Publikationsdatum:
2017-04-04
Beschreibung:
We investigated chemical and isotopic compositions of clinopyroxene crystals from well age-constrained juvenile scoria
clasts, lava flows, and hypoabyssal magmatic ejecta representative of the whole eruptive history of the Alban Hills Volcanic
District. The Alban Hills is a Quaternary ultra-potassic district that was emplaced into thick limestone units along the
Tyrrhenian margin of Italy. Alban Hills volcanic products, even the most differentiated, are characterised by low SiO2 content.
We suggest that the low silica activity in evolving magmas can be ultimately due to a decarbonation process occurring at the
magma/limestone interface. According to the liquid line of descent we propose, the differentiation process is driven by
crystallisation of clinopyroxene+leuciteFapatiteFmagnetite coupled with assimilation of a small amount of calcite and/or
with interaction with crustal CO2. By combining age, chemical data, strontium and oxygen isotopic compositions, and REE
content of clinopyroxene, we give insights into the evolution of primitive ultrapotassic magmas of the Alban Hills Volcanic
District over an elapsed period of about 600 kyr. Geochemical features of clinopyroxene crystals, consistent with data coming
from other Italian ultrapotassic magmas, indicate that Alban Hills primary magmas were generated from a metasomatized
lithospheric mantle source. In addition, our study shows that the 87Sr / 86Sr and LREE/HREE of Alban Hills magmas
continuously diminished during the 600–35 ka time interval of the Alban Hills eruptive history, possibly reflecting the
progressive depletion of the metasomatized mantle source of magmas.
Beschreibung:
Published
Beschreibung:
330–346
Beschreibung:
JCR Journal
Beschreibung:
reserved
Schlagwort(e):
Clinopyroxene
;
87Sr / 86Sr
;
REE
;
Ultrapotassic rocks
;
Alban Hills
;
04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous
;
04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
Repository-Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Materialart:
article
Permalink