[Home ] [Archive]    
:: Main :: About :: Current Issue :: Archive :: Search :: Submit :: Contact ::
:: Volume 25, Number 2 (7-2017) ::
2017, 25(2): 367-380 Back to browse issues page
Geochemical and textural characteristics of plagioclase as evidence for open-system processes: Case study from Bazman volcano (SE Iran)
Abstract:   (59 Views)

Textural and Geochemical characteristics of plagioclase phenocrysts in Andesitic and basaltic rocks of Bazman volcano (from Makran volcanic arc) show evidence of interaction between basaltic and andesitic magmas. Plagioclase phenocrysts in andesites and basalts are composed of three major parts of core, mantle and rim, with similarity of the anorthite contents in cores and mantles. The cores of the phenocrysts, which seem to be in equilibrium with the andesitic magma rather than the basaltic one (­An39-60), exhibit different styles of oscillatory zoning. The trace element (Fe, Mg, Sr, Ba) concentrations in different zones of the cores also remain constant or change proportional to the anorthite content and may exhibit dynamic processes in the magma reservoir during the core formation in andesitic magma. The engulfed cores and sieve texture in the mantles of plagioclases may have formed in response to changes in temperature and composition of the surrounding melt. Elevated anorthite content of plagioclases (An40-65), accompanied by jump of the Fe, and Mg content, in addition to change in the  patterns of Sr, and Ba in the sieve-textured mantle may show the replenishment of magma reservoir by new basaltic magma. Increase of An  in the rim of basaltic plagioclases (from An53 to An74) and decrease of An in the rims of andesitic plagioclases  (from An69 to An53), indicate that the two magmas gained their contrasting compositional identity most probably as a result of sudden upward movement. These constraints, along with other evidence like weakly-zoned pyroxene microphenocrysts with rounded rims, suggest that the rocks originated in the course of replenishment of mafic melts either with chemical or/and thermal interaction of the melts.

Keywords: Makran, Open system processes, trace element, mineral zoning, magma replenishment.
Full-Text [PDF 137 kb]   (49 Downloads)    
Type of Study: Research | Subject: Special
Received: 2017/06/13 | Accepted: 2017/06/13 | Published: 2017/06/13
Add your comments about this article
Your username or email:

Write the security code in the box >

XML   Persian Abstract   Print

Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:

Geochemical and textural characteristics of plagioclase as evidence for open-system processes: Case study from Bazman volcano (SE Iran). Iranian Journal of Crystallography and Mineralogy. 2017; 25 (2) :367-380
URL: http://ijcm.ir/article-1-796-en.html
Volume 25, Number 2 (7-2017) Back to browse issues page
مجله بلورشناسی و کانی شناسی ایران Iranian Journal of Crystallography and Mineralogy
Persian site map - English site map - Created in 0.048 seconds with 793 queries by yektaweb 3426