caa a22 4500 475826345 CHVBK 20180406123829.0 cr unu---uuuuu 170329e20000801xx s 000 0 eng 10.1007/s004450000077 doi (NATIONALLICENCE)springer-10.1007/s004450000077 Segregation structures in vapor-differentiated basaltic flows [Elektronische Daten] [Martial Caroff, René C. Maury, Joseph Cotten, Jean-Philippe Clément]  Vesicle cylinders represent a spectacular kind of segregation structure involving residual liquids formed in situ during the cooling of lava flows. These vertical pipes, commonly found within basalt flows typically 2-10 m thick, are interpreted as the product of a vapor-driven differentiation process. The olivine phenocrysts and the earliest generation of groundmass olivines found in cylinder-bearing basalts appear to have been generally affected by magmatic oxidation, resulting in high-temperature iddingsite (HTI) alteration. This feature is also observed within cylinder-free basalt flows which exhibit other kinds of vesicular segregation structures, such as vesicle-rich pegmatoid segregation sheets and/or segregation vesicles. Detailed textural, petrological, and geochemical characteristics of two types of cylinders, three types of vesicle sheets, and five types of segregation vesicles are described, based on the study of 12 occurrences of HTI-bearing basalt flows from oceanic shield volcanoes or continental basalt plateaus. We propose a general classification of these segregation structures likely to derive from vapor differentiation. Flow thickness is probably the main factor influencing their morphology. Finally, we suggest that the concomitant occurrence of olivine oxidation and vapor-differentiation effects results from the late persistence of water oversaturation after eruption, perhaps due to a high rate of magma ascent. Springer-Verlag Berlin Heidelberg, 2000 Key words Lava flows nationallicence Vesicle cylinders nationallicence Segregation sheets nationallicence Segregation vesicles nationallicence Water oversaturation nationallicence Ocean island basalts nationallicence Flood basalts nationallicence Caroff Martial UMR no. 6538 "Domaines Océaniques”, Université de Bretagne Occidentale, B.P. 809, 29285 Brest, France e-mail: caroff@univ-brest.fr, FR aut Maury René C. UMR no. 6538 "Domaines Océaniques”, Université de Bretagne Occidentale, B.P. 809, 29285 Brest, France e-mail: caroff@univ-brest.fr, FR aut Cotten Joseph UMR no. 6538 "Domaines Océaniques”, Université de Bretagne Occidentale, B.P. 809, 29285 Brest, France e-mail: caroff@univ-brest.fr, FR aut Clément Jean-Philippe UMR no. 6538 "Domaines Océaniques”, Université de Bretagne Occidentale, B.P. 809, 29285 Brest, France e-mail: caroff@univ-brest.fr, FR aut https://doi.org/10.1007/s004450000077 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s004450000077 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Caroff Martial UMR no. 6538 "Domaines Océaniques”, Université de Bretagne Occidentale, B.P. 809, 29285 Brest, France e-mail: caroff@univ-brest.fr, FR aut NATIONALLICENCE 700 1- Maury René C. UMR no. 6538 "Domaines Océaniques”, Université de Bretagne Occidentale, B.P. 809, 29285 Brest, France e-mail: caroff@univ-brest.fr, FR aut NATIONALLICENCE 700 1- Cotten Joseph UMR no. 6538 "Domaines Océaniques”, Université de Bretagne Occidentale, B.P. 809, 29285 Brest, France e-mail: caroff@univ-brest.fr, FR aut NATIONALLICENCE 700 1- Clément Jean-Philippe UMR no. 6538 "Domaines Océaniques”, Université de Bretagne Occidentale, B.P. 809, 29285 Brest, France e-mail: caroff@univ-brest.fr, FR aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer