THE ALBANO MAAR (ALBAN HILLS VOLCANIC DISTRICT, ITALY): ACTIVE OR DORMANT VOLCANO?

Abstract

F. Marra, D. B. Karner, The Albano Maar (Alban Hills Volcanic District, Italy): active or dormant volcano? (IT ISSN 0394-
3356, 2005).
We discuss the geochronological interpretation of several stratigraphic sections where either primary or reworked volcanic products of
the most recent eruptive activity of the Albano maar are exposed. A recently performed set of 112 single- and multiple-crystal 40Ar/39Ar age determinations, totalling 244 dated crystals from samples of the Albano products, suggests that no magmatic activity occurred after 36 ka. Therefore, based on the lack of evidence for eruptive activity in historical time, Albano should be defined an inactive volcano. The time elapsed since the last eruption, however, does not overrun the average recurrence time (45 kyr) for the overall volcanic activity of the Alban Hills Volcanic District through the last 600 kyr, indicating that Albano should be regarded as a dormant volcano rather than extinct.
Differently from direct 40Ar/39Ar dating of the volcanic products, recent C14 age determination on two paleosoils have suggested that
eruptive activity younger than 5,000 years occurred at the Albano maar. This interpretation contrasts with the absence of any volcanic
deposit in the sedimentary fill of the Albano crater spanning the time interval 25 ka - Present, therefore we believe that the possibility
that the dated organic material may have been affected by problems of contamination should be carefully considered. Indeed, stratigraphic, paleomorphologic and paleoclimatic data that we present in this paper are as well compatible with an early emplacement around 39-36 ka for all of these volcaniclastic products, either primary or reworked.