Mathiasite-loveringite and priderite in mantle xenoliths from the Alto Paranaiba Igneous Province, Brazil: genesis and constraints on mantle metasomatism

Author(s)

Almeida, Vidya V. ^{[1, 2]} ; Janasi, Valdecir de A. ^[1] ; Svisero, Darcy P. ^[1] ; Nannini, Felix ^{[1, 3]}

Affiliation

^[1] Univ Sao Paulo, Inst Geociencias, Dept Mineral & Geotect, BR-05508080 Sao Paulo - Brazil

^[2] Geol Survey Brazil, CPRM, SUREG SP, BR-01304010 Sao Paulo - Brazil

^[3] Geol Survey Brazil, CPRM, SUREG RE, BR-50770011 Recife, PE - Brazil

• Document type: Journal article
• Source: CENTRAL EUROPEAN JOURNAL OF GEOSCIENCES; v. 6, n. 4, p. 614-632, DEC 2014.
• Web of Science Citations: 4

Abstract

Alkali-bearing Ti oxides were identified in mantle xenoliths enclosed in kimberlite-like rocks from Limeira 1 alkaline intrusion from the Alto Paranaiba Igneous Province, southeastern Brazil. The metasomatic mineral assemblages include mathiasite-loveringite and priderite associated with clinopyroxene, phlogopite, ilmenite and rutile. Mathiasite-loveringite (55-60 wt.% TiO2; 5.2-6.7 wt.% ZrO2) occurs in peridotite xenoliths rimming chromite (similar to 50 wt.% Cr2O3) and subordinate ilmenite (12-13.4 wt.% MgO) in double reaction rim coronas. Priderite (Ba/(K+Ba)< 0.05) occurs in phlogopite-rich xenoliths as lamellae within Mg-ilmenite (8.4-9.8 wt.% MgO) or as intergrowths in rutile crystals that may be included in sagenitic phlogopite. Mathiasite-loveringite was formed by reaction of peridotite primary minerals with alkaline melts. The priderite was formed by reaction of peridotite minerals with ultrapotassic melts. Disequilibrium textures and chemical zoning of associated minerals suggest that the metasomatic reactions responsible for the formation of the alkali-bearing Ti oxides took place shortly prior the entrainment of the xenoliths in the host magma, and is not connected to old (Proterozoic) mantle enrichment events. (AU)

• FAPESP's process: 06/01925-4 - Mineralogy and petrology of mantle xenoliths from Ubatuba (SP) and Coromandel (MG) regions
• Grantee: Vidya Vieira de Almeida
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 07/00635-5 - Contributions from the mantle and different crust reservoirs to the Neoproterozoic granitic magmatism in SE Brazil
• Grantee: Valdecir de Assis Janasi
• Support Opportunities: Regular Research Grants