Establishing the geochronology of epicontinental successions remains a difficult task, especially in the absence of ash layers, a scattered depositional record preventing effective application of magnetostratigraphy, and the isolated character of basins, which excludes the use of the standard biostratigraphy of planktonic fossil groups. The relatively new and rapidly advancing dating methods based on cosmogenic nuclides provide a solution in many geological tasks previously considered a conundrum. The specific advantage of the methods is found in their broad range of applicability in the Pliocene and Late Miocene age, in contrast with the routinely used radiocarbon and luminescence dating.
The attendees at the workshop will be able to familiarize themselves with the principles of the dating methods and their applications, sampling strategies, and the processing of samples from the rock right through to measuring isotopic ratios and age calculations as the final output. Special emphasis will be given to limitations of the methods across sedimentary environments. The workshop should serve as a basis for the attendees to design their own dating approach for specific geological problems.
The first part of the workshop will focus on authigenic 10Be/9Be dating, which employs meteoric 10Be produced in the atmosphere. The method certainly has great potential in the establishment of depositional ages for clay, the most common type of sediment on Earth, up to an age of 14 Ma. Current advances in our understanding of the method’s applicability will be presented – these are mostly taken from the Central and Eastern European Neogene basins. The factors affecting the method in alluvial, shallow lacustrine/marine and offshore settings will also be discussed.
The second part of the workshop will focus on applications of the cosmogenic nuclides produced in situ. These can be extracted from quartz (10Be and 26Al) and from carbonates (36Cl). Firstly, the exposure dating of sedimentary bodies, such as river terraces, using a depth profile strategy will be introduced. Apart from a simple depositional scenario, the principles of age calculation in the case of multiple depositional events will be presented. The attendees will also be briefed on burial 26Al/10Be dating and the pitfalls of its application, for example, in the case of periglacial depositional systems.
Provenance Analysis is an established discipline in Sedimentary Geology. The proliferation of analytical techniques has increased the resolution to which both actualistic and deep-time geological settings can be reconstructed. Nevertheless, understanding compositional data generated from bulk-rock vs single-grain techniques and how to integrate them into geological models requires deep knowledge of (i) all factors controlling the generation of sediments (tectonics, climate, and lithology), their transfer and deposition (downstream grain-size fining, hydraulic sorting), and diagenesis (dissolution vs authigenesis); (ii) potential analytical biases, and (iii) processing of compositional data and integration of different database using state-of-the-art statistical workflows. Case studies and exercises aim at stressing both the need and importance of coupling provenance analysis with sedimentology, geomorphology, structural geology, and climatology, and how to use compositional data for numerical modelling, making Provenance Analysis ‘Quantitative’ (QPA). Eventually, we will explore how QPA can contribute to climate change research and applications for the energy transition.
Coastal landscape transformations and accumulation of related sedimentary successions are triggered by complex feedbacks deriving from the combined action of river flows, winds, waves and tidal currents. Dominance of one or more of these processes, that can change over short spatial and temporal scales, implies its major control on morphodynamic processes and on the amount of sediment flux occurring in specific depositional environments and sub-environments. Understanding the interactions between these processes, how they change both in time and space, and the preservation of these interactions in the stratigraphic record is crucial to properly understand the dynamics of coastal systems. And this increased understanding can help increase the predictive power of geological model developed from the interpretation of preserved strata. Nevertheless, although dominance of a specific forcing on morphodynamic processes implies its control on sediment flux, such a dominance does not necessarily result in a widespread occurrence of sedimentary structures related to such process. Vice versa, the common occurrence of specific sedimentary structures cannot guarantee dominance of related genetic process on the overall sediment flux and geomorphic processes. In addition, many sedimentary structures are not unique or diagnostic of a single process and/or depositional environment. In this workshop we aim at discussing the non-linear and controversial relationship between dominance of processes in paralic systems and their preserved signature by analysing sediment cores from two modern environments located 30 km apart. The cores were recovered from the Venice Lagoon and the Po River, both located in northern Italy. The microtidal Venice Lagoon extends for 550 km2 and is the largest brackish waterbody in the Mediterranean. The lagoon does not receive any riverine input, and tidal currents conveyed sediments resuspended from tidal flats during storms into a widespread network of channels. The Po River, the largest Italian river, is 650 km long and has an averaged water discharge of ca 500 m3/sec at its mouth. The river mouth experiences the same tidal excursion as the Venice Lagoon. Sedimentary cores recovered from the distal reach of the Po River and from tidal channels of the Venice Lagoon will be observed and discussed in the frame of this workshop. Since both the cored systems experience the same tides but different fluvial inputs, such a comparison will allow to discuss the preserved signature of tidal processes in the Po River and Venice Lagoon channels, which are dominated by riverine and tidal processes, respectively. These examples will be used to discuss the effective processes in charge for controlling sediment flux and morphodynamic processes, and their under- and/or overinterpretation in the sedimentary record of paralic systems. Comparisons with example from the ancient record and other modern examples will also be discussed and used to integrate observations from cores.
Luminescence dating is a rapidly growing geochronological method with increasingly evolving protocols and signals besides applications, making it an ever more used technique. Sediments and sedimentary environments are without a doubt the most targeted when in need of chronologies in geological and geoarchaeological contexts, yet many times the sampling strategies pursued do not fulfil the minimum requirements needed to obtain an acceptable age, or they are simply not enough to resolve the scientific question posed.
Luminescence dating depends on the ability of quartz and feldspar mineral grains to store energy (trapped charge) when exposed to natural ionising radiation readily available in the environment. The trapped charges may be released by stimulation from two main sources: by heat, causing Thermo-Luminescence (TL), or by light, causing Optically Stimulated Luminescence (OSL). Thus, choosing luminescence as the dating method is highly dependent not only on the type of material available for dating but also on the depositional environment and all the geological (and even anthropological) processes involved previously (e.g., erosion and transport) as well as its geometry and extension. Understanding the depositional setting and the geological forces around it prior to sampling is key as is the timescale considered and the precision required.
In sedimentological contexts, luminescence measures the last time a quartz and feldspar mineral grain was buried. Hence, everything that happens to those grains in-situ during and after burial will affect its signal, thus affecting the resulting age. When the stimulation is natural, a wildfire (in the case of TL) and the sun (in the case of OSL) are the main contributors to erase (bleach or zero) and reset the luminescence signals. Artificial and anthropic factors may also stimulate and reset both TL and OSL signals, namely in the form of earths, ovens, fire, lights. Hence, the importance of knowing what to date, which material to choose, or what units or layers to either avoid or sample.
This course is aimed at providing sufficient tools and practical training to design suitable and proper sampling strategies for luminescence dating in both archaeological and geological settings, focusing on sediments and sedimentary environments. Limitations, as well as advantages of the method, will be discussed and past experiences will be shared. Please do not hesitate to bring your own examples of stratigraphies and samples already collected or future field campaigns.