1,721,321 research outputs found
Higher than present global mean sea level recorded by an Early Pliocene intertidal unit in Patagonia (Argentina)
Full text linkReconstructions of global mean sea level from earlier warm periods in Earth?s history can helpconstrain future projections of sea level rise. Here we report on the sedimentology and age ofa geological unit in central Patagonia, Argentina, that we dated to the Early Pliocene(4.69?5.23 Ma, 2σ) with strontium isotope stratigraphy. The unit was interpreted as representativeof an intertidal environment, and its elevation was measured with differential GPS atca. 36m above present-day sea level. Considering modern tidal ranges, it was possible toconstrain paleo relative sea level within ±2.7m (1σ). We use glacial isostatic adjustmentmodels and estimates of vertical land movement to calculate that, when the Camaronesintertidal sequence was deposited, global mean sea level was 28.4 ± 11.7m (1σ) above present.This estimate matches those derived from analogous Early Pliocene sea level proxies inthe Mediterranean Sea and South Africa. Evidence from these three locations indicates thatEarly Pliocene sea level may have exceeded 20m above its present level. Such high globalmean sea level values imply an ice-free Greenland, a significant melting of West Antarctica,and a contribution of marine-based sectors of East Antarctica to global mean sea level.Fil: Rovere, Alessio. Universitat Bremen; AlemaniaFil: Pappalardo, Marta. Universidad de Pisa; ItaliaFil: Richiano, Sebastián Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; ArgentinaFil: Aguirre, Marina Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Sandstrom, Michael R.. Columbia University; Estados UnidosFil: Hearty, Paul J.. University of Texas at Austin; Estados UnidosFil: Austermann, Jacqueline. Columbia University; Estados UnidosFil: Castellanos, Ignacio. Universidad Nacional de La Plata; ArgentinaFil: Raymo, Maureen E.. Columbia University; Estados Unido
(Appendix 2) Global Plio-Pleistocene sedimentation rates
No full textSedimentation rates are averages of all stable oxygen isotope records aligned to the LR04 age model (data set: doi:10.1594/PANGAEA.701576). The normalized rate divides each record's sedimentation rate by its mean before averaging
Sea-level trends across The Bahamas constrain peak last interglacial ice melt
Full text linkDuring the last interglacial (LIG) period, global mean sea level (GMSL) was higher than at present, likely driven by greater high-latitude insolation. Past sea-level estimates require elevation measurements and age determination of marine sediments that formed at or near sea level, and those elevations must be corrected for glacial isostatic adjustment (GIA). However, this GIA correction is subject to uncertainties in the GIA model inputs, namely, Earth’s rheology and past ice history, which reduces precision and accuracy in estimates of past GMSL. To better constrain the GIA process, we compare our data and existing LIG sea-level data across the Bahamian archipelago with a suite of 576 GIA model predictions. We calculated weights for each GIA model based on how well the model fits spatial trends in the regional sea-level data and then used the weighted GIA corrections to revise estimates of GMSL during the LIG. During the LIG, we find a 95% probability that global sea level peaked at least 1.2 m higher than today, and it is very unlikely (5% probability) to have exceeded 5.3 m. Estimates increase by up to 30% (decrease by up to 20%) for portions of melt that originate from the Greenland ice sheet (West Antarctic ice sheet). Altogether, this work suggests that LIG GMSL may be lower than previously assumed
(Appendix 3) Age model conversions of the SPECMAP and S95 age models to the LR04 age model
No full textConversions to the LR04 age model (this paper, data set: doi:10.1594/PANGAEA.701576) from the S95 composite age model (Sites V19-30, 677, and 846; Shackleton, 1995) and the SPECMAP stack (Imbrie et al., 1984). AGE gives the ages of the S95 and SPECMAP stac
- …
