Chronostratigraphy of Monte Vulture volcano (southern Italy): secondary mineral microtextures and 39Ar-40Ar systematics

Abstract

The eruptive history of Monte Vulture has been the subject of several geochronological investigations during the past decades, which reliably dated only a small number of eruptions. Understanding the causes of suboptimum data yield in the past requires an interdisciplinary approach. We re-analyzed samples from previous works and present new data on samples from the main volcanostratigraphic units of Monte Vulture, so as to provide an improved, consistent chronostratigraphic database. Imaging of minerals by cathodoluminescence and backscattered electrons reveals that heterochemical, high-temperature deuteric reaction textures are ubiquitous. Such observations are common in metamorphic rocks but had not frequently been reported from volcanic rocks. In view of the mineralogical complexity, we base our chronological interpretation on isochemical steps, defined as steps for which the Cl/K and/or the Ca/K ratios are constant. Isochemical steps carry the isotopic signature of chemically homogeneous mineral phases and therefore allow a wellconstrained age interpretation. Comparison of old and new 39 Ar-40 Ar data proves the reproducibility of age spectra and their shapes. This quantifies the analytical reliability of the irradiation and mass-spectrometric analyses. Anomalous age spectra are a reproducible property of some specific samples and correlate with mineralogical anomalies. The present data allow us to fine-tune the age of the volcanostratigraphic units of Monte Vulture during the known interval of main volcanic activity from ca. 740 to 610 ka. After a very long stasis, the volcanic activity in the Monte Vulture area resumed with diatremic eruptions, one of which (Lago Piccolo di Monticchio, the site of a palynologicalpaleoclimatological drilling) was dated at ca. 140 ka.

COEXISTING Ba-FELDSPAR AND MELILITE IN A MELAFOIDITE LAVA AT MT. VULTURE, ITALY: ROLE OF VOLATILES AND ALKALINE EARTHS IN BRIDGING A PETROLOGICAL INCOMPATIBILITY

“…1) and has an age between 630 and 570 ka (cf. Villa & Buettner 2009). Its unusual clinopyroxene-rich nature has been well known since the paper of Hieke Merlin (1967).…”

The role of carbon from recycled sediments in the origin of ultrapotassic igneous rocks in the Central Mediterranean

“…Mildly potassic to sodic volcanic rocks were erupted between 740 and 130 ka during the upper Pleistocene ( Fig. 2) (e.g., Villa and Buettner, 2009), with a final carbonatitic lava flow occurring at Toppo del Lupo (e.g., Beccaluva et al, 2002;Bindi et al, 1999;D'Orazio et al, 2007D'Orazio et al, , 2008De Astis et al, 2006;De Fino et al, 1986;Melluso et al, 1996;Rosatelli et al, 2000;Stoppa et al, 2008). The Vulture alkaline rocks and carbonatites show intermediate characteristics between subduction-related and intraplate volcanic rocks.…”

The earliest securely dated hominin fossil in Italy and evidence of Acheulian occupation during glacial MIS 16 at Notarchirico (Venosa, Basilicata, Italy)

“…It is covered by two embedded volcano‐sedimentary units, the Piano Regio Formation related to the maximum volcanic activity of the Vulture and the Tufarelle Formation Figs ( and ). The Monte Vulture's chronostratigraphy has been studied since 1988 from geochemical, sedimentological and chronological points of view (Laurenzi et al ., ; Brocchini et al ., ; Giannandrea, ; Villa and Buettner, ). Related 40 Ar/ 39 Ar ages are reported in Fig.…”

“…40 Ar/ 39 Ar ages are from (A) Petrosino et al . (), (B) Villa and Buettner (), (C) Brocchini (). All ages were recalculated relative to ACS‐2 at 1.193 Ma (Nomade et al ., ) and using the total decay constant of 40 K recommended by Steiger and Jäger ().…”

“…) (Lefèvre et al ., ) found in the Masseria Boccaglie unit previously dated by 40 Ar/ 39 Ar to 654 ± 11 ka (Marker M8) and 655 ± 25 ka for the Unità di Masseria Boccaglie itself (Laurenzi et al ., ; Brocchini et al ., ). This unit was subsequently redefined as Rionero Subsynthem (Giannandrea, ; Villa and Buettner, ). Level 2‐5 located at the base of level 2‐6 includes archaeosurfaces E and E1.…”