Spatial and temporal robustness of Sr/Ca‐SST calibrations in Red Sea corals : evidence for influence of mean annual temperature on calibration slopes

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Paleoceanography and Paleoclimatology 33 (2018): 443-456, doi:10.1029/2017PA003276.Sr/Ca ratios recorded in the aragonite skeleton of massive coral colonies are commonly used to reconstruct seasonal‐ to centennial‐scale variability in sea surface temperature (SST). While the Sr/Ca paleothermometer is robust in individual colonies, Sr/Ca‐SST relationships between colonies vary, leading to questions regarding the utility of the proxy. We present biweekly‐resolution calibrations of Sr/Ca from five Porites spp. corals to satellite SST across 10° of latitude in the Red Sea to evaluate the Sr/Ca proxy across both spatial and temporal scales. SST is significantly correlated with coral Sr/Ca at each site, accounting for 69–84% of Sr/Ca variability (P ≪ 0.01). Intercolony variability in Sr/Ca‐SST sensitivities reveals a latitudinal trend, where calibration slopes become shallower with increasing mean annual temperature. Mean annual temperature is strongly correlated with the biweekly‐resolution calibration slopes across five Red Sea sites (r2 = 0.88, P = 0.05), while also correlating significantly to Sr/Ca‐SST slopes for 33 Porites corals from across the entire Indo‐Pacific region (r2 = 0.26, P < 0.01). Although interannual summer, winter, and mean annual calibrations for individual Red Sea colonies are inconsistently robust, combined multicoral calibrations are significant at summer (r2 = 0.53, P ≪ 0.01), winter (r2 = 0.62, P ≪ 0.01), and mean annual time scales (r2 = 0.79, P ≪ 0.01). Our multicoral, multisite study indicates that the Sr/Ca paleothermometer is accurate across both temporal and spatial scales in the Red Sea and also potentially explains for the first time variability in Sr/Ca‐SST calibration slopes across the Indo‐Pacific region. Our study provides strong evidence supporting the robustness of the coral Sr/Ca proxy for examining seasonal to multicentury variability in global climate phenomena.Singapore Ministry of Education; National Research Foundation Singapore Grant Number: NRFF‐2012‐03; U.S. National Science Foundation Grant Number: OCE‐1031288; King Abdullah University of Science and Technology Grant Numbers: USA 00002, KSA 0001

A review of last interglacial sea-level proxies in the western Atlantic and southwestern Caribbean, from Brazil to Honduras

We use a standardized template for Pleistocene sea-level data to review last interglacial (Marine Isotope Stage 5 - MIS 5) sea-level indicators along the coasts of the western Atlantic and southwestern Caribbean, on a transect spanning from Brazil to Honduras and including the islands of Aruba, Bonaire, and Curaçao. We identified six main types of sea-level indicators (beach deposits, coral reef terraces, lagoonal deposits, marine terraces, Ophiomorpha burrows, and tidal notches) and produced 55 standardized data points, each constrained by one or more geochronological methods. Sea-level indicators are well preserved along the Brazilian coasts, providing an almost continuous north-to-south transect. However, this continuity disappears north of the Rio Grande do Norte Brazilian state. According to the sea-level index points (discrete past position of relative sea level in space and time) the paleo sea-level values range from ~5.6 to 20m above sea level (a.s.l.) in the continental sector and from ~2 to 10ma.s.l. in the Caribbean islands. In this paper, we address the uncertainties surrounding these values. From our review, we identify that the coasts of northern Brazil, French Guiana, Suriname, Guyana, and Venezuela would benefit from a renewed study of Pleistocene sea-level indicators, as it was not possible to identify sea-level index points for the last interglacial coastal outcrops of these countries. Future research must also be directed at improving the chronological control at several locations, and several sites would benefit from the re-measurement of sea-level index points using more accurate elevation measurement techniques. The database compiled in this study is available in spreadsheet format at the following link: https://doi.org/10.5281/zenodo.5516444 (Version 1.02; Rubio-Sandoval et al., 2021)

Two-dimensional X-ray diffraction as a tool for the rapid, non-destructive detection of low calcite quantities in aragonitic corals

Paleoclimate reconstructions based on reef corals require precise detection of diagenetic alteration. Secondary calcite can significantly affect paleotemperature reconstructions at very low amounts of ~1%. X-ray powder diffraction is routinely used to detect diagenetic calcite in aragonitic corals. This procedure has its limitations as single powder samples might not represent the entire coral heterogeneity. A conventional and a 2-D X-ray diffractometer were calibrated with gravimetric powder standards of high and low magnesium calcite (0.3% to 25% calcite). Calcite contents <1% can be recognized with both diffractometer setups based on the peak area of the calcite [104] reflection. An advantage of 2-D-XRD over convenient 1-D-XRD methods is the nondestructive and rapid detection of calcite with relatively high spatial resolution directly on coral slabs. The calcite detection performance of the 2-D-XRD setup was tested on thin sections from fossil Porites sp. samples that, based on powder XRD measurements, showed <1% calcite. Quantification of calcite contents for these thin sections based on 2-D-XRD and digital image analysis showed very similar results. This enables spot measurements with diameters of ∼4 mm, as well as systematic line scans along potential tracks previous to geochemical proxy sampling. In this way, areas affected by diagenetic calcite can be avoided and alternative sampling tracks can be defined. Alternatively, individual sampling positions that show dubious proxy results can later be checked for the presence of calcite. The presented calibration and quantification method can be transferred to any 2-D X-ray diffractometer

The Antares Collaboration : Contributions to the 34th International Cosmic Ray Conference (ICRC 2015, The Hague)

The ANTARES detector, completed in 2008, is the largest neutrino telescope in the Northern hemisphere. Located at a depth of 2.5 km in the Mediterranean Sea, 40 km off the Toulon shore, its main goal is the search for astrophysical high energy neutrinos. In this paper we collect the 21 contributions of the ANTARES collaboration to the 34th International Cosmic Ray Conference (ICRC 2015). The scientific output is very rich and the contributions included in these proceedings cover the main physics results, ranging from steady point sources, diffuse searches, multi-messenger analyses to exotic physics

All-sky Search for High-Energy Neutrinos from Gravitational Wave Event GW170104 with the ANTARES Neutrino Telescope

Advanced LIGO detected a significant gravitational wave signal (GW170104) originating from the coalescence of two black holes during the second observation run on January 4$^{\textrm{th}}$, 2017. An all-sky high-energy neutrino follow-up search has been made using data from the ANTARES neutrino telescope, including both upgoing and downgoing events in two separate analyses. No neutrino candidates were found within $\pm500$ s around the GW event time nor any time clustering of events over an extended time window of $\pm3$ months. The non-detection is used to constrain isotropic-equivalent high-energy neutrino emission from GW170104 to less than $\sim4\times 10^{54}$ erg for a $E^{-2}$ spectrum

The ANTARES Collaboration: Contributions to ICRC 2017 Part I: Neutrino astronomy (diffuse fluxes and point sources)

Papers on neutrino astronomy (diffuse fluxes and point sources, prepared for the 35th International Cosmic Ray Conference (ICRC 2017, Busan, South Korea) by the ANTARES Collaboratio

The ANTARES Collaboration: Contributions to ICRC 2017 Part II: The multi-messenger program

Papers on the ANTARES multi-messenger program, prepared for the 35th International Cosmic Ray Conference (ICRC 2017, Busan, South Korea) by the ANTARES Collaboratio