Publication Date:
2017-04-04
Description:
New major and trace element data, and Sr–Nd–Pb-O isotopic ratios for volcanic mafic rocks outcropping at Monti
Ernici in the Mid Latina Valley (southern Latium) are reported, with the aim of investigating the nature and evolution of Plio-
Quaternary K-rich volcanism in Central Italy. Petrographical and geochemical studies allow us to identify mafic rocks ranging
from ultrapotassic (HKS) to shoshonitic (SHO), and calc-alkaline (CA), these last ones being identified for the first time. The CA
rocks exhibit the most primitive signatures for Sr, Nd, and Pb isotopes (87Sr/86Sr = 0.706326-0.706654; 143Nd/144Nd = 0.512388–
0.512361; 206Pb/204Pb = 18.944-18.940). The δ18O values are variable (δ18Ocpx from +5.75 to +7.08 ‰; and δ18Ool from +5.50 to
+6.23 ‰), suggesting interaction with carbonate wall rocks. Radiogenic isotope ratios and incompatible elements distribution have
several characteristic in common with equivalent rocks from Pontine Islands (Ventotene), Campania and Aeolian arc volcanoes.
Conversely, the HKS rocks closely resemble the ultrapotassic rocks from the Roman Province (87Sr/86Sr = 0.709679–0.711102;
δ18Ocpx from +6.27 to +7.08 ‰). The high ratios of LILE (Large Ion Lithophile Elements: Rb, Cs, Th, U, K, LREE) and HFSE
(High Field Strength Elements: Ta, Nb, Zr, Hf, Ti), and radiogenic isotope compositions of CA to HKS rocks indicate that all
suites contain subduction-related components, and suggest a N-MORB-type mantle source variably contaminated by hydrous fluids
and/or melts released by undergoing slabs, possibly during two distinct stages of metasomatism. The coexistence of ultra-alkaline
and sub-alkaline orogenic magmatism, combined with tectonic, geophysical and geological evidence, support the possibility that
the mantle beneath central-southern Italy (Ernici-Roccamonfina Province) was vertically zoned and produced different magma
suites during time.
Description:
Published
Description:
479-497
Description:
3.5. Geologia e storia dei sistemi vulcanici
Description:
JCR Journal
Description:
reserved
Keywords:
Monti Ernici
;
Latium magmatic Province
;
calcalkaline rocks
;
04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology
;
04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
;
04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Permalink
