Orals: Fri, 2 May | Room D3
The Messinian Salinity Crisis was the most extreme paleoenvironmental perturbation that has ever taken place in the Mediterranean. Approximately 7 million years ago, the straits connecting the Mediterranean Sea to the Atlantic Ocean started to restrict, and by 5.5 million years they closed. High-amplitude fluctuations in both temperature and salinity gave place to a hypersaline isolated Mediterranean, where marine organisms struggled to survive. In our recently published studies, we assembled and revised the marine fossil record from before and after the crisis in order to quantify the effect of the crisis on the biodiversity of the Mediterranean. We documented for the first time a clear perturbation of the biota even during the restriction phase, as well as a high degree of reorganisation of the marine ecosystem after the crisis, with most of the change in the taxonomic composition attributed to species turnover. Only a handful of endemic Mediterranean species may have survived the crisis. Furthermore, the present-day NW-to-SE decreasing gradient in species richness first appeared after the Messinian salinity crisis, suggesting that neither the distance from the Atlantic source nor the temperature gradient are the causes of the gradient today. Finally, we propose a model for the disruption in marine functional connectivity patterns, which is associated with the formation of a large evaporitic basin. This model can now be tested against the diverse ecosystem structures of the past that are associated with marginal marine basins formed due to the birth and death of the oceans.
How to cite: Agiadi, K., Hohmann, N., Coll, M., Vasiliev, I., Camerlenghi, A., and Garcia-Castellanos, D. and the expert team: The impact of the Messinian Salinity Crisis on Mediterranean marine biodiversity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1488, https://doi.org/10.5194/egusphere-egu25-1488, 2025.
The Gulf of Cadiz (NE Atlantic) is dominantly influenced by subtropical gyre waters that are advected by the Azores Current, as reflected by the strong contribution of subtropical species to the planktonic foraminifera fauna. Late Pleistocene sediment records from the Gulf of Cadiz also revealed incursions of subpolar waters based on the presence of Neogloboquadrina pachyderma during abrupt stadial events when the Atlantic meridional overturning circulation was reduced and the subarctic front moved into the lower mid-latitudes of the North Atlantic. To expand our regional knowledge on the interplay between climate variability and planktonic foraminifera faunas, we generated planktonic foraminifera assemblage and other paleoclimate data at millennial-scale resolution between Marine Isotope Stage (MIS) 52 (1.54 Ma) and MIS 18 (0.74 Ma) at IODP Site U1387 (36°48´N, 7°43´W) on the southern Portuguese margin. Here we focus on the evolution of the Neogloboquadrinids, namely N. atlantica dextral, N. incompta and N. pachyderma.
N. atlantica dextral was present continuously since MIS 52 until early MIS 40, when it went extinct around 1.3 Ma ago. This extinction event falls into the period when abundances of N. pachyderma were greatly reduced in the North Atlantic and the Mediterranean Sea, where this period was dated between 1.37 and 1.21 Ma (Lourens et al., 1996, doi:10.1029/96PA02691). At Site U1387, the onset of low N. pachyderma abundances coincided exactly with the Mediterranean Sea date, but abundances started to increase already around 1.22 Ma, i.e. with the first abrupt cold events during the MIS 37/MIS 36 transition.
On the southern Portuguese margin, MIS 36 was a peculiar glacial period with relative warm sea-surface temperatures throughout. We, nevertheless, observed the continuous presence of N. pachyderma and N. incompta. In late MIS 36 and extending into MIS 35, a larger sized N. incompta variant with 4 to 4.5 chambers and a thicker shell structure, more reminiscent of N. dutertrei or N. atlantica, appeared. This variant co-occurred with noticeable contributions of tropical species in the assemblages leading us to interpret it as a subtropical gyre variant. During late MIS 35, also larger sized N. pachyderma specimens started appearing in the assemblages and their contributions became prominent during MIS 28, in particular between 1.01 and 1 Ma, before slowly diminishing towards the end of the early Pleistocene. Already since MIS 52, we detected the co-occurrence of N. pachyderma with subtropical and tropical species. During some of the warmer interglacial periods like MIS 51, MIS 49, MIS 47, and MIS 31, when the subtropical fauna dominated (≥30 %), N. pachyderma specimens were present nearly continuously. Given the strong influence of subtropical waters reflected in the faunas, we believe that those N. pachyderma specimens also present a subtropical gyre variant, potentially predecessors of the modern-day genotypes found in the mid-latitudinal subtropical North Atlantic. Overall, the Site U1387 time series reveal that the early Pleistocene appears to be an important period for Neogloboquadrinid evolution and that the potential occurrence of subtropical water variants cannot be overlooked when interpreting faunal data from that period.
How to cite: Voelker, A., Duque-Castaño, M., Mega, A., O'Neill, E., Salgueiro, E., and Rodrigues, T.: Neogloboquadrinids in the mid-latitudinal, subtropical NE Atlantic during the Early-to-Middle Pleistocene: evidence for “not (sub)polar” variants and one extinction, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2260, https://doi.org/10.5194/egusphere-egu25-2260, 2025.
Because of its fast growth, gypsum can rapidly entrap biogenic material and biomolecules, allowing for excellent preservation at geological time scale. The characterization of biota having thrived in the gypsum-mother brines can contribute to elucidate the paleoenvironmental conditions in the water column and at the seafloor during the formation of ancient salt giants; such reconstruction is challenged by the absence of modern analogues. A prominent example are the primary gypsum deposits that accumulated in the Mediterranean basin about 6 Ma ago, during the Messinian salinity crisis (MSC), when this basin turned into the youngest salt giant in Earth history following its partial isolation from the Atlantic Ocean. Two main types of gypsum are recognized: a) bottom-grown selenite, consisting of vertically-oriented twinned crystals and b) laminar gypsum cumulate, formed by the accumulation at the seafloor of tiny gypsum crystals nucleated in the water column, mixed with organic-rich material. Biosignatures in both types of gypsum were investigated through optical, electron and confocal laser scanning microscopy, Raman spectroscopy, and lipid biomarker analyses. Bottom grown gypsum is typified by abundant diatom remains that indicate deposition in a marine basin influenced by freshwater input. Other abundant components are filamentous microfossils corresponding to remains of sulfide oxidizing bacteria. These biogenic remains are commonly coated by microbial dolomite microcrystals and authigenic clays, which suggest that organic matter and biogenic silica underwent severe early diagenetic alteration. Planktic diatoms, calcareous nannofossils and early diagenetic dolomite are also recognized in cumulate gypsum deposits. Such composition suggests high primary productivity in the water column, inducing the export of organic matter to the seafloor and the formation of dolomite following bacterial sulfate reduction. The mechanisms promoting gypsum nucleation in the water column are instead still enigmatic. The late Miocene gypsum represents an excellent archive of biosignatures, including bacterial cells. The microbial assemblage indicates that gypsum formed in relatively deep, stratified marine basins with intermittent sulfidic bottom-water conditions, promoting intense microbially-mediated early diagenetic processes at the expenses of organic matter and biogenic silica. Such circumstances imply that the paucity of skeletal remains in the MSC sedimentary record may be the result of a taphonomic bias rather than of inhospitable hypersaline conditions induced by massive evaporation of the Mediterranean water mass.
How to cite: Dela Pierre, F., Nallino, E., Natalicchio, M., Pellegrino, L., Aloisi, G., Birgel, D., Guibourdenche, L., and Peckmann, J.: Gypsum as an archive of biosignatures: what can we learn from the late Miocene Mediterranean salt giant?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4440, https://doi.org/10.5194/egusphere-egu25-4440, 2025.
Timing is important for comprehending Earth's biological and climatic processes shaping evolution, extinction, and recovery. Causes and consequences of changing climate can be unraveled only if geological proxy data from different regions are synchronized in time so that causality arguments can be tested rigorously. Many key climate proxy records of the last 100 million years come from deep ocean sediments, but they are currently not sufficiently synchronized across regions on Milankovitch cycle level. The acquisition of accurate chronological data that allow for synchronization across regions is of paramount importance for meaningful interpretations of proxy records.
Here we make the case to form an international coordination network to synchronize regional climate records of the last 100 million years. This network will contribute to revise and recalibrate the dating tools available to paleoclimatologists - that is, the local and regional information obtained from bio-, magneto-, and chemo-stratigraphy as well as radioisotopic geochronology - with the synchronizing tool of astrochronology. Cross-fertilization of expertise is needed to generate new age models for sediment records from which key climate events have been or can be reconstructed, including micropaleontological studies of scientific ocean drilling legacy material. We invite the scientific community to recognize this shortcoming, to join our efforts, and to help raise funds to make the envisaged Time Integrated Matrix for Earth Sciences (TIMES) program a reality.
How to cite: Westerhold, T., Agnini, C., Anagnostou, E., Hilgen, F., Hönisch, B., Meckler, N., Pälike, H., Wade, B., Sosdian, S., and Kasbohm, J.: Paleoclimate reconstructions need better age models, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5060, https://doi.org/10.5194/egusphere-egu25-5060, 2025.
The majority of micropaleontological observations of Cretaceous successions were conducted on deposits in the Atlantic and Tethyan oceans. However, the southern high-latitude Cretaceous formations remains understudied. During expedition Leg 369 of the International Ocean Discovery Program (IODP), 73 cores were collected from Site 1512 in the Australian Bight, targeting deposits of the Turonian to Santonian interval.
Twenty-nine samples were analyzed using plain polarized light microscope. From each sample, approximately 300 foraminifera specimens were extracted and classified into distinct groups based on their morphological characteristics. These groupings enabled further analysis, which involved sorting the specimens according to taxonomic types. To highlight key distinguishing features, selected taxa were examined using scanning electron microscopy (SEM). A total of fifty-nine taxa were identified, forty-two of which were formally defined at the species level. Species identification depended on established taxonomic frameworks.
Several of the southern-latitude taxa exhibit significant variation in morphology compared to the formerly described planktonic, calcareous, and agglutinated foraminifera from the Northern Hemisphere. Seven newly reported species were identified in the current material: Sculptobaculites sp. 1, Bulbobaculites sp. 1, Bulbobaculites sp. 2, Bulbobaculites sp. 3, Gerochammina sp. 1, Rectogerochammina sp. 1, and Praedorothia sp. 1. In addition, two Turonian biozones defined in the Northern Hemisphere were recognized. The first is planktonic Whiteinella brittonensis foraminiferal biozone consisting of Whiteinella brittonensis, Whiteinella aumalensis, Whiteinella baltica, Muricohedbergella delrioensis, and infrequently observed Planohedbergella prairiehillensis. The second is Bulbobaculites problematicus biozone characterized by agglutinated foraminifera, including Bulbobaculites problematicus, Spiroplectammina navarroana, Eobigenerina variabilis, Textulariopsis rioensis, Textulariopsis texhomensis, and Gerochammina lenis.
The establishment of these biozones provides valuable connections to those in the Northern Hemisphere during the Turonian age. Additionally, this research sheds light on the enigmatic 'Austral Province', a previously understudied region of Late Cretaceous foraminifera. By analyzing the faunal composition, we gain insights into key drivers of foraminifera distribution, including ocean circulation patterns (paleoceanography) and climate conditions (paleoclimate). These findings have significant implications for understanding the dynamics of the Tethys and Atlantic oceans.
How to cite: Hilali, I., Wolfgring, E., Waskowska, A., and Kaminski, M.: Insight into the Turonian to Santonian Foraminiferal Biostratigraphy in the Southern Hemisphere , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7790, https://doi.org/10.5194/egusphere-egu25-7790, 2025.
The ANZIC* Continent and Ocean Research & Education (CORE) grant, previously known as the ANZIC-IODP Legacy Analytical Funding (AILAF) scheme, began in 2012 with a visionary initiative: to provide "Special Funding" for innovative analytical research in Australia and New Zealand on existing samples collected throughout the DSDP, ODP, IODP I, and IODP II—many during expeditions undertaken by the JOIDES Resolution. Since its inception, this grant program has been pivotal in advancing scientific research related to ocean drilling and micropaleontology, creating a bridge between archived materials and groundbreaking new discoveries.
In this talk we will highlight three exemplary micropalaeontology projects from the ANZIC community that were supported by the CORE grant scheme, showcasing the enduring value of archived ocean drilling materials:
- Improving Species Identification from Short Sedimentary Ancient DNA (sedaDNA) Sequences. This project develops ‘sedaDNA-at-1.0,’ a new bioinformatics tool for assembling short sedaDNA sequences into longer fragments, enabling more accurate species-level identification. By comparing outputs from traditional and enhanced computational approaches, this tool provides a valuable resource for sedaDNA researchers, with implications for reconstructing past ecosystems.
- Ecosystem Change Through the Neogene in Australia: Documenting the rise of C4 vegetation by using leaf wax isotope ratios from marine sediments collected during DSDP Leg 90 and ODP Leg 122, this project documents the timing of the C3 to C4 plant transition in central and northwestern Australia. The transition occurred at ~3.5 Ma, significantly later than on other continents, highlighting regional variations in vegetation thresholds and offering insights into the future vulnerabilities of Australian ecosystems.
- Extension of Stable Isotope Records at Site U1361 on Wilkes Land Continental Rise, East Antarctica: This project presents a complete ~4-million-year nitrogen and organic carbon isotope record from IODP Site U1361. The results highlight an isotopically light period between ~1.6–0.35 million years, followed by an increase in the last 0.35 Ma. These findings provide new insights into ocean circulation changes in the Indo-Pacific Sector of the Southern Ocean during the Mid-Pleistocene and Mid-Brunhes Transitions.
These three projects represent just a fraction of the outcomes from more than 100 CORE-funded studies, totaling nearly $2 million in grants. Collectively, these initiatives demonstrate the diverse scientific potential of archived materials and reinforce the enduring legacy of the JOIDES Resolution.
The CORE grant is particularly valuable for early-career researchers (ECRs) and students, offering them an opportunity to conduct meaningful research without requiring extensive sea-time. By leveraging the extensive archives of IODP’s sub-seafloor samples, recipients are addressing globally significant questions, advancing our understanding of Earth's processes, and developing critical research skills.
*ANZIC: Australian & New Zealand International Scientific Drilling Consortium
How to cite: Kachovich, S., Lawler, K.-A., and Hackney, R.: DNA to deep time: micropaleontology examples from the ANZIC Continent and Ocean Research & Education (CORE) grant scheme unlocking the secrets of ocean archives, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7863, https://doi.org/10.5194/egusphere-egu25-7863, 2025.
In recent years, there has been an increasing number of studies describing significant disturbances of the global carbon cycle during the latest Cretaceous. One example of these disturbances is the Mid-Maastrichtian Event (MME), which was likely related to changes in deep ocean circulation, particularly in the Atlantic realm.
To track and characterize the influence of the MME in deep-water environments in the equatorial South American margin, we conducted micropaleontological (benthic foraminifers) and geochemical analyses of sediments from Ocean Drilling Program (ODP) Site 1258 (Demerara Rise, offshore Suriname). Both geochemical tracers and benthic foraminiferal assemblages suggest the occurrence of paleoenvironmental reorganizations during the entire Maastrichtian, related to changes of intermediate to deep-water oxygenation and surface productivity. Benthic foraminiferal assemblages, characterized by typical deep-sea taxa (Aragonia, Nuttallides truempyi, Coryphostoma, Strictocostella, among others), indicate suboxic bottom water conditions with some oxygenation pulses, which correlate with changes in elemental ratios of redox-sensitive trace metals (Ni/Al, Cu/Al). Sediment elemental ratios (log(Fe/Ca), Si/Ti, Fe/K) indicate fluctuations in the silica and carbonate export via surface productivity, and a probable hydroclimate disturbance since the early Maastrichtian. During the MME, three phases of environmental evolution occurred: (1) high surface productivity and reduced bottom water oxygenation during subinterval MME1, (2) moderate surface productivity and increased bottom water oxygenation in subinterval MME2, and (3) recovery in surface productivity, suboxic conditions in the deep-sea, and more humid conditions during subinterval MME3. These paleoenvironmental disturbances were probably caused by increased influence of high-latitude deep-waters (North Atlantic source instead of the Southern Ocean) on low latitudes, which likely influenced latitudinal migrations of the Paleo-Intertropical Convergence Zone.
How to cite: Patarroyo, G., Kochhann, K., Alegret, L., and Fauth, G.: Benthic foraminifera and paleoenvironmental turnover across the mid-Maastrichtian event in the Tropical Atlantic Ocean (ODP Site 1258), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14451, https://doi.org/10.5194/egusphere-egu25-14451, 2025.
Understanding abrupt environmental changes, including those caused by the rapidly warming oceans, requires a compilation of paleoenvironmental data obtained from marine sedimentary archives, such as Ocean Drilling Program (ODP) cores. Dinoflagellate cysts serve as sensitive and reliable indicators of past environments, and their application has gained prominence over the last decades, especially for high-resolution studies in the northeastern Pacific Ocean. Dinoflagellates are one of the most diverse and abundant groups of microalgae in coastal environments and are major primary producers. Many dinoflagellates form highly resistant organic-walled resting cysts that accumulate in sediments throughout their life cycle. The records of these microfossils provide valuable information about upper water masses at the time of cyst deposition.
In this presentation, we summarize insights gained from two high-resolution dinoflagellate cyst sedimentary records — one from the California Margin (ODP Hole 1017E) and the other one from the Santa Barbara Basin (SBB; ODP Hole 893A). Census data of cysts from the Holocene and the Last Interglacial (Over and Pospelova, 2022) enable us to identify shifts in ecosystems responding to climate change. These data were used for quantitative and qualitative reconstructions of past sea-surface temperatures, salinity, primary productivity, and potentially significant forest fires during the warm Dansgaard-Oeschger interstadial event 2 (~23,000 years ago).
How to cite: Pospelova, V., Bringué, M., and Mertens, K. N.: Late Quaternary dinoflagellate cysts record abrupt climate changes along the California margin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15868, https://doi.org/10.5194/egusphere-egu25-15868, 2025.
The termination of the Messinian salinity crisis 5.33 million years ago is often attributed to the Zanclean megaflood, a catastrophic event that rapidly refilled the Mediterranean Sea. This study provides compelling evidence for this megaflood, tracing its impact from an onshore shallow marine corridor in southeastern Sicily to the offshore Noto Canyon. Key indicators include (i) over 300 streamlined, asymmetrical erosional ridges aligned with the flood direction, (ii) a poorly sorted breccia layer situated between the Messinian and Lower Zanclean Trubi Formations, (iii) soft-sediment deformation and clastic injections within the breccia and underlying layers, and (iv) a 20 km-wide erosional channel linking the ridges to Noto Canyon. Numerical modeling reveals how the excavation of the channel and canyon influenced the flow's velocity and direction. These findings confirm that the Messinian salinity crisis ended with a catastrophic flood, highlighting a significant Mediterranean sea-level drop prior to the event.
How to cite: Micallef, A., Barreca, G., Hübscher, C., Camerlenghi, A., Carling, P., Abril Hernandez, J. M., Periáñez, R., Garcia-Castellanos, D., Ford, J., Haimerl, B., Hartge, M., Preine, J., and Caruso, A.: Land-to-sea indicators of the largest megaflood in the geological record, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3249, https://doi.org/10.5194/egusphere-egu25-3249, 2025.
During the Messinian, the Mediterranean Basin became highly sensitive to environmental changes due to the gradual restriction of water exchange with the Atlantic Ocean. This led to the widespread deposition of organic-rich layers known as sapropels, indicating significant disturbances in the carbon and oxygen cycles. These sediments formed under conditions of oxygen depletion, likely due to periodic weakening of the thermohaline circulation. Understanding the causes and extent of this circulation weakening in the past is crucial for predicting present and future deoxygenation trends in the Mediterranean under climate warming.
For this purpose, we investigate a Messinian sapropel-bearing succession cropping out at Monte dei Corvi (Ancona, central Italy) with mineralogical, petrographic, micropaleontological and stable carbon and oxygen isotopic analyses. Our findings reveal that sapropel deposition occurred due to increased sea surface buoyancy, which inhibited thermohaline circulation, consequently reducing bottom-water oxygen content and impacting bioturbating organisms. Within the lithological cycle, the recovery of an efficient thermohaline circulation is recorded by thin packstone layers underlying the marly limestone/marlstone, which record intense bottom currents activity. The accumulation of marly limestone/marlstone during periods of high primary productivity and organic carbon export to the seafloor led to bottom hypoxia but not organic matter preservation. Furthermore, the latter was deposited with surficial seawater density in the range of modern Adriatic, suggesting that primary productivity can promote bottom hypoxia even with similar modern deep oxygen renewal rates. These lithological changes were likely influenced by variations in the Adriatic Deep Water formation system paced by precession-driven climatic and oceanographic changes.
Integration of previously published Sea Surface Temperature (SST) data with our new isotopic data indicates that variations in Sea Surface Salinity (SSS) primarily controlled sapropel deposition, with the SSTs of sapropel deposits aligning closely with projected SST in the Eastern Mediterranean at the end of this century under climate warming. In this future scenario, warming will be coupled with an SSS increase, which likely counteract the density loss provided by temperature, making the bottom deoxygenation in the Eastern Mediterranean abysses unlikely. However, we caution that additional factors such as winter heat waves and eutrophication could exacerbate Mediterranean oxygen depletion and should be considered in model-based projections.
How to cite: Mancini, A. M. and Negri, A.: The climatic and oceanographic setting during the Messinian in Northern Adriatic Sea: what can be learned for present and future deoxygenation dynamics?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6386, https://doi.org/10.5194/egusphere-egu25-6386, 2025.
The European Micropalaeontological Reference Centre (EMRC) was established in 2015 in order to provide a permanent archive for published micropaleontological collections. The centre is housed in the office of Micropress Europe on the second floor in the main building of the AGH University of Krakow, next to the grand staircase. The EMRC originally was set up using the Heron-Allen Library at the Natural History Museum as a model – as a research centre containing collections of archived microslides, microscopes, a library of micropaleontological books and journals, and a large collection of reprints. The centre provides a welcoming atmosphere for visitors who wish to carry out micropalaeontological research or simply view collections.
Since its establishment, a number of Micropalaeontologists have deposited type slides or their entire published collections at the EMRC. The foraminiferal collection now consists of 25 wooden cabinets, each housing on between 1,000 and 2,000 microscope slides. One cabinet is reserved for primary type specimens (holotypes, paratypes and metatypes). The EMRC collection now houses the holotypes of over 60 species of foraminifera, and >250 paratypes and metatypes.
In 2023, we acquired the microslide collection of D.G. Jenkins, which includes the shipboard micropalaeontological samples from DSDP Legs 9 and 29. In the summer of 2024, we archived the first shipment of micropalaeontological samples and slides from the collections of W.A. Berggren, who participated in several of the early DSDP expeditions. These include slides and residues from the JOIDES Expedition cores (the precursor of the Deep Sea Drilling Project expeditions) and the early DSDP expeditions (Legs 1, 2, 3, 4, 12, 13, 14, 15, 22, 72). The Berggren collection at the EMRC includes the shipboard micropalaeontological samples from DSDP Leg 12 as well as a sizable collection of picked faunal slides from DSDP Site 516 used by Berggren to revise the Miocene zonation of planktonic foraminifera, which was published in the DSDP Leg 72 volume. The Kaminski Collection at the EMRC contains the shipboard micropalaeontological slides from ODP Legs 105 and 123, and numerous picked slides from DSDP/ODP Sites 263, 643, 767, 959, from the ACEX Expedition to the Arctic Ocean, and from the Leg 323 sites in the Bering Sea. The Gradstein Collection contains the slides from DSDP Leg 44. The newly acquired Brent Wilson Collection contains slides from DSDP Sites 148 and 926. The EMRC has quickly become a major repository tasked with helping preserve our worldwide DSDP/ODP heritage. A complete list of slide collections housed at the EMRC will be made available on the Micropress Europe website.
Micropaleontologists can arrange to visit the European Micropalaeontological Reference Centre by contacting the Curator, Dr. Justyna Kowal-Kasprzyk, at the AGH University of Krakow [j.kowal.kasprzyk@gmail.com].
How to cite: Kaminski, M. A. and Kowal-Kasprzyk, J.: The DSDP/ODP Microslide Archive at the European Micropalaeontological Reference Centre in Kraków Poland , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6494, https://doi.org/10.5194/egusphere-egu25-6494, 2025.
Deep-water agglutinated foraminifera (DWAF) are crucial tools for paleoenvironmental analysis and biostratigraphic correlation in deep marine environments below the carbonate compensation depth (CCD). This study investigates the DWAF acmes in the Paleocene–Eocene sediments of IODP Hole U1511B, which was collected from the Tasman Abyssal Plain during Expedition 371. Cosmopolitan taxa, which have been previously documented from regions such as the Carpathians, Boreal North Atlantic, and Western Tethys, dominate the assemblages, which consist of 89 species across 43 genera. The identified acmes—Rzehakina, Spiroplectammina, Reticulophragmium, Trochammina, ammodiscids, and Karrerulina—display remarkable similarities to previously recognized events in the western Tethys and North Atlantic. The stratigraphy of Site U1511B exhibits a coarsening-upward sequence of greenish-gray Paleocene claystones that transition into reddish-brown Eocene sediments. The Paleocene/Eocene boundary is delineated by a hiatus. These acmes are associated with periods of ecological instability, such as the Paleocene–Eocene Thermal Maximum (PETM) and Early Eocene Climatic Optimum (EECO), which are indicative of changes in sedimentary regimes, oxygenation, and trophic conditions. The global extent of these faunal responses to climatic and oceanographic changes is illustrated by the observed DWAF successions, which align closely with acmes from the Western Tethys, Polish Carpathians, and Boreal North Atlantic, despite the semi-isolated position of the Tasman Sea during the Paleogene. The utility of DWAF as biostratigraphic indicators in abyssal environments devoid of calcareous fossils is emphasized by the presence of well-known acmes, including Rzehakina fissistomata and Spiroplectammina spectabilis. This research supports the hypothesis that DWAF acmes are triggered by substantial paleoenvironmental changes, such as global oligotrophy, sediment flux fluctuations, and organic matter redistribution during significant climatic events. The discovery of these acmes at Site U1511B contributes to the refinement of the Paleocene–Eocene stratigraphic framework in the abyssal ocean and the advancement of our understanding of global paleoceanographic events during the Paleogene.
How to cite: Korin, A., Hikmahitar, S., Alegret, L., Waskowska, A., and Kaminski, M.: Paleocene to Eocene Deep-Water Agglutinated Foraminiferal Acmes: A Global Perspective, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8334, https://doi.org/10.5194/egusphere-egu25-8334, 2025.
Hydrological restriction from the Atlantic Ocean transformed the Mediterranean Sea into a giant saline basin during the Messinian Salinity Crisis (5.97 – 5.33 million years ago). It is still unclear if the deposition of nearly one million km3 of evaporite salts during this event was triggered by a major (≥ 1 km) evaporative drawdown, or if it took place in a brine-filled Mediterranean connected to the Atlantic. Here we present evidence for a two-phase accumulation of the Mediterranean salt layer based on the chlorine stable isotope composition of halite. During the first phase, lasting approximately 35 kyr, halite deposition occurred only in the eastern Mediterranean, triggered by the restriction of Mediterranean outflow to the Atlantic, in an otherwise brine-filled Mediterranean basin. During the second phase, halite accumulation occurred across the entire Mediterranean, driven by a rapid (< 10 kyr) evaporative drawdown event during which sea-level dropped 1.7-2.1 km and ~0.85 km in the eastern and western Mediterranean, respectively. During this extreme drawdown event, the eastern Mediterranean basin lost up to 83% of its water volume, and large parts of its margins were desiccated, while its deep Ionian and Herodotus sub-basins remained filled with > 1 km-deep brine.
How to cite: Aloisi, G., Moneron, J., Guibourdenche, L., Camerlenghi, A., Gavrieli, I., Bardoux, G., Agrinier, P., Ebner, R., and Gvirtzman, Z.: Chlorine isotopes constrain a major drawdown of the Mediterranean Sea during the Messinian Salinity Crisis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12427, https://doi.org/10.5194/egusphere-egu25-12427, 2025.
The Messinian Salinity Crisis (MSC) resulted in the generation of the last “Salt Giant” on Earth and was one of the biggest ecological crises in recent geological history. Given the large volume of data collected, and the high-resolution of the astronomically tuned and dated sedimentary successions, the MSC offers a unique opportunity to study the effect of short-term environmental variability and its impact on biological communities, particularly the resilience of microbial communities. The late Miocene Sorbas basin in south-western Spain hosts one of the most complete records of the MSC and has been used as a reference for astronomical tuning. However, in the absence of sedimentological and micropaleontological data from the shaly pre-evaporitic successions, it is hard to understand the impact of the extreme salinities, anoxia, and desiccation on the aquatic biosphere and on water conditions (i.e. temperatures, salinities and stratification). In this study, new constraints have been derived from the analyses of organic debris in shales from both pre- and inter-evaporitic deposits from a new 176,5-m drill core section in the Sorbas basin.
Our results from the analysis of the pre-evaporitic Abad formation and the black shales of the Yesares member, deposited in the inter-evaporitic cycles, reveal differences in biomarker-composition that can be related to changes in water conditions before and after the onset of the MSC. Squalane, framboidal pyrite, and sulphur reducing bacteria in the Abad formation suggest the presence of oxygen-restricted and saline waters before the precipitation of primary gypsum. After the establishment of hypersaline conditions (i.e. gypsum precipitation), a new phase of anoxia developed in the basin with the precipitation of marls and organic-rich laminites in the first inter-evaporitic eventof the Yesares member. Here the presence of isorenieratene-derivatives in the form of aryl isoprenoids can be interpreted as evidence of green sulphur bacteria. These bacteria use sulfur as an electron donor under anoxic conditions and perform photosynthesis underlow-light conditions, meaning that anoxia at this time extended up to the photic zone (<200m). Our data suggest that if a chemocline was present before gypsum precipitation it was weaker and perturbed by seasonal variation, while the chemocline was more stable during the inter-evaporitic stage.
How to cite: Schito, A., Sierra Ramirez, N., Bowden, S., Gibert Beotas, L., and Gomez Rivas, E.: Organic geochemistry as a proxy for unravelling water’s conditions in the Messinian succession of the Sorbas basin (Spain), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12863, https://doi.org/10.5194/egusphere-egu25-12863, 2025.
Maria Bianca Cita has often been called the Lady of the abyss, or the Lady of the Mediterranean. Passionate, determined, self-confident and respected in the world, Maria Bianca was a trailblazer in the disciplines of stratigraphy, micropaleontology and marine geology in Italy and internationally.
She began her research activity with a free teaching position in Geology in 1955 at the University of Milano, and later she approached stratigraphy and micropaleontology when these disciplines where under rapid evolution, in particular studying planktonic foraminifera of Mesozoic and Cenozoic formations. She became the first in Italy to face the problems of the Cretaceous/Paleogene boundary as early as the mid 1950s. Her studies introduced the applicability of planktonic foraminiferal zonation, established in Trinidad in 1957, to the Italian and Mediterranean area, a premise that led this zonation to become the stratigraphic worldwide "standard" for the Cretaceous - Recent interval.
In the late 1960s, she became involved in scientific ocean drilling aboard the Glomar Challenger for the Deep Sea Drilling Project (DSDP), sensing that this project would revolutionize our knowledge of the history of our planet. If the Italian scientific community has had and has today the privilege to participate in scientific ocean drilling programs, it owes it largely to Maria Bianca Cita, who successfully brought Italy to the Ocean Drilling Program (ODP) in 1986.
In Italy, aboard the CNR oceanographic vessel Bannock, her extraordinary intuition for geology led to a series of scientific discoveries. These include the Eastern Mediterranean anoxic basins, discovered in a 1984 expedition that generated dozens of studies and publications all over the world, the mud volcanoes then studied and drilled for decades, the 'Homogenite' megaturbidite attributed to the Minoan eruption of Santorini (hypothesis later revised, but all observations and deposition models remained hers). An incubator of lines of research that have spread globally.
The greatest scientific challenge for Maria Bianca Cita was the formulation of the theory of the desiccation of the Mediterranean Sea during the long-known Messinian salinity crisis, which according to her and co-authors Bill Ryan and Ken Hsü had involved two extraordinary processes that, although still debated, have been successively supported by a host of multidisciplinary evidence: 1) that the level of the Mediterranean dropped well below the eustatic variations during the evaporitic phase, and 2) that the end of the salinity crisis occurred due to a mega-flood in Gibraltar. A theory that has left its mark on the scientific community, on future generations of researchers, and on public opinion.
Those who shared research in the laboratory, cruises, participation in scientific meetings, and teaching wish to remember her attitude, made of commitment, curiosity, openness and a staunch dedication to pass these values on to younger generations.
How to cite: Camerlenghi, A., Erba, E., Malinverno, A., Premoli Silva, I., and Aloisi, G.: Maria Bianca Cita, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12903, https://doi.org/10.5194/egusphere-egu25-12903, 2025.
Deep-sea hypersaline anoxic basins (DHABs) in the Mediterranean Sea are extreme environments shaped by the interplay of salt tectonics and sedimentary processes over geological time scales. The foundational work of Maria Bianca Cita, who first provided evidence of the Messinian Salinity Crisis and contributed to the discovery of Mediterranean DHABs, has profoundly influenced our understanding of these unique settings. Her research revealed the dramatic environmental shifts that shaped the Mediterranean, laying the groundwork for investigating the relationship between salt tectonics and hypersaline basins.
Currently, eight main DHABs are recognized in the eastern Mediterranean, but a comprehensive geomorphological characterization of these features and their surrounding regions remains lacking. The seafloor in these areas is often described as exhibiting a "cobblestone topography," reflecting the complex terrain generated by salt tectonic deformation. However, high-resolution multibeam surveys from recent studies reveal a significant diversity of landforms that could characterize hundreds of square kilometers in the eastern Mediterranean Basin.
Using data collected during recent European-funded research cruises in the Mediterranean, we conducted a detailed geomorphometric analysis to better characterize the salt-tectonic-associated landforms mapped in the Levantine Basin. Our results confirm spatial patterns reflecting the influence of tectonic forces and sedimentary dynamics in shaping the DHABs, consistent with previous studies, while also unveiling a broader variety of submarine landforms associated with salt tectonics. This study highlights an underestimated ecological and environmental variability in the extreme environments of the deep Mediterranean. By focusing on these underexplored morphologies, we honor the legacy of Maria Bianca Cita and deepen our understanding of the unique ecosystems and geological processes that define the Mediterranean deep sea.
How to cite: Tessarolo, C., Savini, A., De Lange, G., and Corselli, C.: Salt Tectonics and Hypersaline Anoxic Basins: Processes and Forms Shaping Significant Extreme Environments in The Mediterranean Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15434, https://doi.org/10.5194/egusphere-egu25-15434, 2025.
Benthic foraminiferal studies from the Cretaceous of Australia provide critical insights into paleoenvironmental and biostratigraphic correlations across the Southern Hemisphere. This study contextualizes data from International Ocean Discovery Programme (IODP) Sites U1512, U1513, U1514 and U1516 , and significant data from other sources. We present the significance of calcareous and agglutinated benthic foraminiferal data for our understanding of palaeoenvironmental dynamics in the mid- to Upper Cretaceous sediments of the southern hemisphere, relying on complementary data from planktonic foraminifera as well as calcareous nannofossils.
In the Albian, the benthic foraminiferal record at Site U1513 illustrates transitions from neritic to upper bathyal environments, initially marked by the dominance of agglutinated taxa such as Ammodiscus and Haplophragmoides. The shift to calcareous benthic foraminifera, including the markers Gavelinella intermedia and Osangularia schloenbachi, reflects increasing marine influence. These assemblages correlate with records from the Kerguelen Plateau, the Great Artesian Basin, and South America, providing a coherent framework for Southern Hemisphere biostratigraphy during the Albian.
The Cenomanian-Turonian interval captures the impact of Oceanic Anoxic Event 2 (OAE 2). At Sites U1513, U1516, and U1512, a reduced diversity in calcareous benthic foraminifera and the increased dominance of agglutinated taxa highlights the environmental stress linked to dysoxic conditions. These changes are mirrored across the Southern Hemisphere, with parallels in South Africa and Walvis Ridge.
The Coniacian and Santonian successions at Site U1513 document stable bathyal environments dominated by calcareous benthic taxa such as Gavelinella berthelini and Notoplanulina rakauroana. These assemblages exhibit remarkable correlations with other Southern Hemisphere records, including the Falkland Plateau and New Zealand. This synthesis underscores the significance of calcareous and agglutinated benthic foraminifera for correlations through the Southern Hemisphere and helps to improve our understanding of the interplay between local and global paleoenvironmental dynamics, and oceanographic and climatic developments during the Cretaceous.
How to cite: Wolfgring, E., Amaglio, G., Kaminski, M., Petrizzo, M. R., and Watkins, D.: The significance of Benthic Foraminiferal Deep-Sea Drilling data in the Cretaceous Austral Realm, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15698, https://doi.org/10.5194/egusphere-egu25-15698, 2025.
Abundances and assemblage composition of benthic foraminiferal, dinoflagellate cysts and pollen were analysed together with sedimentological and geochemical proxies to investigate paleoenvironmental changes recorded in the Gulf of Corinth during MIS 1-5. The Gulf of Corinth is a relatively young (<5 Ma) and active continental rift zone in the eastern Mediterranean Sea, currently connected to the Ionian Sea through a shallow sill (60 m of depth) and to the Aegean Sea via the Corinth Canal (Isthmus; 6 km-wide). The coring sites of the IODP Expedition 381 are located in the central part of the gulf and the Alkyonides Gulf, a shallow semi-enclosed sub-basin within the northeastern part of the Gulf of Corinth. The closed drainage system and the high sedimentation rates make the study area ideal for investigating the complex interactions between sedimentary input, tectonics and climate through the basin’s evolution.
The benthic foraminiferal, dinocyst and pollen records are highly variable during both the Last Interglacial Complex and the Holocene. Mesotrophic to eutrophic marine conditions prevailed, as indicated by the high abundance of infaunal foraminiferal species (Bolivina spp., Melonis affinis, Bulimina spp., Cassidulina carinata, Valvulineria bradyana), with marine dinocysts (Nemaosphaeropsis labyrinthus, Spinifireties ramosus) and montane trees likely occurring during high sea-levels. During glacial and interstadial intervals, benthic foraminifers are mostly absent whereas abundant brackish dinocysts (Pyxidinopsis psilata) indicate a sea-level drop below sill level and the subsequent (semi-)isolation of the basin. Steppic pollen taxa predominate during the same intervals. Inorganic carbon content and elemental values varied following the inferred sea-level fluctuations, as well as the benthic foraminiferal oxygen isotope record which is discontinuous and conditionally limited to the presence of well-preserved benthic foraminifera. The beginning of the Holocene is marked by the re-establishment of marine conditions as the sea-level rose above the sill and the basin re-connected with the Mediterranean Sea.
This study is funded through projects GR 5285/3-1 “Late Quaternary dynamics of marine paleoenvironments and ecosystems in the Gulf of Corinth (eastern Mediterranean)” and PA 2664/8-1 “Linking marine and terrestrial ecosystem responses to climate variability since the Last interglacial in the Eastern Mediterranean” of the Deutsche Forschungsgemeinschaft (DFG).
How to cite: Koukousioura, O., Panagiotopoulos, K., Fatourou, E., Kafetzidou, A., Diz, P., Kouli, K., and Grunert, P.: Paleoenvironmental changes during MIS 1-5 in the Gulf of Corinth (eastern Mediterranean): IODP Expedition 381, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18087, https://doi.org/10.5194/egusphere-egu25-18087, 2025.
Convergence between African and European plates generates compressional strain, primarily concentrated along the northern African margin. This is testified on the Algerian margin by numerous earthquakes (e.g. Bougrine et al., 2019) and by the presence of active folds and thrusts. Multi-channel seismic reflection profiles from the MARADJA I survey reveal north-verging thrusts rooted below the Messinian units, and the geometries of the Messinian salt structures. This study examines the characteristics o+ salt tectonics offshore Algiers and Dellys, focusing on the effect of the positive structural inversion of the former passive margin on geometries, timing, and mechanisms o+ salt deformation. The interpretation of seismic refection and multi-beam bathymetric data of the MARADJA I survey, along with its comparison with analogue models, allowed us to reconstruct the salt tectonics processes on the margin and to identify the predominant role of a plateau uplift on salt deformation. Early and ubiquitous salt deformation by downbuilding was followed by a major phase of plateau uplift (end of Messinian Crisis), leading to westward gravity gliding and a slowdown of the salt deformation above the plateau. Km-tall salt structures were developed and thick minibasins deposited. Salt tectonics is nowadays active only where the relationship between salt and overburden thickness is favorable.
How to cite: Travan, G., Gaullier, V., Déverchère, J., and Vendeville, B.: Interplay of positive structural inversion and salt tectonics: The case study of the central Algerian margin, Western Mediterranean, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20036, https://doi.org/10.5194/egusphere-egu25-20036, 2025.
