Introduction to special section: Balancing, restoration, and palinspastic reconstruction

Methods to quantify deformation and reverse the process of strain as a mode to illustrate geologic evolution through time have been previously used for a number of decades. Early efforts on the quantification of bed reconstruction were completed either by manually weighing the sections on delicate balances and obtaining the average height and thickness of strata to be reconstructed by applying a scale factor (Chamberlin, 1910), or by hand-drafting sections with conserved bed length between the folded and faulted sedimentary layers, mainly in a 2D cross section (Bally et al., 1966; Dahlstrom, 1969) or map framework (Dennison and Woodward, 1963). Cross-section techniques initially applied to contractional thrust and fold belts and have proven useful in other structural settings, such as extensional and inverted domains. Development of 3D techniques enabled the analysis of strike-slip and salt tectonics where out-of-plane changes of rock volume could be addressed. Through the years, the widespread application of these techniques to predict fault and horizon geometry at depth has generated newer approaches and more sophisticated algorithms, and it has also demonstrated the potential of structural modeling techniques (e.g., construction of balanced sections, palinspastic reconstruction, kinematic and geomechanical restoration, and forward modeling) in reducing the risk and uncertainty associated with the interpretation of geophysical/geological dat

Analysis of Salt-Sediment Interaction Associated with Steep Diapirs and Allochthonous Salt: Flinders and Willouran Ranges, South Australia, and the Deepwater Northern Gulf of Mexico

The eastern Willouran Ranges and northern Flinders Ranges, South Australia contain Neoproterozoic and Cambrian outcrop exposures of diapiric breccia contained in salt diapirs, salt sheets and associated growth strata that provide a natural laboratory for testing and refining models of salt-sediment interaction, specifically allochthonous salt initiation and emplacement and halokinetic deformation. Allochthonous salt, which is defined as a sheet-like diapir of mobile evaporite emplaced at younger stratigraphic levels above the autochthonous source, is emplaced due to the interplay between the rate of salt supply to the front of the sheet and the sediment-accumulation rate, and may be flanked by low- to high-angle stratal truncations to halokinetic folds. Halokinetic sequences (HS) are localized (<1000 m) unconformity-bound successions of growth strata adjacent to salt diapirs that form as drape folds due to the interplay between salt rise rate (R) and sediment accumulation rate (A). HS stack to form tabular and tapered composite halokinetic sequences (CHS), which have narrow and broad zones of thinning, respectively. The concepts of CHS formation are derived from outcrops in shallow water to subaerial depositional environments in La Popa Basin, Mexico and the Flinders Ranges, South Australia. Current models for allochthonous salt emplacement, including surficial glacial flow, advance above subsalt shear zones and emplacement along tip thrusts, do not address how salt transitions from steep feeders to low-angle sheets and the model for the formation of halokinetic sequences has yet to be fully applied or tested in a deepwater setting. Thus, this study integrates field data from South Australia with subsurface data from the northern Gulf of Mexico to test the following: (1) current models of allochthonous salt advance and subsalt deformation using structural analysis of stratal truncations adjacent to outcropping salt bodies, with a focus on the transition from steep diapirs to shallow salt sheets in South Australia; and (2) the outcrop-based halokinetic sequence model using seismic and well data from the Auger diapir, located in the deepwater northern Gulf of Mexico. Structural analysis of strata flanking steep diapirs and allochthonous salt in South Australia reveals the transition from steep diapirs to shallowly-dipping salt sheets to be abrupt and involves piston-like breakthrough of roof strata, freeing up salt to flow laterally. Two models explain this transition: 1) salt-top breakout, where salt rise occurs inboard of the salt flank, thereby preserving part of the roof beneath the sheet; and 2) salt-edge breakout, where rise occurs at the edge of the diapir with no roof preservation. Shear zones, fractured or mixed `rubble zones' and thrust imbricates are absent in strata beneath allochthonous salt and adjacent to steep diapirs. Rather, halokinetic drape folds, truncated roof strata and low- and high-angle bedding intersections are among the variety of stratal truncations adjacent to salt bodies in South Australia. Interpretation and analysis of subsurface data around the Auger diapir reveals similar CHS geometries, stacking patterns and ratios of salt rise and sediment accumulation rates, all of which generally corroborate the halokinetic sequence model. The results of this study have important implications for salt-sediment interaction, but are also critical to understanding and predicting combined structural-stratigraphic trap geometry, reservoir prediction and hydrocarbon containment in diapir-flank settings

Comparison of Suprasalt and Subsalt Depositional and Halokinetic History of Patawarta Diapir, Flinders Ranges, South Australia

Outcrops of mixed carbonate/siliciclastic strata comprise the Neoproterozoic Wonoka Formation and Patsy Hill Member of the Bonney Sandstone at Patawarta diapir in the Flinders Ranges, South Australia, which is a ramping allochthonous salt sheet flanked by suprasalt and subsalt minibasin strata. Lithofacies distribution, thicknesses, and stratal geometries are described and analyzed to correlate suprasalt and subsalt Wonoka and Patsy Hill strata within a depositional and halokinetic sequence stratigraphic framework. Regionally, Wonoka and Patsy Hill strata represent a regressive sequence deposited in a storm-dominated carbonate shelf environment. The subsalt minibasin at Patawarta diapir contains upward-shallowing outer wave-dominated shelf to coastal plain facies in the Wonoka Formation and tidally-dominated barrier bar facies in the Patsy Hill Member, which form, respectively, 3rd order highstand and lowstand systems tracts. The Patsy Hill Member records a major shift in depositional systems from the underlying carbonate-dominated Wonoka Formation to the overlying siliciclastic-dominated Bonney Sandstone. Wonoka strata correlate laterally between the suprasalt and subsalt minibasins in terms of facies distribution and depositional setting. In contrast, Patsy Hill facies show significant lateral variation between suprasalt and subsalt positions, suggesting deposition was strongly controlled by the bathymetric high of the diapir. This is especially evident from the lateral distribution of quartzite pebble conglomerates in the Patsy Hill, which record different periods of exposure and erosion of the allochthonous salt sheet during deposition. Subsalt Wonoka and Patsy Hill strata compose a tapered composite halokinetic sequence that displays upturn over a distance of 560 m and stratal thinning (1100 to 110 m) toward the diapir. Suprasalt Wonoka and Patsy Hill strata display significant but gradual thinning (1,638 to 19 m) over a distance of 4-5 km forming a broad, open fold with local upturn at the salt-sediment interface. The geometric and depositional elements from the suprasalt and subsalt minibasins at Patawarta diapir were evaluated to generate a depositional model that accounts for lateral and vertical salt migration and salt-modified bathymetry in a shallow marine environment characterized by allochthonous salt

Lateral Terminations of salt walls and megaflaps: an example from Gypsum Valley Diapir, Paradox Basin, Colorado, USA

Descriptions of exposed salt structures help improve the ability to interpret the geometry and evolution of similar structures imaged in seismic reflection data from salt‐bearing sedimentary basins. This study uses detailed geologic mapping combined with well and seismic data from the southeastern end of the Gypsum Valley diapir (Paradox Basin, Colorado), to investigate the three‐dimensional geometry of the terminations of both the salt wall and its associated megaflap. The salt wall trends NW‐SE and is characterized by highly asymmetric stratal architecture on its northeastern and southwestern flanks, with thicker, deeper, gently dipping strata in the depositionally proximal (NE) minibasin and thinned older strata rotated to near‐vertical in a megaflap on the distal (SW) side. The megaflap terminates to the SE through a decrease in maximum dip and ultimately truncation by a pair of radial faults bounding a down‐dropped block with lower dips. East of these faults, the salt wall termination is a moderately plunging nose of salt overlain by gently southeast‐dipping strata, separated from the down‐dropped NE minibasin by a counterregional fault. From this analysis, and by comparison with analogue structures located elsewhere in the Paradox Basin and in the northern Gulf of Mexico, we propose a series of simple end‐member models in which salt walls and megaflaps may terminate abruptly or gradually. We suggest that controlling factors in determining these geometries include the original thickness and spatial distribution of the deep salt, the presence of nearby diapirs (which determines the fetch area for salt flow into the diapir), spatial patterns of depositional loading, and variations in the nature and location of salt breakout through the roof of the initial salt structure

Allochthonous Salt Initiation and Advance in the Northern Flinders and Eatern Willouran Ranges South Australia:Using outcrops to test Subsurface -based Models from the Gulf of Mexico

The northern Flinders Ranges and eastern Willouran Ranges, South Australia, expose Neoproterozoic salt diapirs, salt sheets, and associated growth strata that provide a natural laboratory for testing and refining models of allochthonous salt initiation and emplacement. The diapiric Callanna Group (∼850–800 Ma) comprises a lithologically diverse assemblage of brecciated rocks that were originally interbedded with evaporites that are now absent. Using stereonet analysis to derive three-dimensional information from two-dimensional outcrops of stratal geometries flanking salt diapirs and beneath salt sheets, we evaluate 10 examples of the transition from steep diapirs to salt sheets, 3 of ramp-to-flat geometries, and 2 of flat-to-ramp transitions. Stratal geometries adjacent to feeder diapirs range from a minibasin-scale megaflap to halokinetic drape folds to high-angle truncations and appear to have no relationship to subsequent allochthonous salt development. In all cases, the transition from steep diapirs to salt sheets is abrupt and involved piston-like breakthrough of thin roof strata, which permitted salt to flow laterally. We suggest two models to explain the transition from steep diapirs to subhorizontal salt: (1) salt-top breakout, where salt rise occurs inboard of the salt flank, thereby preserving part of the roof strata beneath the sheet; and (2) salt-edge breakout, where rise occurs at the edge of the diapir with no roof preservation. Lateral emplacement of salt sheets is dependent on the interplay between the rate of salt supply to the front of the sheet and the sediment-accumulation rate. When the ratio of salt-supply rate to sediment-accumulation rate is high to moderate, thrust advance produces base-salt flats and truncation ramps, respectively. Halokinetic folds are absent because the thrust emerges at the base of the sea-floor scarp and mass-transport complexes are rare as a result of relatively low scarp relief. If the ratio is low, pinned inflation leads to drape folding of the top salt and cover into a fold ramp, with occasional slumping of the sheet and its roof and further breakout on thrust or reverse faults. In the shallow-water depositional environments of South Australia, lateral emplacement of salt sheets occurred through some combination of thrust advance, extrusive advance, and open-toed advance, with no evidence for subsalt thrust imbricates, shear zones, or continuous rubble zones. In deep-water environments, such as the northern Gulf of Mexico, thrust imbricates and rubble zones, which represent slumped carapace, are more common. The presence of slumped carapace is caused primarily by higher topographic relief related to thicker hemipelagic roofs, a lack of dissolution, and gravity-driven transport of overburden strata to the toes of large canopies

Multi-Material Tissue Engineering Scaffold with Hierarchical Pore Architecture

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Multi-material polymer scaffolds with multiscale pore architectures are characterized and tested with vascular and heart cells as part of a platform for replacing damaged heart muscle. Vascular and muscle scaffolds are constructed from a new material, poly(limonene thioether) (PLT32i), which meets the design criteria of slow biodegradability, elastomeric mechanical properties, and facile processing. The vascular–parenchymal interface is a poly(glycerol sebacate) (PGS) porous membrane that meets different criteria of rapid biodegradability, high oxygen permeance, and high porosity. A hierarchical architecture of primary (macroscale) and secondary (microscale) pores is created by casting the PLT32i prepolymer onto sintered spheres of poly(methyl methacrylate) (PMMA) within precisely patterned molds followed by photocuring, de-molding, and leaching out the PMMA. Prefabricated polymer templates are cellularized, assembled, and perfused in order to engineer spatially organized, contractile heart tissue. Structural and functional analyses show that the primary pores guide heart cell alignment and enable robust perfusion while the secondary pores increase heart cell retention and reduce polymer volume fraction

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

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

Enhanced Detection of Human Plasma Proteins on Nanostructured Silver Surfaces

In chemical and medical research, recent methods combine the tools of nanotechnology, chemistry and biology in a way that introduces the most modern processes to current medical practice. The main blood plasma proteins – albumin and globulin and their amino acid sequences, are carriers of important information about human health. In this paper we employed silver nanostructured surfaces prepared by electrodeposition. Consequently, electrochemical deposition is introduced as a convenient, fast and cost‐effective method for the preparation of metallic nanostructures with required morphology. Silver nanostructured surfaces were applied as the templates for Surface Enhanced Raman Spectroscopy (SERS) of albumin and globulin in the role of model analytes. We also studied the effect of a working electrode polishing process on electrodeposition and identification of proteins. The aqueous solutions of albumin and globulin were applied onto these Ag nanostructured substrates separately. An analytical signal enhancement factor of 3.6×102 was achieved for a band with a Raman shift of 2104cm‐1 for globulin deposited onto silver nanostructured film on unpolished stainless steel substrate. The detection limit was 400g/mL. Plasma or serum could present a preferable material for non‐ invasive cancer disease diagnosis using the SERS method