Open AccessPetrologic features of mesoproterozoic lamprophyric dykes from Montevideo (Piedra Alta terrane, South Uruguay)
Author(s) -
Rossana Muzio,
Natália Martino,
Elena Peel
Publication year - 2021
Publication title -
earth sciences research journal/earth sciences research journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.181
H-Index - 15
eISSN - 2339-3459
pISSN - 1794-6190
DOI - 10.15446/esrj.v25n2.89652
Subject(s) - phlogopite , porphyritic , geology , mafic , geochemistry , amphibole , pyroxene , augite , biotite , leucite , plagioclase , olivine , paleontology , chemistry , ceramic , quartz , organic chemistry , mantle (geology)
Mafic dykes of lamprophyric affinity cropping out along the coastal area of Montevideo city are described. These dykes trend N75º-85º and crosscut 2.1 Ga Paleoproterozoic metamorphic units of the Rio de la Plata craton. They show mainly porphyritic textures with phlogopite and clinopyroxene macrocrysts in a groundmass composed of carbonates, phlogopite, augite, and feldspathoids. Ocellar structures filled by leucite, carbonates and fibrous alkaline amphibole are present. The mineralogical assembly allows their classification as lamprophyres (minettes), but according to their chemical nature, they can be classified as alkaline lamprophyres. A crystallization age of 1.42 Ga, by Ar-Ar method (on biotite/phlogopite) was obtained.