Journal of


  (Formerly Journal of the Czech Geological Society)

< previous | issue | next >
Received: 15 March 2016
Accepted: 24 August 2017
Online: 19 November 2017
H. Editor: V. Rapprich
  full text (PDF, 1.76 MB)
Export to RIS
Export to BibTeX
Export to Mendeley

Original Paper

Nadeesha S. Madugalla, Amarasooriya Pitawala, Geeth Manthilake

Primary and secondary textures of dolomite in Eppawala carbonatites, Sri Lanka: implications for their petrogenetic history

Journal of Geosciences, volume 62 (2017), issue 3, 187 - 200


Textural studies of carbonate minerals over the past three decades revealed that their textures are useful tool for understanding of petrogenesis of carbonatites. Petrographic, cathodoluminescence (CL) and electron-microprobe studies on textures of calcite and dolomite were performed for interpretation of evolution of Eppawala carbonatites in Sri Lanka. The studied carbonatites are dominated by calcite with subordinate dolomite. Calcites occur in two different morphological forms, reflecting two generations: as grains with dolomite inclusions (type-1) and dolomite-free (type-2) ones. Dolomites were subdivided into five distinct morphological types: randomly distributed, coarse-grained dolomite (type-1), rod-shaped or vermicular dolomite microcrysts within the type-1 calcite (type-2), inclusions of dolomite within the type 1 calcite forming plug- or wedge-shaped arrangements (type-3), dolomite microcrysts along the grain boundaries of type 1 calcite (type-4) and clusters of dolomite crosscutting the type 1 calcite (type-5).
The geochemical results indicate that these five morphological types accounts for three different generations of dolomites. Type-1 dolomite and type-1 calcite are interpreted as primary magmatic. Type-2 and type-3 represent exsolved dolomite formed by exsolution from type-1 calcite. Type-4 and type-5 dolomites are recrystallized and reorganized dolomites of exsolved type-2 and type-3 dolomites. Type-2 calcite reflects later recrystallization event. The composition of type-1 calcite indicates minimum temperatures of exsolution of c. 650 °C. The exsolution and recrystallization kinetics reflected the equilibration of carbonatite magma at two crustal depths during the petrogenesis of Eppawala carbonatite. The re-localization may have been related to the deformations experienced by the country rocks.

Journal of Geosciences, Published by © Czech Geological Society, with support from the Czech Geological Survey.
Webdesign inspired by aTeo. Hosted at the server of the Institute of Petrology and Structural Geology, Charles University, Prague.
ISSN: 1803-1943 (online), 1802-6222 (print)
email: jgeosci(at)
cover_rotated.gif, 15kB

SNIP (Scopus, 2022): 0.826

IF (WoS, 2022): 1.4

5 YEAR IF (WoS, 2022): 1.8

Policy: Open Access

ISSN: 1802-6222

E-ISSN: 1803-1943