Conference Agenda

Interactions among tectonics, erosion, and climate shape topography and the evolution of orogenic systems. Thermochronometry, which reconstructs the thermal histories of rocks during exhumation, is a key tool for quantifying links among tectonic uplift, erosion, and landscape development. In carbonate-dominated lithologies, however, thermochronological studies are limited by the scarcity of suitable minerals for commonly used low-temperature systems. Because fission-track and (U-Th)/He methods rely on apatite or zircon, which are generally absent in carbonate rocks, there is a clear need for alternative approaches capable of resolving shallow crustal processes and recent landscape evolution in carbonate-dominated regions.

This study explores calcite/dolomite thermoluminescence (TL) thermochronology as a novel ultra-low-temperature thermochronometer for constraining cooling histories below ~50-70 °C over timescales of up to ~20 Ma. We apply this approach to carbonate successions across the Dinarides-Hellenides transition in Albania, where contractional and extensional tectonic domains coexist. Previous low-temperature studies in Albania have highlighted contrasting exhumation patterns between these domains, but they have focused mainly on arenitic and igneous lithologies, leaving the extensive carbonate sequences of the fold-and-thrust belt largely unexplored.

By targeting these carbonate-dominated successions, this study tests the potential of TL thermochronology in a structurally complex, carbonate-rich orogen. Systematic sampling along horizontal and vertical profiles will help reconstruct age-elevation relationships and spatial variations in exhumation rates. The study aims to evaluate whether carbonate TL can fill an important methodological gap in ultra-low-temperature thermochronometry and constrain the Neogene to Quaternary thermal and exhumation evolution of the Albanian Dinarides-Hellenides transition.

The Kaapvaal Craton (KC) in South Africa preserves more than 3.6 Ga of geological history, including the formation and breakup of several supercontinents. While the Archean to Paleoproterozoic tectono-metamorphic-magmatic evolution (3.6-2.0 Ga) is well known from basement outcrops and overlying sedimentary record, relatively little is known about the burial and exhumation history since the Mesoproterozoic. To close this gap of knowledge, we present new results of in situ (U-Th)/He dating of zircon, apatite, rutile, and titanite, from various lithologies and areas of the KC, comprising the Bushveld Igneous Complex, and adjacent Archaean to Paleoproterozoic basement units and related (meta)sedimentary rocks. In our study, single spot in-situ (U-Th)/He data are compared with conventional He dates obtained by single grain analyses by means of a modern, high-throughput workflow for data analysis. The new data are subsequently used the compare the upper crustal T-t evolution of the central part of the Kaapvaal Craton (Bushveld Igneous Complex), with those of surrounding orogenic belts (e.g. Limpopo Belt), aiming to place new constraints on the paleogeographic evolution during Rodinia and Gondwana formation and break-up.

The (U–Th)/He system is a popular low-temperature thermochronometer that is mostly applied to apatite and zircon. Their typical closure temperatures around 70°C and 180°C enable dating shallow crustal cooling. (U–Th)/He data are therefore used to reconstruct the thermal history of sedimentary basins, the exhumation of cratonic plateaus, or the spatial and temporal evolution of mountain chains. They can also be employed to constrain the timing of past meteorite impacts or volcanic activity.

The analytical workflow in (U–Th)/He thermochronometry consists of crystal dimension measurements and two subsequent mass spectrometric analyses. Daughter nuclides (⁴He) are released from single crystals by infrared laser heating and quantified with a gas mass spectrometer. After dissolving these single crystals, parent nuclides (particularly ²³⁸U and ²³²Th) are quantified by inductively coupled plasma mass spectrometry (ICP-MS). Both these analyses are typically conducted by isotope dilution techniques, adding spike isotopes such as ³He, ²³⁵U, and ²³⁰Th.

Analytical routines for both external calibration and isotope dilution ICP-MS analysis were established at the University of Salzburg to save limited radionuclide spikes. On-line addition of Cr and Bi internal standards permits an ICP-MS precision of <1% (1σ SD) for the external calibration technique, similar to that obtained by classical isotope dilution. Accuracy of both procedures is documented by Durango and MK-1 reference apatite (U–Th)/He dates. For zircon, external calibration ICP-MS analysis is not suitable to calculate (U-Th)/He dates due to evaporative sample loss upon complex acid digestion procedures, but absolute concentrations can still be utilized for trace element patterns and quality control.

Laterites are deep, mineralogically stratified weathering profiles that develop under tropical to subtropical conditions and are widespread across continental surfaces. Their resistance to surface processes allows them to persist over tens of millions of years, making them valuable archives of long-term landscape evolution and paleoclimate, particularly in tectonically stable regions. However, robust age constraints remain scarce due to limited possibilities for dating this material. (U–Th)/He dating of iron (oxyhydr)oxides from lateritic iron duricrusts is a relatively recent method to constrain the formation and evolution of laterites.
Our new (U–Th)/He data from mid-altitude (400–600 m a.s.l.) lateritic duricrusts in central French Guiana yield Late Cretaceous to Quaternary ages, documenting multiple weathering episodes throughout the Cenozoic. The dataset includes the first Late Cretaceous and Early Paleogene iron (oxyhydr)oxide (U–Th)/He ages from the Amazon craton that are unrelated to banded iron formations, which are known for their high resistance. These results demonstrate the potential of common laterites as a record. Comparison with datasets from across French Guiana reveals spatial patterns in weathering ages that offer new insights into regional geomorphological evolution and paleohydrological dynamics.