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Article: Clinopyroxene megacrysts in Cenozoic volcanic rocks from Hainan Island and the Leizhou Peninsula, Southern China

TitleClinopyroxene megacrysts in Cenozoic volcanic rocks from Hainan Island and the Leizhou Peninsula, Southern China
Authors
Issue Date1997
PublisherTaylor & Francis Inc. The Journal's web site is located at http://www.tandf.co.uk/journals/TIGR
Citation
International Geology Review, 1997, v. 39 n. 3, p. 239-251 How to Cite?
AbstractThree types of clinopyroxene megacrysts have been collected from Cenozoic basaltic rocks from Hainan Island and the Leizhou Peninsula in southern China. These megacrysts are dark green, black, and pale green in color, and are classified as Al-augite, Al-rich Fe-Na salite, and endiopside, respectively. Although they have different geochemical compositions, they all exhibit convex-upward, MREE-enriched patterns. The Al-augite megacrysts contain 8.45 to 9.01% Al2O3, 1.26 to 1.59% TiO2, 1.60 to 1.88% Na2O; have Mg# values of 69.5 to 75.4; and possess ΣREE contents of 24.7 to 26.9 ppm. Their LREE contents are enriched relative to the HREE (La/Ybn = 3.05 to 4.09). The Al-rich Fe-Na salite megacrysts have higher FeOT (10.4 to 11.4%) and Na2O (2.07 to 2.78%) contents, and lower Mg′ values (54.9 to 59.9), than do the Al-augite megacrysts. They contain high ΣREE contents (29.4 to 41.9 ppm) and have pronounced LREE/HREE enrichment (La/Ybn, = 3.86 to 20.6). Their Al2O3 contents (10.1 to 12.2%) are much higher than those of the Al-augite megacrysts (8.45 to 9.01%). One Al-rich Fe-Na salite megacryst has 87Sr/86Sr of 0.702913 ± 25 and 143Nd/144Nd of 0.512939 ± 20. The endiopside megacrysts possess high En and low Fs contents (Mg# values up to 89.3), and are characterized by high Cr2O3 (0.35 to 0.61%) and low Al2O3 (6.38 to 6.98%),TiO2 (0.30 to 0.48%), and ΣREE (7.71 ppm) contents. They have similar values of normalized LREE and HREE (La/Ybn = 1.09). One endiopside megacryst has 87Sr/86Sr of 0.703946 ± 40 and 143Nd/144Nd of 0.512816 ± 18. The Al-rich Fe-Na salite megacrysts in this study can be distinguished compositionally from Fe-Na salite megacrysts of previous studies. On the basis of the present study, these megacrysts are considered representative of a distinctive type of megacryst that may have a unique origin. Prior to this, endiopside megacrysts have not been described from alkaline basalts. A total of four types of clinopyroxene megacrysts now can be described from Cenozoic basaltic rocks worldwide - i.e. Al-augite, Fe-Na salite, Al-rich Fe-Na salite, and endiopside.
Persistent Identifierhttp://hdl.handle.net/10722/150995
ISSN
2015 Impact Factor: 2.365
2015 SCImago Journal Rankings: 1.248
References

 

DC FieldValueLanguage
dc.contributor.authorZhou, DJen_HK
dc.contributor.authorSun, Men_HK
dc.contributor.authorWang, YFen_HK
dc.contributor.authorMalpas, Jen_HK
dc.contributor.authorMoLan, Een_HK
dc.date.accessioned2012-06-26T06:15:36Z-
dc.date.available2012-06-26T06:15:36Z-
dc.date.issued1997en_HK
dc.identifier.citationInternational Geology Review, 1997, v. 39 n. 3, p. 239-251en_HK
dc.identifier.issn0020-6814en_HK
dc.identifier.urihttp://hdl.handle.net/10722/150995-
dc.description.abstractThree types of clinopyroxene megacrysts have been collected from Cenozoic basaltic rocks from Hainan Island and the Leizhou Peninsula in southern China. These megacrysts are dark green, black, and pale green in color, and are classified as Al-augite, Al-rich Fe-Na salite, and endiopside, respectively. Although they have different geochemical compositions, they all exhibit convex-upward, MREE-enriched patterns. The Al-augite megacrysts contain 8.45 to 9.01% Al2O3, 1.26 to 1.59% TiO2, 1.60 to 1.88% Na2O; have Mg# values of 69.5 to 75.4; and possess ΣREE contents of 24.7 to 26.9 ppm. Their LREE contents are enriched relative to the HREE (La/Ybn = 3.05 to 4.09). The Al-rich Fe-Na salite megacrysts have higher FeOT (10.4 to 11.4%) and Na2O (2.07 to 2.78%) contents, and lower Mg′ values (54.9 to 59.9), than do the Al-augite megacrysts. They contain high ΣREE contents (29.4 to 41.9 ppm) and have pronounced LREE/HREE enrichment (La/Ybn, = 3.86 to 20.6). Their Al2O3 contents (10.1 to 12.2%) are much higher than those of the Al-augite megacrysts (8.45 to 9.01%). One Al-rich Fe-Na salite megacryst has 87Sr/86Sr of 0.702913 ± 25 and 143Nd/144Nd of 0.512939 ± 20. The endiopside megacrysts possess high En and low Fs contents (Mg# values up to 89.3), and are characterized by high Cr2O3 (0.35 to 0.61%) and low Al2O3 (6.38 to 6.98%),TiO2 (0.30 to 0.48%), and ΣREE (7.71 ppm) contents. They have similar values of normalized LREE and HREE (La/Ybn = 1.09). One endiopside megacryst has 87Sr/86Sr of 0.703946 ± 40 and 143Nd/144Nd of 0.512816 ± 18. The Al-rich Fe-Na salite megacrysts in this study can be distinguished compositionally from Fe-Na salite megacrysts of previous studies. On the basis of the present study, these megacrysts are considered representative of a distinctive type of megacryst that may have a unique origin. Prior to this, endiopside megacrysts have not been described from alkaline basalts. A total of four types of clinopyroxene megacrysts now can be described from Cenozoic basaltic rocks worldwide - i.e. Al-augite, Fe-Na salite, Al-rich Fe-Na salite, and endiopside.en_HK
dc.languageengen_US
dc.publisherTaylor & Francis Inc. The Journal's web site is located at http://www.tandf.co.uk/journals/TIGRen_HK
dc.relation.ispartofInternational Geology Reviewen_HK
dc.titleClinopyroxene megacrysts in Cenozoic volcanic rocks from Hainan Island and the Leizhou Peninsula, Southern Chinaen_HK
dc.typeArticleen_HK
dc.identifier.emailSun, M: minsun@hku.hken_HK
dc.identifier.emailMalpas, J: jgmalpas@hku.hken_HK
dc.identifier.authoritySun, M=rp00780en_HK
dc.identifier.authorityMalpas, J=rp00059en_HK
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.scopuseid_2-s2.0-0031474856en_HK
dc.identifier.hkuros34270-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0031474856&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume39en_HK
dc.identifier.issue3en_HK
dc.identifier.spage239en_HK
dc.identifier.epage251en_HK
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridZhou, DJ=7403394310en_HK
dc.identifier.scopusauthoridSun, M=25932315800en_HK
dc.identifier.scopusauthoridWang, YF=22836907700en_HK
dc.identifier.scopusauthoridMalpas, J=7006136845en_HK
dc.identifier.scopusauthoridMoLan, E=6505718812en_HK
dc.customcontrol.immutablesml 130311-

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