17:15 〜 18:45
[HQR06-P06] Holocene high resolution T-R cycles and the birth of modern coastal systems (NW Sardinia,Mediterranean Sea)
The reconstruction of the Holocene to present-day coastal evolution according to very high frequency “natural” fluctuations and increasingly human impacts represents the tool to forecast the possible scenarios of environmental changes.
In this respect, the Holocene climate at Mediterranean scale is already well defined and characterized by an alternation of short-lasting (millennial scale) relatively warm and cold phases. Similarly, ultra high-resolution studies on the Holocene sedimentary coastal plain deposits highlighted the presence of ultra (1-2 ka) high-frequency T-R cycles dominated by abrupt landward/seaward shifting of the shoreline.
Three coastal plains (Porto Ferro, Porto Conte, Calick-Maria Pia) around Alghero (NW Sardinia) were investigated with a multidisciplinary approach. The studied sedimentary sequence is characterized by poorly-drained coastal plain deposits (ponds, salt marshes, channel-fill), coastal dunes along with lagoon and washover bodies.
, Logs correlations and a robust geochronological framework based on luminescence and radiocarbon dating indicate the presence of three key surfaces bounding 3 high-frequency T-R cycles developed during the last 8.0 ka.
The first T-R cycle rests unconformable on the Permian bedrock is associated with the Holocene Climate Optimum and developed during the final stages of the early-middle Holocene rapid sea level rise (about 6.0 ka). An important erosive surface, associated with a rapid seaward shifting of the shoreline and a sea level fall of several metres bounds the base of the second T-R cycle. This developed as transgressive up to the Roman Warm period (2.6 ka) when become regressive showing clear progradational character.
Finally, the third T-R cycle is bounded at the base by an erosive surface associated with the rapid shoreline seaward shifting related to the cold Little Ice Age (Regressive semi-cycle). Post 1850 AD sea live rose again and allowed developing of the most recent transgressive semi-cycle. The continuous sea level rise still recorded may be at least in part due to the influence on humans on climate (Anthropocene transgression).
This study of the coastal plain/barrier-lagoon systems of northwest Sardinia revealed that the modern beach system started to prograde from about 2.6 ka.
In this respect, the Holocene climate at Mediterranean scale is already well defined and characterized by an alternation of short-lasting (millennial scale) relatively warm and cold phases. Similarly, ultra high-resolution studies on the Holocene sedimentary coastal plain deposits highlighted the presence of ultra (1-2 ka) high-frequency T-R cycles dominated by abrupt landward/seaward shifting of the shoreline.
Three coastal plains (Porto Ferro, Porto Conte, Calick-Maria Pia) around Alghero (NW Sardinia) were investigated with a multidisciplinary approach. The studied sedimentary sequence is characterized by poorly-drained coastal plain deposits (ponds, salt marshes, channel-fill), coastal dunes along with lagoon and washover bodies.
, Logs correlations and a robust geochronological framework based on luminescence and radiocarbon dating indicate the presence of three key surfaces bounding 3 high-frequency T-R cycles developed during the last 8.0 ka.
The first T-R cycle rests unconformable on the Permian bedrock is associated with the Holocene Climate Optimum and developed during the final stages of the early-middle Holocene rapid sea level rise (about 6.0 ka). An important erosive surface, associated with a rapid seaward shifting of the shoreline and a sea level fall of several metres bounds the base of the second T-R cycle. This developed as transgressive up to the Roman Warm period (2.6 ka) when become regressive showing clear progradational character.
Finally, the third T-R cycle is bounded at the base by an erosive surface associated with the rapid shoreline seaward shifting related to the cold Little Ice Age (Regressive semi-cycle). Post 1850 AD sea live rose again and allowed developing of the most recent transgressive semi-cycle. The continuous sea level rise still recorded may be at least in part due to the influence on humans on climate (Anthropocene transgression).
This study of the coastal plain/barrier-lagoon systems of northwest Sardinia revealed that the modern beach system started to prograde from about 2.6 ka.