Computer Science
Scientific paper
Aug 1984
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1984e%26psl..69..263t&link_type=abstract
Earth and Planetary Science Letters, Volume 69, Issue 2, p. 263-276.
Computer Science
8
Scientific paper
18O/16O analyses were made on a set of leucite-bearing igneous rocks from a variety of localities around the world. The samples chosen for study all have relatively primitive characteristics, such as low SiO2 contents (42-52 wt.%). Whole-rock δ18O values from the 10-15 m.y. old Australian leucitites range from +7.1 to +11.0; however, none of these values represents the original δ18O of the erupted lava, as every sample has undergone some subsolidus 18O enrichment. The δ18O values of the primary magmas (~ +6.5) can be accurately calculated from the δ18O of clinopyroxene mineral separates. However, the leucite mineral separates (pure, stoichiometric KA1Si2O6) have δ18O = +8.8 to +10.6, and clearly have not retained their primary igneous oxygen isotopic compositions. The whole-rock δ18O values exhibit a positive correlation with H2O+ contents, and extrapolation to a plausible water content for such a subaerially erupted lava ( <0.5 wt.% H2O) gives a range of primary δ18O values of +5.8 to +6.8. The much less hydrated Bufumbira, Africa and Gaussberg, Antarctica samples have δ18O = +6.7 to +7.9 and +6.1 to +7.0, respectively. These have probably undergone only minor subsolidus 18O enrichments. The San Venanzo, Italy, samples are even less hydrated, so their extremely high δ18O values of +10.8 to +12.0 are definitely magmatic values. Those data confirm our earlier conclusions that the leucite-bearing magmas erupted in north-central Italy are unique in having much higher δ18O values than potassic rocks from southern Italy or anywhere else in the world. The northward increase in δ18O in the leucite-bearing rocks of Italy is thus clearly a manifestation of progressively greater interaction between mantle-derived magmas (δ18O = +5.5 to +7.5) and the high-18O sedimentary and metasedimentary rocks of the Italian continental crust (δ18O = +15 to +25), which were strongly heated during the episode of Tuscan anatectic granitic magmatism.
Cundari Aldo
Taylor Hugh P.
Turi Bruno
No associations
LandOfFree
18O/16O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with 18O/16O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and 18O/16O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1675364