Glacio and hydro-isostasy in the Mediterranean Sea: Clarks zones and role of remote ice sheets

oleh: G. Spada, P. Stocchi

Format: Article
Diterbitkan: Istituto Nazionale di Geofisica e Vulcanologia (INGV) 2007-06-01

Deskripsi

Solving the sea-level equation for a spherically symmetric Earth we study the relative sea-level curves in the
 Mediterranean Sea in terms of Clarks zones and we explore their sensitivity to the time-history of Late-Pleistocene
 ice aggregates. Since the Mediterranean is an intermediate field region with respect to the former ice
 sheets, glacio- and hydro-isostasy both contribute to sea-level variations throughout the Holocene. In the bulk of
 the basin, subsidence of the sea floor results in a monotonous sea-level rise, whereas along continental margins
 water loading produces the effect of «continental levering», which locally originates marked highstands followed
 by a sea-level fall. To describe such peculiar pattern of relative sea-level in this and other mid-latitude closed
 basins we introduce a new Clarks zone (namely, Clarks zone VII). Using a suite of publicly available ice sheet
 chronologies, we identify for the first time a distinct sensitivity of predictions to the Antarctic ice sheet. In particular,
 we show that the history of mid to Late Holocene sea-level variations along the coasts of SE Tunisia may
 mainly reflect the melting of Antarctica, by a consequence of a mutual cancellation of the effects from the Northern
 Hemisphere ice-sheets at this specific site. Ice models incorporating a delayed melting of Antarctica may account
 for the observations across the Mediterranean, but fail to reproduce the SE Tunisia highstand.