Evidence from cosmic ray exposure (CRE) dating for the existence of a pre-Minoan caldera on Santorini, Greece

Abstract

International audience\textcopyright 2016, Springer-Verlag Berlin Heidelberg.Cosmic ray exposure (CRE) dating was performed on the caldera cliffs of Santorini with the aim of detecting cliff segments predating the Minoan eruption (17th century BCE). The methodology involved the determination of in situ-produced cosmogenic 36Cl concentration in basaltic-to-rhyodacitic whole rocks cropping out in the cliffs. After the samples were processed following the chemical protocol of 36Cl preparation for silicate rocks, 36Cl concentrations were measured by accelerator mass spectrometry (AMS). Important challenges during the implementation procedure were related to large amounts of radiogenic 36Cl, complex modeling of inherited 36Cl, and dominance of the thermal and epithermal (low-energy) neutron capture production pathway. Nevertheless, quantitative assessments on the basis of the contribution of the low-energy neutron capture pathway percent to the total production rate validated the calculated CRE dates. Current CRE ages demonstrate that an ancient caldera existed on pre-Minoan Santorini, occupying at least the northern half of the modern-day caldera

Post-eruptive flooding of Santorini caldera and implications for tsunami generation

“…Before the eruption, Santorini already had a shallow caldera that had formed during an eruption 18 ky previously51819 (Fig. 6a).…”

“…( a – c ) Pre-eruptive morphology of the volcano18192021 and the main phases of the eruption12345. Before the eruption there existed an ancient caldera in the northern half of the volcanic field1819.…”

“…Before the eruption there existed an ancient caldera in the northern half of the volcanic field1819. This caldera was lagoonal, as shown by the presence of fragments of ancient travertine, stromatolites and brackish to marine fauna in the LBA ejecta2021.…”

A Comment on “A major Change in the Stratigraphy of the Santorini Volcano in Greece”

“…The UPS (age 3.6 ka) and the LPS2 (best age estimate 172 ka; [15]) are the products of different eruptions, as concluded by all previous researchers who have worked in detail on the geology of Santorini. There is to date no convincing evidence that the pre-LBA caldera, which undoubtedly existed in the northern basin of the present-day caldera [2] [3] [4], extended into the southern basin.…”

“…do not question the existence of an ancient caldera at Santorini (probably associated with an eruption 22 ky ago). It was proposed based on the presence of stromatolite fragments in the UPS [2], and was confirmed first by geomorphological mapping [3], then by 36 Cl cosmic-ray exposure dating [4], of the caldera cliffs. Evidence published to date places this ancient structure largely in the northern basin of the present-day caldera; any extension further south is as yet unconstrained.…”