Seismic atlas of the "Messinian Salinity Crisis" markers in the Mediterranean and Black seas – Volume 2

Lofi, J. ... et. al.-- European Geosciences Union General Assembly 2014 (EGU2014), 27 april - 2 may 2014, Vienna, Austria.-- 1 pageThe Seismic atlas of the >Messinian Salinity Crisis> markers in the Mediterranean and Black seas – Volume 2 is a publication project in the framework of the study of the Messinian Salinity Crisis. It follows the publication of a first volume in 2011 (see Editors’ websites: http://ccgm.free.fr & http://sgfr.free.fr) and aims to illustrate the seismic characteristics of the MSC markers over news study areas. The Messinian Salinity Crisis is a huge outstanding succession of events that deeply modified the Mediterranean area within a short time span at the geological scale. In 2011, a seismic atlas of the Messinian markers in the Mediterranean and Black seas has been published [1]. This collective work summarizes, in one publication with a common format, the most relevant seismic features related to this exceptional event in the offshore domain. It also proposes a new global and consistent terminology for the MSC markers in the entire offshore Mediterranean area in order to avoid nomenclatural problems. Throughout 13 study areas, the seismic facies, geometry and extend of the Messinian markers (bounding surfaces and depositional units) are described. The Atlas however does not provide a complete description of all what that is known about the MSC and about the geology of each study area. Accordingly, illustrations in the Atlas should be used for a global description of the offshore imprints of the MSC at a broad scale, or for local information or site-specific general interpretations. Interpreted seismic data were carefully selected according to their quality, position and significance. Raw and interpreted seismic profiles are available on CD-Rom. Volume 2 is currently under preparation with the objectives : (1) to image the Messinian seismic marker from margins and basins that have not been illustrated in the first volume and (2) to complete the extension map of the MSC markers in the offshore and onshore domains at the Mediterranean scale. As the first volume, Volume 2 will also aim to share the geological interpretation of seismic reflection data imaging Messinian markers, to make this information accessible to the non geophysician community and to be a reference work that can be used by teachers and future researchers working on the Messinian event. This publication project is still open to anybody from industry and academia willing to contribute. At the present time, 16 new sites have been identified. Publication of the Seismic atlas of the >Messinian Salinity Crisis> markers in the Mediterranean and Black seas – Volume 2 is planned for Fall 2014. For more details, contactPeer Reviewe

Facies architecture of Miocene subaqueous clinothems of the New Jersey passive margin: Results from IODP-ICDP Expedition 313

Understanding the history, causes, and impact of sea-level changes is a challenge for our societies that face accelerated global sea-level rise. In this context, improvement of our knowledge of sea-level changes and shoreline migration at geological time scales is critical. The preserved, laterally correlative sedimentary record of continental erosion on passive margins has been used to reconstruct past sea level. However, the detailed nature of a basic clinothem progradational pattern observed on many of these margins is still poorly known. This paper describes the sedimentary facies and interprets the depositional environments and the architecture of the clinothems of the New Jersey shelf (offshore northeastern USA) to depict the origin and controls of the distribution of the sediment on the margin. We analyze 612 cores totaling 1311 m in length collected at three sites 60 km offshore Atlantic City, New Jersey, during International Ocean Discovery Program–International Continental Scientific Drilling Program (IODP-ICDP) Expedition 313. The three sites sampled the lower to middle Miocene passive margin sediments of the New Jersey shelf clinothems. We also collected wireline logs at the three sites and tied the sedimentary architecture to the geometry observed on seismic profiles. The observed sediment distribution in the clinoform complex differs from that of current models based on seismic data, which predict a progressive increase in mud and decrease in sand contents in a seaward direction. In contrast, we observe that the clinoforms are largely composed of muds, with sands and coarser material concentrated at the rollover, the bottomset, and the toe of the slope. The shelf clinothem topsets are storm-influenced mud whereas the foreset slope is composed of a mud wedge largely dominated by density current deposits (e.g., low-density turbidites and debrites). The architecture of the clinothem complex includes a composite stack of ~30-m-thick clinothem units each made up of four systems tracts (Transgressive, Highstand, Forced-Regres­sive, and Lowstand Systems Tract) building individual transgressive-regres­sive sequences. The presence of mud-rich facies deposited during highstands on the topset of the clinoform, 40–60 km offshore from the sand-prone shoreface deposit (observed in the New Jersey onshore delta plain), and the lack of subaerial erosion (and continental depositional environments) point to a depositional model involving a subaerial delta (onshore) feeding a distant subaqueous delta. During forced regressions, shelf-edge deltas periodically overstep the stacks of flood-influenced, offshore-marine mud wedges of the New Jersey subaqueous delta, bringing sand to the rollover and building up the large-scale shelf-prism clinothems. The clinothem complex develops on a gently dipping platform with a ramp-like morphology (apparent dip of 0.75°–0.5°) below mean storm wave base, in 30–50 m of water depth, 40–60 km seaward of the coastal area. Its shape depends on the balance between accom­mo­da­tion and sedimentation rates. Subaqueous deltas show higher accumulation rates than their subaerial counterparts and prograde three times further and faster than their contemporaneous shoreline. The increase in the intensity of waves (height and recurrence intervals) favors the separation between subaqueous and subaerial deltas, and as a consequence, the formation of a flat topset geometry, a decrease in flood events and fluvial discharge, an overall progressive decrease in sediment grain size (from sequence m5.45, ca. 17.8–17.7 Ma, onwards), as well as an increase in sedimentation rates on the foresets of the clinoforms. All of these are recognized as preliminary signals that might characterize the entry into the Neogene icehouse world

A reference time scale for Site U1385 (Shackleton Site) on the SW Iberian Margin

Weproduced a composite depth scale and chronology for Site U1385 on the SWIberianMargin. Using log(Ca/Ti)measured by core scanning XRF at 1-cm resolution in all holes, a composite section was constructed to166.5 meter composite depth (mcd) that corrects for stretching and squeezing in each core. Oxygen isotopesof benthic foraminifera were correlated to a stacked d18O reference signal (LR04) to produce an oxygen isotopestratigraphy and age model.Variations in sediment color contain very strong precession signals at Site U1385, and the amplitude modulationof these cycles provides a powerful tool for developing an orbitally-tuned agemodel.We tuned the U1385 recordby correlating peaks in L* to the local summer insolation maxima at 37°N. The benthic d18O record of Site U1385,when placed on the tuned agemodel, generally agrees with other time scaleswithin their respective chronologicuncertainties.The age model is transferred to down-core data to produce a continuous time series of log(Ca/Ti) that reflectrelative changes of biogenic carbonate and detrital sediment. Biogenic carbonate increases during interglacialand interstadial climate states and decreases during glacial and stadial periods. Much of the variance in thelog(Ca/Ti) is explained by a linear combination of orbital frequencies (precession, tilt and eccentricity), whereasthe residual signal reflects suborbital climate variability. The strong correlation between suborbital log(Ca/Ti)variability and Greenland temperature over the last glacial cycle at Site U1385 suggests that this signal can beused as a proxy for millennial-scale climate variability over the past 1.5 Ma.Millennial climate variability, as expressed by log(Ca/Ti) at Site U1385, was a persistent feature of glacial climatesover the past 1.5Ma, including glacial periods of the early Pleistocene (‘41-kyrworld’)when boundary conditionsdiffered significantly from those of the late Pleistocene (‘100-kyr world’). Suborbital variability was suppressedduring interglacial stages and enhanced during glacial periods, especially when benthic d18O surpassed ~3.3–3.5‰. Each glacial inception was marked by appearance of strong millennial variability and each deglaciatio

Petrophysics of Chicxulub Impact Crater's Peak Ring

A new set of physical property measurements was undertaken on 29 peak-ring samples from the IODP-ICDP Expedition 364. Among the studied lithologies, the dominant one recovered in the peak ring consists of shocked granitoid rocks (19 samples). Porosity measurements with two independent methods (triple weight and C-14-PMMA porosity mapping) concur and bring new observations on the intensity and distribution of fracturing and porosity in these shocked target rocks. Characterization of the porous network is taken a step further with two other independent methods (electrical and permeability measurements). Electrical properties such as the cementation exponent (1.59 m < 1.87) and the formation factor (21 F < 103) do not compare with other granites from the published literature; they point at a type of porosity closer to clastic sedimentary rocks than to crystalline rocks. Permeabilities of the granitoid rocks range from 0.1 to 7.1 mD under an effective pressure of similar to 10 MPa. Unlike other fresh to deformed and altered granitoid rocks from the literature compared in this study, this permeability appears to be relatively insensitive to increasing stress (up to similar to 40 MPa), with implications for the nature of the porous network, again, behaving more like cemented clastic rocks than fractured crystalline rocks. Other analyzed lithologies include suevite and impact melt rocks. Relatively low permeability (10(-3) mD) measured in melt-rich facies suggest that, at the matrix scale, these lithologies cutting through more permeable peak-ring granitoid rocks may have been a barrier to fluid flow, with implications for hydrothermal systems.Peer reviewe

Rochechouart 2017-Drilling Campaign: First Results

No abstract available

Evolution of the gulf of Cadiz margin and southwest Portugal contourite depositional system : Tectonic, sedimentary and paleoceanographic implications from IODP expedition 339

Acknowledgments This research used samples and data collected through the Integrated Ocean Drilling Program (IODP). The research was partially supported through the CTM 2008-06399-C04/MAR, CTM 2012-39599-C03, CGL2011-26493, CTM2012-38248, SA263U14, IGCP-619, INQUA 1204 and FWF P25831-N29 Projects. Some data were collected with 94-1090-C03-03 (FADO) and MAR-98-0209 (TASYO) Projects. Research was conducted in the framework of the Continental Margins Research Group of the Royal Holloway University of London, People and the Program (Marie Curie Actions) of the European Union's Seventh Framework Program FP7/2007-2013/ under REA Grant Agreement No. 290201 MEDGATE’. We are very grateful to REPSeOL, TGS–NOPEC, and the CSIC-Institut Jaume Almera (http://geodb.ictja.csic.es) for allowing us to use an unpublished seismic data from the Gulf of Cadiz. We thank J. Aguire (UGR, Spain) for comments and suggestions concerning the Pliocene and Quaternary outcrops, B. van den Berg (USAL) for organizing a thought-provoking field-trip to Cadiz, Spain in November, 2014, M. Ángel Caja, L. García Diego, and J. Tritlla (REPSOL) for provenance and diagenetic analysis of early Pliocene sandstones and debrites, and L.J. Lourens (Utrecht University) for providing us the eccentricity and 200-Kys glacio-eustatic sea-level curves included in the Figure 16. Both Prof. D.A.V. Stow (Heriot-Watt Univ., UK) and F.J. Hernández-Molina (RHUL, UK), as the main co-proponents of the IODP Proposal 644 and the co-chiefs of the IODP Exp. 339, thanks to IODP, Exp. IODP 339 Scientists; JR crew and technicians, as well as all people, institutions and companies involved in making IODP a success since 2003. Finally, we also thank the editor, Gert J. De Lange and the reviewers T. Mulder (Bourdeaux Univ.); D. Van Rooij (Ghent Univ) and J. Duarte (Monash Univ.) for their very positive and helpful feedback and discussions in publishing this research.Peer reviewedPublisher PD

Freshening of the Mediterranean Salt Giant: controversies and certainties around the terminal (Upper Gypsum and Lago-Mare) phases of the Messinian Salinity Crisis

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 Mediterranean margins (Stage 1, 5.97-5.60 Ma) and subsequently &gt; 2 km of halite on the basin floor, which formed the so-called Mediterranean Salt Giant (Stage 2, 5.60-5.55 Ma). The final MSC Stage 3, however, was characterized by a "low-salinity crisis", when a second calcium-sulfate unit (Upper Gypsum; substage 3.1, 5.55-5.42 Ma) showing (bio)geochemical evidence of substantial brine dilution and brackish biota-bearing terrigenous sediments (substage 3.2 or Lago-Mare phase, 5.42-5.33 Ma) deposited in a Mediterranean that received relatively large amounts of riverine and Paratethys-derived low-salinity waters. The transition from hypersaline evaporitic (halite) to brackish facies implies a major change in the Mediterranean’s hydrological regime. However, even after nearly 50 years of research, causes and modalities are poorly understood and the original scientific debate between a largely isolated and (partly) desiccated Mediterranean or a fully connected and filled basin is still vibrant. Here we present a comprehensive overview that brings together (chrono)stratigraphic, sedimentological, paleontological, geochemical and seismic data from all over the Mediterranean. We summarize the paleoenvironmental, paleohydrological and paleoconnectivity scenarios that arose from this cross-disciplinary dataset and we discuss arguments in favour of and against each scenario

Drilling-induced and logging-related features illustrated from IODP-ICDP Expedition 364 downhole logs and borehole imaging tools

Expedition 364 was a joint IODP and ICDP mission-specific platform (MSP) expedition to explore the Chicxulub impact crater buried below the surface of the Yucatán continental shelf seafloor. In April and May 2016, this expedition drilled a single borehole at Site M0077 into the crater's peak ring. Excellent quality cores were recovered from ~ 505 to ~1335m below seafloor (m b.s.f.), and high-resolution open hole logs were acquired between the surface and total drill depth. Downhole logs are used to image the borehole wall, measure the physical properties of rocks that surround the borehole, and assess borehole quality during drilling and coring operations. When making geological interpretations of downhole logs, it is essential to be able to distinguish between features that are geological and those that are operation-related. During Expedition 364 some drilling-induced and logging-related features were observed and include the following: effects caused by the presence of casing and metal debris in the hole, logging-tool eccentering, drilling-induced corkscrew shape of the hole, possible re-magnetization of low-coercivity grains within sedimentary rocks, markings on the borehole wall, and drilling-induced changes in the borehole diameter and trajectory

Ocean Drilling Perspectives on Meteorite Impacts

Extraterrestrial impacts that reshape the surfaces of rocky bodies are ubiquitous in the solar system. On early Earth, impact structures may have nurtured the evolution of life. More recently, a large meteorite impact off the Yucatán Peninsula in Mexico at the end of the Cretaceous caused the disappearance of 75% of species known from the fossil record, including non-avian dinosaurs, and cleared the way for the dominance of mammals and the eventual evolution of humans. Understanding the fundamental processes associated with impact events is critical to understanding the history of life on Earth, and the potential for life in our solar system and beyond. Scientific ocean drilling has generated a large amount of unique data on impact pro- cesses. In particular, the Yucatán Chicxulub impact is the single largest and most sig- nificant impact event that can be studied by sampling in modern ocean basins, and marine sediment cores have been instrumental in quantifying its environmental, cli- matological, and biological effects. Drilling in the Chicxulub crater has significantly advanced our understanding of fundamental impact processes, notably the formation of peak rings in large impact craters, but these data have also raised new questions to be addressed with future drilling. Within the Chicxulub crater, the nature and thickness of the melt sheet in the central basin is unknown, and an expanded Paleocene hemipelagic section would provide insights to both the recovery of life and the climatic changes that followed the impact. Globally, new cores collected from today’s central Pacific could directly sample the downrange ejecta of this northeast-southwest trending impact. Extraterrestrial impacts have been controversially suggested as primary drivers for many important paleoclimatic and environmental events throughout Earth history. However, marine sediment archives collected via scientific ocean drilling and geo- chemical proxies (e.g., osmium isotopes) provide a long-term archive of major impact events in recent Earth history and show that, other than the end-Cretaceous, impacts do not appear to drive significant environmental changes

Early paleocene paleoceanography and export productivity in the Chicxulub crater

The Chicxulub impact caused a crash in productivity in the world''s oceans which contributed to the extinction of ~75% of marine species. In the immediate aftermath of the extinction, export productivity was locally highly variable, with some sites, including the Chicxulub crater, recording elevated export production. The long-term transition back to more stable export productivity regimes has been poorly documented. Here, we present elemental abundances, foraminifer and calcareous nannoplankton assemblage counts, total organic carbon, and bulk carbonate carbon isotope data from the Chicxulub crater to reconstruct changes in export productivity during the first 3 Myr of the Paleocene. We show that export production was elevated for the first 320 kyr of the Paleocene, declined from 320 kyr to 1.2 Myr, and then remained low thereafter. A key interval in this long decline occurred 900 kyr to 1.2 Myr post impact, as calcareous nannoplankton assemblages began to diversify. This interval is associated with fluctuations in water column stratification and terrigenous flux, but these variables are uncorrelated to export productivity. Instead, we postulate that the turnover in the phytoplankton community from a post-extinction assemblage dominated by picoplankton (which promoted nutrient recycling in the euphotic zone) to a Paleocene pelagic community dominated by relatively larger primary producers like calcareous nannoplankton (which more efficiently removed nutrients from surface waters, leading to oligotrophy) is responsible for the decline in export production in the southern Gulf of Mexico. © 2021. American Geophysical Union. All Rights Reserved