During the last glacial cyclc, glaciers drained north-eastward into the Strait of Magellan. The timing of the last advances has been amhiguous but the older dates of 16,590-15,800 up to 10,050 yr for deglaciation have been reported. This paper focuses on the Strait of Magellan where, after the last glacial cycle, the marine ingression is well defied. Along the coasts of the eastern Atlantic side of the Straits, it is possible to observe at least four orders of terraces, prevalently marine lying on a meso-Tertiary sedimentary basement or on glacial and glaciofluvial deposits, linked to the last Quaternary main glacial stages. The four main ordcrs of terraced sequences have been mapped, described and dated using 14C. Their stratigraphic position and their radiocarbon dating, refer to the Lower Holocene. This time period connects them to the isostasy rebound. The First and oldest Order, were found regularly between altitudes of 18 and 25 metres. The Second Order is distributed between 6 and I I metres, and is mainly represented by fossiliferous gravel deposits; sands and silts are also present. It regularly covers most of the coastal stretch and extcnds in the backland. The age of formation of the marine deposits, by C14 dating, is comprised on average between 6,000 and 7,000 years B.P. The Third Order is following the present-day beach, between altitudes of 3 and 5 metres, at the foot of the Second Order terrace. It is made up of gravels and sands and refers preferrably to a marine environment. At a slightly lower elevation, lies the Fourth Order marine tcrrace, distribuited between 1.5 and 3 metres. All terraces present well-preserved characteristics of paleobeach environments (berms, spits and ridges). The First Order terrace belongs to the palaeogeography, which was evolved during the first phase of the last deglaciation. The other orders are connected with subsequent stages of the last deglaciation, but the influences of the tectonics in their evolution cannot be excluded.

Coastal mapping of the Quaternary marine deposits in the Strait of Magellan (Chile)

DEMURO, SANDRO;
2004-01-01

Abstract

During the last glacial cyclc, glaciers drained north-eastward into the Strait of Magellan. The timing of the last advances has been amhiguous but the older dates of 16,590-15,800 up to 10,050 yr for deglaciation have been reported. This paper focuses on the Strait of Magellan where, after the last glacial cycle, the marine ingression is well defied. Along the coasts of the eastern Atlantic side of the Straits, it is possible to observe at least four orders of terraces, prevalently marine lying on a meso-Tertiary sedimentary basement or on glacial and glaciofluvial deposits, linked to the last Quaternary main glacial stages. The four main ordcrs of terraced sequences have been mapped, described and dated using 14C. Their stratigraphic position and their radiocarbon dating, refer to the Lower Holocene. This time period connects them to the isostasy rebound. The First and oldest Order, were found regularly between altitudes of 18 and 25 metres. The Second Order is distributed between 6 and I I metres, and is mainly represented by fossiliferous gravel deposits; sands and silts are also present. It regularly covers most of the coastal stretch and extcnds in the backland. The age of formation of the marine deposits, by C14 dating, is comprised on average between 6,000 and 7,000 years B.P. The Third Order is following the present-day beach, between altitudes of 3 and 5 metres, at the foot of the Second Order terrace. It is made up of gravels and sands and refers preferrably to a marine environment. At a slightly lower elevation, lies the Fourth Order marine tcrrace, distribuited between 1.5 and 3 metres. All terraces present well-preserved characteristics of paleobeach environments (berms, spits and ridges). The First Order terrace belongs to the palaeogeography, which was evolved during the first phase of the last deglaciation. The other orders are connected with subsequent stages of the last deglaciation, but the influences of the tectonics in their evolution cannot be excluded.
2004
Coastal Cartotgraphy; Quaternary geology; Magellan Straits
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/16525
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact