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Article: Polymetamorphism of mafic granulites in the North China Craton: Textural and thermobarometric evidence and tectonic implications

TitlePolymetamorphism of mafic granulites in the North China Craton: Textural and thermobarometric evidence and tectonic implications
Authors
Issue Date2001
PublisherGeological Society Publishing House. The Journal's web site is located at http://www.geolsoc.org.uk/sp
Citation
Geological Society Special Publication, 2001, v. 184, p. 323-342 How to Cite?
AbstractThe basement of the North China Craton can be divided into the Archaean Eastern and Western Blocks, separated by major Palaeoproterozoic terrane boundaries that roughly correspond with the limits of a 100-300 km wide zone, named the Trans-North China Orogen. Some mafic granulites from the orogen and adjoining areas in the Eastern and Western Blocks preserve textural evidence for two granulite facies events involving contrasting P-T paths. The first event is characterized by three distinct mineral assemblages, M1a to M1c. M1a is represented by fine-grained orthopyroxene + clinopyroxene + plagioclase ± quartz, which is surrounded by the M1'b garnet + quartz symplectite, which itself is mantled by the M1c plagioclase + biotite symplectite. These assemblages and their P-T estimates define an anticlockwise P-T path, with peak metamorphism of 7.0-8.0 kbar and 800-850°C (M1a) followed by isobaric cooling to 700-750°C (M1b) and pressure-decreasing cooling to 630-700°C (M1c). The second event also includes three mineral assemblages, M2a to M2c. M2a represents growths of garnet porphyroblasts and matrix orthopyroxene + plagioclase + clinopyroxene + quartz; M2b consists of orthopyroxene + plagioclase ± clinopyroxene symplectites or coronas; and M2c is represented by plagioclase + hornblende symplectites. These assemblages and their P-T estimates define a clockwise P-T path, with peak metamorphism of 9.2-9.8 kbar and 820-850°C (M2a), followed by near-isothermal decompression (M2b) of 7.0-7.6 kbar and 760-810°C and cooling (M2c) to 690-760°C. The isobaric cooling, anticlockwise, P-T path of the first granulite facies event is similar to the P-T paths inferred for the c. 2.5 Ga metamorphosed mafic granulites from the Eastern and Western Blocks, whereas the near-isothermal decompression, clockwise, P-T path of the second granulite facies event is similar to the P-T paths inferred for the c. 1.8 Ga metamorphosed khondalite series in the Western Block and some mafic granulites in the Trans-North China Orogen. These relations suggest that the polymetamorphic granulites were derived from the reworking of the 2.5 Ga metamorphosed granulites during the 1.8 Ga collision between the Eastern and Western Blocks that resulted in the final amalgamation of the North China Craton.
Persistent Identifierhttp://hdl.handle.net/10722/72892
ISSN
2015 SCImago Journal Rankings: 0.747
References

 

DC FieldValueLanguage
dc.contributor.authorZhao, Gen_HK
dc.contributor.authorCawood, PAen_HK
dc.contributor.authorWilde, SAen_HK
dc.contributor.authorSun, Men_HK
dc.date.accessioned2010-09-06T06:46:05Z-
dc.date.available2010-09-06T06:46:05Z-
dc.date.issued2001en_HK
dc.identifier.citationGeological Society Special Publication, 2001, v. 184, p. 323-342en_HK
dc.identifier.issn0305-8719en_HK
dc.identifier.urihttp://hdl.handle.net/10722/72892-
dc.description.abstractThe basement of the North China Craton can be divided into the Archaean Eastern and Western Blocks, separated by major Palaeoproterozoic terrane boundaries that roughly correspond with the limits of a 100-300 km wide zone, named the Trans-North China Orogen. Some mafic granulites from the orogen and adjoining areas in the Eastern and Western Blocks preserve textural evidence for two granulite facies events involving contrasting P-T paths. The first event is characterized by three distinct mineral assemblages, M1a to M1c. M1a is represented by fine-grained orthopyroxene + clinopyroxene + plagioclase ± quartz, which is surrounded by the M1'b garnet + quartz symplectite, which itself is mantled by the M1c plagioclase + biotite symplectite. These assemblages and their P-T estimates define an anticlockwise P-T path, with peak metamorphism of 7.0-8.0 kbar and 800-850°C (M1a) followed by isobaric cooling to 700-750°C (M1b) and pressure-decreasing cooling to 630-700°C (M1c). The second event also includes three mineral assemblages, M2a to M2c. M2a represents growths of garnet porphyroblasts and matrix orthopyroxene + plagioclase + clinopyroxene + quartz; M2b consists of orthopyroxene + plagioclase ± clinopyroxene symplectites or coronas; and M2c is represented by plagioclase + hornblende symplectites. These assemblages and their P-T estimates define a clockwise P-T path, with peak metamorphism of 9.2-9.8 kbar and 820-850°C (M2a), followed by near-isothermal decompression (M2b) of 7.0-7.6 kbar and 760-810°C and cooling (M2c) to 690-760°C. The isobaric cooling, anticlockwise, P-T path of the first granulite facies event is similar to the P-T paths inferred for the c. 2.5 Ga metamorphosed mafic granulites from the Eastern and Western Blocks, whereas the near-isothermal decompression, clockwise, P-T path of the second granulite facies event is similar to the P-T paths inferred for the c. 1.8 Ga metamorphosed khondalite series in the Western Block and some mafic granulites in the Trans-North China Orogen. These relations suggest that the polymetamorphic granulites were derived from the reworking of the 2.5 Ga metamorphosed granulites during the 1.8 Ga collision between the Eastern and Western Blocks that resulted in the final amalgamation of the North China Craton.en_HK
dc.languageengen_HK
dc.publisherGeological Society Publishing House. The Journal's web site is located at http://www.geolsoc.org.uk/spen_HK
dc.relation.ispartofGeological Society Special Publicationen_HK
dc.titlePolymetamorphism of mafic granulites in the North China Craton: Textural and thermobarometric evidence and tectonic implicationsen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0305-8719&volume=184&spage=323&epage=242&date=2001&atitle=Polymetamorphism+of+mafic+granulites+in+the+North+China+Craton:+textural+and+thermobarometric+evidence+and+tectonic+implications.en_HK
dc.identifier.emailZhao, G: gzhao@hkucc.hku.hken_HK
dc.identifier.emailSun, M: minsun@hku.hken_HK
dc.identifier.authorityZhao, G=rp00842en_HK
dc.identifier.authoritySun, M=rp00780en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1144/GSL.SP.2001.184.01.16en_HK
dc.identifier.scopuseid_2-s2.0-0035176519en_HK
dc.identifier.hkuros57274en_HK
dc.identifier.hkuros58103-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0035176519&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume184en_HK
dc.identifier.spage323en_HK
dc.identifier.epage342en_HK
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridZhao, G=7403296321en_HK
dc.identifier.scopusauthoridCawood, PA=7004146041en_HK
dc.identifier.scopusauthoridWilde, SA=35254758600en_HK
dc.identifier.scopusauthoridSun, M=25932315800en_HK

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