The H 2 O content of basalt glasses from Southwest Pacific back-arc basins
The H 2 O content of 35 glasses from Southwest Pacific back-arc basins (Lau, North Fiji, Woodlark and Manus) have been determined by infrared spectroscopy. On a plot of K 2 O vs. H 2 O the glass data define two distinct trends characterized by different slopes. Trend I, with a slope (K 2 O/H 2 O) of...
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ftunivtasecite:oai:ecite.utas.edu.au:96750 2023-05-15T18:16:02+02:00 The H 2 O content of basalt glasses from Southwest Pacific back-arc basins Danyushevsky, LV Falloon, TJ Sobolev, AV Crawford, AJ Carroll, M Price, RC 1993 https://doi.org/10.1016/0012-821X(93)90089-R http://ecite.utas.edu.au/96750 en eng Elsevier Science Bv http://dx.doi.org/10.1016/0012-821X(93)90089-R Danyushevsky, LV and Falloon, TJ and Sobolev, AV and Crawford, AJ and Carroll, M and Price, RC, The H 2 O content of basalt glasses from Southwest Pacific back-arc basins, Earth and Planetary Science Letters, 117, (3-4) pp. 347-362. ISSN 0012-821X (1993) [Refereed Article] http://ecite.utas.edu.au/96750 Earth Sciences Geology Igneous and Metamorphic Petrology Refereed Article PeerReviewed 1993 ftunivtasecite https://doi.org/10.1016/0012-821X(93)90089-R 2019-12-13T21:59:01Z The H 2 O content of 35 glasses from Southwest Pacific back-arc basins (Lau, North Fiji, Woodlark and Manus) have been determined by infrared spectroscopy. On a plot of K 2 O vs. H 2 O the glass data define two distinct trends characterized by different slopes. Trend I, with a slope (K 2 O/H 2 O) of 0.25, can be explained by addition of a subduction-related component with K 2 O/H 2 O = 0.25 to a depleted mid-ocean ridge basalt mantle source (N- or D-MORB-like). Trend II, which coincides with the N- to E-MORB compositional spectrum, can be produced by addition of a non-subduction component, possibly an alkaline magma with K 2 O/H 2 O∼ 1.5, to the same depleted mantle source. The K 2 O/TiO 2 and K/Nb values of E-MORB and back-arc basin basalts (BABB) of Trend II suggest that the enriched component involved in their genesis is not derived from a typical ocean island basalt (OIB, e.g. Hawaiian) mantle source. Our data show that the entire spectrum of BABB compositions can be explained by different degrees of mixing of a mantle source of either D-, N- or E-MORB composition with the subduction-related component, characterized by a K 2 O/H 2 O value of 0.25. Different BABB types correlate with tectonic setting. Samples from the Trend II are associated with relatively stable spreading ridges, whereas those affected by the subduction-related component are always associated with more complex tectonic settings, or come from young or incipient back-arc basins. Pronounced E-MORB affinities of mantle sources are demonstrated only for samples from the Lau, North Fiji and Scotia Sea basins. The most H 2 O enriched BABB of Trend I partly overlap in terms of H 2 O and K 2 O content and H 2 O/TiO 2 and K 2 O/TiO 2 values with island arc tholeiites. This suggests involvement of similar subduction-related components in the genesis of these two magma types. Because a larger database is now available, the K 2 O/H 2 O vs. TiO 2 tectonic discriminan diagram of Muenow et al. [2] appears to be less useful than when originally proposed. The very low K 2 O/H 2 O value ( < 0.05) of the H 2 O-bearing phase involved in boninite genesis implies that it maybe a fluid derived from the subducted slab. The significantly higher K 2 O/H 2 O value (0.25) of the subduction-related component involved in petrogenesis of BABB and some arc tholeiites indicates that it was a melt, rather than a fluid. This K 2 O/H 2 >O value (0.25) is also of some interest, as the same value occurs in depleted MORB. Article in Journal/Newspaper Scotia Sea Ocean Island eCite UTAS (University of Tasmania) Scotia Sea Pacific Earth and Planetary Science Letters 117 3-4 347 362 |
institution |
Open Polar |
collection |
eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Earth Sciences Geology Igneous and Metamorphic Petrology |
spellingShingle |
Earth Sciences Geology Igneous and Metamorphic Petrology Danyushevsky, LV Falloon, TJ Sobolev, AV Crawford, AJ Carroll, M Price, RC The H 2 O content of basalt glasses from Southwest Pacific back-arc basins |
topic_facet |
Earth Sciences Geology Igneous and Metamorphic Petrology |
description |
The H 2 O content of 35 glasses from Southwest Pacific back-arc basins (Lau, North Fiji, Woodlark and Manus) have been determined by infrared spectroscopy. On a plot of K 2 O vs. H 2 O the glass data define two distinct trends characterized by different slopes. Trend I, with a slope (K 2 O/H 2 O) of 0.25, can be explained by addition of a subduction-related component with K 2 O/H 2 O = 0.25 to a depleted mid-ocean ridge basalt mantle source (N- or D-MORB-like). Trend II, which coincides with the N- to E-MORB compositional spectrum, can be produced by addition of a non-subduction component, possibly an alkaline magma with K 2 O/H 2 O∼ 1.5, to the same depleted mantle source. The K 2 O/TiO 2 and K/Nb values of E-MORB and back-arc basin basalts (BABB) of Trend II suggest that the enriched component involved in their genesis is not derived from a typical ocean island basalt (OIB, e.g. Hawaiian) mantle source. Our data show that the entire spectrum of BABB compositions can be explained by different degrees of mixing of a mantle source of either D-, N- or E-MORB composition with the subduction-related component, characterized by a K 2 O/H 2 O value of 0.25. Different BABB types correlate with tectonic setting. Samples from the Trend II are associated with relatively stable spreading ridges, whereas those affected by the subduction-related component are always associated with more complex tectonic settings, or come from young or incipient back-arc basins. Pronounced E-MORB affinities of mantle sources are demonstrated only for samples from the Lau, North Fiji and Scotia Sea basins. The most H 2 O enriched BABB of Trend I partly overlap in terms of H 2 O and K 2 O content and H 2 O/TiO 2 and K 2 O/TiO 2 values with island arc tholeiites. This suggests involvement of similar subduction-related components in the genesis of these two magma types. Because a larger database is now available, the K 2 O/H 2 O vs. TiO 2 tectonic discriminan diagram of Muenow et al. [2] appears to be less useful than when originally proposed. The very low K 2 O/H 2 O value ( < 0.05) of the H 2 O-bearing phase involved in boninite genesis implies that it maybe a fluid derived from the subducted slab. The significantly higher K 2 O/H 2 O value (0.25) of the subduction-related component involved in petrogenesis of BABB and some arc tholeiites indicates that it was a melt, rather than a fluid. This K 2 O/H 2 >O value (0.25) is also of some interest, as the same value occurs in depleted MORB. |
format |
Article in Journal/Newspaper |
author |
Danyushevsky, LV Falloon, TJ Sobolev, AV Crawford, AJ Carroll, M Price, RC |
author_facet |
Danyushevsky, LV Falloon, TJ Sobolev, AV Crawford, AJ Carroll, M Price, RC |
author_sort |
Danyushevsky, LV |
title |
The H 2 O content of basalt glasses from Southwest Pacific back-arc basins |
title_short |
The H 2 O content of basalt glasses from Southwest Pacific back-arc basins |
title_full |
The H 2 O content of basalt glasses from Southwest Pacific back-arc basins |
title_fullStr |
The H 2 O content of basalt glasses from Southwest Pacific back-arc basins |
title_full_unstemmed |
The H 2 O content of basalt glasses from Southwest Pacific back-arc basins |
title_sort |
h 2 o content of basalt glasses from southwest pacific back-arc basins |
publisher |
Elsevier Science Bv |
publishDate |
1993 |
url |
https://doi.org/10.1016/0012-821X(93)90089-R http://ecite.utas.edu.au/96750 |
geographic |
Scotia Sea Pacific |
geographic_facet |
Scotia Sea Pacific |
genre |
Scotia Sea Ocean Island |
genre_facet |
Scotia Sea Ocean Island |
op_relation |
http://dx.doi.org/10.1016/0012-821X(93)90089-R Danyushevsky, LV and Falloon, TJ and Sobolev, AV and Crawford, AJ and Carroll, M and Price, RC, The H 2 O content of basalt glasses from Southwest Pacific back-arc basins, Earth and Planetary Science Letters, 117, (3-4) pp. 347-362. ISSN 0012-821X (1993) [Refereed Article] http://ecite.utas.edu.au/96750 |
op_doi |
https://doi.org/10.1016/0012-821X(93)90089-R |
container_title |
Earth and Planetary Science Letters |
container_volume |
117 |
container_issue |
3-4 |
container_start_page |
347 |
op_container_end_page |
362 |
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1766189442408644608 |