Holger Kuhlmann

Archaeological sites in Northwest Africa are rich in human fossils and artefacts providing proxies for behavioural and evolutionary studies. However, these records are difficult to underpin on a precise chronology, which can prevent robust assessments of the drivers of cultural/behavioural transitions. Past investigations have revealed that numerous volcanic ash (tephra) layers are interbedded within the Palaeolithic sequences and likely originate from large volcanic eruptions in the North Atlantic (e.g. the Azores, Canary Islands, Cape Verde). Critically, these ash layers offer a unique opportunity to provide new relative and absolute dating constraints (via tephrochronology) to synchronise key archaeological and palaeoenvironmental records in this region. Here, we provide an overview of the known eruptive histories of the potential source volcanoes capable of widespread ashfall in the region during the last ~300,000 years, and discuss the diagnostic glass compositions essential for robust tephra correlations. To investigate the eruption source parameters and weather patterns required for ash dispersal towards NW Africa, we simulate plausible ashfall distributions using the Ash3D model. This work constitutes the first step in developing a more robust tephrostratigraphic framework for distal ash layers in NW Africa and highlights how tephrochronology may be used to reliably synchronise and date key climatic and cultural transitions during the Palaeolithic.

The mobile Drilling Information System (mDIS) is ICDP’s (Internal Continental Scientific Drilling Program) database management software, initially designed for the acquisition of data gained during a drilling campaign. It is now in use for three years and is by far exceeding its intended application. MDIS has now been installed in core repositories with varying requirements and it is currently been tested for the use as a laboratory data collection application.The system is based on 25 years of sample and data management at ICDP. It is a database backed web application that is entirely based on open-source code, is platform-independent and has a responsive design. Beyond the basic data registration and management, mDIS provides functionality for QR code label-printing, data export and report generation. Application specific XML export supports International Generic Sample Number (IGSN) registration and data visualization in the “Corelyzer” software (https://cse.umn.edu/csd/corelyzer). Third party software can interface the mDIS through its REST application programming interface (API). Version 3 of the mDIS software features an updated, consistent data model and n:m relations.Driven by the pandemic, the “expedition mDIS” has mostly been installed as a SaaS (software as a service) variant hosted on a shared ICDP server rather than an offline virtual box application on a personal computer. This solution facilitates training and enhanced support by the ICDP-OSG, it provides continuity by the use of a single project database throughout the project lifespan, and it provides uncomplicated data access to scientists that are currently off-site. Next to the design of further print labels, reports and entry masks for borehole measurements, the most significant extension for the “expedition mDIS” is a digital visual core description allowing for printing a stratigraphic column while simultaneously filling the database. Inspired by a user, our next plan is to develop an add-on for managing sample requests in mDIS.MDIS has now been implemented in several core repositories (“curation mDIS”), amongst them the Bremen Core Repository (BCR) of the International Ocean Discovery Program (IODP), were curators face up to several thousand samples a week during sample parties. The simultaneous input and processing of large amounts of data lead to new challenges in terms of data handling and database performance. The mDIS has been supplemented with modules to curate and store different sample types, to design and adapt sample series, to add a contact data base and adaptable reports. One of the most important add-ons is the so called “sample-sheet”, which facilitates fast data entry and automated printing of sample labels during large sampling parties.For more information please visit the ICDP homepage (https://www.icdp-online.org/support/data-samples), the mDIS Documentation website (https://data.icdp-online.org/mdis-docs) or contact us directly. MDIS is open source and as such available for all projects and everybody who is interested.

In tropical eastern Africa, vegetation distribution is largely controlled by regional hydrology, which has varied over the past 20 000 years. Therefore, accurate reconstructions of past vegetation and hydrological changes are crucial for a better understanding of climate variability in the tropical southeastern African region. We present high-resolution pollen records from a marine sediment core recovered offshore of the Rufiji River delta. Our data document significant shifts in pollen assemblages during the last deglaciation, identifying, through changes in both upland and lowland vegetation, specific responses of plant communities to atmospheric (precipitation) and coastal (coastal dynamics and sea-level changes) alterations. Specifically, arid conditions reflected by a maximum pollen representation of dry and open vegetation occurred during the Northern Hemisphere cold Heinrich event 1 (H1), suggesting that the expansion of drier upland vegetation was synchronous with cold Northern Hemisphere conditions. This arid period is followed by an interval in which forest and humid woodlands expanded, indicating a hydrologic shift towards more humid conditions. Droughts during H1 and the shift to humid conditions around 14.8 kyr BP in the uplands are consistent with latitudinal shifts of the intertropical convergence zone (ITCZ) driven by high-latitude Northern Hemisphere climatic fluctuations. Additionally, our results show that the lowland vegetation, consisting of well-developed salt marshes and mangroves in a successional pattern typical for vegetation occurring in intertidal habitats, has responded mainly to local coastal dynamics related to marine inundation frequencies and soil salinity in the Rufiji Delta as well as to the local moisture availability. Lowland vegetation shows a substantial expansion of mangrove trees after ~ 14.8 kyr BP, suggesting an increased moisture availability and river runoff in the coastal area. The results of this study highlight the decoupled climatic and environmental processes to which the vegetation in the uplands and the Rufiji Delta has responded during the last deglaciation.

The sea surface temperature (SST) of the tropical Indian Ocean is a major component of global climate teleconnections. While the Holocene SST history is documented for regions affected by the Indian and Arabian monsoons, data from the near‐equatorial western Indian Ocean are sparse. Reconstructing past zonal and meridional SST gradients requires additional information on past temperatures from the western boundary current region. We present a unique record of Holocene SST and thermocline depth variations in the tropical western Indian Ocean as documented in foraminiferal Mg/Ca ratios and δ¹⁸O from a sediment core off northern Tanzania. For Mg/Ca and thermocline δ¹⁸O, most variance is concentrated in the centennial to bicentennial periodicity band. On the millennial time scale, an early to mid‐Holocene (~7.8–5.6 ka) warm phase is followed by a temperature drop by up to 2°C, leading to a mid‐Holocene cool interval (5.6–4.2 ka). The shift is accompanied by an initial reduction in the difference between surface and thermocline foraminiferal δ¹⁸O, consistent with the thickening of the mixed layer and suggestions of a strengthened Walker circulation. However, we cannot confirm the expected enhanced zonal SST gradient, as the cooling of similar magnitude had previously been found in SSTs from the upwelling region off Sumatra and in Flores air temperatures. The SST pattern probably reflects the tropical Indian Ocean expression of a large‐scale climate anomaly rather than a positive Indian Ocean Dipole‐like mean state.