Messinian Times Research Articles

Sedimentary facies controls on reservoir quality of the Abu Madi Formation, offshore Nile Delta Basin, Egypt

The present study investigates the sedimentological analysis and petrophysical properties of the Messinian Abu Madi reservoir (AMR), offshore Nile Delta Basin in order to determine how facies heterogeneities control reservoir quality. This approach was performed by integrating core data from Mina-1 well and BE-1 well and wireline logs from four wells (BN-1, BN-2, BE-3 and Mina-1). Based on core studies, seven clastic facies have been identified, of which five form sandstone reservoirs. These facies have accumulated within a deep incised canyon-fill during four successive fluvial sub-environments; braided fluvial channel, point bar, floodplain, and abandoned channel. These fluvial sediments were changed into tidally influenced fluvial/estuarine deposits with aggradational-retrogradational stacking patterns due to a transgressive event during the Messinian time. Based on the well log petrophysical evaluation, the Abu Madi reservoir has a total porosity of 0.20–0.26 v/v and effective porosity in the 0.18–0.25 v/v range. Shale volume ranges from 0.04 to 0.09 v/v, and water saturation ranges between 0.15 and 0.45 v/v. Four reservoir rock types were recognized and interpreted as a function of composition and therefore having different petrophysical characteristics. RRT1 and RRT2 show good petrophysical properties and good reservoir quality. The best reservoir quality occurs in massive sandstones (RRT3), which have porosities up to 26% and permeabilities up to 1440 mD. RRT4 has a poor reservoir quality with porosity of 5.4% and permeability of 0.6 mD. The reservoir porosity heterogeneities and reservoir quality have been strongly impacted by the original composition and primary depositional facies.

New constraints on the closure of the Betic Seaway and the western Mediterranean palaeoclimate during the Messinian Salinity Crisis from the Campo Coy Basin (SE Spain)

The Campo Coy Basin (SE Spain) exposes >1 km of sedimentary succession with a variety of rocks including a thick evaporitic succession previously associated with the Messinian time. These evaporites were supposedly deposited in a restricted Mediterranean-Atlantic seaway connecting the Lorca and Guadix-Baza basins, although no chronological or geochemical data existed. Here we use palaeomagnetism together with vertebrate and foraminifera biostratigraphy to constrain the age of the Campo Coy succession between <9 Ma and 4.7 Ma. We use geochemistry (δ34S, δ18O and 87Sr/86Sr values) of the gypsum deposits to evaluate their marine or continental origin. In addition, we describe the underlying and overlying lithostratigraphic units to reconstruct the palaeogeographic evolution of this region. Our results show that the sediments were deposited in a continental environment, indicating that the Betic Seaway was already closed in this region during the late Tortonian and that the neighbouring marine basins of Guadix-Baza and Lorca were disconnected during that time. The δ34S, δ18O and 87Sr/86Sr values of the gypsum indicate recycling from the Triassic sulphates. Sedimentary facies of the evaporites point to an environment dominated by a saline lake with continental sabkha episodes developed during the driest periods. Well-defined and laterally continuous evaporitic cyclicity suggests an orbital forcing and high sedimentation rates preceding the Messinian Salinity Crisis (MSC). Alluvial deposits are contemporaneous with the MSC indicating a dry continental environment in this region during the Mediterranean restriction. Overlaying lacustrine carbonates are rich in small vertebrate fauna including African species that migrated to Europe during the MSC. These carbonates have low δ18O and δ13C values characteristic for freshwater input in an open lake just after the Zanclean flood, suggesting that a wet climate followed the MSC.

Vegetation climate and marine environmental reconstruction in the western Mediterranean (southern Rifian corridor, Morocco) over the Tortonian-Messinian transition

The Southern Rifian Corridor was a gateway connecting the Mediterranean Sea to the Atlantic Ocean in the Late Miocene. Its rapid narrowing at the Tortonian - Messinian transition around 7.2 Ma, resulting from very intense tectonic activity, has triggered an ecological crisis well before the deposition of the Messinian Salinity crisis evaporites.The sedimentary successions deposited in the Saïs Basin have recorded different events regarding biostratigraphic, environmental, tectonic, and eustatic that characterized the area during the late Miocene. In order to get information on the marine and continental environment during the Tortonian-Messinian Transition (TMT), a palynological and biostratigraphic study was carried out on two boreholes in the Saïs Basin.The biostratigraphic analyses based on the planktonic foraminifera of the boreholes studied reveals the succession of several biostratigraphic events, allowing us to attribute these sedimentary deposits to the late Tortonian - early Messinian time interval including the recognition of the T/M boundary.The abundance of continental inputs (pollen, spores, BOM, WOM, and COM in the palynofacies) and the low D/S ratio values indicated that the Saïs basin was a neritic epicontinental environment suffering a significant influence of terrigenous inputs. The temperature index shows that the thermal conditions of the surface water were warm.In the late Tortonian, faunal and floristic assemblages indicate an open, relatively deep, outer platform type marine environment with a slight tendency towards an inner platform context. At the Tortonian-Messinian boundary, there is an increase in land inputs and relative reduction in the diversity of both microfauna and microflora. The presence of cold-water taxa probably indicates moderate cooling. In Lower Messinian the marine environment, was external platform with tendencies towards an internal area.The cover is opened and dominated by herbaceous plants that colonize the low altitudes, while trees colonized the middle altitudes. The climate was hot and humid in the mid-altitude and dry in the lowlands.

Gravity modeling reveals a Messinian foredeep depocenter beneath the intermontane Fucino Basin (Central Apennines)

Residual gravity anomalies over Central Italy clearly indicate a prominent regional minimum over the Fucino Basin. Here, we forward model this anomaly along seven cross-sections. The modeling results validate the geometries and petrophysical properties of the Plio-Quaternary units previously proposed by reflection seismic data interpretation. Moreover, we suggest that a thick wedge-shaped sequence is present beneath the Plio-Quaternary post-orogenic units. Based on the inferred density and velocity properties, as well as outcrop evidence from around the Fucino Basin, this sequence would likely represent thick (~1700 m) siliciclastic syn-orogenic Messinian foredeep deposits. The proposed model implies a long-lasting tectonic inheritance history for the Fucino area, which originally hosted primary paleogeographic Mesozoic-Miocene boundaries. In the Messinian-Recent time, the Fucino has continuously represented a first-order tectonic depocenter for siliciclastic sediments, despite differences in tectonic regime (syn-orogenic Messinian, post-orogenic Plio-Quaternary) and palaeoenvironments (Messinian marine flysch, Plio-Quaternary alluvial-lacustrine facies). The compaction-corrected sedimentation rate (~0.89 mm yr−1), suggests a foredeep activity possibly spanning the entire pre-evaporitic, evaporitic and post-evaporitic Messinian time and is comparable to the sedimentation rate observed in the larger Pliocene Apennine foredeep, ~100 km northeast of the study area, suggesting a self-similarity of the belt-foreland system across time and space.

Tectonic Inversion and Geomorphic Evolution of the Algerian Margin Since Messinian Times: Insights From New Onshore/Offshore Analog Modeling Experiments

AbstractTectonic inversion of passive margins is a common but poorly documented process preceding subduction inception. We perform here a comprehensive land‐sea experimental modeling of this key process by reproducing the morphotectonic and sedimentary evolution of the central Algerian margin over the last 6 Myr. Our approach is based on scaled analog models integrating interactions between crustal shortening and surface processes, including erosion, water transport, sedimentation, gravitational instabilities, and base‐level changes. A challenge was to simulate the effects of the Messinian Salinity Crisis (MSC) through a major sea‐level oscillation and halite deposition. By using realistic boundary conditions, adapted analog material, and robust, first‐order parameters for physiography setups, we successfully reproduce the morphotectonic domains and the time‐dependent geometrical relationships between fluvio‐deltaic sedimentary systems, erosional surfaces, and thrust faults as observed since Messinian times. Our results highlight (1) the key role played by the MSC sea‐level oscillation on an ultra‐fast building, destruction and re‐sedimentation of fans and deltas from the upper slope to the abyssal plain; (2) the development of a large popup structure subparallel to the coastline, with progressive strain migration from the backthrust on land toward a frontal thrust of opposite vergence at mid‐slope and the margin toe; and (3) the importance of lateral changes in initial wedge shape and strain distribution for determining the non‐cylindrical geometry of the margin and progradation of piggy‐back basins during tectonic inversion. Our results support that the central Algerian margin is witnessing the early building of an accretionary wedge combining thin‐skinned and thick‐skinned tectonic styles.

The response of water column and sedimentary environments to the advent of the Messinian salinity crisis: insights from an onshore deep-water section (Govone, NW Italy)

AbstractDuring Messinian time, the Mediterranean underwent hydrological modifications culminating 5.97 Ma ago with the Messinian salinity crisis (MSC). Evaporite deposition and alleged annihilation of most marine eukaryotes were taken as evidence of the establishment of basin-wide hypersalinity followed by desiccation. However, the palaeoenvironmental conditions during the MSC are still a matter of debate, chiefly because most of its sedimentary record is buried below the abyssal plains of the present-day Mediterranean Sea. To shed light on environmental change at the advent and during the early phase of the MSC, we investigated the Govone section from the Piedmont Basin (NW Italy) using a multidisciplinary approach (organic geochemical, petrographic, and carbon and oxygen stable isotope analyses). The Govone section archives the onset of the crisis in a succession of organic-rich shales and dolomite-rich marls. The MSC part of the succession represents the deep-water equivalent of sulphate evaporites deposited at the basin margins during the first phase of the crisis. Our study reveals that the onset of the MSC was marked by the intensification of water-column stratification, rather than the establishment of widespread hypersaline conditions. A chemocline divided the water column into an oxygen-depleted, denser and more saline bottom layer and an oxygenated, upper seawater layer influenced by freshwater inflow. Vertical oscillations of the chemocline controlled the stratigraphic architecture of the sediments pertaining to the first stage of the MSC. Accordingly, temporal and spatial changes of water masses with different redox chemistries must be considered when interpreting the MSC event.

New seismic evidence of the Messinian paleomorphology beneath Lake Maggiore area (Italy)

Lake Maggiore is located on the boundary between the regions of Piedmont and Lombardy, in Northern Italy, and is one of the main sub-alpine lakes. The availability in this area of an extended seismic database composed by different grids projects (ISMES, PNR20/ Magadino and ENI Po Plain) associated with a well dataset (ViDEPI Project), offers the opportunity to investigate with unprecedented details the buried geomorphology of the paleo- canyons of the Ticino and Toce Rivers along the Southern Alps margin. The canyons were originated by the drop of the Mediterranean Sea level occurred during the Messinian Salinity Crisis (MSC) which paved the way to deep fluvial erosion along the Po Plain Basin margin. The paleo-canyon of the Ticino River is, for the first time, entirely displayed on a depth map from Magadino (Switzerland) to the Po Plain south of Sesto Calende (Italy) with a 3D representation option. The interpretation results confirm the existence of a continuous subsurface paleo-canyon of Messinian Age hidden beneath the recent sediments of Lake Maggiore. The canyon extends northward along the Ticino Valley in Switzerland and southward on the subsurface of the Po Plain (Italy). Seismic evidence indicates that the Messinian paleo- Ticino River probably had a different pathway as compared to the present day. Moreover, from seismic and geomorphological data interpretation, we hypothesize that the Toce, currently one of the main tributaries of Lake Maggiore, had a different path during the Messinian Age, and probably flowed the floor of the Orta Valley towards the Po Plain. Therefore, the fluvial capture of the river Toce River by the Ticino River is datable to post Messinian time.

Hydrocarbon Generation, In-Source Conversion of Oil to Gas and Expulsion: Petroleum System Modeling of the Duwi Formation, Gulf of Suez, Egypt

A multiple forward 1D modeling approach on four wells in the Abu Rudeis-Sidri oil field has been performed in accordance with the plate tectonics and crustal development of the Gulf of Suez, Egypt. The current work intends to simulate the hydrocarbon generating capability, in-source conversion of oil to gas, expulsion and adsorption (retention) of marine sulfur-rich Duwi kerogen. The integration of log responses and organic geochemistry indicate mature organic-rich intervals that have been confirmed by the 1D model. The rifting phases and its associated thermal cooling have a prominent contribution on the thermal maturation, particularly the Mio-Pliocene event. The elevated basal heat flow associated with the lithosphere thinning due to different rifting phases accelerates the thermal maturation of the high sulfur content of Duwi organic-rich interval. The pre-rift sequences are thermal insulators in contrast to the post-rift sequences of evaporites that can cool the underlying strata. Hydrocarbon generation, gas secondary cracking and expulsion are influenced by the post-rift thermal subsidence (the first and second phases). The kerogen has attained a thermal maturity level to generate liquid hydrocarbon since the Messinian (~ 5.8 Ma) and thermogenic gas secondary cracking since Zanclean (~ 3.57 Ma). The hydrocarbon generation (Early Pliocene) is related to the combination of basin burial (accompanied the first phase post-rift thermal subsidence) and the rift renewal through the Pliocene (Messinian Time Event). The gas generation is related to the second phase post-rift thermal subsidence that is accompanied by the deposition of the Post-Zeit Formation. Most of the hydrocarbons attained peak bulk generation during Pliocene (5.8 Ma), which dominated until expulsion commenced (2.52 Ma). The expulsion onset (Late Pliocene) attained subsequent to gas generation and after rift structural trap formation in Late Oligocene–Early Miocene. The expulsion onset (2.52 Ma) related mainly due to a high transformation ratio of kerogen, compaction and partly because of higher initial values of TOC (4.8%) as compared with its present-day values (3.2%). Applying the sensitivity analysis inferred that the source rock properties (HI and TOC) are not assigned as a controlling factor in the maturation process. The eroded thickness has small influence on the maturation process. In contrast, the excellent correlation (Pearson correlation coefficient = 1) supports that heat flow superimposed on the burial-related maturation.

Hydrocarbon-generating potential of the Eocene Thebes Formation, Gulf of Suez: 1D basin modeling as a supplementary tool for source rock evaluation

The present work provides high-resolution modeling of the thermal maturation of the Eocene Thebes Formation using a multi-1D approach. The model focuses not solely on the thermal maturity but also on timing of hydrocarbon generation (primary generation and secondary cracking), adsorption by organic matter, and expulsion. The time-lapse conceptual model was developed using well log data, geochemical analyses, and composite logs. The stratigraphic sequence of the Belayim Marine oil field was subdivided into a time series based on the tectonic framework of the Gulf of Suez. An elevated basal heat flow has been assigned throughout the rifting phases and basin evolution. The simulation developed for seven wells reveals variations in burial, thermal history, and accordingly the thermal maturity. The predicted thermal maturity ranges from immature to mature with a different tendency to generate hydrocarbons (both primary generation of oil and/or gas secondary cracking) dependent on kerogen type, basin development, and burial history. Hydrocarbon generation (oil) starts after the Messinian Time Event during the deposition of the Post-Zeit Formation. Hydrocarbon generation was related to burial rather than basin evolution for the 113-M-27, BM-23, BM-65, and BM-70 wells. Conversely, generation correlated principally to basin development particularly Messinian Time Event for the 113-M-34 well. Expulsion occurred subsequent to generation of thermogenic gas (secondary cracking of generated oil). It is not possible to investigate the relationship between the production index and thermal maturity as a consequence of expulsion that reduced the S1 values. The different levels of thermal maturity (potential, active, and effective source rock) allow for the differentiation of regions of potential hydrocarbon accumulation that were charged from the Thebes Formation.

Fault growth mechanisms and scaling properties in foreland basin system: The case study of Monte Alpi, Southern Apennines, Italy

The present work focuses on the comprehension of the growth mechanisms and dimensional properties of the pre-Pliocene Monte Alpi fault network by mean of integrated field and laboratory analyses. After this multidisciplinary approach, detailed throw profiles are computed for each fault belonging to the Monte Alpi network. Subsequently, the dimensional properties of the individual faults are calculated. Data obtained from this work are discussed in terms of fault growth mechanisms and timing of deformation, and reported in a conceptual tectonic evolution model of the Messinian foreland basin system. Data suggest that originally isolated fault segments developed during the earliest stages of foreland basin formation by re-activation of a pre-existing, Early Cretaceous fault set, and formation of an orthogonal one. These two fault sets formed a scale-independent network. Differently, the same fault sets were also active during its subsequent development forming a scale-dependent fault network characterized by T- and Y-shaped fault intersections. This deformation controlled the half-graben depocenters evolution filled by up to ca. 600 meters of terrigenous deposits during the Late Messinian time.

Extensional Messinian basins in the Central Mediterranean (Calabria, Italy): new stratigraphic and tectonic insights

The direction of extension and the architecture of the Messinian basins of the Central Mediterranean region is a controversial issue. By combining original stratigraphic analysis of wells and seismic profiles collected offshore and onshore Calabria, we reassess the tectonic evolution that controlled the sedimentation and basement deformation during Messinian times. Three main deep sedimentary basins in the Calabria area record a Messinian succession formed by two clays/shales-dominated subunits subdivided by a halite-dominated subunit. The correlation with the worldwide recognized stratigraphic features permit to define the chronology of the stratigraphic and tectonic events. Three main rift basins that opened in a N-S direction have been recognized. On the contrary a fourth supradetachment basin opened toward the East. We found that the basin subsidence was controlled by two stages of activity of normal faults and that Messinian rift basins evolve in a deep-water environment. The overall pattern of extensional faults of the Central Mediterranean corresponds to normal faults striking parallel to the trench and normal faults striking at an oblique angle to the trench (Fig. 14). In particular in Campania and Calabria regions are present two rifts parallel to trench and an intervening rift orthogonal to the trench. We maintain that the recognized Messinian rift basins can be interpreted according to the “Double-door saloon tectonics”.

Global versus regional influence on the carbonate factories of Oligo-Miocene carbonate platforms in the Mediterranean area

The Oligocene-Miocene is a key interval that was characterized by a cooling trend associated with a progressive decrease of atmospheric CO2 concentrations that ends in the Present days.In the Central Mediterranean area, during this interval, three main carbonate platform domains developed in the foreland zone of the Apennines: the Latium-Abruzzi-Campana and Apulia domain in the central and south-eastern sectors of the chain and the Hyblea and Pelagian carbonate platforms in the south and south-western sectors. This work analyzes the impact and interplay of global and regional factors controlling the development of different carbonate factories and facies associations over the Chattian and the early Messinian time interval. Three well-studied examples of the central Mediterranean will be used: the Chattian ramp of Malta, the Latium-Abruzzi ramp, and the Bolognano ramp within the northern portion of the Apulian carbonate platform (outcropping on Majella Mountain).The Malta ramp represents the reference model for the heterozoan Oligo-Miocene carbonate factory, since it developed far from terrigenous input, in persistent oligotrophic conditions, and within a tropical climate. In contrast, the evolution of the central Apennine ramps is strictly related to the geodynamic evolution of the Apennines and simultaneously to global oceanographic changes.The Chattian Apennine ramps are affected by a basin conformation that favored the development of dominant currents and related dune fields. Successively, these ramps were exposed to strong Aquitanian volcanism that induced a shift towards an aphotic-dominated carbonate factory. Since the Burdigalian the development of the Apennines has affected the evolution of the investigated ramps through the eastward migration of foredeep systems and related nutrient input. This influence becomes more evident between the Tortonian and Messinian, during which reef-rimmed platforms developed in the rest of the Mediterranean while red algae still dominated in the Apennine ramps. Amongst the global events, the C-cycle perturbation, occurring between the late Burdigalian and Serravallian (Monterey event), leaves a clear sign on the two Apennine ramps.

Mélange versus forearc contributions to sedimentation and uplift, during rapid denudation of a young Banda forearc-continent collisional belt

New sedimentary geochemistry and petrographic analyses provide the most extensive sedimentary documentation yet of the rapid denudation of the young Timor orogen. The data from three basins including two widely-separated, well-dated sections of the Synorogenic Megasequence of Timor-Leste, and a re-dated DSDP 262, constrain the source and timing of detrital sediment flux during forearc-continent collision along the Timor sector of the Banda Arc. The exhumed synorogenic piggy-back basins formed above a mélange unit that developed at the expense of a weak stratigraphic horizon in the Mesozoic stratigraphy, and was exhumed to the sea floor in latest Messinian time. Following an interval of deep marine chalky marl sedimentation, an increasingly muddy sediment flux indicates that the island of Timor became emergent and shed sediment by 4.5Ma. Comparison of exhumed sections with similar patterns in the DSDP262 chemistry suggests that the sediment source was probably located some 50–60km distant from the basin, which is consistent with the Aileu region of Timor-Leste that shows an appropriate exhumation history. All sedimentation between 4.5 and 3.2Ma was probably derived from a low-relief, rapidly eroding, and mudstone-dominated landscape with geochemical affinities to the Triassic-mudstone-derived synorogenic mélange. The mélange unit overlies and surrounds the Banda Terrane, and was presumably structurally emplaced by propagation of a decollement through the Triassic rocks during the collision. After 3.2Ma, sedimentation was dominated by hard rock lithologies of the Banda Terrane, consisting of forearc cover and basement, the latter including elements of metamafic rocks and metapelites. This phase of sedimentation was accompanied by rapid uplift, which may have been partly driven by a transient imbalance between rock uplift and denudation as resistant lithologies emerged from below mélange-like mudstone. Previous work has suggested that the timing of collision in Timor-Leste and West Timor was substantially different. Our reevaluation of DSDP 262 facies migration history in the context of the re-dating presented here, favours a relatively synchronous onset of uplift in both halves of the island, but with different partitioning of strain between the foreland and hinterland in each half of the island.

Thermal maturity and hydrocarbon generation of the Dawi Formation, Belayim Marine Oil Field, Gulf Of Suez, Egypt: a 1D Basin Modeling Case Study

The Upper Senonian Dawi Formation of Belayim Marine Oil Field, Gulf Of Suez, Egypt, is a promising source rock. However, the generation and expulsion of hydrocarbons from it are not assigned yet. This study throws the light on the maturation (generation and expulsion) of hydrocarbons from Dawi formation through the construction and evaluation of a multi-1D approach within the framework of a fully integrated dynamic geologic model which was performed with PetroMod software. The first step in a new basin model is to construct a conceptual model, so in this study, the penetrated preserved stratigraphic sequence divided into uninterrupted time series based on petrophysical interpretation of the logged sequence and age-equivalent formations. Detailed well log interpretation was performed for the reservoirs and organic-rich source rock intervals and integrated into a conceptual model used for 1D basin modeling. Geochemical data is used to calibrate the log interpretation in this respect, which enabled basin modeling with extraordinarily high resolution of the stratigraphic sequence, resulting in a detailed and calibrated burial and thermal model. The simulations for four wells in the study area show differences in burial, thermal history and maturity, and, in consequence, differences in petroleum generation and expulsion with time. The maturity of the organic-rich interval varies from immature to mature with a different tendency to produce oil depending on the kerogen type, basin evolution, and burial through time. The Dawi Formation of the Upper Senonian age has relatively high organic carbon content and the capacity to generate petroleum liquids and possibly gas by secondary cracking. The Dawi Formation generated oil around the Late Miocene-Messinian (∼5.88 Mabp) during deposition of the Zeit Formation at oil windows’ depth of 2384 m (TVDss). The organic-rich interval of the Dawi Formation in Belayim Marine Oil Field concession, Dawi-S, entered the oil windows close to the Late Miocene (Messinian ∼5.88 Mabp) during the deposition of Zeit Formation and has been in the wet gas windows (gas onset) since ∼5.42 Mabp (Late Miocene-Messinian). The oil windows’ depths range between 2329 m (∼3.5 Mabp Pliocene-Piacenzian) at BM-23 well and 2384 m (∼5.88 Mabp Late Miocene-Messinian) at 113-M-27 well, before the maximum burial was reached. The expulsion of hydrocarbons mainly related to basin evolution due to the Messinian Time Event ∼5.2 to ∼4 Mabp (Pliocene-Zanclean) and it started at ∼5.2 Mabp. If sufficient residual kerogen has remained, increased temperature, according to the combined effect of Tertiary deposition and elevated temperature in the Late Tertiary, may have led to late-stage oil expulsion in favorable parts of the basin.

Synchronous onset of the Messinian evaporite precipitation: First Mediterranean offshore evidence

The Messinian Salinity Crisis (MSC) was a major ecological crisis affecting shallow and deep-water settings over the entire Mediterranean basin. However, the evolution of the MSC and its ecological impacts have mainly been explained on the basis of sediments from onshore outcrops. Lack of complete and physically connected records from onshore and offshore settings has inhibited comprehensive understanding of basin behaviour during the MSC. Herein we present a continuous record from an intermediate-depth basin on the Balearic Promontory that comprises late Tortonian–Messinian marls and evaporitic beds from the first MSC phase (i.e., Primary Lower Gypsum-PLG stage). Well-log and biostratigraphic data allow us establishing a large-scale calibration to the astronomical solutions, and to correlate pre-MSC sediments with classical rhythmic successions outcropping onshore. Thickness and characteristic sedimentary patterns observed in the offshore evaporitic records resemble those from marginal PLG sequences. Furthermore, seismic reflectors from a Bedded Unit (BU), which corresponds to an evaporitic interval according to well-to-seismic ties, are correlated with the onshore PLG sequences. This correlation constitutes the first attempt to link well-known marginal sequences with intermediate-depth offshore settings, which have previously only been studied through seismic imaging. Our time-calibration provides direct evidence supporting a synchronous onset of the PLG phase between onshore and offshore settings along the southwestern Balearic Promontory margin. Those BU reflectors, which were positively correlated to the PLG, were likely precipitated offshore the continental shelf at Messinian times. These results suggest that gypsum precipitation and/or preservation was not always limited to 200 m water-depths and could occur in non-silled basins. Finally, we only found a major erosion at the top of the PLG sequences, implying that the MSC drawdown occurred after the precipitation of the onshore lower evaporites. Studied sequences provide new insights into the PLG precipitation/preservation settings, as well as into the land-sea correlations of MSC units, and thus could potentially help refine current MSC models.

A sequence stratigraphic model for the Upper Miocene–Pliocene basin fill of the Pannonian Basin, eastern Hungary

Interpretations of subsurface data and computer simulations of basin-fill history in the late Neogene Pannonian Basin of eastern Hungary established a regional stratigraphic model presented in this paper. Three fluvial systems overfilled the basin: a large system from the NE, another from the NW and a third smaller system transported sediments from the territory of Romania, from the SE. Large part of the basin had been filled by Messinian time (late Miocene); the remaining lake was located in southeastern Hungary and neighboring countries. In the Tortonian stage, the three fluvial systems advanced concomitantly (with small-scale, high-frequency cycles), toward the basin center. A significant relative lake-level drop occurred in the Messinian, which induced large-scale erosion and fluvial incision and generated an unconformity surface that provides a major division in the Pannonian strata; it appears as a significant stratigraphic divide that separates two different stages in the history of the Pannonian Basin. In the upper Messinian-Pliocene stage, the basin underwent a tectonic inversion; the shallow lake was filled up rapidly by lowstand turbidites and prograding delta-slope sediments. The inversion continues up to the present day. Turbidites and lowstand prograding wedges associated with the Messinian event may be targets for hydrocarbon exploration. Four main stages can be identified in the Upper Miocene–Pliocene basin fill history: (1) Tortonian highstand regression with several low-rank relative lake-level cycles; (2) Messinian lake-level drop, accompanied by the formation of the “Messinian unconformity” and the deposition of a falling-stage systems tract (FST). The “Messinian unconformity” is a composite surface, represented by a subaerial unconformity at the margins, and a basal surface of forced regression in the depocenters; (3) relative rise of lake level, when the FST turned to a lowstand systems tract (LST); (4) tectonic inversion (basinward tilt and marginal uplift) during or at the beginning of the LST.

3D geometry of growth strata in a fault-propagation fold: insights into space–time evolution of the Crevillente Fault (Abanilla-Alicante sector), Betic Cordillera, Spain

This work presents a 3D geometric model of growth strata cropping out in a fault-propagation fold associated with the Crevillente Fault (Abanilla-Alicante sector) from the Bajo Segura Basin (eastern Betic Cordillera, southern Spain). The analysis of this 3D model enables us to unravel the along-strike and along-section variations of the growth strata, providing constraints to assess the fold development, and hence, the fault kinematic evolution in space and time. We postulate that the observed along-strike dip variations are related to lateral variation in fault displacement. Along-section variations of the progressive unconformity opening angles indicate greater fault slip in the upper Tortonian–Messinian time span; from the Messinian on, quantitative analysis of the unconformity indicate a constant or lower tectonic activity of the Crevillente Fault (Abanilla-Alicante sector); the minor abundance of striated pebbles in the Pliocene-Quaternary units could be interpreted as a decrease in the stress magnitude and consequently in the tectonic activity of the fault. At a regional scale, comparison of the growth successions cropping out in the northern and southern limits of the Bajo Segura Basin points to a southward migration of deformation in the basin. This means that the Bajo Segura Fault became active after the Crevillente Fault (Abanilla-Alicante sector), for which activity on the latter was probably decreasing according to our data. Consequently, we propose that the seismic hazard at the northern limit of the Bajo Segura Basin should be lower than at the southern limit.

Fault-controlled evaporite deformation in the Levant Basin, Eastern Mediterranean

Abstract During the Messinian Salinity Crisis a multi-layered salt giant of 1.5 km thickness was precipitated in the Levant Basin, easternmost Mediterranean Sea. Incipient deformation of this geologically young salt layer was commonly explained by gravity-driven processes only. Based on high-quality depth-migrated seismic data, we show for the first time, how sub-salt extensional faults influence the internal deformation pattern of the Messinian evaporites in the Levant Basin. Extensional faulting started in the Middle Miocene and lasted until Late Messinian times. We suggest faulting to have caused the development of fault-propagation folds within the evaporite unit. Subsequently, folds may have accommodated tectonic shortening at the Latakia Ridge and evolved into the presently observed complex intra-evaporite fold pattern. While fault-controlled evaporite deformation is evident in the northern part of the Levant Basin only, evaporites are increasingly influenced by Nile-derived differential sediment loading towards the south. Locally, zones of reduced amplitudes in the sub-salt domain terminate into phase-reversed bright spots within the lower part of the evaporites, indicating active fluid migration and potentially evaporite dissolution. Finally, we present a high-resolution velocity model of the Messinian evaporites, based on model-based processing and residual moveout analysis. Relatively high interval velocities of acoustically transparent evaporites (3850–4240 km/s) are consistent with halite, whereas lower velocities of reflective layers (3650–4030 km/s) may point towards the presence of low-velocity evaporite facies like gypsum.

Salt tectonics and crustal tectonics along the Eastern Sardinian margin, Western Tyrrhenian: New insights from the “METYSS 1” cruise

Abstract The Tyrrhenian Sea is usually interpreted to be a Neogene back-arc basin that opened by continental rifting and oceanic spreading caused by the eastward migration of the Apennine subduction system during Miocene and Pliocene times. Rifting of the southern Tyrrhenian Sea started first along the Eastern Sardinian margin during the middle to late Miocene times, including the Messinian. The “METYSS” project aims at better constraining the relationships between crustal tectonics, salt tectonics and sedimentation from Messinian times to present-day. The “METYSS 1” cruise (2009) allowed to acquire about 1200 km of HR seismic-reflection profiles along the Eastern Sardinian margin, Western Tyrrhenian Sea. This data set clearly illustrates that this area has been highly dissected during the rifting stage by N–S trending normal faults delineating ridges and basins, as previously described. The Messinian seismic markers (UU and MU) locally display fan-shaped stratal geometries, but the mechanism responsible for such geometries, salt tectonics or rifting, has yet to be carefully deciphered. We also mapped the spatial distribution of the mobile salt. The highly variable thickness of the small confined salt basins may be related to the initial pre-Messinian basin geometry, to the fact that salt deposition was syn-rift or to salt movement. Southeastward, salt tectonics is vigorous in unconfined basins and appears to have started early during the UU deposition. More surprisingly, our data demonstrate that some of the major faults have been significantly reactivated during the post-rift period, up to late Quaternary time, as shown by bathymetric scarps and associated debris flows. Moreover, some of this post-rift deformation can be evidenced within the Plio-Quaternary sequence by a regional unconformity. The post-Miocene deformation style varies greatly between different areas of the margin, and can also be strongly influenced by the presence or absence of mobile Messinian salt.

The “Brecciated Limestones” of Maiella, Italy: Rheological implications of hydrocarbon-charged fluid migration in the Messinian Mediterranean Basin

The upper Messinian “Brecciated Limestones” of the Maiella area (Central Italy) reveal clues to the rheological behavior of the sedimentary column during fluid migration processes, as well as the timing of a major phase of methane release. Seep limestones have been studied worldwide in ancient and present-day settings. However, investigations of the complex rheologic behavior shown by the wide array of brecciated facies have received less attention. In this work special emphasis was placed on fabric and facies analyses, comparisons of the various scales of observation, and integrated stable isotope analyses (δ18O and δ13C), all within the context of the precisely-dated stratigraphy of the late Messinian sediments of the Mediterranean Basin.Above the basin scale Messinian Erosional Surface (MES), widespread brecciated limestone buildups and minor concretions constitute microbial carbonate bodies laterally embedded or passing to a marly-pelitic succession. In situ fluid-driven brecciation, together with the occurrence of fluid migration paths, are interpreted to represent vestiges of a mud volcano feeder system. However, chaotic textures testify to complex rheological behavior, where brittle and plastic responses in the same micro-environments co-occurred during fluid migration through a partially lithified sedimentary column.Different patterns of tar-bearing facies and degrees of brecciation, coupled with a geochemical dataset yielding wide ranges of δ18O (from +4 to −10‰ PDB-1) and δ13C values (from +4 to −40‰ PDB-1), point to two distinct stages of ascending hydrocarbon-charged fluids: in an earlier phase, fluids were mostly typified by low-molecular-weight hydrocarbons and induced widespread brecciation in the sedimentary column; in a later phase, fluid migration was accompanied by crude oil migration. During the early phase, fluid migration through the sedimentary column developed both: (a) with large vigorous fluxes, creating neoformed feeder channels and causing high degrees of brecciation; and (b) via slow seepage, favouring authigenic carbonate precipitation in the host sediment and causing negligible brecciation.In our proposed scenario, the Maiella area witnessed a hydrocarbon-rich fluid migration event (mainly methane) during the late Messinian, accompanied by authigenic carbonate precipitation and widespread brecciation. We suggest that this event was triggered by the sudden depressurization induced by the major drawdown of the Mediterranean Sea in late Messinian times.