http://www.cnr.it/ontology/cnr/individuo/prodotto/ID29423
Cooling kinetics experiments on different Stromboli lavas: Effects on crystal morphologies and phases composition. (Articolo in rivista)
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- Label
- Cooling kinetics experiments on different Stromboli lavas: Effects on crystal morphologies and phases composition. (Articolo in rivista) (literal)
- Anno
- 2006-01-01T00:00:00+01:00 (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
- 10.1016/j.jvolgeores.2006.03.025 (literal)
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- Conte A.M.; Perinelli C.; Trigila R. (literal)
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- DOI: 10.1016/j.jvolgeores.2006.03.025 (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali
- Note
- ISI Web of Science (WOS) (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- Conte: I.G.G.-C.N.R.-Sezione di Roma c/o Dipartimento di Scienze della Terra, Università degli Studi di Roma \"La Sapienza\", P.le Aldo Moro 5, 00185 Roma, Italy. Perinelli: Dipartimento di Scienze della Terra, Università degli Studi di Pisa, Via S. Maria 53, 56126 Pisa, Italy. Trigila: Dipartimento di Scienze della Terra, Università degli Studi di Roma \"La Sapienza\" P.le Aldo Moro 5, 00185 Roma, Italy (literal)
- Titolo
- Cooling kinetics experiments on different Stromboli lavas: Effects on crystal morphologies and phases composition. (literal)
- Abstract
- Controlled cooling experiments at atmospheric pressure and fO2 of the NNO buffer were performed on three Stromboli lavas of
calcalkaline (CA), high-K calcalkaline (HKCA) and shoshonitic (SHO) affinities. The experiments were conducted at cooling rates
of 900°C/h (fast cooling rate-->FCR) and 1°C/h (slow cooling rate-->SCR), respectively, to investigate the kinetic factors
governing textural and compositional features such as phase growth morphology, phase relations and phase compositions. The
experiments produced different types of textures as both the cooling rate and the quenching temperatures were varied. In general,
FCR experiments show a decrease of crystal size as well as a change in crystal shape from euhedral, to granular, to skeletal up to
dendritic morphology with decreasing temperatures. SCR experiments produce less variable crystal size and crystal morphology.
Measurements of plagioclases indicate that the crystal size and calculated crystal growth are functions of cooling rate; crystal
growth rates are about two orders of magnitude higher in FCR experiments than SCR ones. Such textural responses are in
agreement with the empirical calibration based on the plagioclase size dependence on cooling rate developed by Cashman (1993).
Experimental phase relations display three main features of the crystallization process: (1) the delay in the crystallization of the
liquidus phase in the FCR experiments with respect to the SCR ones; (2) crystallization, controlled by the multiphase cotectic
relations (plagioclase+pyroxenes±olivine), is more enhanced for FCR experiments compared to that of SCR ones at the lowest
experimental temperature (1100°C); (3) crystallization of augite and pigeonite is sensitive to cooling rate and system compositions;
pigeonite, not found in the natural rocks, crystallizes in the CA sample across SCR and FCR runs, and in the HKCA sample just in
the SCR experiments.
FCR and SCR experiments produce similar liquid lines of descent for both CA and HKCA starting materials suggesting that the
processes of nucleation and growth play reciprocal roles through mass balance as cooling rate varies. This is not true for the SHO
composition where the trends of melt composition appear to be especially influenced by the different amounts of olivine
crystallization at the different cooling rates. Data on mineral compositions show that plagioclase and clinopyroxene are the phases
more strongly affected by the cooling gradients; crystals from SCR experiments and, to a lesser extent, from FCR experiments,
show zoning patterns mainly at the lowest experimental temperature. (literal)
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