2022

A new paper of Lawal just got published in the distinguished MPG! The paper deals with the utilization of state-of-the-art geophysical techniques for unraveling multi-level channel complexes (CLLCs) in the Levant Basin. The study also points out that when buried and linked to seafloor fluid seepage, the interactions between distinct elements of the CLLCs and fluid seepage cum migration processes remain poorly understood. This study uses 3D seismic data, attribute analysis, and advanced blending workflow to reveal the interaction between a verified seafloor pockmark, the GalC pockmark, and contiguous shallow (<200 m) buried Quaternary channel-lobe system within the eastern Nile deep-sea fan (NDSF) in the Levant. The GalC pockmark is an elongate, ~2.8 km long ridge-flank pockmark. By co-rendering shallow multilevel amplitude maps, we reveal that the pockmark is intimately associated with and overlies a ~518 m wide and up to 40 m deep NE-SW oriented faulted sinuous turbidite channel and a similarly oriented sediment lobe at the ridge location. The channel and lobe are marked by low-high amplitude infill and are focused toward the overlying pockmark by the host ridge. The high and low amplitude characters may manifest potential gas-bearing coarse-grained and silt-prone deposits respectively. This relationship suggests a depositional and structural control on gas seepage at the pockmark. We propose that microbial methane generation, accumulation, and release led to gas venting, while the lobe and channel margin permit lateral-up-dip and sub-vertical migration of gas to the pockmark respectively. This work opens a new paradigm on hydrocarbon migration and seepage as it links a verified gas seep to a seafloor-focused shallow buried channel and lobe system, with implications for understanding similar systems in sedimentary basins globally. 

A new paper with members of our lab just got published in the distinguished JQSR! Together with colleagues from Australia, we re-examine the stratigraphic sequence of Williams Point using detailed excavations, micromorphological analysis and geochemical characterization (XRF, XRD, palaeoecology, stable isotope analysis of gypsum hydration water, and biogenic carbonates) and present a revised chronology using single-grain optically stimulated luminescence (OSL) within a Bayesian framework. Our new chronostratigraphic data generally support previous interpretations for Williams Point, but crucially refines the timing of several of the key sedimentological units. The deeper-water lacustrine facies on the lake floor, unconformably overlying the Miocene Etadunna Formation, were deposited 206 ± 13 ka. A palaeoplaya, or oxidized shallow lake deposits, formed at 153 ± 11 ka, and the uppermost shallow water lacustrine facies at the base of the cliff was deposited at 131 ± 9 ka. An unconformity separates these sediments from the overlying fluvio-lacustrine phase, securely constrained (with eight OSL samples) to 86 ± 4 ka. The isotopic composition of the palaeo-lake water (δ18O and δD), reconstructed from the hydration water of syndepositional gypsum formed in-situ in these fluvio-lacustrine sediments, indicates wetter conditions at 95-78 ka than at ca. 232–131 ka. Based on the provenance analysis these fluvio-lacustrine and lacustrine sediments were sourced from the northern catchments within the Lake Eyre basin but with an additional contribution from the northern Flinders Ranges. An erosional unconformity separates this sedimentary unit from the overlying Coxiella beach facies, which dates to 71 ± 4 ka. This beach facies is interpreted to represent a regressional shoreline or near-shore deposit formed during Marine Isotope Stage 4. This is the most reliable palaeolake level indicator in the sequence and indicates a maximum water depth of 12 m. The overlying Williams Point aeolian unit (WPAU) dates to 49 ± 4 ka, slightly younger than previous estimates. These results bring fresh perspectives to a site that has held a heavy sway over previous views of the Quaternary history of Australia's arid zone.

A new paper with members and past members of our lab just came out in Scientific Reports! The paper deals with the identification of giant seafloor craters off-shroe Norway. Giant seafloor craters are known along many a continental margin with recurrent mass-wasting deposits. However, the impact of breakup-related magmatism on the evolution of such craters is barely understood. Using high-quality geophysical datasets, this work examines the genetic relationship among the location of magmatic sills, forced folds and the formation of giant paleo-seafloor craters underneath an ancient mass-transport complex in the Møre and Vøring basins, of-fshore Norway. The data reveal that forced folding of near-seafloor strata occurred because of the intrusion of several interconnected magmatic sills. Estimates of 1-dimensional uplift based on well data show that uplift occurred due to the intrusion of magma in Upper Cretaceous to Lower Eocene strata. Our findings also prove that subsurface fluid plumbing associated with the magmatic sills was prolonged in time and led to the development of several vertical fluid flow conduits, some of which triggered mass wasting in Neogene to Recent times. The repeated vertical expulsion of subsurface fluids weakened the strata on the continental slope, thereby promoting mass wasting, the selective cannibalization of the paleo-seafloor, and the formation of elongated craters at the basal shear zone of the mass-transport complex. Significantly, the model presented here proves a close link between subsurface magmatic plumbing systems and mass wasting on continental margins. 

A new paper just came out in Journal of African Earth Sciences leaded by one of our PhD students! The paper entitled: Depositional history of Lake Chala (Mt. Kilimanjaro, equatorial East Africa) from high-resolution seismic stratigraphy shows a new interpretation of a dense grid of high-resolution seismic reflection profiles presenting a seismic-based reconstruction of the complete depositional history of Lake Chala as well as a first-order age model for the major documented stages in lake evolution. The seismic stratigraphic sequence comprises 16 distinct and finely-stratified units (U1-U16, youngest to oldest), grouped into five major depositional stages. Stage I (U16, ca. 249-212 ka) marks the initiation of sedimentation in an originally ring-shaped depositional area surrounding two central tuff cones emerging from the basin floor. Stage II (U15-U12, ca. 212-114 ka) represents the onset of basin-wide sedimentation above the tuff cones, implying a gradual rise in lake depth and shift to more strictly hemipelagic sedimentation. Stage III (U11-U8, ca. 114-97 ka) represents the development of a relatively flat lake floor during a period of significantly reduced lake depth. Stage IV (U7-U4, ca. 97–20.5 ka) is again characterized by largely undisturbed hemipelagic sedimentation under mostly high lake-depth conditions. Stage V (U3-U1, 20.5 ka BP to Present) represents the establishment of the present-day, very broad and flat basin floor under fluctuating lake level. Reassessing the Moernaut et al. (2010) suggestion of a minor disconformity at ca. 100 m sub-bottom depth, we here interpret this seismic feature as a thick turbidite related to a mass wasting event. Consequently we can affirm continuity of lacustrine sedimentation in the depocenter of Lake Chala throughout the past ca. 250,000 years. 

Congrats Ahmad for the first paper of his PhD!

As part of a new collaborative initiative with Prof. Guy Bar-Oz from the Department of Archeology at the University of Haifa, we went to drill dumb mounds on the outskirts of Halusa, an abandoned city dated to the Byzantine period. The project, led by Prof. Bar-Oz and Prof. Dr. Michael Heinzelmann from the University of Cologne, Germany, aims to better understand the reasons behind the abandonment of the cities in the Negev desert, in an attempt to better disentangle the possible climate impact on ancient sociaties from cultural collapse.