Sequential growth of deformation bands in carbonate grainstones in the hangingwall of an active growth fault: Implications for deformation mechanisms in different tectonic regimes

Abstract

a b s t r a c tDeformation bands in porous sandstones have been extensively studied for four decades, whereas comparatively less is known about deformation bands in porous carbonate rocks, particularly in extensional settings. Here, we investigate porous grainstones of the Globigerina Limestone Formation in Malta, which contain several types of deformation bands in the hangingwall of the Maghlaq Fault: (i) bed-parallel pure compaction bands (PCB); (ii) pressure solution-dominated compactive shear bands (SCSB) and iii) cataclasis-dominated compactive shear bands (CCSB). Geometric and kinematic analyses show that the bands formed sequentially in the hangingwall of the evolving Maghlaq growth fault. PCBs formed first due to fault-controlled subsidence and vertical loading; a (semi-)tectonic control on PCB formation is thus documented for the first time in an extensional setting. Pressure solution (dominating SCSBs) and cataclasis (dominating CCSBs) appear to have operated separately, and not in concert. Our findings therefore suggest that, in some carbonate rocks, cataclasis within deformation bands may develop irrespective of whether pressure solution processes are involved. We suggest this may be related to stress state, and that whereas pressure solution is a significant facilitator of grain size reduction in contractional settings, grain size reduction within deformation bands in extensional settings is less dependent on pressure solution processes.

Mechanical behavior, failure mode, and transport properties in a porous carbonate

“…Rotevatn et al . [] in their recent work only found compaction bands in a rather limited area around an active fault and concluded that these structures could only grow in zones with different and specific host rock properties. Existing laboratory studies support this idea.…”

“…Both field [ Mollema and Antonellini , ; Schultz et al ., ; Eichhubl et al ., ], laboratory [ Baud et al ., ; Tembe et al ., ], and theoretical [ Wang et al ., ] studies suggest that compaction bands developed in relatively homogeneous high porosity (typically >20%) sandstone. Significantly less work was dedicated to the occurrence of compaction bands in limestone formations, even if several field examples were reported in Italy [ Tondi et al ., ; Rustichelli et al ., ] and more recently in Cyprus [ Rotevatn et al ., ]. Rotevatn et al .…”

Inelastic Compaction in High‐Porosity Limestone Monitored Using Acoustic Emissions

“…An increasing number of experimental studies have reported compaction localization in carbonates (Arroyo, Castellanza, & Nova, ; Baxevanis et al, ; Cilona et al, , ) but to date, the link between these results and the field examples (Tondi et al, ; Rustichelli et al, ; Rotevatn et al, ) remains unclear. Our new AE location data on SML show without ambiguity that compaction localization occurred in this rock.…”

Investigating the controls on fault rock distribution in normal faulted shallow burial limestones, Malta, and the implications for fluid flow

“…Cataclasis in carbonate rocks is commonly accompanied by grain boundary pressure solution, documented at a variety of burial depths (e.g. Cilona et al, 2012;Viti et al, 2014;Rotevatn et al, 2016). Additionally, the presence of phyllosilicate material within the faulted stratigraphy have been shown to produce alternative fault rock textures to those observed in Malta.…”

“…However, the lithofacies juxtaposition is the same as for the VLF; a GL hanging wall juxtaposed against an Xlendi footwall. The lack of a distributed damage zone may be due to strain accommodation via the formation of an intense array of deformation bands in the hanging wall, as described byRotevatn et al (2016), combined with the junction with a series of conjugate slip surfaces that are parallel to the principal orientations of this deformation band array. Due to there being no distributed damage zone, cataclasite at the 50 m displacement fault zone is more continuous than for the m and 90 m displacement fault zones (FRC = 0.8, 0.15, and 0.47 respectively).…”