T67 Sea-Level Changes from Minutes to Millennia

Sunday, 19 October 2014
1:00 PM - 5:00 PM
306

HOLOCENE SEA-LEVEL DATABASE FOR THE CARIBBEAN REGION

Paper number: T67-12
Program: Technical Sessions
Time: 3:35 PM – 3:50 PM

Authors

Abstract

Records of Holocene relative sea level (RSL) from far-field locations are integral to understand the mechanisms that drive the nature and timing of deglacial meltwater contributions and provide background rates of change to compare with the magnitude of 20thcentury RSL rise. The Caribbean region has traditionally been considered far-field (i.e., with negligible glacio-isostatic adjustment (GIA) influence), although recent studies have indicated otherwise. Here, we consider spatial variations in glacio-isostatic, tectonic and local contributions on a spatially comprehensive, Holocene RSL database from the Caribbean region and provide constraints for earth parameters of GIA models.

The database contains over 500 index points, which define the position of RSL in time and space, and over 300 limiting dates, which provide an upper or lower bound on the position of RSL. The database incorporates sea-level observations from 5°N to 27°N (Guyana to Florida Keys) and 54°W to 90°W (Mexico to Suriname), and spans a temporal range from 12 ka BP to present. Index points are derived from two indicators: (1) mangrove peat deposits, which form in the upper half of the tidal range in the Caribbean; and (2) monospecific Acropora palmata frameworks, the growth of which is constrained to the upper 5 m of water depth. Corals that did not meet these criteria were classified as marine limiting dates. The peat deposits are categorized on the basis of their susceptibility to compaction (intercalated vs basal). In addition, the influence of temporal changes in tidal range on index points is considered.

The reconstructions demonstrate that RSL did not exceed the present height (0 m) during the Holocene in the majority of locations, with the possible exception of a small highstand (< 2 m) at Suriname/Guyana located furthest away from the former Laurentide Ice Sheet. A noisy-input Gaussian process regression model calculates that the rates of RSL change were highest during the early Holocene (3-8 mm/yr) and have decreased over time (< 2 mm/yr), which is related to the reduction of ice equivalent meltwater input and collapse of the proglacial forebulge. We compared the reconstructions to predictions from most recent ICE-NG (VMX) series of global models of GIA and assessed the relative regional influence of tectonic vertical land movements on RSL records.