Blanca Ausin

Universidad de Salamanca · Department of Geology

Ocean dynamics served an important role during past dramatic climate changes via impacts on deep-ocean carbon storage. Such changes are recorded in sedimentary proxies of hydrographic change on continental margins, which lie at the ocean–atmosphere–earth interface. However, interpretations of these records are challenging, given complex interplays...

Accurate chronologies are the backbone of paleoclimate research, yet for marine sedimentary records the same age model is often applied to co-eval components that may have experienced different pre-depositional histories, leading to aliasing in corresponding proxy signals. Here we demonstrate 14C age discrepancies among several proxy carriers and u...

Continental margins play a fundamental role in the carbon cycle as primary oceanic locations of organic carbon (OC) burial. However, gaps remain in our understanding of factors controlling the distribution and preservation of organic matter (OM) in these heterogeneous and dynamic systems. In particular, the impact of hydrodynamic processes on the a...

Alkenone signatures preserved in marine sedimentary records are considered one of the most robust paleothermometers available and are often used as a proxy for paleoproductivity. However, important gaps remain regarding the provenance and fate of alkenones, as well as their impact on derived environmental signals in marine sediments. Here, we analy...

Marine sediments comprise the primary long‐term sink of organic matter (OM) in marine systems. Disentangling the diverse origins of OM and the influence of the main processes that determine organic carbon (OC) fate at a global scale has proven difficult due to limited spatial data coverage. Thus, comprehensive studies of the spatial distribution of...

Long chain alkyl diols (LCDs) are lipid biomarkers that occur ubiquitously in sediments. Their abundance and distributions are increasingly used as the basis of molecular proxies for environmental parameters such as sea surface temperature (SST) via the Long chain Diol Index (LDI), and upwelling intensity and nutrient conditions (parametrized as di...

Marine sediments comprise the primary long-term sink of organic matter (OM) in marine systems. A key mechanism for stabilization of OM in marine sediments occurs via protection on mineral surfaces. However, fine-grained minerals are prone to resuspension and redistribution prior to final burial, potentially further exposing OM to degradation. Here,...

For decades, the Oligocene has been a relatively overlooked period. Nevertheless, this time span (34.5-23 Ma) is gathering increasing attention because recent estimates of CO2 levels and the size of the Antartic ice-sheets are comparable to their present-day values, highlighting the potential of Oligocene climate variability to better model the sen...

Supporting Information for abrupt intrinsic and extrinsic responses of southwestern Iberian vegetation to millennial‐scale variability over the past 28 ka

We present new high‐resolution pollen records combined with palaeoceanographic proxies from the same samples in deep‐sea cores SHAK06‐5K and MD01‐2444 on the southwestern Iberian Margin, documenting regional vegetation responses to orbital and millennial‐scale climate changes over the last 28 ka. The chronology of these records is based on high‐res...

Alkenone signatures preserved in marine sedimentary records are considered one of the most robust paleothermometers available, and are often used as a proxy for paleoproductivity. However, important gaps remain on the provenance and fate of alkenones, and their impact on derived environmental signals in marine sediments. Here, we analyze the abunda...

Alkenone-derived U k' 37 is one of the most well-established proxies to reconstruct sea surface temperature (SST). Yet, decoupling of alkenone-SST from surface sediments with surface temperature of the water column overlying the depositional site is often observed in continental margins. Here, we address the influence of the interplay between alken...

Nowadays, primary productivity variations at the SW Iberian Margin (IbM) are primarily controlled by wind-driven upwelling. Thus, major changes in atmospheric circulation and wind regimes between the Marine Isotope Stages (MIS) 12 and 9 could have driven substantial changes in phytoplankton productivity which remains poorly understood. We present a...

Link for free download: https://authors.elsevier.com/a/1cXd%7E-4PR%7EQyx Detailed assessments of past changes in surface and deep ocean reservoir ages are required to obtain robust ¹⁴C-based chronologies of planktic foraminifera and provide insights into ocean circulation changes and the C cycle. Here, we use plateau tuning on foraminiferal ¹⁴C da...

Changes in the geometry of ocean meridional overturning circulation (MOC) are crucial in controlling past changes of climate and the carbon inventory of the atmosphere. However, the accurate timing and global correlation of short-term glacial-to-deglacial changes of MOC in different ocean basins still present a major challenge. The fine structure o...

To investigate past changes in the Mediterranean Overflow Water (MOW) to the Atlantic, we analyzed the strength of the MOW and benthic δ13C along the last 250 kyr at Integrated Ocean Drilling Program (IODP) Site U1389 in the Gulf of Cadiz, near the Strait of Gibraltar. Both the strength of the MOW and the benthic δ13C were mainly driven by precessi...

The number of sedimentary records collected along the Brazilian continental margin has increased significantly in recent years, but relatively few are located in shallow waters and register paleoceanographic processes in the outer shelf–middle slope prior to 10–15 ka. For instance, the northward flow up to 23–24∘ S of cold and fresh shelf waters so...

Since Ohkouchi et al. (2002) pioneering work, compound specific radiocarbon (14 C) dating has been largely used to explore 14 C age discrepancies between co-deposited sedimentary components in a wide range of depositional settings. Older 14 C ages of bulk organic carbon (OC) and alkenones relative to co-deposited planktonic foraminifera have been m...

In light of the current rate of anthropogenic climate change, it is becoming increasingly critical to enhance knowledge of past abrupt climate events and subsequent responses of the Earth system. One period that can provide such insight is the last ~28 kyr, with several abrupt changes occurring over the course of the deglaciation. The Portuguese Ma...

International Ocean Discovery Program (IODP) Expedition 378 was designed to recover the first comprehensive set of Paleogene sedimentary sections from a transect of sites strategically positioned in the South Pacific to reconstruct key changes in oceanic and atmospheric circulation. These sites would have provided an unparalleled opportunity to add...

This study combines high-resolution records of nannofossil abundances, oxygen and carbon stable isotopes, core scanning X-ray fluorescence (XRF), and ice rafted debris (IRD) to assess the paleoceanographic changes that occurred during the last deglaciation on the SW Iberian Margin. Our results reveal parallel centennial-scale oscillations in coccol...

The number of sedimentary records collected along the Brazilian margin has grown significantly in recent years. However, few are useful in elucidating the paleoclimatic evolution of relatively shallow waters (< 1,000 m in depth) influenced by continental shelf areas. In this study, we present traditional and new organic and inorganic proxies (alken...

Abstract. Changes in the geometry of ocean Meridional Overturning Circulation (MOC) are crucial in controlling changes of climate and the carbon inventory of the atmosphere. However, the precise timing and global correlation of short-term glacial-to-deglacial changes of MOC in different ocean basins still present a major challenge. A possible solut...

The majority of paleoceanographic investigations assume that co-depositional sedimentary components are synchronous. In reality, however, these components might have experienced differing pre-depositional histories. Here we report large radiocarbon (14 C) age disparities among several co-occurring sedimentary components (i.e., foraminifera, total o...

Variations in primary productivity and the upwelling system dynamics in the SW Iberian margin have been assessed by combining nannofossil, XRF, Ice Rafted Debris (IRD) and stable carbon and oxygen isotope records from a very well-dated sediment core for the last 28 kyr. Centennial variations in upwelling and related productivity have proven to be p...

Antarctic ice sheet margin extent and the sensitivity of benthic δ18O to orbital forcing have varied on million‐year timescales during the Oligocene to Early Miocene. However, few Sea Surface Temperature (SST) records for this time interval exist to evaluate links between polar processes and mean temperature outside polar regions. Here, we present...

The isotopic and quantitative properties of organic carbon (OC), the U k' 37 ratio from alkenones, and the TEX86 ratio from GDGTs are among the most applied paleoclimate proxies from marine cores. As much of the organic matter in marine sediments, these proxy-bearing components associate with mineral surfaces by sorption. Considering that mineral p...

Alkenones or long-chain unsaturated ketones (C36-C39) are a category of lipids produced exclusively by a class of marine phytoplankton (haptophyte algae) present in the surface of the oceans. These compounds are biomarkers (molecular proxies) traditionally used in paleoceanographic reconstructions through the proportions between their most abundant...

This study identifies temporal biases in the radiocarbon ages of the planktonic foraminifera species Globigerina bulloides and Globigerinoides ruber (white) in a sediment core from the SW Iberian margin (so-called Shackleton site). Leaching of the outer shell and measurement of the radiocarbon content of both the leachate and leached sample enabled...

We compiled modern and fossil relative abundance of coccolithophore species Florisphaera profunda from published and unpublished datasets, along with ocean environmental variable data from satellite remote sensing and physical measurements. The database includes relative abundances of F. profunda in sediment trap (n = 26) and core-top (n = 1258), a...

Supporting Information S1

We examine instrumental and methodological capabilities for microscale (10-50 µgC) radiocarbon analysis of individual compounds in the context of paleoclimate and paleoceanography applications for which relatively high precision measurements are required. An extensive suite of data for 14C-free and modern reference materials processed using differe...

Ocean net primary productivity (Npp) is a key component of the marine carbon cycle. Multi-model Npp projections based on a few decades of satellite data show large uncertainties, in particular at low latitudes (30 NÀ30 S). Calibration of sedimentary proxies with satellite-based Npp estimates allows for the quantitative reconstruction of this variab...

A systematic investigation of the spatial and temporal variability in coccolithophore abundance and distribution through the water column of the NW Iberian coastal upwelling system was performed. From July 2011 to June 2012, monthly sampling at various water depths was conducted at two parallel stations located at 42� N. Total coccosphere abundance...

For the first time a systematic investigation of the coccolithophore ecology based on the spatial and temporal variability in their abundance and distribution through the water column was performed for the NW Iberian coastal upwelling system. From July 2011 to June 2012 monthly sampling at different water depths was conducted at two stations locate...

For the first time during an Integrated Ocean Drilling Program (IODP) Expedition (Exp. 339, Mediterranean Outflow) water samples for living coccolithophore distributions and mudline samples for coccoliths, benthic foraminifera, and geochemical analyses in the underlying surface sediments were collected. In total, 14 water samples (from 5 to 20 m wa...

A new data set of 88 marine surface sediment samples and related oceanic environmental variables (temperature, salinity, chlorophyll a, oxygen, etc.) was studied to quantify the relationship between assemblages of coccolithophore species and modern environmental conditions in the western Mediterranean Sea and the Atlantic Ocean, west of the Strait...

A new dataset of 88 marine surface sediment samples and related oceanic environmental variables (temperature, salinity, chlorophyll a, oxygen, etc.) was studied to quantify the relationship between assemblages of coccolithophore species and modern environmental conditions in the Western Mediterranean Sea and the Atlantic Ocean, west of the Strait o...

Coccolithophore productivity and surface water dynamics for the last 25 kyr in the Alboran Sea (Western Mediterranean) are described in a study of high-resolution sedimentary records from two cores, HER-GC-T1 and CEUTA10PC08, whose locations are currently characterized by different hydrographic conditions. Fossil coccolithophore assemblages and oxy...

Coccolithophore productivity and surface water dynamics for the last 25 kyr in the Alboran Sea (Western Mediterranean) are described in a study of high-resolution sedimentary records from two cores, HER-GC-T1 and CEUTA10PC08, whose locations are currently characterized by different hydrographic conditions. Fossil coccolithophore assemblages and oxy...

High-resolution paleoproductivity variations have been reconstructed in a productive cell in the Alboran Sea for the Holocene. Fossil coccolithophore assemblages have been studied along with the -estimated sea-surface temperature (SST) and other paleoenvironmental proxies. The appearance of this cell is suggested at 7.7 ka cal. BP and was linked to...

Coccolithophore records along with oxygen isotopes and sea surface temperature (SST) profiles from two different cores located in the Alboran Sea (Western Mediterranean) are used to describe variations in primary productivity and surface water dynamics during the last 25 kyr in the study area. By combining these proxies with other from different na...

In the Alboran Sea, the so-called North Atlantic Surface Waters (NASW) enters in the Mediterranean Sea while Western Mediterranean Deep Waters (WMDW) flow in opposite direction. Gravity core HER-GC-T1 was recovered in the coastal upwelling out off Málaga (Alboran Sea) under the direct influence of the entering NASW named as Atlantic Jet (AJ). Produ...

High resolution analysis of coccolithophore assemblage and SST-Mg/Ca derived records in the Western Mediterranean during the Holocene: productivity reconstruction in an upwelling region B. Ausín 1 (b_ausin@usal.es) ; J-A. Flores 1 (flores@usal.es); F-J. Sierro 1 (sierro@usal.es); I. Hernández-Almeida 2 (ivan.hernandez@giub.unibe.ch); I. Cacho 3 (ic...

High-resolution reconstruction of productivity using Coccolithophores in two sites of the Alboran Sea (Western Mediterranean) during the last 25 kyr. B. Ausín 1 (b_ausin@usal.es); J-A. Flores 1 (flores@usal.es); F-J. Sierro 1 (sierro@usal.es); I. Cacho 2 (icacho@ub.edu); G. Francés 3 (gfrances@uvigo.es)

The Strait of Gibraltar connects the Atlantic Ocean with the Mediterranean Sea, leading to a two-layer circulation model: North Atlantic Surface Waters (NASW) entering the Mediterranean Sea and Western Mediterranean Deep Waters (WMDW) flowing in opposite direction. Gravity core HER-GC-T1 was recovered in the coastal upwelling out off Málaga (Albora...

We used 5-yr concomitant data of tracer distribution from the BATS (Bermuda Time-series Study) and ESTOC (European Station for Time-Series in the Ocean, Canary Islands) sites to build a 1-D tracer model conservation including horizontal advection, and then compute net production and shallow remineralization rates for both sites. Our main goal was t...

We used 5-year concomitant data of tracers distribution from the BATS (Bermuda Time-series Study) and ESTOC (European Station for Time-Series in the Ocean, Canary Islands) sites to build a 1-D tracer model conservation including horizontal advection and compute net production and shallow remineralization rates at both sites. Net production rates co...