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Distinguishing peperite from other sediment-matrix igneous breccias: lessons from the Iberian Pyrite Belt
Citation
Rosa, CJP and McPhie, J and Relvas, JMRS, Distinguishing peperite from other sediment-matrix igneous breccias: lessons from the Iberian Pyrite Belt, Journal of Volcanology and Geothermal Research, 315 pp. 28-39. ISSN 0377-0273 (2016) [Refereed Article]
Copyright Statement
Copyright 2016 Elsevier B.V.
DOI: doi:10.1016/j.jvolgeores.2016.02.007
Abstract
Breccias composed of coarse monomictic porphyritic igneous clasts and fine-grained matrix are common in subaqueous volcanic successions. We use the descriptive name "sediment-matrix igneous breccia" for this facies and have recognized at least five different origins among examples in the Iberian Pyrite Belt: (1) peperite; (2) sediment-infill volcanic breccia; (3) mud-matrix resedimented hyaloclastite; (4) mud-rich water-settled fiamme breccia; and (5) apparent sediment-matrix igneous breccia. Because the components and textures are similar, discriminating among the different origins can be very difficult. Both peperite and sediment-infill volcanic breccia can occur along top contacts of thick intervals of felsic coherent and monomictic breccia facies. The presence of peperite indicates that the contact is intrusive, whereas the presence of sediment-infill volcanic breccia indicates that the contact is depositional. Hence, correct distinction between peperite and sediment-infill volcanic breccia is an important means of discriminating felsic intrusions from felsic lavas and domes. The distinction underpins the reconstruction of volcanic centers and facies architecture, and the ordering of volcanic, intrusive, sedimentary and mineralizing events in ancient submarine volcanic successions. In addition, in volcanic-hosted massive sulfide districts such as the Iberian Pyrite Belt, paleoseafloor positions are considered highly prospective for massive sulfide ore bodies. Correct interpretation of sediment-matrix igneous breccias is also important in this context, because sediment-infill volcanic breccia, mud-matrix resedimented hyaloclastite and mud-rich water-settled fiamme breccia all form or are deposited at the seafloor, and hence delineate paleoseafloor positions. In contrast, peperite and apparent sediment-matrix igneous breccias form subsurface and do not delineate paleoseafloor positions.
Item Details
Item Type: | Refereed Article |
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Keywords: | Iberian Pyrite Belt, peperite, sediment-matrix breccia, VHMS deposit, peperite, sediment-infill volcanic breccias |
Research Division: | Earth Sciences |
Research Group: | Geology |
Research Field: | Volcanology |
Objective Division: | Expanding Knowledge |
Objective Group: | Expanding knowledge |
Objective Field: | Expanding knowledge in the earth sciences |
UTAS Author: | McPhie, J (Professor Jocelyn McPhie) |
ID Code: | 115043 |
Year Published: | 2016 |
Funding Support: | Australian Research Council (SC9700069) |
Web of Science® Times Cited: | 9 |
Deposited By: | Ecology and Biodiversity |
Deposited On: | 2017-03-06 |
Last Modified: | 2018-04-20 |
Downloads: | 0 |
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