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Archaeological excavations at the DK site in the eastern Olduvai Basin, Tanzania, age-bracketed between ∼1.88 Ma (Bed I Basalt) and ∼1.85 Ma (Tuff IB), record the oldest lahar inundation, modification, and preservation of a hominin “occupation” site yet identified. Our landscape approach reconstructs environments and processes at high resolution to explain the distribution and final preservation of archaeological materials at the DK site, where an early hominin (likely Homo habilis ) assemblage of stone tools and bones, found close to hominin specimens OH24 and OH56, developed on an uneven heterogeneous surface that was rapidly inundated by a lahar and buried to a depth of 0.4–1.2 m (originally ∼1.0–2.4 m pre-compaction). The incoming intermediate to high viscosity mudflow selectively modified the original accumulation of “occupation debris,” so that it is no longer confined to the original surface. A dispersive debris “halo” was identified within the lahar deposit: debris is densest immediately above the site, but tails off until not present >150 m laterally. Voorhies indices and metrics derived from limb bones are used to define this dispersive halo spatially and might indicate a possible second assemblage to the east that is now eroded away. Based upon our new data and prior descriptions, two possibilities for the OH24 skull are suggested: it was either entrained by the mudflow from the DK surface and floated due to lower density toward its top, or it was deposited upon the solid top surface after its consolidation. Matrix adhering to material found in association with the parietals indicates that OH56 at least was relocated by the mudflow. [ABSTRACT FROM AUTHOR]

Permeability is one of the most important petrophysical parameters to describe the reservoir properties of sedimentary rocks, pertaining to problems in hydrology, geothermics, and hydrocarbon reservoir analysis. Outcrop analogue studies, well core measurements, and individual sample analysis take advantage of a variety of commercially available devices for permeability measurements. Very often, permeability data derived from different devices need to be merged within one study (e.g. outcrop minipermeametry and lab-based core plug measurements). To enhance accuracy of different gas-driven permeability measurements, devicespecific aberrations need to be taken into account. The application of simple one-to-one correlations may draw the wrong picture of permeability trends. For this purpose, transform equations need to be established. This study presents a detailed comparison of permeability data derived from a selection of commonly used Hassler cells and probe permeameters. As a result of individual crossplots, typical aberrations and transform equations are elaborated, which enable corrections for the specific permeameters. Permeability measurements of the commercially available ErgoTech gas permeameter and the TinyPerm II probe permeameter are well-comparable over the entire range of permeability, with R2 = 0.955. Aberrations are mostly identified in the permeability range <10 mD, regarding the TinyPerm II and the minipermeameter/Hassler-cell combination at Darmstadt University, which need to be corrected and standardized. Applying standardizations which consider these aberration intervals strongly improves the comparability of permeability data sets and facilitates the combination of measurement principles. Therefore, the utilization of such correlation tests is highly recommended for all kinds of reservoir studies using integrated permeability databases. [ABSTRACT FROM AUTHOR]

Permeability is one of the most important petrophysical parameters to describe the reservoir potential of sedimentary rocks, contributing to problems in hydrology, geothermics, or hydrocarbon reservoir analysis. Outcrop analog studies, well core measuremeasurements, 5 or individual sample analysis take advantage of a variety of commercially available devices for permeability measurements. Very often, permeability data derived from different devices need to be merged within one study, e.g. outcrop mini-permeametry and lab-based core plug measurements. To enhance accuracy of different gas-driven permeability measurements, device-specific aberrations need to be taken into account The application of simple one-to-one correlations may draw a wrong picture of permeability trends. For this purpose, transform equations need to be established. This study presents a detailed comparison of permeability data derived from a selection of commonly used Hassler cells and probe permeameters. As a result of individual cross-plots, typical aberrations and transform equations are elaborated which enable corrections for the specific permeameters. Permeability measurements of the commercially available ErgoTech Gas Permeameter and the TinyPerm II probe-permeameter are well-comparable over the entire range of permeability, with R2 = 0.967. Major aberrations are identified among the TinyPerm II and the mini-permeameter/Hassler-cell combination at Darmstadt University, which need to be corrected and standardized within one study. However, transforms are critical to their use, as aberrations are frequently limited to certain permeability intervals. In the presented examples, deviations typically tend to occur in the lower permeability range < 10 mD. Applying standardizations which consider these aberration intervals strongly improve the comparability of permeability datasets and facilitate the combination of measurement principles. There-fore, the utilization of such correlation tests is highly recommended for all kinds of reservoir studies using integrated permeability databases. [ABSTRACT FROM AUTHOR]

A combined tectonic-stratigraphic interpretation of three-dimensional seismic reflection, wireline log and core data is presented in this study focussing on a tight gas field in East Frisia, NW Germany. Upper Rotliegend reservoir rocks in the study area are of fluvio-aeolian origin and include dune, minor sandflat and wet to dry interdune deposits. Source rocks are Westphalian coals and a top seal is provided by Zechstein evaporites. Detailed analyses of palaeo-topography, fault activity and accommodation space development for strata of Permian age (Rotliegend and Zechstein groups) indicate that local depocentres developed within small-scale fault-controlled transtensional sub-basins. Synsedimentary half-graben development and fault activity occurred during Upper Rotliegend II (mainly Elbe Subgroup) deposition. Many Upper Rotliegend structures were then reactivated during the Triassic, Jurassic and Cretaceous, often with enhanced offsets and increased lateral extent. As a consequence, Rotliegend structures and stratigraphy were significantly displaced resulting in the relocation of former Rotliegend depocentres and associated tight gas reservoir facies. This tectonic overprint hampers the prediction of potential Rotliegend reservoirs, and shows that palaeo-environmental restoration is required in areas which have undergone multi-phase deformation histories. Exploration strategies in the study area have favoured drilling locations in present-day structural highs. This study suggests that sediment traps were controlled by synsedimentary Upper Rotliegend II to Zechstein palaeo-topography, defining a new concept for future tight gas exploration. [ABSTRACT FROM AUTHOR]

Abstract Palaeolandscape studies are an essential tool for understanding adaptation and use of plant- and water-related affordances by hominins. A number of high-resolution palaeolandscape analyses have been carried out at Olduvai Gorge (northern Tanzania) over the last two decades but none have focused on the Tuff ID-IE stratigraphic interval (1.83–1.84 Ma). At locality HWK W, this interval presents earthy facies, including siliceous earth, earthy claystone, sandy earth, and earthy sandstone facies varieties, which are rare for Bed I. These facies have been interpreted at other stratigraphic levels to represent densely vegetated wetlands. Additionally, the HWK W site has yielded quantities of fossil bone and tools eroding to the surface. Within the Tuff ID-IE interval, and during regression periods of Palaeolake Olduvai, fluvial and wetland facies were deposited. During this period, the phytoliths and plant macrofossils show that the vegetation was dominated by palms, associated with a mix of C 3 and C 4 grasses as well as sedges. The variation in phytolith types within these facies implies a locally diverse palaeoenvironmental micro-mosaic, with stacked transgressive sequences, varying from vegetated fluvial channels to vegetated levées and then backswamp subenvironments. Diatoms are particularly rich at Trench T155 and are associated with sponge spicules, indicating the presence of freshwater palaeowetlands with clear water. The extensive diatom valve fragmentation and the differences among trenches suggest that the diatom depositional environment was a heterogeneous river-fed palaeowetland or a vegetated fluvial channel affected by periodic droughts. A diverse fauna was recovered, comprising autochthonous hippopotamus and crocodile elements as well as herbivores drawn to the freshwater resource. Oldowan lithic artifacts were also recovered and some bone was processed through percussion and cutting by early hominins, likely Homo habilis. Overall, the first landscape reconstruction undertaken at HWK W locality during the Tuff ID-IE interval shows a dynamic and richly vegetated area that would have provided hominins with fresh water, scavengeable carcasses, as well as with edible plant affordances (palm fruits, starch-rich rhizomes from sedges and Typha). The presence of palms suggests the area supported a diversity of trees, affording hominins refuge from predators. Highlights • Tuff ID-IE interval at HWK W was a palm dominated landscape. • Fluvial and wetland facies dominated after lake withdrawal periods. • The river-fed wetlands were occupied by aquatic fauna, hippopotamus and crocodiles. • Palms and a diversity of trees affording hominins refuge from predators. • The wetland provided hominins with potable fresh water and plant resources. [ABSTRACT FROM AUTHOR]

Sandstones with carbonate cements are found in a variety of depositional settings (e.g. fluvial, lacustrine, deltaic, shallow marine) with abundances ranging from just a few volume percent to pervasive pore-filling cements and are of major interest due to their impact on reservoir quality. Despite the widespread occurrence of such cements, predictive models for eogenetic carbonate cementation have yet to be developed. Hence, investigations on the controls and distribution of early carbonate precipitation are necessary to improve the accuracy of predictions of the nature and distribution of diagenetic alterations. We conducted a petrological and petrophysical analysis of early near-surface carbonate cementation in siliciclastic and mixed siliciclastic-carbonate sandstones from fluvial and shallow marine environments to reconstruct eogenetic processes and their associated controls. Furthermore, sediment burial scenarios up to a loading of 50 MPa were simulated with the reservoir quality prediction software Touchstone to evaluate the impact of carbonate cements on the compaction behaviour of the rocks. Results highlight the importance of climate, depositional environment and detrital composition and texture in regards to the precipitation processes of near-surfaces carbonate cements and burial development. Our data shows that the presence and distribution of early carbonate cements reflects a complex interaction of several parameters, such as the composition and texture of detrital material in the source area, the availability and infiltration of meteoric or marine waters and the presence of precursor carbonate during deposition. Burial simulations demonstrate the strengthening effect of early carbonate cementation and its influence on the development of intergranular volume and porosity during burial with up to five times less porosity loss due to compaction than without near-surface cementation. • Climate, depositional environment and detrital composition are the main controls on the precipitation and distribution of early carbonate cements in sandstones. • Early carbonate cements can strongly influence further diagenetic processes, and the evolution of the pore system and intergranular volume. • Burial simulations up to a loading of 50 MPa show a significant impact of early carbonate cements on compaction when comparing early cemented rock with equivalent control simulations that lack in carbonate cement. [ABSTRACT FROM AUTHOR]

The Olduvai Gorge palaeoanthropological site, in northern Tanzania, encompasses about two million years of earth history. The sedimentary facies of Palaeolake Olduvai have been used to reconstruct lake transgressions and regressions, up to total drying out, interpreted to reflect wet/dry climate cycles. Although multidisciplinary research has been conducted during the past decades to reconstruct the palaeoenvironments and palaeolandscapes of the Gorge, very few focused on the DK site located about 2 km farther east in the Gorge. We present here a vegetation study at DK for Bed I, the oldest stratum, based upon the phytolith and diatom recovery of the basalt lava to Tuff IB stratigraphic interval. These results have been analysed in relation to the different facies in which they occur: sandy diamictite, sandstone, sandy waxy claystone, waxy claystone, and sandy diatomite. The phytolith results from diamictite samples indicate a similar vegetation composition during these more arid periods. Conversely, waxy claystone and sandy waxy claystone samples show a higher diversity in the vegetation composition. The diatoms were indicative of a fresh water pool environment. Thus the DK site would have provided plant foods for hominins, such as fruits from trees and shrubs and starch-rich rhizomes and tubers from sedges and reeds. Overall, the results at DK site present a different vegetation landscape in comparison to previously published phytolith results from other Olduvai stratigraphic levels and regions. [ABSTRACT FROM AUTHOR]

Stylolites are rough dissolution surfaces that show three different scaling regimes in space and time. On the small scale surface energy dominates and stylolites roughen very slowly with a growth exponent of about 0.5 and a roughness exponent of about 1.0. On the intermediate scale elastic energy dominates and the surfaces roughening is happening faster with a growth exponent of about 0.8 and a roughness exponent of about 0.5. The transitional length between these two scaling regimes is determined by the stress during stylolite growth and termed as cross-over length scale. On the large scale another transition is reached beyond which the stylolite amplitude remains constant, this length scale is termed the correlation length. The correlation length is determined by time of growth or by the amount of compaction that happened at the interface as well as by the stylolite's system size. This length scale grows as a function of time and the dynamic exponent, which is about 2 in the surface energy dominated regime and 0.625 in the elastic energy dominated regime. We present examples of these scaling regimes for numerical as well as natural stylolites and show how the exponents can be used to determine the stylolite compaction through the different regimes. The numerical stylolites show an increase of correlation length as a function of system size in self-affine time series. Large samples of natural tectonic stylolites from Jurassic limestones of the Franconian Alb (SE Germany) exhibit all three scaling regimes in a self-affine space series. The important length scales in the natural system are the grain size or noise at 30 μm, the cross-over length between the surface and elastic energy dominated regimes at 1.4 mm and the correlation length at 5.7 cm. The overall compaction on the tectonic stylolite is estimated to be in the range of 8 cm. • Stylolites grow in 3 distinct scaling regimes. • Stylolites experience 3 characteristic length scales, the grain-size, cross-over and the correlation length. [ABSTRACT FROM AUTHOR]

Global tectonic and climatic models for the Permian-Triassic boundary (PTB) are highly debated. One of the most disputed topics is the temperature increase associated with CO 2 emissions generated by the Siberian Trap volcanism and its potential influence on chemical weathering and associated variations in sediment fluxes. By integrating crustal architecture, plate modelling, structural kinematics, and two climatic models, we reconstruct the drainage evolution of Variscan tectonostratigraphic units from the SE portion of the Germanic Basin, from which we also extract the parameters necessary to calculate sediment flux across a time-scale of 28 Ma (Guadalupian-Lower Triassic). We reconstruct the sedimentary response to climatic and tectonic perturbations using Quantitative Provenance Analysis (QPA) and integrate compositional data into a sedimentological framework, paleodrainage and paleoclimatic models. Raman heavy mineral analysis, as well as geochronology and geochemistry of detrital apatite, zircon, and rutile, document variation in drainage lithologies and sediment flux which are controlled by regional extensional tectonics and increasingly humid conditions at the PTB. The sedimentary successions of the SE Germanic Basin record climatic perturbations on a 104 years timescale, while the effects of tectonics are visible on a 106 years timescale. The interplay of climate, tectonics and lithology, and their effects on sediment production and drainage evolution resulted in changes in sediment flux from 2.3 Mt./yr during the Guadalupian (Capitanian), to 3.80 Mt./yr in the Lopingian (Changhsingian) to 7.44 Mt./yr at the end of the Lower Triassic (Olenekian). The multifaceted workflow provided in this study represents the first step towards more precise reconstructions of sediment routing systems in deep-time and provides the first ground-truthed quantification of sediment flux across the Permian-Triassic Boundary. • Drainage modifications are efficiently identified via Quantitative Provenance Analysis. • Constraining Environmental Signals in deep-time requires paleoclimatic/tectonic models. • Paleodrainage analysis provides the parameters to calculate sediment flux. • Sediment flux increases in the Lower Triassic in response to climate change. [ABSTRACT FROM AUTHOR]

We report a newly extended stratigraphic sequence with associated Palaeolithic sites from the area of the extinct Kilombe volcano in central Kenya. The extended archaeological sequence runs from Oldowan finds, through the Acheulean, and up to the Middle Stone Age. The sedimentary sequences within the Kilombe caldera and south flanks of the mountain have been dated through 40Ar/39Ar measurements and palaeomagnetic studies. A series of 40Ar/39Ar values date the geological sequence from 2.493 ± 0.095 Ma, near the beginning of the Lower Pleistocene, through to 0.118 ± 0.030 Ma near the Middle to Upper Pleistocene transition. It includes the first entirely new area of Oldowan localities in East Africa south of Ethiopia for thirty years, and the first in a rugged mountainous setting. Trachyte lavas of Kilombe mountain were extruded during and after c. 2.5 Ma, followed by formation of a caldera and subsequent caldera lake, and sedimentation of a sequence of tuffs, diamictites, sandstones, and claystones. Sections in the mid-part of this intra-caldera fill-sequence have produced dates of 1.8–1.7 Ma, associated with an Oldowan industry and fauna dated precisely at 1.814 ± 0.004, and overlain by Acheulean finds at higher level. On the southern outward flanks of Kilombe mountain, a second major sequence is bounded at the base by trachyphonolite and a tuff yielding dates in the range 1.58–1.50 Ma. The main Acheulean archaeological site (GqJh1) falls within the overlying sedimentary sequence and has an age of c. 1.0 Ma, on the basis of a new 40Ar/39Ar date for the Three-Banded Tuff and palaeomagnetic reversal stratigraphy. Further 40Ar/39Ar dates indicate an age of c. 0.48–0.46 Ma for a marker ashflow tuff (AFT), prominent across the area. At Moricho, west of Kilombe, sediments above the AFT have been dated in the range 270,000–120,000 years and are associated with Middle Stone Age assemblages. In total, these sites attest to hominin activity from an Oldowan horizon dated to 1.8 Ma up to Later Stone Age stone scatters within the last 100,000 years. • Kilombe volcano preserves an end-to-end Pleistocene record dated by Argon40/Argon39 and palaeomagnetism. • The volcano formed ~2.5 Ma and before 1.8 Ma developed a caldera lake attracting animals and hominins. • New Oldowan and Acheulean industries are represented in strikingly high-altitude occupations of landscape. • Sedimentary sequences on the mountain southern flank date up to ~1.58 Ma and include Acheulean and MSA industries. • The AFT marker tuff dated to ~0.48 Ma overlies the latest Acheulean, and underlies a series of early MSA occurrences. [ABSTRACT FROM AUTHOR]

For five decades Olduvai Gorge has been a key site to reconstruct and understand the relationship between environmental and landscape conditions and use of affordances by early African hominin populations. Following the first Olduvai Gorge Coring project (OGCP) during 2014, a multiproxy microbiological analysis, which includes phytoliths, pollen, diatoms, sponge spicules and chrysophyte cysts, was undertaken on samples collected from various borehole cores. The aim of the study is to better understand palaeoenvironmental and palaeovegetation conditions and changes through time and their relationship to hominin presence and evolution. This study details the first palaeobotanical and palaeoenvironmental study of Borehole 2A at Olduvai Gorge. It represents the as yet oldest known sedimentary sequence in the Olduvai Basin for a portion of the pre-Bed I Naibor Soit Formation; this is a unit that is not accessible in any natural exposures in Olduvai Gorge, and has only recently been encountered by drilling. Here we present the results from a particularly phytolith-prone portion between ~2.09 Ma and 2.12 Ma. Phytolith results indicate a savannah environment dominated by grasses, where Poaceae were a key component and where the C 3 Pooideae grasses were mostly dominant, alternating with C 4 grasses. Oscillations between grass subfamilies, C 3 Pooideae, C 4 Chloridoideae, and C 4 Panicoideae to lesser degrees, indicate five substantial climatic shifts, varying between more humid and arid conditions. Associated with phytoliths, freshwater indicators such as diatoms, sponge spicules and chrysophyte cysts were also identified, suggesting the presence of wetlands in the lake catchment area. Pollen is extremely rare in the sediments but when present, comprises fungal spores and Poaceae pollen, thus supporting the wetland and grassland reconstructions, respectively. These results offer for the first time, a whole picture of the palaeovegetation and associated palaeoenvironments for this pre-Bed I period. Together with previous results from other areas and chronological periods, they improve our understanding of the evolution and adaptation of early hominins and their close relationship to the surrounding landscape. • Study of oldest pre-Bed I palaeovegetation yet known (~2.09–2.12 Ma) at Olduvai. • Landscape was dominated by savannah-type environment with grasses and woody plants. • C 3 /C 4 ratio fluctuations record at least 5 climatic shifts. • Fresh water markers, including sponges, indicate presence of nearby wetlands. [ABSTRACT FROM AUTHOR]