TY - JOUR
T1 - Correlation of deposits and vent locations of the proximal Campanian Ignimbrite deposits, Campi Flegrei, Italy, based on natural remanent magnetization and anisotropy of magnetic susceptibility characteristics
AU - Ort, Michael H.
AU - Rosi, Mauro
AU - Anderson, Charles D.
N1 - Funding Information:
This research was supported by the Gruppo Nazionale per la Vulcanologia (CNR) of Italy. The manuscript was greatly improved by a review by Eric Baer and an anonymous reviewer.
PY - 1999/8
Y1 - 1999/8
N2 - Correlation of the distal deposits of the Campanian Ignimbrite with their proximal equivalents in the Campi Flegrei caldera is complicated by a lack of medial exposures, complex and limited proximal stratigraphic sections, and large lateral facies changes. Paleomagnetic data from 10 sites in and near the Campi Flegrei yield natural remanent magnetizations (NRM) that are statistically indistinguishable from the distal Campanian Ignimbrite. In addition, their virtual geomagnetic pole (VGP) yields a possible correlation with Lac du Bouchet, France, secular variation data that indicate an age of approximately 32,850 14C years. The secular variation curve at this age was only briefly at this VGP, and did not return to it for > 10,000 years, so the paleomagnetic correlation of proximal and distal deposits is unique and robust. The date is consistent with 14C dates from the Campanian Ignimbrite, but younger than 39Ar/40Ar dates for the same rocks. This suggests that a better correction factor for cosmic flux for this time period is needed to calibrate older 14C dates. Anisotropy of magnetic susceptibility (AMS) data show that the proximal deposits have an oblate (disk-shaped), poorly lineated magnetic fabric. The distal deposits are much better lineated. The difference may be due to chaotic depositional currents in the proximal areas, in which particles were not well aligned. With greater distance of travel, and loss of energy, particles within the flow became aligned and developed stronger AMS lineations. Early eruptions of the Piperno Tuff were from a central vent north of Pozzuoli, whereas later tuffs that underlie the Breccia Museo may have been emplaced by flows associated with ring vents located on the northern and southern caldera margins.
AB - Correlation of the distal deposits of the Campanian Ignimbrite with their proximal equivalents in the Campi Flegrei caldera is complicated by a lack of medial exposures, complex and limited proximal stratigraphic sections, and large lateral facies changes. Paleomagnetic data from 10 sites in and near the Campi Flegrei yield natural remanent magnetizations (NRM) that are statistically indistinguishable from the distal Campanian Ignimbrite. In addition, their virtual geomagnetic pole (VGP) yields a possible correlation with Lac du Bouchet, France, secular variation data that indicate an age of approximately 32,850 14C years. The secular variation curve at this age was only briefly at this VGP, and did not return to it for > 10,000 years, so the paleomagnetic correlation of proximal and distal deposits is unique and robust. The date is consistent with 14C dates from the Campanian Ignimbrite, but younger than 39Ar/40Ar dates for the same rocks. This suggests that a better correction factor for cosmic flux for this time period is needed to calibrate older 14C dates. Anisotropy of magnetic susceptibility (AMS) data show that the proximal deposits have an oblate (disk-shaped), poorly lineated magnetic fabric. The distal deposits are much better lineated. The difference may be due to chaotic depositional currents in the proximal areas, in which particles were not well aligned. With greater distance of travel, and loss of energy, particles within the flow became aligned and developed stronger AMS lineations. Early eruptions of the Piperno Tuff were from a central vent north of Pozzuoli, whereas later tuffs that underlie the Breccia Museo may have been emplaced by flows associated with ring vents located on the northern and southern caldera margins.
KW - AMS
KW - Campanian Ignimbrite
KW - NRM
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U2 - 10.1016/S0377-0273(99)00034-7
DO - 10.1016/S0377-0273(99)00034-7
M3 - Article
AN - SCOPUS:0033399808
SN - 0377-0273
VL - 91
SP - 167
EP - 178
JO - Journal of Volcanology and Geothermal Research
JF - Journal of Volcanology and Geothermal Research
IS - 2-4
ER -