 280 kyr, has been selected as main continental target of the project. Intense Quaternary peri-Tyrrhenian volcanism, produced a large number of tephra that emplaced in the adjacent continental sedimentary basins, making this area suitable for the application of tephrochronology, useful for correlation and synchronization of geological records. Preliminary geophysical exploration surveys (electrical resistivity tomography and ground magnetic) were conducted across the Castiglione maar to reconstruct the subsurface structure and geometry of the basin and identify the best drilling site. Two parallel borehole (C1 and C2) were drilled in order to maximize the amount of recover and avoid large stratigraphic gaps. We retrieved 116 and 126,5 m of alternating sands, clay and silt sediments for drills C1 and C2, respectively. An additional core C3 has been afterwards located between the two boreholes, to increase the recovery of the upper 15 m of succession, strongly disturbed in the two former drills. Several tephra layers were already identified and sampled.

The sediment cores will be sampled for high-resolution multi-proxies analyses: stratigraphic, micropaleontological, palynological, geochemical (stable isotopic composition), and paleomagnetic. Moreover, a robust chronology for Castiglione records will be produced by combining ⁴⁰Ar/³⁹Ar dating of the tephra layers back to 280 kyr, and ¹⁴C dating within the last 45 kyr. In addition, a paleomagnetic chronostratigraphy will be derived, providing original target curves and an environmental magnetic investigation will be carried out, by using rock magnetic properties variations in sediments as environmental/climatic proxies.