Lateglacial and Holocene coastal evolution in the Minho estuary (N Portugal): Implications for understanding sea-level changes in Atlantic Iberia

Abstract

The absence of accurate sea-level index points in SW Europe has long precluded the development of Holocene sea-level curves and the correct understanding of tectonic activity. In order to understand the coastal evolution and the major drivers in the Minho area, Portugal, we have combined micropaleontological and sedimentological data, where the chronological framework is provided by 13 radiocarbon ages. The stratigraphic reconstruction is in agreement with regional models of evolution and provides new sea-level index points that support a regional isostatic model producing the first complete Holocene sea-level curve from this area. Field data and model reconstructions present a good agreement for the region considered and vertical land movement estimates derived from the isostatic model are in agreement with GPS vertical velocities. At regional scale, our results support a north–south trend for SW Europe, where isostatic rebound seems to be minimized in the south of the Iberian Peninsula while local factors (sedimentation, local geomorphology, etc.) tend to dominate during the late Holocene. This newly produced sea-level curve has helped to improve isostatic model predictions and provide pre-anthropogenic sea-level rise rates against which modern rates can be compared.

Relative sea-level changes in the Basque coast (northern Spain, Bay of Biscay) during the Holocene and Anthropocene: The Urdaibai estuary case

“…The Brest tide-gauge record provides a comparable trend, although it exhibits a lower rate (1.4 mm y À1 ) for the 20th century (W€ oppelmann et al, 2007). These disagreements could be explained by different vertical land motions (e.g., Leorri et al, 2012Leorri et al, , 2013 or water masses redistribution resulting from atmospheric (Marcos and Tsimplis, 2008) and steric contributions (Tsimplis et al, 2011). At the same time, these differences strongly suggest the need to perform local reconstructions since sea-level changes occur at different time and spatial scales.…”

Climate-driven episodes of dune mobilization and barrier growth along the central coast of Portugal

“…However, considering that the sea-level rise rate stabilized and significantly reduced around 7 ka ago (Vis et al 2008;Leorri et al 2013), we do not consider this factor as a trigger mechanism during these short-term events, although it must contribute to the overall retrograding trend of the system. Finally, it is assumed that neotectonics had a minimal impact on the evolution of the coast (Vis et al 2008;Leorri et al 2013). …”

“…These results suggest a scenario of barrier evolution for highenergy and linear coasts characterized by landwards shoreline translation since the mid Holocene, when sea level reached its present position (Vis et al 2010a;Leorri et al 2013). To further investigate the recent evolution of these environments and understand the major drivers behind it, we examine the coastal segment between Mira Beach and Mondego Cape.…”

Evolution of Two Urbanized Estuaries: Environmental Change, Legal Framework, and Implications for Sea-Level Rise Vulnerability

“…We also drew upon reconstructions of past geography and bathymetry [6,[16][17][18][19][20][21][22], which provided information on the patterns of post-glacial flooding of the estuary, and the emergence and expansion of wetlands. For the Tagus estuary, we analyzed prior studies of historical change and paleostratigraphy, especially the exceptional work of Vis [23] and others [24][25][26][27][28][29], and complemented them with the abundant information provided by historical maps [9,[30][31][32][33][34][35][36][37][38][39] and historical documentation of land-use [40][41][42][43]. We also consulted historical data [41][42][43] and studies of historical and modern distribution of wetlands [44][45][46][47].…”