Folding and fracturing of rocks adjacent to salt diapirs

Rowan, Mark G.; Muñoz, Josep Antón; Giles, Katherine A.; Roca, Eduard; Hearon, Thomas E.; Fiduk, J. Carl; Ferrer, Oriol; Fischer, Mark P.

doi:10.1016/j.jsg.2020.104187

Cited by 23 publications

(8 citation statements)

References 145 publications

(306 reference statements)

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“…Finally, areas across faults are characterised by a marked increase in fractures, folds and cleavage, often masking bedding/lamination due to large internal strain (Figures 13g,h and 18). In general, the lack of increased small‐scale deformation near salt structures but an increase near faults is entirely consistent with field observations in other salt provinces such as La Popa Basin in Mexico (Rowan et al., 2003), the Spanish Pyrenees and the Zagros Mountains in Iran (see Rowan et al., 2020 for a review).…”

Section: Discussionsupporting

confidence: 84%

“…Third, we interpret that the near‐salt anticline affecting the Umberatana along the SW side of the South Angepena diapir (Figure 10) was not caused by halokinetic drape folding. Although unclear, we hypothesise that its origin may be due to either: (a) remnants of pre‐existing folding before passive diapir rise juxtaposed it against salt; (b) fault‐related folding away from the salt with strata on one side of the fault subsequently juxtaposed against the salt by ongoing fault slip (see Rowan et al., 2020); or (c) shortening‐related deformation against non‐evaporitic Callanna Group rocks.…”

Section: Interpretation Of Field Geometries and Surface Datamentioning

confidence: 98%

“…metre‐scale or smaller) deformation in strata flanking the Callanna breccia bodies, suggesting that the Callanna lithologies were weaker than the surrounding rocks at the time of deformation (i.e. larger percentage of evaporites in the Callanna; see Rowan et al., 2020); (e) flanking folds, unconformities and conglomerates that we interpret as composite halokinetic sequences (CHS; see Giles & Rowan, 2012), displaying thickness and facies changes away from the Callanna interface and (f) short‐distance (tens of metres) changes of geometry/structural style in the areas where the Callanna breccia thins out, suggesting rapid changes in structural style between areas across diapirs and areas where country rocks were not pierced by salt. Our interpretation is in line with similar structures seen elsewhere in the Flinders Ranges and interpreted as long‐lived passive diapirs and salt sheets (Dalgarno & Johnson, 1968; Dyson, 1996; Hearon, Rowan, Giles, et al., 2015; Kernen et al., 2012, 2019; Rowan et al., 2019).…”

Section: Interpretation Of Field Geometries and Surface Datamentioning

confidence: 99%

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The transition from salt diapir to weld and thrust: Examples from the Northern Flinders Ranges in South Australia

Vidal-Royo¹,

Rowan

Ferrer

et al. 2021

Basin Research

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The interactions between salt diapirs, thrust welds and thrusts in contractional belts are poorly understood due to, first, the inability of seismic data to distinguish between thrusts and welds or resolve associated sub‐resolution deformation, and second, the paucity of good field examples. The Warraweena area in the Northern Flinders Ranges of South Australia contains examples of Neoproterozoic to Early Cambrian squeezed diapirs linked by steep reverse faults formed during the Delamerian Orogeny. Benefiting from good field exposures, we use geological mapping, cross‐section construction and conceptual structural models to assess the three‐dimensional geometry and evolution of the structures, the lateral transition from diapirs to linking faults and the variability of associated meso‐ and small‐scale deformation. Three discrete diapirs consist of narrow outcrops of Callanna Group megabreccia (Willouran in age) up to 5‐km long. Their diapiric origin is confirmed by local development of caprock, steepening of flanking strata in composite halokinetic sequences and reworked diapir and roof debris in adjacent strata. The surrounding rocks display only background levels of small‐scale deformation. In contrast, the linking faults show no evidence of precursor diapirism, have fault‐related anticlines up to 100s of m in wavelength in their hanging walls, and an associated increase in small‐scale deformation (i.e. millimetre to metre scale folds, fractures and shear fabrics). The transitions from diapirs to faults occur within less than 200 m as short thrust welds at the diapir terminations. The exposed structures are analogous to those found on the subsurface of other salt basins such as the Gulf of Mexico and the South Atlantic conjugate margins. The results of this work can aid geoscientists evaluating three‐way traps against squeezed diapirs, welds or faults, and can help them to predict the style and abundance of both halokinetic and small‐scale structures that are below seismic resolution.

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Section: Discussionsupporting

confidence: 84%

Section: Interpretation Of Field Geometries and Surface Datamentioning

confidence: 98%

Section: Interpretation Of Field Geometries and Surface Datamentioning

confidence: 99%

See 1 more Smart Citation

The transition from salt diapir to weld and thrust: Examples from the Northern Flinders Ranges in South Australia

Vidal-Royo¹,

Rowan

Ferrer

et al. 2021

Basin Research

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“…Moreover, periodic exposure of a diapir to erosion may create localised, angular, halokinetic unconformities that can later serve as barriers or conduits for fluid flow, and across which permeability and permeability anisotropy may change dramatically. In category three, although there is disagreement regarding the origin and timing of some types of deformation that occurs near‐salt structures (e.g., Alsop et al, 2000; Rowan et al, 2020), numerous studies have documented that kilometre‐ and larger‐scale faults often form in association with diapirs (e.g., Alsop, 1996; Carruthers et al, 2013; Coleman et al, 2018; Davison et al, 2000; Withjack & Scheiner, 1982) and that these faults play significant roles in the nearby fluid system structure; compartmentalising reservoirs or serving as conduits for hydrocarbon migration (e.g., Banga et al, 2002; Esch & Hanor, 1995; Steen et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

A two‐stage, fault‐controlled paleofluid system at the southern termination of the Gypsum Valley salt wall, Paradox Basin, Colorado, USA

et al. 2022

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This study combines field structural analysis with thin‐section petrography, U‐Pb dating, and strontium, carbon and oxygen isotopic analysis of calcite fracture fills to constrain the evolution of the 2‐5 km scale paleofluid system around the faulted, plunging fold nose comprising the southern termination of the Gypsum Valley salt wall in the Paradox Basin, U.S.A. Brittle deformation in this region began with the formation of a down‐to‐the‐northeast, counter‐regional fault and then progressed into jointing and faulting in a radial pattern, followed by jointing in a concentric pattern. Coupled with increases in fracture abundance toward the faults, multiple stages of mineralization suggest that the faults served as efficient and long‐lived conduits for vertical fluid migration. Although fracture cement textures and calcite colour are variable throughout the area, the distribution of these characteristics does not correlate with fracture orientation, relative age, stratigraphic or structural position. Irrespective of the type of calcite comprising the fracture cements, δ13C values average near −7‰ (VPDB), whereas δ18O values cluster into groups whose averages are roughly 6‰ apart, with the more negative grouping stratigraphically restricted to fracture cements in Jurassic rocks. The stratigraphic segregation of δ18O values suggests the paleofluid system contained two distinct paleofluids, a more recent one comprised of meteoric waters and an older one comprising brine that originated in Pennsylvanian strata. 87Sr/86Sr ratios in fracture‐filling calcite cements indicate that the older fluid underwent fluid‐rock interaction with Permian strata and that this evolved fluid migrated upwards along the faults until the Triassic or Jurassic. Thereafter, fluid migrating along the faults was more meteoric and appears to have migrated downward along the faults, where it interacted with Permian strata. Consistent U‐Pb dates from carbonates precipitated from the older fluid suggest this stage of the paleofluid system was active around 240 Ma. Local burial history models and published temperatures for fracture cements elsewhere in the basin suggest the younger stage of the paleofluid system occurred during the Latest Cretaceous to Oligocene. This study highlights the spatial and temporal complexity of fluid systems in the vicinity of salt structures and emphasises the need to interpret them through careful integration of high resolution stratigraphic and structural data in the context of evolving salt tectonics.

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“…Hancock, 1985;Tavani et al 2015), diapiric structures (e.g. Rowan et al 2020), post-orogenic collapse and stabilization of cratons (Mondal & Mamtani, 2016;Mondal et al 2020). Fracture formation often involves reactivation of the pre-existing host rock fabric under a compatible stress field (Donath, 1961;Hoek, 1964;Attewell & Sandford, 1974;Ikari et al 2015;Mazzarini et al 2019;.…”

Section: Introductionmentioning

confidence: 99%

Influence of fluid pressure changes on the reactivation potential of pre-existing fractures: a case study in the Archaean metavolcanics of the Chitradurga region, India

Bhowmick

Mondal

2021

Geol. Mag.

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The metavolcanics of Chitradurga region host numerous shallow crustal veins and fractures and faults of multiple orientations. Several high and low Pf cycles have been recorded in the region, leading to the reactivation of most of the pre-existing fractures for high Pf and selective reactivation of some well-oriented fractures under low Pf conditions. The pre-existing anisotropy (magnetic fabric) in the metavolcanics acted as the most prominent planar fabric for fracture propagation and vein emplacement under both conditions, thereby attaining maximum vein thickness. In this study, we emphasize the reactivation propensity of these pre-existing fracture planes under conditions of fluid pressure variation, related to the high and low Pf cycles. Multiple cycles of fluid-induced fracture reactivation make it difficult to quantify the maximum/minimum fluid pressure magnitudes. However, in this study we use the most appropriate fluid pressure magnitudes mathematically feasible for a shallow crustal depth of ∼2.4 km. We determine the changes in the reactivation potential with states of stress for the respective fracture orientations under both high and low Pf conditions. Dependence of fluid pressure variation on the opening angle of the fractures is also monitored. Finally, we comment on the failure mode and deformation behaviour of the fractures within the prevailing stress field inducing volumetric changes at the time of deformation. We find that deformation behaviour is directly related to the dip of the fracture planes.

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Folding and fracturing of rocks adjacent to salt diapirs

Cited by 23 publications

References 145 publications

The transition from salt diapir to weld and thrust: Examples from the Northern Flinders Ranges in South Australia

The transition from salt diapir to weld and thrust: Examples from the Northern Flinders Ranges in South Australia

A two‐stage, fault‐controlled paleofluid system at the southern termination of the Gypsum Valley salt wall, Paradox Basin, Colorado, USA

Influence of fluid pressure changes on the reactivation potential of pre-existing fractures: a case study in the Archaean metavolcanics of the Chitradurga region, India

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