Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes : evidence for a solvus relation between phlogopite and aspidolite
Magmatic Na-rich phlogopite (1–5 wt% Na2O) is present as a late-crystallizing mineral in two groups of texturally and mineralogically distinct gabbroic xenoliths at Volcán San Pedro (36°S, Chile), an Andean arc volcano. Phlogopites are characterized by high 100·Mg/(Mg + Fe) (up to 83) and high Cr2O3...
Saved in:
Main Authors: | , , |
---|---|
Other Authors: | |
Format: | Article |
Language: | English |
Published: |
2012
|
Subjects: | |
Online Access: | https://hdl.handle.net/10356/95483 http://hdl.handle.net/10220/8721 http://ammin.geoscienceworld.org.ezlibproxy1.ntu.edu.sg/content/86/1-2.toc |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Institution: | Nanyang Technological University |
Language: | English |
id |
sg-ntu-dr.10356-95483 |
---|---|
record_format |
dspace |
spelling |
sg-ntu-dr.10356-954832019-12-06T19:15:48Z Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes : evidence for a solvus relation between phlogopite and aspidolite Costa, Fidel Dungan, Michael Singer, Brad S. School of Physical and Mathematical Sciences DRNTU::Science::Geology Magmatic Na-rich phlogopite (1–5 wt% Na2O) is present as a late-crystallizing mineral in two groups of texturally and mineralogically distinct gabbroic xenoliths at Volcán San Pedro (36°S, Chile), an Andean arc volcano. Phlogopites are characterized by high 100·Mg/(Mg + Fe) (up to 83) and high Cr2O3 contents (up to 0.4 wt%), and they are always found surrounding variably resorbed olivine, pyroxenes, Cr-spinel, and in some cases, plagioclase. We interpret these micas as the result of open-system processes involving infiltration of water-rich evolved melts [with high Na/(Na + K)] and reaction with refractory minerals. The highest 100·Na/(Na + K) (~70) and Na2O concentrations (~5 wt%) in phlogopite appear to require reaction with liquids of unrealistically high Na/(Na + K) if no other factor is considered. This, together with the observation that phlogopites consist of alternating Na-rich and Na-poor cleavage-parallel bands, can be best interpreted by the presence of a solvus between the aspidolite (Na) and phlogopite (K) end-members. The high proportions (up to 15 vol%) of Na-rich phlogopite in two different groups of gabbroic xenoliths suggest that it might be a more common and abundant mineral than has been previously recognized, and that it may be used as an indicator of open-system processes. 2012-10-08T06:17:13Z 2019-12-06T19:15:48Z 2012-10-08T06:17:13Z 2019-12-06T19:15:48Z 2001 2001 Journal Article Costa, F., Dungan, M., & Singer, B. S. (2001). Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes: evidence for a solvus relation between phlogopite and aspidolite. American Mineralogist, 86(1-2), 29-35. 0003-004X https://hdl.handle.net/10356/95483 http://hdl.handle.net/10220/8721 http://ammin.geoscienceworld.org.ezlibproxy1.ntu.edu.sg/content/86/1-2.toc en American mineralogist © 2001 Mineralogical Society of America. |
institution |
Nanyang Technological University |
building |
NTU Library |
country |
Singapore |
collection |
DR-NTU |
language |
English |
topic |
DRNTU::Science::Geology |
spellingShingle |
DRNTU::Science::Geology Costa, Fidel Dungan, Michael Singer, Brad S. Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes : evidence for a solvus relation between phlogopite and aspidolite |
description |
Magmatic Na-rich phlogopite (1–5 wt% Na2O) is present as a late-crystallizing mineral in two groups of texturally and mineralogically distinct gabbroic xenoliths at Volcán San Pedro (36°S, Chile), an Andean arc volcano. Phlogopites are characterized by high 100·Mg/(Mg + Fe) (up to 83) and high Cr2O3 contents (up to 0.4 wt%), and they are always found surrounding variably resorbed olivine, pyroxenes, Cr-spinel, and in some cases, plagioclase. We interpret these micas as the result of open-system processes involving infiltration of water-rich evolved melts [with high Na/(Na + K)] and reaction with refractory minerals. The highest 100·Na/(Na + K) (~70) and Na2O concentrations (~5 wt%) in phlogopite appear to require reaction with liquids of unrealistically high Na/(Na + K) if no other factor is considered. This, together with the observation that phlogopites consist of alternating Na-rich and Na-poor cleavage-parallel bands, can be best interpreted by the presence of a solvus between the aspidolite (Na) and phlogopite (K) end-members. The high proportions (up to 15 vol%) of Na-rich phlogopite in two different groups of gabbroic xenoliths suggest that it might be a more common and abundant mineral than has been previously recognized, and that it may be used as an indicator of open-system processes. |
author2 |
School of Physical and Mathematical Sciences |
author_facet |
School of Physical and Mathematical Sciences Costa, Fidel Dungan, Michael Singer, Brad S. |
format |
Article |
author |
Costa, Fidel Dungan, Michael Singer, Brad S. |
author_sort |
Costa, Fidel |
title |
Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes : evidence for a solvus relation between phlogopite and aspidolite |
title_short |
Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes : evidence for a solvus relation between phlogopite and aspidolite |
title_full |
Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes : evidence for a solvus relation between phlogopite and aspidolite |
title_fullStr |
Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes : evidence for a solvus relation between phlogopite and aspidolite |
title_full_unstemmed |
Magmatic Na-rich phlogopite in a suite of gabbroic crustal xenoliths from Volcán San Pedro, Chilean Andes : evidence for a solvus relation between phlogopite and aspidolite |
title_sort |
magmatic na-rich phlogopite in a suite of gabbroic crustal xenoliths from volcán san pedro, chilean andes : evidence for a solvus relation between phlogopite and aspidolite |
publishDate |
2012 |
url |
https://hdl.handle.net/10356/95483 http://hdl.handle.net/10220/8721 http://ammin.geoscienceworld.org.ezlibproxy1.ntu.edu.sg/content/86/1-2.toc |
_version_ |
1681049886355619840 |