Quaternary evolution of the southern sector of the Campanian Plain and early Somma-Vesuvius activity: insights from the Trecase 1 well |
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Authors: | D Brocchini C Principe D Castradori M A Laurenzi L Gorla |
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Institution: | (1) Piombino (LI), Italy, IT;(2) Istituto di Geoscienze e Georisorse – Area della Ricerca CNR di Pisa S. Cataldo, Pisa, Italy, IT;(3) AGIP S.p.A, San Donato Milanese, Italy, IT |
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Abstract: | Summary The present review of data on the Trecase 1 well, including stratigraphy, updated 40 Ar/39Ar ages and the results of newly performed calcareous nannofossil studies, serves to resolve the chronological contradictions
pointed out by Bernasconi et al. (1981) and Balducci et al. (1983) concerning the onset of volcanic activity in the area now
occupied by the Somma-Vesuvius Volcanic Complex. New 40 Ar/39Ar data indicate that volcanic activity in this area started about 0.4 myr B.P. After such time, tephritic magmatic activity,
distributed in small scattered centers, developed and alternated with periods of volcanic quiescence and marine sedimentation.
This first phase of magmatic activity ended in the Vesuvian area about 0.3 myr B.P. and was followed by a period of marine
sedimentation in a marginal environment. Complete emergence of the shoreline occurred about 37,000 yr B.P. as a result of
sea level changes during the last glacial period and deposition of the 60 m thick Campanian ignimbrite (CI). Volcanic activity
reappeared in the Vesuvian area only after the CI eruption. Magma rising along and at the intersection of linear and curved
tectonic and volcano-tectonic elements (linked to the pre-existing Pleistocene tectonic trend and formation of the vast Phlegraean
Fields caldera) formed a number of small lava and scoria edifices. One of these tephritic centers lies above the CI deposits
under the Trecase 1 well area. The CI bottom in the Trecase 1 well is currently at an altitude of − 120 m a.s.l.; this allows
estimating the maximum tectonic subsidence over the last 37,000 yr. by the southern sector of the Vesuvian area to be about
30 m.
Received April 12, 2000; revised version accepted March 1, 2001 |
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