Scientific article
Open access

Ophiolite complex from La Tetilla, southwestern Colombia, South America

Published inThe Journal of Geology, vol. 95, p. 377-395
Publication date1987

A disrupted ophiolitic complex of Cretaceous age from the Romeral fault zone in the southwestern Colombian Andes occurs in the La Tetilla area near Popayan. It represents a peculiar association of low-Ti and high-Ti tholeiitic basalts among the ophiolitic complexes from the Romeral Zone. It includes: (1) A main sequence (with incipient metamorphism under prehnite-pumpellyite to greenschist facies conditions) con- sisting in ascending order of cumulus wehrlite and gabbro, massive gabbro, and basaltic and doleritic lavas and breccias. The basalts are characterized by the crystallization of clinopyroxene prior to plagioclase (cpx-phyric basalt group) and have a primitive low-Ti tholeiite composition (Mg numbers between 70.6 and 65.4). The clinopyroxene chemistry is consistent with this magmatic affinity. The plutonic rocks can be related to a similar low-Ti tholeiitic magma. (2) A sequence of pervasively metamorphosed basalts (with greenschist facies metamorphism of oceanic type) structurally underlies the main sequence. Basalts are characterized by the order of crystallization: ol-plag-cpx (plag-phyric basalt group) and high-Ti tholeiitic chemistry. (3) A sequence of foliated metabasalts (with greenschist to amphibolite transition metamorphism) including low-Ti picritic and high-Ti tholeiitic basalts. Different tectonic settings can be inferred from the petrological features of the recognized magmatic sequences, but constraints by the regional setting are still insufficient to permit a unique interpretation. The one proposed tentatively is that the low-Ti basalts and the plutonics, which are probably cogenetic, formed in an intraoceanic arc at an early stage of develop ment, similar to many supra-subduction zone ophiolites. The high-Ti basalts could have been associated with the former sequence prior to the tectonic emplacement, and could represent remnants of an ocean island volcanism.

  • Ophiolites: Colombie
  • Swiss National Science Foundation - 2.895.083
  • Swiss National Science Foundation - 2.634.085
Citation (ISO format)
SPADEA, P. et al. Ophiolite complex from La Tetilla, southwestern Colombia, South America. In: The Journal of Geology, 1987, vol. 95, p. 377–395.
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Article (Published version)
  • PID : unige:143455
ISSN of the journal0022-1376

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