Chaotic three-dimensional distribution of Ba, Rb, and Sr in feldspar megacrysts grown in an open magmatic system

Year:

2011

Type of Publication:

Article

Authors:

Słaby, Ewa; Śmigielski, Michał; Śmigielski, Tomasz; Domonik, Andrzej; Simon, Klaus; Kronz, Andreas

Journal:

Contributions to Mineralogy and Petrology

Volume:

162

Pages:

909-927

ISSN:

0010-7999

BibTex:

@article{springerlink:10.1007/s00410-011-0631-6, author = "Ewa Słaby and Michał Śmigielski and Tomasz Śmigielski and Andrzej Domonik and Klaus Simon and Andreas Kronz", abstract = "As has been demonstrated in recent years, the heterogeneities of coeval magmas can be more successfully revealed by zoned megacrysts rather than by analysis of the whole rocks hosting them. Here, the geochemical heterogeneities of feldspar megacrysts from the Karkonosze granite, Poland, are investigated by LA-ICP-MS. The crystals are the product of migration and growth in regions of poorly mixed magmas. 3D-modeling of the Ba, Sr, and Rb distributions emphasizes the importance of micro-domain growth morphologies. Two models of element behavior—a relative concentration model and a composition gradient model—provide a potentially effective tool for tracking the mixing process on a microscale. Measured concentrations of elements of different mobilities do not agree with what might be expected from the mixing of two end-member magmas. If mixing was the only process occurring, linear correlations between the concentrations of any two elements should be observed; this, however, is not the case. For combinations of any two of the three elements, modeling reveals differing non-linear correlations between concentrations. The megacryst heterogeneities provide an insight into how mixing magmas are chaotically advected to growing crystals and the degree of inter-magma element exchange between the magmas.", issn = "0010-7999", journal = "Contributions to Mineralogy and Petrology", note = "10.1007/s00410-011-0631-6", pages = "909-927", publisher = "Springer Berlin / Heidelberg", title = "{C}haotic three-dimensional distribution of {B}a, {R}b, and {S}r in feldspar megacrysts grown in an open magmatic system", url = "http://dx.doi.org/10.1007/s00410-011-0631-6", volume = "162", year = "2011", }

Note:

10.1007/s00410-011-0631-6

Abstract:

As has been demonstrated in recent years, the heterogeneities of coeval magmas can be more successfully revealed by zoned megacrysts rather than by analysis of the whole rocks hosting them. Here, the geochemical heterogeneities of feldspar megacrysts from the Karkonosze granite, Poland, are investigated by LA-ICP-MS. The crystals are the product of migration and growth in regions of poorly mixed magmas. 3D-modeling of the Ba, Sr, and Rb distributions emphasizes the importance of micro-domain growth morphologies. Two models of element behavior—a relative concentration model and a composition gradient model—provide a potentially effective tool for tracking the mixing process on a microscale. Measured concentrations of elements of different mobilities do not agree with what might be expected from the mixing of two end-member magmas. If mixing was the only process occurring, linear correlations between the concentrations of any two elements should be observed; this, however, is not the case. For combinations of any two of the three elements, modeling reveals differing non-linear correlations between concentrations. The megacryst heterogeneities provide an insight into how mixing magmas are chaotically advected to growing crystals and the degree of inter-magma element exchange between the magmas.