RECONNAISSANCE STUDY OF TRACE-ELEMENT ZONATION IN GARNET FROM THE CENTRAL STRUCTURAL DOMAIN, NORTHEASTERN BRAZIL - AN EXAMPLE OF POLYMETAMORPHIC GROWTH

被引：5

作者：

DELIMA, ES

VANNUCCI, R

BOTTAZZI, P

OTTOLINI, L

机构：

[1] Departamento de Geologia, Universidade Federal de Pernambuco, Recife, PEI

[2] Dipartimento di Scienze della Terra, Pavia, Via Bassi 4

[3] CNR-Centro di Studio per la Cristallochimica e la Cristallografia, Pavia, Via Bassi 4

来源：

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES | 1995年 / 8卷 / 3-4期

关键词：

D O I：

10.1016/0895-9811(95)00016-9

中图分类号：

P [天文学、地球科学];

学科分类号：

07 ;

摘要：

Trace-element and major-element zoning in garnet from regionally metamorphosed rocks of the Serido Formation, Central Structural Domain, Northeastern Brazil, was measured with an ion- and electron-microprobe. The distribution of major and trace elements is different in the three garnets analyzed. Two of them (garnet SS-21 and SV-2) show a zoning profile with respect to some major elements, whereas the third garnet (SS-40) presents a fairly flat profile. Trace-element zoning is also different in these garnets and can be divided into: I) elements which show an approximately Bat profile; II) elements which show an approximately flat profile, but present a sharp step-like increase at boundary core/rim; III) elements which show a continuous increase or decrease from core to rim; and III) elements which show an irregular behavior. The discontinuities in Ti, V and Eu/Eu* profiles are interpreted as indications of overgrowth of garnet during a second episode of metamorphism. The inflections (Y and Cr) and hump (Sc) probably represent a partial re-equilibration of these elements during the second metamorphic event. The flat profiles in major elements indicate re-equilibration (diffusion) during the second metamorphism, at P/T conditions of high amphibolite facies.

引用

页码：315 / 324

页数：10

共 22 条

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