Francisco J Sierro

Universidad de Salamanca · Department of Geology

The Sicily Channel, located in the central Mediterranean Sea, represents a key point for the regional oceanographic circulation, as it is regarded as the sill that separates the western and eastern basins. Therefore, it is regarded as a unique zone in the well-documented west-to-east Mediterranean productivity gradient. Here we present a time serie...

The full understanding of climate feedbacks responsible for the amplification of deglaciations requires robust chronologies for these climate transitions, but, in the case of marine records, radiocarbon chronologies are possible only for the last glacial termination. Although the assumed relationships between the marine isotopic record and the orbi...

El objetivo principal del proyecto ALGEMAR (PID2021-123825OB) es mejorar el conocimiento de los depósitos marinos profundos, concretamente aquellos generados por la interacción de procesos sedimentarios gravitacionales y por corrientes de fondo. El estudio de estos depósitos es un tema de gran actualidad tanto en el mundo académico, ya que su regis...

La Cuenca del Guadalquivir durante el Mioceno hasta la actualidad fue rellenada por una serie de unidades clásticas progradantes de ENE a OSO de sección sigmoidal (Martínez del Olmo, et al., 1984). Asociada a este relleno, la cuenca presenta en su parte media casi una veintena de yacimientos de hidrocarburos de gas seco biogénico, que han sido trad...

Pteropods are a group of cosmopolitan holoplanktic gastropods that produce an aragonite shell and play an important role in both marine ecosystems and geochemical cycles. In addition to being affected by anthropogenic impacts that include warming and changes in carbonate system parameters, the Mediterranean Sea is considered to be understudied conc...

The Sorbas Basin (Spain) has been a key study area for the understanding of the Late Miocene Messinian Salinity Crisis (MSC) (5.97-5.33 Ma). The MSC deposits of the Sorbas Basin consist of four sedimentary units: (1) the pre-MSC Abad marls topped by (2) the evaporitic Yesares gypsum member, followed by two non-evaporitic units known as the (3) Sorb...

Understanding deep-time marine biodiversity change under the combined effects of climate and connectivity changes is fundamental for predicting the impacts of modern climate change in semi-enclosed seas. We quantify the Late Miocene–Early Pliocene (11.63–3.6 Ma) taxonomic diversity of the Mediterranean Sea for calcareous nannoplankton, dinocysts, f...

The Messinian Salinity Crisis and its precursor events have been the greatest environmental perturbation of the Mediterranean Sea to date, offering an opportunity to study the response of marine ecosystems to extreme hydrological change and a large-scale biological invasion. The restriction of the marine connection between the Mediterranean and the...

Recent studies highlight the role of the Mediterranean Outflow Water (MOW), in the intensification of the Atlantic Meridional Overturning Circulation and as source of heat and salty water to high latitudes. During the Late Miocene the MOW suffered major changes and likely a total collapse during the Messinian Salinity Crisis (MSC). In order to stud...

Evolutionary or adaptative changes in Noelaerhabdaceae coccolithophores occurred in parallel with major changes in carbonate export and burial during scenarios of low orbital eccentricity, with a ∼400 kyr recurrence, during the Pleistocene. Coeval with these conditions of enhanced proliferation, here we report that the calcification of specimens wa...

The late Miocene‐early Pliocene (7.4‐4.5 Ma) is a key interval in Earth's history where intense reorganization of atmospheric and ocean circulation occurred within a global cooling scenario. The Southern African monsoon (SAFM) potentially played an important role in climate systems variability during this interval. However, the dynamics of this imp...

The Subantarctic Zone of the Southern Ocean plays a disproportionally large role on the Earth system. Model projections predict rapid environmental change in the coming decades, including ocean acidification, warming, and changes in nutrient supply which pose a serious risk for marine ecosystems. Yet despite the importance of the Subantarctic Zone,...

Planktonic Foraminifera are unique paleo-environmental indicators through their excellent fossil record in ocean sediments. Their distribution and diversity are affected by different environmental factors including anthropogenically forced ocean and climate change. Until now, historical changes in their distribution have not been fully assessed at...

Evolutionary or adaptative changes in Noelaerhabdaceae coccolithophores occurred in parallel with major changes in carbonate export and burial during scenarios of low orbital eccentricity, with a ~ 400 kyr recurrence, during the Pleistocene. Coeval with these conditions of enhanced proliferation, here we report a globally enhanced calcification int...

The Mediterranean Sea sustains a rich and fragile ecosystem currently threatened by multiple anthropogenic impacts that include, among others, warming, pollution, and changes in seawater carbonate speciation associated to increasing uptake of atmospheric CO2. This environmental change represents a major risk for marine calcifiers such as planktonic...

In order to better constrain the chronology of the Messinian Salinity Crisis (MSC) onland and to provide new observations on the stratigraphic position of the Messinian erosional surface as well as evidence for continentalization, we have studied the Mio-Pleistocene succession of the island of Ibiza, ideally located in a strategic position between...

The composition of planktonic foraminiferal assemblages in surface sediments of the Mediterranean Sea shows a pronounced zonal gradient. This gradient is different from what is observed in the open ocean, indicating that the assemblage composition may respond to environmental variables other than the otherwise dominant surface water temperature. He...

The orbital configuration of Marine Isotope Stage (MIS) 19 provides a good analogue to our present interglacial, and it is marked by millennial-scale climate variability. To evaluate how orbital and millennial-scale climate changes interact during this interglacial we have conducted a high-resolution study of planktonic foraminifera assemblages at...

Los microfósiles son una herramienta excepcional para hacer reconstrucciones climáticas y oceanográficas en sedimentos marinos debido a su alta abundancia, y a que muchos grupos permiten hacer estudios geoquímicos, especialmente los que presentan conchas de carbonato cálcico. En particular, las asociaciones de foraminíferos planctónicos han sido am...

Despite the rise in published evidence of deep‐marine bottom current processes and associated deposits there are still very few documented outcrop examples. Herein are reported results of a contourite channel system related to the late Miocene palaeo‐Mediterranean Outflow Water in the Rifian Corridor, Morocco. This work aims to unravel the sediment...

The aim of this work is to investigate the variability of planktic foraminifera calcification in the northwestern Mediterranean Sea on seasonal, interannual and pre-industrial Holocene time scales. This study is based on data from a 12-year-long sediment trap record retrieved in the in the Gulf of Lions and seabed sediment samples from the Gulf of...

A partir del cálculo de los flujos de los cocolitofóridos en dos localidades del Pacífico ecuatorial (ODP Leg 138) se realiza el análisis espectral, con el objeto de determinar si se define cierta periodicidad en su distribución. El intervalo de estudio considerado es entre los 4 y los 2 Ma, y a su vez ha sido subdividido en dos; de 4 a 3,2 y de 3,...

Calcareous nannofossil assemblages and fragmentation ratios of two coccolithophore species (Coccolithus pelagicus and Calcidiscus leptoporus) were analysed in samples from ODP Site 1090, South Atlantic (42° 54.8′S, 8° 53.9′E), to obtain valuable insights into the paleoceanographic evolution and carbonate preservation trends during the late Pliocene...

Benthic foraminiferal, sedimentological, and stable isotope analyses performed on early Zanclean sediments from Alboran Basin ODP Site 976 and southern Spanish land-based sections in the Malaga, Nijar and Sorbas basins have enabled the reconstruction of Mediterranean environmental conditions immediately after the Messinian Salinity Crisis. The pres...

Detrital grains content in contourite sediments has been used as a Mediterranean Overflow Water (MOW) strength proxy along Iberian Margin in different ways. Fine sand fraction is considered to be an allogenic-detrital component and is widely used as a MOW strength proxy, whereas the coarser fraction mainly consist of pelagic and bioclastic particle...

We present a new high-resolution reconstruction of annual sea-surface temperatures (SSTa) and net primary productivity (NPP) using novel coccolithophore-based models developed for the Eastern Equatorial Pacific (EEP). We combined published coccolithophore census counts from core-tops in the Eastern Pacific with 32 new samples from the Equatorial re...

The planktonic foraminiferal species Globorotalia truncatulinoides is widely used as a biostratigraphic proxy for the Quaternary in the Mediterranean region. High-resolution quantitative studies performed on sediment cores collected in the central and western Mediterranean Sea evidence a significant abundance of G. truncatulinoides during the Middl...

The study of planktic and benthic δ¹⁸O at site U1389 in the Gulf of Cadiz allowed us to reconstruct climate variability during the penultimate glacial period at an unprecedented millennial scale resolution. Hereby, a sequence of interstadial-stadial episodes similar to the Dansgaard-Oeschger events recorded during Marine Isotope Stage (MIS)3, were...

Ocean Acidification (OA) is considered a major threat and is projected to impact all areas of global ocean, therefore understanding its ecological impacts remains a priority for science and management. The Mediterranean Sea is considered a highly vulnerable region, so we analyzed material coming from Planier sediment trap in order to characterize t...

The Late Miocene deposits in the Sorbas Basin (Spain) have been of an extreme importance in the understanding of the Messinian Salinity Crisis (MSC) events (5.97-5.33 Ma). They consist of four formations. The pre-crisis Abad marls topped by the evaporitic Yesares gypsum member, followed by two non-evaporitic units known as the Sorbas and Zorreras m...

Foreland basins are normally dominated by turbidite deposits in the early stages of their evolution. In this work, we show evidences of bottom current influence in the Algarve basin, which evolved as a foredeep basin of the Betic-Rif orogeny, during which the paleo-Mediterranean Outflow Water (MOW) was active through the Betic and Rifian corridors....

Trace fossil assemblages are studied at Ocean Discovery Program Site 977 to characterize the response of the macrobenthic trace maker community to deep paleoenvironmental conditions during the Termination V (TV) and interglacial Marine Isotope Stage (MIS) 11 at the western Mediterranean Alboran Sea. An assemblage composed of Chondrites, Planolites,...

Integration of foraminiferal and geochemical data (stable isotope and elemental composition) from West Alboran Basin (WAB) ODP Site 976 allowed evaluation of the effects of the initial Mediterranean – Atlantic restriction event preceding the Messinian Salinity Crisis (MSC) in a context of late Miocene cooling and diminishing water – mass exchange c...

Long-chain unsaturated alkenones produced by haptophyte algae are widely used as paleotemperature indicators. The unsaturation relationship to temperature is linear at mid-latitudes, however, non-linear responses detected in subpolar regions of both hemispheres have suggested complicating factors in these environments. To assess the influence of bi...

We present a high-resolution analysis of seven marine sediment records from the western Mediterranean in a transect from the Algero-Balearic basin to the Alboran Sea, spanning the last 20 ka, to decipher the paleoenvironmental and paleoceanographic evolution of the Western Mediterranean Sea. To do so, diverse elemental ratios have been used for rec...

Recently, fixed ages assigned to Late Quaternary biostratigraphic events across different latitudes have been questioned. The non-homogeneous nature of the paleoceanographic events, which left their imprint in the planktonic Foraminifera fossil records, suggest asynchronous limits for these datums. Nonetheless, intrinsic differences (e.g. bioturbat...

A Correction to this paper has been published: https://doi.org/10.1007/s00367-021–00,703-w

Planktonic foraminifer oxygen isotopes through MIS 12 were analysed from Ocean Drilling Program Site 977 in the Alboran Sea. After the correction of the sea surface temperature (SST) effect on the δ¹⁸O composition of foraminiferal calcite, the resulting seawater δ¹⁸O (δ¹⁸Ow) was used to reconstruct variations in the δ¹⁸Ow of the Atlantic inflow int...

Late Miocene contourite deposits related to the paleo-Mediterranean Outflow Water (MOW) were identified in the Betic and Rifian corridors prior to the restriction of the Mediterranean-Atlantic gateway during the latest Miocene. In this study, we identified for the first time their downstream continuation in the Gulf of Cádiz through seismic stratig...

The sensitivity of coccolithophores to changing CO2 and its role modulating cellular photosynthetic carbon isotopic fractionation (εp) is crucial to understand the future adaptation of these organisms to higher CO2 world and to assess the reliability of εp for past CO2 estimation. Here, we present εp measured on natural fossil samples across the gl...

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...

Though the Strait of Gibraltar today is the only seaway that connects the Mediterranean Sea with the global ocean, in the late Miocene the Mediterranean-Atlantic gateway was composed of multiple connections through the Betic and Rifian corridors. Due to the position of the Gibraltar Arc in region of convergence of the African European plates, the a...

The Mediterranean-Atlantic water-mass exchange provides the ideal setting for deciphering the role of gateway evolution in ocean circulation. However, the dynamics of Mediterranean Outflow Water (MOW) during closure of the Late Miocene Mediterranean-Atlantic gateways are poorly understood. Here, we define the sedimentary evolution of Neogene basins...

There is an increasing interest in understanding the role of coccolithophores, a group of major calcifying phytoplankton, in the marine carbon cycle: they have a dual contribution to the operation of the carbonate and biological pumps during their lifecycle. How the recent changes in seawater carbonate chemistry are affecting their production and c...

The Messinian Salinity Crisis (MSC), still highly discussed within the scientific community, affected the Mediterranean Sea between 5.97 and 5.33 Ma and led to the deposition of huge evaporite accumulations both in its marginal and deep basins. During this profound palaeoecological change, the connections between the Atlantic Ocean and Mediterranea...

Idealized facies of bottom current deposits (contourites) have been established for fine‐grained contourite drifts in modern deep‐marine sedimentary environments. Their equivalent facies in the ancient record however are only scarcely recognized due to the weathered nature of most fine‐grained deposits in outcrop. Facies related to the erosional el...

La Crisi di Salinità del Messiniano ha interessato il Mar Mediterraneo tra 5.97 e 5.33 Ma ed ha portato alla deposizione di enormi accumuli di depositi evaporitici sia nei bacini marginali che in quelli profondi. Anche se tuttora largamente dibattuto, questo evento paleo-ambientale estremo è stato probabilmente causato dalla riduzione o addirittura...

The late Miocene evolution of the Mediterranean Basin is characterized by major changes in connectivity, climate and tectonic activity resulting in unprecedented environmental and ecological disruptions. During the Messinian Salinity Crisis (MSC, 5.97-5.33 Ma) this culminated in most scenarios first in the precipitation of gypsum around the Mediter...

Late Miocene sedimentary records in the Gibraltar arch region hold fundamental information on the Atlantic-Mediterranean connectivity before, during and after the Messinian Salinity Crisis (MSC; 5.96-5.33 Ma). In this work we tackle this still unresolved problem through a detailed foraminifer-based biostratigraphy, micro- paleontological and geoche...

Late Miocene sedimentary records in the Gibraltar arch region hold fundamental information on the Atlantic-Mediterranean connectivity before, during and after the Messinian Salinity Crisis (MSC; 5.96-5.33 Ma). In this work we tackle this still unresolved problem through a detailed foraminifer-based biostratigraphy, micropaleontological and geochemi...

During each Heinrich stadial (HS), temperatures in southern Europe typically dropped several degrees during several hundred to few thousand years. We have developed a one-dimensional thermal conduction model that transfers the typical surface temperature anomaly of a HS to a series of hypothetical underlying caves. The results show that with increa...

Despite numerous efforts to properly differentiate between contourites and other deep-water deposits in cores and outcrops, reliable diagnostic criteria are still lacking. The co-occurrence of downslope and along-slope sedimen-tary processes makes it particularly difficult to differentiate these relatively homogeneous deposits. The main aim of this...

A high-resolution study of the MIS 12/MIS 11 transition and the MIS 11 (430–376 kyr) coccolithophore assemblages at Ocean Drilling Program Site 977 was conducted to reconstruct the palaeoceanographic and climatic changes in the Alboran Sea from the variability in surface water conditions. The nannofossil record was integrated with the planktonic ox...

A high-resolution coccolithophore analysis, along with oxygen and carbonate isotopes and UK´37 alkenone-derived sea-surface temperatures (SSTs), was carried out on western Mediterranean ODP Site 977 (Alborán Sea) sediments, with the aim of reconstructing changes in palaeoproductivity and surface dynamics at the millennial scale during Marine Isotop...

The Lutetian to Priabonian strata of the Jaca Basin record the transition from deep-marine to terrestrial environments, while passing through intermediate deltaic systems. In this work, we summarise the calcareous nannoplankton content from the Jaca town transect. The sedimentary succession starts with the Roncal-Fiscal megaturbidite (Mt-5), contin...

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...

Paleoceanographic information from submarine overflows in the vicinity of oceanic gate- ways is of major importance for resolving the role of ocean circulation in modulating Earth’s climate. Earth system models are currently the favored way to study the impact of gateways on global-scale processes, but studies on overflow-related deposits are more...

The Southern Ocean is warming faster than the average global ocean and is particularly vulnerable to ocean acidification due to its low temperatures and moderate alkalinity. Coccolithophores are the most productive calcifying phytoplankton and an important component of Southern Ocean ecosystems. Laboratory observations on the most abundant coccolit...

The massive North Atlantic iceberg discharges of the last glacial period, the so-called Heinrich events (HE), resulted in atmospheric and oceanic responses of the Mediterranean region that remain poorly documented and understood. This paper focuses on the climatic phases termed Heinrich stadials (HS) 4 and 5 generated by the HE 4 and 5 that occurre...

In August of 1970, during Mediterranean Sea Leg 13, when the Glomar challenger ventured Mediterranean waters, nobody was expecting to run into one of the most exiting scientific discoveries regarding the Mediterranean Sea evolution. Cores and seismic surveys made possible the discovery of a basin-wide Messinian evaporitic deposit buried beneath the...