Volcanism - climate interaction: A test case from the Azores archipelago (VolClimA)

• Applicant: Dr. Julie Christin Belo
• Subject Area: Geology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 509166013

The recognition of global climate changes as a control on volcanism came from studies on Iceland, and other glacier-covered regions, which demonstrated a significant increase in volcanic activity after the last glaciation, probably facilitated by unloading of the lithosphere during glacier retreat. Moreover, marine tephra records show a clear increase in frequency of tephra layers from arc- related explosive eruptions at the onset of the Quaternary glaciations. While the physical processes that link climate changes to volcanism are subject of ongoing discussions, this topic is especially relevant for our present-day situation because anthropogenically enforced deglaciation may lead to increased volcanic activity and hazards. It has been recognized that records of volcanic activity, long enough to cover many glacial cycles, share the same periodicities with the global climate record (Milankovitch periods). The observed coincidences of periodic fluctuations in the volcanic eruption frequency with periods of orbitally paced climate changes are presently the strongest evidence that volcanism may be forced by either the orbital parameters themselves (e.g., solid Earth tides) or by their global climatic effects (e.g., global-scale mass redistributions during (de)glaciation and glacial continental erosion). While basically all studies agree that global climate changes somehow affect volcanism, typically leading to increased volcanism during deglaciation periods, the results regarding periodicities and timing differ significantly in detail. This has so far hindered the development of a unified theory to explain the underlying physical mechanisms. To tackle this problem, it is necessary to investigate a relevant number of long and precise chronostratigraphic tephra records from different geotectonic settings (arc and ocean islands/hotspots), and latitudes and to study these records regarding systematic changes of temporal and spatial variations. All studies that investigated long-term volcanic time series regarding volcanism-climate interaction so far used marine tephra records either from volcanic-arcs or global compilations, but a detailed long-term study of an ocean island setting is still missing. In the proposed project I aim to produce, to geochemically analyze (major and trace elements, dating techniques), to date (14C, Ar/Ar, oxygen isotope stratigraphy), and to statistically evaluate for the first time a long-term record covering of an oceanic island setting (hotspot) that goes beyond the last deglaciation and I aim to use the Azores as a testcase. I will use the exceptional marine sediment records obtained during two RV Meteor cruises (M141 and M186) in combination with samples from the subaerial part of the islands to establish a most complete record of primary and secondary volcanic events.

• DFG Programme: Research Grants