The structure and formation of mud volcano summit calderas

Robert J. Evans*, Simon A. Stewart, Richard J. Davies

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Circular depressions bounded by inward-dipping faults found at the upper terminations of large mud volcano systems (>500 m diameter) are termed 'mud volcano summit calderas'. From new mapping and comparison with previously identified examples we describe a series of common structural and morphological features found at a number of calderas and propose a mechanism for caldera formation. A typical example consists of concentric deformational and volcanic zones including an outermost topographic rim, inward-dipping circular fault system, 'moat' and raised central 'pedestal' of freshly extruded mud volcanic sediment. This distinctive 'moat and pedestal' morphology can be explained in terms of the quantity and rheology of extruded mud, and appears characteristic of calderas from the South Caspian Basin and elsewhere. The association of fresh mud volcanic deposits with the calderas in combination with extensive literature on caldera modelling leads us to conclude that the most likely causal mechanism is subsidence as a result of evacuation of fluids and sediment from shallow structural levels during eruptions. Summit calderas mapped in this study characterize dormant periods of mud volcanism in subaerial and submarine settings, and appear to be a common structural element in the extrusive domain of mud volcano systems.

Original languageEnglish
Pages (from-to)769-780
Number of pages12
JournalJournal of the Geological Society
Volume165
Issue number4
DOIs
Publication statusPublished - Jul 2008
Externally publishedYes

ASJC Scopus subject areas

  • Geology

Fingerprint

Dive into the research topics of 'The structure and formation of mud volcano summit calderas'. Together they form a unique fingerprint.

Cite this