Showing papers on "Sea-level curve published in 2016"

Holocene paleo-sea level changes along the coast of Rio de Janeiro, southern Brazil: Comment on Castro et al. (2014)

Abstract: The present work discusses and reinterprets paleo-sea level indicators used to build Holocene sea-level curve for the coast of Rio de Janeiro at former works. We conclude that: (a) the paleo-sea levels inferred by vermetid remains show that sea-level has fallen over the past 4400 years, at least; (b) the paleo-sea level inferred by the beachrock facies and dated shells of Jacone shows that sea-level was near the present elevation between 8198 and 5786 years before present; and (c) several shells from other beachrocks were deposited probably thousands of years after the specimens died and consequently do not allow precise reconstructions of paleo-sea levels. These conclusions differ from the conclusions of the original paper.

Reply to comment by E. Bard et al. on “Younger Dryas sea level and meltwater pulse 1B recorded in Barbados reef crest coral Acropora palmata” by N. A. Abdul et al.

Abstract: Abdul et al. (2016) presented a detailed record of sea level at Barbados (13.9 - 9 kyr B.P.) tightly constraining the timing and amplitude during the Younger Dryas and Meltwater Pulse 1B (MWP-1B) based on U-Th dated reef crest coral species Acropora palmata. The Younger Dryas slow-stand and the large (14 meter) rapid sea-level jump are not resolved in the Tahiti record. Tahiti sea-level estimates are remarkably close to the Barbados sea level curve between 13.9 and 11.6 kyr but fall below the Barbados sea-level curve for a few thousand years following MWP-1B. By 9 kyr the Tahiti sea level estimates again converge with the Barbados sea level curve. Abdul et al. (2016) concluded that Tahiti reefs at the core sites did not keep up with intervals of rapidly rising sea level during MWP-1B. We counter Bard et al. (2016) by showing: 1) there is no evidence for a hypothetical fault in Oistins Bay affecting one of the Barbados coring locations: 2) that the authors confuse the rare occurrences of A. palmata at depths > 5 meters with the “thickets” of A. palmata fronds representing the reef-crest facies, and 3) that uncertainties in depth habitat proxies largely account for differences in Barbados and Tahiti sea-level differences curves with A. palmata providing the most faithful proxy. Given the range in Tahiti paleo-depth uncertainties at the cored sites, the most parsimonious explanation remains that Tahiti coralgal ridges did not keep up with the sea level-rise of MWP-1B.

Empiric method to infer sea level curve in time domain from shoreline trajectory in space domain using cross-sections through a deltaic system

Abstract: Depositional events at the shoreline can be considered non-uniformly spaced samples of (relative) sea level; the shoreline trajectory constructed from shoreline positions in a cross-section through a delta can therefore be considered a proxy to the sea level curve. The problem is that depositional events are stacked on top of each other in the space domain and in order to infer the sea level curve, one must convert the shoreline trajectory from space- to time-domain. Therefore a method is presented that does exactly that. Shoreline trajectories from a number of cross-sections are used to infer the sea level curve, for two cases: (1) the sea level curve is periodic; (2) depositional events are sufficiently frequent. Here the concept is presented, together with a qualitative analysis of all possible deviations from the simple cases that would cause an error of the inferred sea level curve with respect to the true sea level curve. In this short note the concept of the method is presented; a comprehensive analysis will be presented elsewhere, which will follow after processing of the data from experiments that were conducted in the Eurotank flume facility.