The origin of low-Ca olivine from ultramafic xenoliths and host basaltic lavas in a back-arc setting, James Ross Island, Antarctic Peninsula

Şafak Altunkaynak; Alp Ünal; Geoffrey H. Howarth; Ercan Aldanmaz; Daniel Nývlt

doi:10.1016/j.lithos.2019.05.039

The origin of low-Ca olivine from ultramafic xenoliths and host basaltic lavas in a back-arc setting, James Ross Island, Antarctic Peninsula

Şafak Altunkaynak^*, Alp Ünal, Geoffrey H. Howarth, Ercan Aldanmaz, Daniel Nývlt

^*Corresponding author for this work

Department of Geological Engineering

Research output: Contribution to journal › Article › peer-review

7 Citations (Scopus)

Abstract

The James Ross Island Volcanic Group (JRIVG) at the northern tip of the Antarctic Peninsula is composed of various types of volcanic rocks erupted during the Late Miocene to Late Pleistocene. The sub-aerial lavas are the most abundant erupted products within the suite and are represented by alkali olivine basalts that contain significant amounts of ultramafic xenoliths. Precise determination of chemical compositions of olivine by electron microprobe and LA-ICP-MS reveals more than one compositionally distinct olivine population in the xenoliths and the host lavas. The majority of the olivine grains from the xenolith suite are remarkable for their high Mg/Fe ratios (>Fo₈₈) and low-Ca contents (<500 ppm) and are similar in composition to the mantle olivine, while some others, despite their similarly low-Ca abundances, are characterized by significantly lower Mg/Fe (<Fo₈₅) reflecting some degree of differentiation. We interpret the co-existence of both olivine types with low-Ca contents as reflecting a magmatic cumulate origin of the xenoliths through olivine-dominated fractional crystallization from a H₂O-rich parent magma, during which the presence of water affects the partitioning behavior of elements and reduces the D_CaO ^olivine/melt significantly. The cores of the most primitive olivine macrocrysts (>Fo₈₈) from the basaltic lavas also have low Ca contents compared to MORB olivine at similar Fo, indicating an arc-melt like volatile content of the primary magma. Evaluation of minor and trace element relative abundances in olivine further indicate that the alkaline basalts in the JRIVG are the products of peridotite-dominated partial melting of a volatile-rich mantle source with signatures of mantle hydration most probably promoted by preceding subduction events. The results from olivine chemistry, when combined with the evaluation of primary melt compositions, appear to be consistent with the view that the primary magmas from which the JRIVG basalts were derived are the results of partial melting of a mantle domain that has experienced hydrous silicate melt metasomatism through interaction of peridotitic upper mantle rocks with melts of a slab-derived component, most probably generated by dehydration melting of subducted oceanic crust.

Original language	English
Pages (from-to)	276-287
Number of pages	12
Journal	Lithos
Volume	342-343
DOIs	https://doi.org/10.1016/j.lithos.2019.05.039
Publication status	Published - Oct 2019

Bibliographical note

Publisher Copyright:
© 2019 Elsevier B.V.

Funding

This study was carried under the auspices of Turkish Republic Presidency, supported by the Ministry of Science, Industry and Technology, and coordinated by Istanbul Technical University (ITU) Polar Research Center (PolReC). Field study on James Ross Island was undertaken within the scope of TAEII, Turkey-Czech Republic Bilateral Cooperation, and a collaborative research between Istanbul Technical University and Masaryk University in Brno. We would like to express our special thanks to the expedition members and crew of the J.G. Mendel Station for their friendship and logistic support during the field campaign (January-March 2018). The facility of the J.G. Mendel Station is supported by the Ministry of Education, Youth and Sports of the Czech Republic projects no. LM2015078 and CZ.02.1.01/0.0/0.0/16_013/0001708. Chris Fleischer is thanked for aid during EPMA analytical work at the University of Georgia. We would also like to thank Christel Tinguely for help with laser ablation analyses at the University of Cape Town (UCT). Analytical funding for laser ablation at UCT was from the National Research Foundation (NRF) of South Africa Incentive grant 115370 to GHH. We would like to thank Dejan Milidragovic, Vladislav Rapprich and one anonymous reviewer for helpful comments, and Mike Roden for editorial handling. This study was carried under the auspices of Turkish Republic Presidency, supported by the Ministry of Science, Industry and Technology , and coordinated by Istanbul Technical University (ITU) Polar Research Center (PolReC) . Field study on James Ross Island was undertaken within the scope of TAEII , Turkey-Czech Republic Bilateral Cooperation , and a collaborative research between Istanbul Technical University and Masaryk University in Brno. We would like to express our special thanks to the expedition members and crew of the J.G. Mendel Station for their friendship and logistic support during the field campaign (January-March 2018). The facility of the J.G. Mendel Station is supported by the Ministry of Education, Youth and Sports of the Czech Republic projects no. LM2015078 and CZ.02.1.01/0.0/0.0/16_013/0001708 . Chris Fleischer is thanked for aid during EPMA analytical work at the University of Georgia . We would also like to thank Christel Tinguely for help with laser ablation analyses at the University of Cape Town (UCT) . Analytical funding for laser ablation at UCT was from the National Research Foundation (NRF) of South Africa Incentive grant 115370 to GHH. We would like to thank Dejan Milidragovic, Vladislav Rapprich and one anonymous reviewer for helpful comments, and Mike Roden for editorial handling.

Funders	Funder number
University of Georgia
National Research Foundation
National Research Foundation	115370
Ministerstvo Školství, Mládeže a Tělovýchovy	CZ.02.1.01/0.0/0.0/16_013/0001708, LM2015078
University of Cape Town
Istanbul Teknik Üniversitesi
Bilim, Sanayi ve Teknoloji Bakanliği
Masarykova Univerzita

Keywords

Antarctic Peninsula
Back-arc basalt
Calcium
James Ross Island
Olivine
Xenolith

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.lithos.2019.05.039

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@article{0300be7817ef433c9521b9d268b1add3,

title = "The origin of low-Ca olivine from ultramafic xenoliths and host basaltic lavas in a back-arc setting, James Ross Island, Antarctic Peninsula",

abstract = "The James Ross Island Volcanic Group (JRIVG) at the northern tip of the Antarctic Peninsula is composed of various types of volcanic rocks erupted during the Late Miocene to Late Pleistocene. The sub-aerial lavas are the most abundant erupted products within the suite and are represented by alkali olivine basalts that contain significant amounts of ultramafic xenoliths. Precise determination of chemical compositions of olivine by electron microprobe and LA-ICP-MS reveals more than one compositionally distinct olivine population in the xenoliths and the host lavas. The majority of the olivine grains from the xenolith suite are remarkable for their high Mg/Fe ratios (>Fo88) and low-Ca contents (<500 ppm) and are similar in composition to the mantle olivine, while some others, despite their similarly low-Ca abundances, are characterized by significantly lower Mg/Fe (85) reflecting some degree of differentiation. We interpret the co-existence of both olivine types with low-Ca contents as reflecting a magmatic cumulate origin of the xenoliths through olivine-dominated fractional crystallization from a H2O-rich parent magma, during which the presence of water affects the partitioning behavior of elements and reduces the DCaO olivine/melt significantly. The cores of the most primitive olivine macrocrysts (>Fo88) from the basaltic lavas also have low Ca contents compared to MORB olivine at similar Fo, indicating an arc-melt like volatile content of the primary magma. Evaluation of minor and trace element relative abundances in olivine further indicate that the alkaline basalts in the JRIVG are the products of peridotite-dominated partial melting of a volatile-rich mantle source with signatures of mantle hydration most probably promoted by preceding subduction events. The results from olivine chemistry, when combined with the evaluation of primary melt compositions, appear to be consistent with the view that the primary magmas from which the JRIVG basalts were derived are the results of partial melting of a mantle domain that has experienced hydrous silicate melt metasomatism through interaction of peridotitic upper mantle rocks with melts of a slab-derived component, most probably generated by dehydration melting of subducted oceanic crust.",

keywords = "Antarctic Peninsula, Back-arc basalt, Calcium, James Ross Island, Olivine, Xenolith",

author = "{\c S}afak Altunkaynak and Alp {\"U}nal and Howarth, {Geoffrey H.} and Ercan Aldanmaz and Daniel N{\'y}vlt",

note = "Publisher Copyright: {\textcopyright} 2019 Elsevier B.V.",

year = "2019",

month = oct,

doi = "10.1016/j.lithos.2019.05.039",

language = "English",

volume = "342-343",

pages = "276--287",

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T1 - The origin of low-Ca olivine from ultramafic xenoliths and host basaltic lavas in a back-arc setting, James Ross Island, Antarctic Peninsula

AU - Altunkaynak, Şafak

AU - Ünal, Alp

AU - Howarth, Geoffrey H.

AU - Aldanmaz, Ercan

AU - Nývlt, Daniel

PY - 2019/10

Y1 - 2019/10

N2 - The James Ross Island Volcanic Group (JRIVG) at the northern tip of the Antarctic Peninsula is composed of various types of volcanic rocks erupted during the Late Miocene to Late Pleistocene. The sub-aerial lavas are the most abundant erupted products within the suite and are represented by alkali olivine basalts that contain significant amounts of ultramafic xenoliths. Precise determination of chemical compositions of olivine by electron microprobe and LA-ICP-MS reveals more than one compositionally distinct olivine population in the xenoliths and the host lavas. The majority of the olivine grains from the xenolith suite are remarkable for their high Mg/Fe ratios (>Fo88) and low-Ca contents (<500 ppm) and are similar in composition to the mantle olivine, while some others, despite their similarly low-Ca abundances, are characterized by significantly lower Mg/Fe (85) reflecting some degree of differentiation. We interpret the co-existence of both olivine types with low-Ca contents as reflecting a magmatic cumulate origin of the xenoliths through olivine-dominated fractional crystallization from a H2O-rich parent magma, during which the presence of water affects the partitioning behavior of elements and reduces the DCaO olivine/melt significantly. The cores of the most primitive olivine macrocrysts (>Fo88) from the basaltic lavas also have low Ca contents compared to MORB olivine at similar Fo, indicating an arc-melt like volatile content of the primary magma. Evaluation of minor and trace element relative abundances in olivine further indicate that the alkaline basalts in the JRIVG are the products of peridotite-dominated partial melting of a volatile-rich mantle source with signatures of mantle hydration most probably promoted by preceding subduction events. The results from olivine chemistry, when combined with the evaluation of primary melt compositions, appear to be consistent with the view that the primary magmas from which the JRIVG basalts were derived are the results of partial melting of a mantle domain that has experienced hydrous silicate melt metasomatism through interaction of peridotitic upper mantle rocks with melts of a slab-derived component, most probably generated by dehydration melting of subducted oceanic crust.

AB - The James Ross Island Volcanic Group (JRIVG) at the northern tip of the Antarctic Peninsula is composed of various types of volcanic rocks erupted during the Late Miocene to Late Pleistocene. The sub-aerial lavas are the most abundant erupted products within the suite and are represented by alkali olivine basalts that contain significant amounts of ultramafic xenoliths. Precise determination of chemical compositions of olivine by electron microprobe and LA-ICP-MS reveals more than one compositionally distinct olivine population in the xenoliths and the host lavas. The majority of the olivine grains from the xenolith suite are remarkable for their high Mg/Fe ratios (>Fo88) and low-Ca contents (<500 ppm) and are similar in composition to the mantle olivine, while some others, despite their similarly low-Ca abundances, are characterized by significantly lower Mg/Fe (85) reflecting some degree of differentiation. We interpret the co-existence of both olivine types with low-Ca contents as reflecting a magmatic cumulate origin of the xenoliths through olivine-dominated fractional crystallization from a H2O-rich parent magma, during which the presence of water affects the partitioning behavior of elements and reduces the DCaO olivine/melt significantly. The cores of the most primitive olivine macrocrysts (>Fo88) from the basaltic lavas also have low Ca contents compared to MORB olivine at similar Fo, indicating an arc-melt like volatile content of the primary magma. Evaluation of minor and trace element relative abundances in olivine further indicate that the alkaline basalts in the JRIVG are the products of peridotite-dominated partial melting of a volatile-rich mantle source with signatures of mantle hydration most probably promoted by preceding subduction events. The results from olivine chemistry, when combined with the evaluation of primary melt compositions, appear to be consistent with the view that the primary magmas from which the JRIVG basalts were derived are the results of partial melting of a mantle domain that has experienced hydrous silicate melt metasomatism through interaction of peridotitic upper mantle rocks with melts of a slab-derived component, most probably generated by dehydration melting of subducted oceanic crust.

KW - Antarctic Peninsula

KW - Back-arc basalt

KW - Calcium

KW - James Ross Island

KW - Olivine

KW - Xenolith

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DO - 10.1016/j.lithos.2019.05.039

M3 - Article

AN - SCOPUS:85067172228

SN - 0024-4937

VL - 342-343

SP - 276

EP - 287

JO - Lithos

JF - Lithos

ER -

The origin of low-Ca olivine from ultramafic xenoliths and host basaltic lavas in a back-arc setting, James Ross Island, Antarctic Peninsula

Abstract

Bibliographical note

Funding

Keywords

UN SDGs

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