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dc.contributor.authorYu, Xun
Lee, Cin-Ty A.
Chen, Li-Hui
Zeng, Gang
dc.date.accessioned 2016-01-28T18:32:41Z
dc.date.available 2016-01-28T18:32:41Z
dc.date.issued 2015
dc.identifier.citation Yu, Xun, Lee, Cin-Ty A., Chen, Li-Hui, et al.. "Magmatic recharge in continental flood basalts: Insights from the Chifeng igneous province in Inner Mongolia." Geochemistry, Geophysics, Geosystems, 16, no. 7 (2015) American Geophysical Union: 2082-2096. http://dx.doi.org/10.1002/2015GC005805.
dc.identifier.urihttps://hdl.handle.net/1911/88233
dc.description.abstract Eruptive sequences can be used as windows into the thermal and chemical evolution of magma chambers. We examined a continuous vertical section of the Baichahe basalt flow associated with the late Cenozoic Chifeng flood basalt in Inner Mongolia, North China. From oldest to youngest, MgO increases, K2O, light rare earths and other incompatible elements decrease, and Nb/La and radiogenic Pb isotopic ratios increase, all of which indicate increasing primitiveness and decreasing contribution of crustal contamination with time. The variable Pb isotope and incompatible element ratios require a component of crustal contamination, most likely of the lower crust (unradiogenic Pb, and low Ce/Pb), in the earliest lavas. Fractional crystallization can explain some of the elemental systematics, but alone cannot explain variable incompatible element ratios and Pb isotopes, nor the temporal trend to more primitive compositions. Crustal assimilation with or without fractional crystallization also cannot explain all the elemental systematics. We find instead that recharge by a primitive magma, in combination with fractional crystallization and decreasing rates of crustal assimilation, is needed to explain the observed geochemical systematics. Our observations suggest that the delivery of fresh basalt to the magma chamber must increase at rates faster than the crust can be assimilated or that the rates of crustal assimilation must decrease. However, progressive addition of primitive magma should heat up the crust and lead to more crustal assimilation. We suggest that during the initial stages of forming a magma chamber, the magma cools and develops an outer crystalline rind of mafic to ultramafic cumulates. This results in a thickening nonconvecting chemical boundary layer, which serves to insulate the magma chamber from further assimilation of crust and cooling, the latter resulting in the reduction of crystallization rates and the buffering of magma compositions at more primitive compositions. We show that certain segments of other large igneous provinces also display an evolution toward more primitive magmas with time, indicating that magmatic recharge may be a common feature of basaltic magma chambers.
dc.language.iso eng
dc.publisher American Geophysical Union
dc.rights Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
dc.title Magmatic recharge in continental flood basalts: Insights from the Chifeng igneous province in Inner Mongolia
dc.type Journal article
dc.citation.journalTitle Geochemistry, Geophysics, Geosystems
dc.subject.keywordmagma chamber
recharge
continental flood basalt
crustal contamination
dc.citation.volumeNumber 16
dc.citation.issueNumber 7
dc.type.dcmi Text
dc.identifier.doihttp://dx.doi.org/10.1002/2015GC005805
dc.type.publication publisher version
dc.citation.firstpage 2082
dc.citation.lastpage 2096


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