Discussion of “Crustal fluid contamination in the Bushveld Complex, South Africa: An analogue for subduction zone fluid migration by Benson, E., Connolly, J.A.D. and Boudreau, A.E. (2020)

ABSTRACT

The principal thesis of the discussion, i.e. that the layered ultramafic-mafic component of the Bushveld Complex, or Rustenburg Layered Suite (RLS), has been subjected to at least some fluid contamination is unquestionable. The logic that it is specifically the Main Zone, i.e. the thickest component of the RLS which is located within the approximate centre of the intrusion where comparatively high rates of fluid interaction have occurred, rather than the Marginal Zone or even the Lower Zone, seems illogical. Two lines of field evidence are offered in support of the contamination of the Main Zone: the occurrence of a breccia pipe (which is located in the Critical Zone) and the discordant, ‘pipe-like’ bodies which are unusually prevalent in specific parts of the RLS. Some of the issues we discuss here are of a procedural nature, specifically, the lack of referencing of our original articles pertaining to the discordant bodies. This has resulted in a series of generalizations which do not hold up to scrutiny. We also discuss our work on the Main Zone which has similarly been ignored and describe why it is not compatible with the new hypothesis.

KEYWORDS:

• Bushveld Complex
• discordant bodies
• Main Zone
• staging chamber

Disclosure statement

No potential conflict of interest was reported by the author.