The lithic assemblages at the Oldowan-Acheulean transition in Bed II of Olduvai Gorge, Tanzania, represent a wide variety of raw materials reflecting both the diversity of volcanic, metamorphic, and ...sedimentary source materials available in the Olduvai basin and surroundings and the preferences of the tool-makers. A geochemical and petrographic systematic analysis of lava-derived archaeological stone tools, combined with textural and mineralogical characterization of quartzite, chert, and other metamorphic and sedimentary raw materials from two Middle and Upper Bed II sites, has enabled us to produce a comprehensive dataset and characterization of the rocks employed by Olduvai hominins, which is used here to establish a referential framework for future studies on Early Stone Age raw material provenancing. The use of rounded blanks for most lava-derived artifacts demonstrates that hominins were accessing lava in local stream channels. Most quartzite artifacts appear to derive from angular blocks, likely acquired at the source (predominantly Naibor Soit hill), though some do appear to be manufactured from stream-transported quartzite blanks. Raw material composition of the EF-HR assemblage indicates that Acheulean hominins selected high-quality lavas for the production of Large Cutting Tools. On the other hand, the HWK EE lithic assemblage suggests that raw material selectivity was not entirely based on rock texture, and other factors, such as blank shape and availability of natural angles suitable for flaking, played a major role in Oldowan reduction sequences.
The Salado and Verde streams constitute the two main seasonally available freshwater courses that flow into the Atlantic coast of the Río Negro province (continental Patagonia, Argentina, 42° South). ...This would have favored their use in the past as corridors for human circulation between the coast and the interior. This paper presents the results of the technomorphological and geochemical analyses of the obsidian artifacts recovered in the area to constrain mobility. The results allow us to propose the existence of toolkit reconditioning or replacement activities, and the identification of different sources of provenance of the obsidians (Sacanana, Telsen, and Portada Covunco, distant up to 800 km from the study area), reinforcing the hypothesis of a coast–inland circulation, with the possible existence of circuits of exchange of this raw material.
Integrating multiproxy results (geochemistry, mineral magnetism, grain size, and C/N ratio variability supported by 14C AMS dating), obtained from a 1.4-m sediment core retrieved from high-altitude ...Anchar Lake, Kashmir Valley, NW Himalaya, we present a 6000-years record of paleoenvironmental and paleolimnological shifts. Phase 1 (6000–4700 cal. yr BP) revealed a wetter climate with a significant terrestrial input corresponding to the gradual strengthening of the westerlies. Phase 2 (4700–3900 cal. yr BP) reflects an overall improved westerly precipitation and autochthonous sources of organic matter (OM). Magnetic parameters also indicate higher lake levels and reducing conditions during this phase. Phase 2 was followed by a gradual diminishing pattern of the westerlies as also represented by phase 3 (3900–2500 cal. yr BP) and phase 4 (2500–1600 cal. yr BP) indicating moderate precipitation conditions, catchment stability, and temperate and/or cold-dry climatic conditions. Phase 5 (1600–500 cal. yr BP) revealed the prevalence of moderately cold/dry and further subdued westerly precipitation. Phase 6 (500 cal. yr BP to present) is represented by reduced westerly precipitation, shrinking lake margins, and significant terrestrial/anthropogenic controls over the lake basin. Mineral magnetic parameters indicate reducing lake bottom water conditions and eutrophication during this phase due to anthropogenic activities. These paleoenvironmental shifts reveal near synchronous changes (within dating uncertainties) with other regional paleoclimate records close to the present Anchar Lake location and reflect the gradual late-Holocene diminishment of the amount of winter/early summer moisture provided by the mid-latitude westerlies.
In the 19th and early to mid-20th centuries, a rush to better understand the European Palaeolithic led to the substantive removal of deposits from limestone caves. In the 21st century the situation ...has changed. Many caves are now excavated, leaving behind a human-made environment of diminished cave sediments and large spoil heaps, with the latter now targeted by those searching for artefacts missed during the original excavations. In an age in which archaeologists are increasingly attempting to balance their roles as cultural heritage educators and destroyers, the question remains - how much do we know about the taphonomy of these features? In this paper we report results from the excavation of a large spoil heap outside Švédův Stůl Cave, in the Moravian Karst region of Czech Republic. Results show heterogeneous sediment formation (revealed primarily through their field characteristics and ED-XRF and Itrax geochemical analyses) and patterns in artefact distributions (evident through assessment of Iron Age, Neolithic and modern artefacts) and faunal remains. This allows partial context to be provided for some artefacts and a methodology to be developed for excavation of overburden.
•Identify intact contexts within archaeological spoil.•Insight into hominin activity in Czech Republic during mid-late Palaeolithic.•Demonstrate how XRF (ED-XRF and Itrax) may unravel complex sediment histories.•Provide a new methodology for excavating overburden.•Flag urgent need to apply these methods before excavation destroys these features.
This research attempts to provide a contribution to the study on coastal barrier‐lagoons in the SE Africa generated by sea‐level fluctuations, and climate change during the Late Holocene. To achieve ...this goal, the grain‐size analysis and morphoscopic description helped to detect cyclic facie sequences with sediments sized over 200 μm mixed with silt, bioclasts and organic matter. Moreover, the magnetic susceptibility and X‐ray diffraction (XRD) analyses displayed over 90% of quartz and isolated mica, feldspar and heavy minerals. Additionally, the X‐ray fluorescence (XRF) results display the interplay between terrigenous (>Ti and Al) and marine influence (S, Cl and ~Ca) over the last ~3,500 cal. yrs. BP. The geochemical tracer fluctuations detected suggest five distinct deposits including beach, washover, lacustrine system, aeolian deflation that rest on top of the Pleistocene palaeodunes, which are tentatively associated with the sea‐level variations, extreme marine events or with local floods. Although the multiproxy data record refers to a study in Bilene‐Mozambique, it is interesting to understand the mechanisms and variables related to the evolutionary dynamics of coastal barrier lagoons generated by sea‐level fluctuations and climate change, especially in the SE Africa.
A late Holocene facie sequence is described by lithostratigraphic data from five sediment cores of a barrier–lagoon system in Mozambique. Coarse sand mixed with silt and heavy minerals was associated with local floods and extreme events, including marine transgression and regression. High‐resolution geochemical analyses distinguished tracers between terrigenous (>Ti and Al) and marine (S, Cl and ~Ca) influence. Tracer fluctuations suggest five distinct deposits including beach, washover, lacustrine system and aeolian deflation that rest on top of the Pleistocene palaeodunes.
Submarine canyons are often hotspots of biomass due to enhanced productivity and funneling of organic matter of marine and terrestrial origin. However, most deep-sea canyons remain poorly studied in ...terms of their role as conduits of terrestrial and marine particles. A multi-tracer geochemical investigation of particles collected yearlong by a sediment trap in Baltimore Canyon on the US Mid-Atlantic Bight (MAB) revealed temporal variability in source, transport, and fate of particulate matter. Both organic biomarker composition (sterol and n-alkanes) and bulk characteristics (δ13C, Δ14C, Chl-a) suggest that while on average the annual contribution of terrestrial and marine organic matter sources are similar, 42% and 52% respectively, marine sources dominate. Elevated Chlorophyll-a and sterol concentrations during the spring sampling period highlight a seasonal influx of relatively fresh phytodetritus. In addition, the contemporaneous increase in the particle reactive micronutrients cadmium (Cd) and molybdenum (Mo) in the spring suggest increased scavenging, aggregation, and sinking of phytodetrital biomass in response to enhanced surface production within the nutricline. While tidally driven currents within the canyon resuspend sediment between 200 and 600m, resulting in the formation of a nepheloid layer rich in lithogenic material, near-bed sediment remobilization in the canyon depositional zone was minimal. Instead, vertical transport and lateral transport across the continental margin were the dominant processes driving seasonal input of particulate matter. In turn, seasonal variability in deposited particulate organic matter is likely linked to benthic faunal composition and ecosystem scale carbon cycling.
•Vertical and lateral transport were the dominant processes driving seasonal input of particulate matter.•Organic biomarkers, isotopes and trace metal offer a multi dimensional approach for deciphering organic matter sources.•Elevated Chlorophyll-α, sterols, and particle reactive micronutrients capture spring seasonal influx of fresh phytodetritus.•Connectivity to adjacent watershed facilitates offshore transport of “aged” terrestrial organic matter and nutrients.
This study includes a palynological and organic geochemical evaluation of Nahr Umr, Zubair, and Yamama Formations in the Subba field, Southern Iraq, represented by three wells (Su-14, Su-9 and Su-8). ...The determination of quantity organic matter showed that the rocks of Nahr Umr Formation had a total organic carbon of 4.76%, indicating very good production of hydrocarbons where type (II) kerogen was dominant, but the rocks were thermally immature. Zubair Formation had a total organic carbon of 1.91% to 2.26%, indicating good to very good production of hydrocarbons where kerogen of types (I) and (II/III) were dominant, with low thermal maturity. Yamama Formation showed a total organic carbon of 1.68%, revealing good production of hydrocarbons where type (I) kerogen was dominant, with low thermal maturity. Facies analysis of Nahr Umr, Zubair and Yamama Formations demonstrated the presence of two facies, namely the distal dysoxic-Oxic shelf and the distal suboxic-Anoxic basin. It is clear that the environment of rock deposition is a marine environment, which is far from the coast.
Modern-day devices, transport, and green energy require growing supply of rare earth elements (REEs), which subsequently provide the basics for attempts on developing the efficient and innovative ...methods for their detection and exploration. Remote sensing data / techniques provide great possibilities to quick and non‑destructive exploration of such deposits, even in relatively unreachable and socially sensitive places. The diagnostic absorption features of REEs are generated in the visible to shortwave infrared (VNIR-SWIR) region of the electromagnetic spectrum, among which, the most prominent absorption features of neodymium (Nd), which could be a key pathfinder for REEs, are displayed in the VNIR region. This study assesses the capability of the Sentinel-2 MSI data for detecting absorption feature of Nd from space. This process was successfully examined and verified in the Esfordi phosphate deposit, Central Iran, and resulted the direct mapping of REE (Nd). For this purpose, firstly, the potential of the Sentinel-2 MSI data for detecting REEs was theoretically evaluated, and then, the adaptive coherence estimator (ACE) algorithm was applied for targeting Nd-bearing zones, using the field spectra of apatite as reference. Field works, X-ray diffraction (XRD), spectroscopy, and the geochemical analyses supported the achievements. The results demonstrated that Sentinel-2 MSI can capably detect the 740 nm absorption band of Nd. Generally, this research attained high overall accuracy of 88.64% for the generated map using in situ collected data for verification.
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