Horseshoe crabs as a group are renowned for their morphological conservatism punctuated by marked shifts in morphology associated with the occupation of non-marine environments and have been suggested to exhibit a consistent developmental trajectory throughout their evolutionary history. Here, we report a new species of horseshoe crab from the Ordovician (Late Sandbian) of Kingston, Ontario, Canada, from juvenile and adult material. This new species provides critical insight into the ontogeny and morphology of the earliest horseshoe crabs, indicating that at least some Palaeozoic forms had freely articulating tergites anterior to the fused thoracetron and an opisthosoma comprising 13 segments.

Turbidity currents commonly bypass sediment in submarine channels on the continental slope, and deposit sediment lobes farther down-dip on the flat and unconfined abyssal plain. Seafloor and outcrop data have shown that the transition from bypass to deposition usually occurs over complex zones referred to as channel–lobe transition zones (CLTZs). Recognition of these zones in cores and outcrop remains challenging due to a lack of characteristic sedimentary facies and structures. This paper focuses on Unit E of the Permian Fort Brown Formation in the Karoo Basin, South Africa, in the Slagtersfontein outcrop complex, which has previously been interpreted as a CLTZ. This study integrates thin-section micrographs, sedimentary facies, bed-set and stratigraphic architecture, and palaeoflow directions to achieve a multiscale analysis of CLTZ features. A novel process-based facies scheme is developed to evaluate deposits in terms of the depositional or erosional tendencies of the flows that formed them. This scheme allows bypass to be distinguished from depositional zones by the spatial distribution of certain sediment facies. Areas of net sediment bypass were predominantly marked by erosive sediment facies and a larger variability in palaeoflow direction while depositional areas showed a lower variability in palaeoflow directions. Metre-scale structures in the bypass-dominated area reveal seafloor erosion and scour formation. Field relations suggest the presence of a ∼500 m long mega-scour in the CLTZ. The characteristic structures documented here are applicable for identifying CLTZs in sparse datasets such as outcrops with limited palaeogeographical context and sediment cores obtained from subsurface systems.

We investigate the shape and strength of the magnetic fabrics (anisotropy of magnetic susceptibility (AMS) data) of various massive granitic plutons from different parts of India, using the eigenvalue method. The study aims to analyse eigenvalues and establish their relationship with various deformational attributes. It involves: (1) calculating eigenvectors and their corresponding eigenvalues from magnetic fabric datasets; (2) finding a link between the geometrical appearance of eigenvectors and the mechanistic issues involved with a specific deformation scenario; and (3) determining shape and strength parameters from the magnetic foliation data distribution.

The statistical analysis for the unimodal magnetic fabric dataset of orthorhombic symmetry class implies that the plane, consisting of intermediate (V2) and minimum (V3) eigenvectors with pole V1, accurately traces the instantaneous stretching axis (ISAmax) of a particular material flow system under a pure shear regime. Moreover, for the distributions of similar symmetry and modality, we infer that the rotational characteristics of eigenvectors with respect to a fixed coordinate cause a distinct shift of such planes (V2–V3) from the ISAmax of a steady-state flow system under simple shear, where a substantial amount of rotational strain is involved. However, our findings also suggest that variation in symmetry and modality of magnetic fabric data distribution of different studied granitoids can directly influence the relative disposition of V2–V3 with respect to the direction of ISAmax. We conclude that eigenvalue analysis of magnetic fabrics is a powerful approach, which can be utilized while studying the salient deformational aspects of any syntectonic massive granitic body.

The Franconian Platform of SE Germany and the underlying Permian and Triassic rocks that developed from latest Permian to Triassic time were affected by multiple compressional and extensional events that created a complex fracture, fault and stylolite network. We reconstructed the spatio-temporal variations of post-Triassic palaeostress fields in the Franconian Platform and Triassic strata using fault-slip and tectonic stylolite inversion. Our highly resolved stress inversion enables us to demonstrate a cyclic stress evolution from the stress regime of normal faulting to thrusting, strike-slip and back to normal faulting. Five main stress fields correlating with two stress cycles are determined for Late Jurassic to Cenozoic time. The first cycle consists of: (SF1) an initially NE–SW-directed horizontal extension during Late Jurassic to Early Cretaceous time; (SF2) NNE–SSW-directed horizontal compression with an early set of tectonic stylolites prior to the development of reverse and thrust faults; and (SF3) a strike-slip-dominated setting with (N)NE–(S)SW horizontal compression representing a first relaxation. The second cycle comprises (SF4) NW–SE-directed horizontal extension during Oligocene–Miocene time; and (SF5) a second strike-slip-dominated regime with WNW–ESE to NW–SE horizontal compression during the Alpine shortening, creating the youngest set of tectonic stylolites. In addition, we consider the transitional stages between thrusting and a strike-slip regime as a snapshot in the process of intraplate tectonics.

The Ediacaran rangeomorph Fractofusus misrai is the most common and best-preserved of the E Surface fossil assemblage in the Mistaken Point Ecological Reserve of southeastern Newfoundland, Canada. Fractofusus has been interpreted as a fusiform epifaunal soft-sediment recliner, and like other rangeomorphs it has a self-similar, fractal-like branching morphology. The rangeomorph branching of Fractofusus has been considered to be identical on the upper and lower surfaces; however, study of specimens with complex biostratinomic histories suggests clear differences between the upper and lower surfaces. The first-order branches grew downwards into the sediment from a high point near the midline but grew above the sediment–water interface at their lateral and distal margins. Our new three-dimensional appreciation of rangeomorph branching in Fractofusus explains many of the taphomorphs of Fractofusus including straight, curved, kinked and tousled forms. The three-dimensional morphology, mode of life, taphonomy and palaeoenvironmental interactions of F. misrai are discussed along with a new three-dimensional reconstruction.

Mosonik, a 3.25 Ma extensively dissected stratovolcano located in the North Tanzanian Divergence of the East African Rift, consists predominantly of phonolite and three types of phonolitic nephelinite distinguished by the presence or absence of amphibole or garnet antecrysts and differing populations of complexly zoned antecrystal and phenocrystal pyroxenes. The antecryst–phenocryst assemblage is typical of hybrid lavas derived by magma mixing. Compositional data are given for all major minerals. Owing to the high modal proportions (30–60 vol. %) of antecrysts and phenocrysts of pyroxene and nepheline plus the hybrid character of the lavas, bulk-rock compositions do not represent those of the parental liquids. Thus, assimilation–fractional crystallization modelling of the bulk-rock major- and trace-element abundances is inappropriate and an unevolved parental magma cannot as yet be defined. Sr–Nd isotopic data for Mosonik and other Older Extrusive Series rocks suggest derivation by partial melting of ancient metasomatized lithospheric mantle with mixing of Sr and Nd from two sources coupled with minor lower crustal contamination, melting being induced by the plume currently impinging on the Tanzanian craton, and representing the initial interaction of the plume with the cratonic lithosphere. In contrast, the Younger Extrusives, as exemplified by Oldoinyo Lengai nephelinite–carbonatite volcanism, could be derived from this ancient metasomatized lithospheric mantle plus a recent plume-derived asthenospheric component and no contamination by crustal material. The isotopically and genetically distinct Natron–Engaruka melilitites are considered to represent direct adiabatic melting of the Tanzanian plume without lithospheric contributions. Carbonatites and melilite-bearing nephelinites also occur at Mosonik but are not considered in this study as they are only a very minor volumetric component of the volcano.

We consider the implications of adding a cap to the yield surface for elastic–plastic and elastic–visco-plastic solids with coupling between deformation, fluid flow and mineral reactions. For a suitable combination of (low) permeability and strain rate, opening-mode veins can form in compression. Such behaviour is enhanced by dissolution and by simultaneous mineral reactions with negative ΔV. These are the opening-mode equivalents of compaction bands in rocks with high permeability. Stylolite parallel veins are considered as forming in this way; such veins are commonly the laminated or ribbon-quartz veins associated with intense gold mineralization. Axial plane veins and melt segregations are in this class also. The addition of a yield surface cap limits the permissible stress states portrayed by a failure-mode diagram and has implications for breccia formation. Failure discontinuities that form at the cap require a decrease in fluid pressure to form as opposed to extension joints and veins that require an increase in fluid pressure; discontinuities that form at the cap are in orientations that are commonly interpreted as reactivated early discontinuities. The switching between high fluid pressure and low fluid pressure, which we call mode-switching, arises from competition between mineral dissolution and deposition. This is an alternative to the fault-valve mechanism and does not require fault reactivation or failure at a ‘seal’ linked to seismicity or fault reactivation. The capped yield surface concept provides a unifying self-consistent approach for vein/breccia formation and for the kinematics of brittle and visco-plastic rocks.

Various genetic models have been proposed for the supergiant Proterozoic Broken Hill Pb–Zn–Ag deposit largely based on geological and geochronological evidence. Here we present Zn, Cd and S isotope compositions as well as Zn/Cd ratios of sphalerite from Broken Hill and minor Broken Hill-type deposits (Australia) to help constrain these models but focus on syngenetic and magmatic–hydrothermal processes, since epigenetic models can be rejected because the orebodies were deformed and metamorphosed by the Olarian Orogeny. Values of δ34SVCDT, δ66ZnAA-ETH and δ114CdNIST SRM 3108 for sphalerite from Broken Hill range from +0.27 to +4.73 ‰, −1.15 to +0.46 ‰ and −0.48 to +0.01 ‰, respectively, while those for the smaller Broken Hill-type deposits range from −5.11 to +1.28 ‰, −0.97 to +0.10 ‰ and −1.02 to +2.59 ‰, respectively. By combining published S isotope data of sulfides from the Broken Hill district with those obtained here, the sources of sulfur via thermochemical sulfate reduction, bacterial sulfate reduction and a magmatic origin cannot be distinguished. However, when the S isotope compositions are considered along with the broad range of Cd and Zn isotope data for sphalerite, which are among the lightest and heaviest yet reported for a sulfide deposit, the isotopic datasets are consistent with low-temperature biogenic processes associated with syngenetic deposition of sulfides. Cadmium isotope compositions when coupled with Zn/Cd ratios of sphalerite have previously been used to classify Pb–Zn deposits, including low-temperature, high-temperature and exhalative ores. However, the Zn/Cd ratios of sphalerite from Broken Hill cannot be used for such classification purposes.

The Niagara Escarpment is a geological feature located in southern Ontario, Canada, and the northeastern United States, comprising highly fractured sandstone, shale and carbonates deposited during the Ordovician and Silurian periods. Differential erosion of the strata has generated a steep cliff face which bisects the city of Hamilton, Ontario. Geological fractures are widespread in the escarpment and result in the formation of unstable blocks of rock subject to erosion through rockfall. This presents structural stability issues of concern due to the proximity of the escarpment to urban infrastructure. We quantify and analyse fracture networks in the escarpment using a combined field- and numerical-modelling-based approach. The location, orientation and aperture of fractures were documented from local outcrops using scanline and area survey methods. Clusters of poles describing the orientation of geological discontinuities were identified in spherical projections, defining three sets: (1) a sub-vertical stratabound set striking N–S, (2) a sub-vertical stratabound set striking E–W, and (3) a set parallel to horizontal sedimentary bedding planes which we infer controlled sub-vertical fracture geometry. Discrete fracture network modelling of fracture sets highlights their high degree of connectivity, and contribution to local geohazards, and quantifies their role in controlling fluid flow through escarpment strata, which is dependent on fracture aperture. Additionally, bedding planes have the potential to act as free surfaces, facilitating stress conditions in which approximately cuboid blocks are produced, and increasing the risk of rockfalls. We conclude that fractures present a first-order control on the fluid-flow properties and stability of the Niagara Escarpment.

Ophiolitic mélanges in Anatolia represent Mesozoic subduction-accretion complexes, which are unusually poor in land-derived coarse-clastic rocks. A segment of the ophiolitic mélange in the Beynam region south of Ankara was studied. The ophiolitic mélange consists of three accretionary units (AUs), which are distinguished by lithology, structure, age and geochemistry. At the base there is a serpentinite mélange, which is overlain by a semi-intact Upper Jurassic ophiolite with boninite geochemistry. The topmost AU consists of ocean-island-like alkali basalts with seamount-derived Triassic shallow-marine limestones and Jurassic radiolarian cherts, which are stratigraphically overlain by Upper Cretaceous fore-arc turbidites. The base of the fore-arc sequence is palaeontologically and isotopically dated to the early to middle Campanian (c. 81 Ma). Detrital zircons from the fore-arc sequence indicate a Late Cretaceous (87–81 Ma) magmatic arc as a source. The formation of the subduction-accretion complex was a two-stage process. The first stage took place during the Late Jurassic – Early Cretaceous, when supra-subduction type oceanic crust was generated, and subduction accretion was intra-oceanic. In the second stage during the Late Cretaceous the subduction jumped inboard, creating an Andean-type convergent margin, and the Jurassic oceanic crust was incorporated in the subduction-accretion complex. The lack of land-derived sandstones in the ophiolitic mélange can be attributed to the intra-oceanic subduction and to the limestone deposition in the upper plate during the main phase of subduction accretion in the Late Jurassic – Early Cretaceous.

Marble in the supracrustal rocks of the Lewisian Complex, Tiree, includes chlorine-bearing amphiboles, chlorine-rich apatite, sulphur-rich scapolite, albite and phlogopite, all of which are regarded as evidence for evaporites in other metamorphosed sequences. Titanite yields U–Pb ages of ∼1.6 Ga, i.e. late Laxfordian, which excludes a younger imprint of sodium metasomatism. Traces of anhydrite, and isotopically heavy pyrite, also indicate deposition from seawater. Elsewhere in the Hebrides, tourmaline in Lewisian Complex marbles may represent seafloor exhalative deposits. Combined, the evidence suggests Lewisian Complex supracrustal marbles formed in an evaporative environment, like other Palaeoproterozoic successions across the North Atlantic region.

Faulted and fractured systems form a critical component of fluid flow, especially within low-permeable reservoirs. Therefore, developing suitable methodologies for acquiring structural data and simulating flow through fractured media is vital to improve efficiency and reduce uncertainties in modelling the subsurface. Outcrop analogues provide excellent areas for the analysis and characterization of fractures within the reservoir rocks where subsurface data are limited. Variation in fracture arrangement, distribution and connectivity can be obtained from 2D fractured cliff sections and pavements. These sections can then be used for efficient discretization and homogenization techniques to obtain reliable predictions on permeability distributions in the geothermal reservoirs. Fracture network anisotropy in the Malm reservoir unit is assessed using detailed structural analysis and numerical homogenization of outcrop analogues from an open pit quarry within the Franconian Basin, Germany. Several events are recorded in the fracture networks from the Late Jurassic the Alpine Orogeny and are observed to be influenced by the Kulmbach Fault nearby with a reverse throw of 800 m. The fractured outcrops are digitized for fluid flow simulations and homogenization to determine the permeability tensors of the networks. The tensors show differences in fluid transport direction where fracture permeability is controlled by orientation compared to a constant value. As a result, it is observed that the orientation of the tensor is influenced by the Kulmbach Fault, and therefore faults within the reservoirs at depth should be considered as important controls on the fracture flow of the geothermal system.

This study corroborates interpretations suggesting that the Makrotantalon Unit on Andros represents a tectonic slice with Pelagonian affinity in the nappe stack of the Cycladic Blueschist Unit. Previously reported Cretaceous 40Ar–39Ar dates of a garnet-glaucophane schist from the Makrotantalon Unit could not be reproduced by Rb–Sr geochronology, but this is not an indication of contamination with excess Ar. Instead, the newly dated samples record disturbance of the Rb–Sr isotope system by partial recrystallization. Subsets of these phengite populations, representing the smaller grain-size fractions, yielded low-precision dates ranging from c. 21 to c. 15 Ma that document deformation-related resetting and recrystallization of a presumably Cretaceous white mica population. Although these Miocene dates cannot be linked with blueschist-facies metamorphism, they provide time constraints on the formation of shear zones that overprinted the original thrust contact during exhumation. The geological relevance of a Cretaceous high-pressure event is confirmed by a Rb–Sr date of c. 121 Ma for an epidote-glaucophane schist collected further away from the tectonic contact. The occurrence of a second blueschist-facies event in the Eocene is verified by Rb–Sr dates of two epidote-glaucophane schists (c. 40 Ma and c. 44 Ma) that can unambiguously be assigned to the Makrotantalon Unit.

Fluids are commonly invoked as the primary cause for weakening of detachment shear zones. However, fluid-related mechanisms such as pressure-solution, reaction-enhanced ductility, reaction softening and precipitation of phyllosilicates are not fully understood. Fluid-facilitated reaction and mass transport cause rheological weakening and strain localization, eventually leading to departure from failure laws derived in laboratory experiments. This study focuses on the Miocene Raft River detachment shear zone in northwestern Utah. The shear zone is localized in the Proterozoic Elba Quartzite, which unconformably overlies the Archaean basement, and consists of an alternating sequence of quartzite and muscovite-quartzite schist. In this study, we characterize fluid-related microstructures to constrain conditions that promoted brittle failure in a plastically deforming shear zone. Thin-section analyses reveal the presence of healed microcracks, transgranular fluid inclusion planes and grain boundary fluid inclusion clusters. Healed microcracks occur in three sets, one sub-perpendicular to the mylonitic foliation, and a set of two conjugate microcracks oriented at ∼40–60° to the mylonitic foliation. Healed microfractures are filled with quartz, which has a distinct fabric, suggesting that microcracks healed while the shear zone was still at conditions favourable for quartz crystal plasticity. Transgranular fluid inclusion planes also occur in three sets, similar in orientation to the healed microfractures. Fluid inclusions commonly decorate grain and subgrain boundaries as inter- and intragranular clusters. Our results document ductile overprint of brittle microstructures, suggesting that, during exhumation, the Raft River detachment shear zone crossed the brittle–ductile transition repeatedly, providing pathways for fluids to permeate through this shear zone.

The relative timing of extinctions and originations is a foundation for reconstructing evolutionary causes. However, there has been a tendency to dismiss reported Ediacaran holdovers in favour of effective extinction around the Cambrian boundary. Here, focusing on the classically Ediacaran frondose biota (Petalonamae), I suggest four main reasons why proposed Ediacaran survivors have previously been denied the acceptance they deserve: denials based on mistaken identity, doppelgängers, a last gasp or dead clades walking. I then point to the lower Cambrian species Stromatoveris psygmoglena as a key example which simultaneously meets these objections. Collectively, Cambrian survivors are a ‘smoking gun’ showing that extinction of the classically Ediacaran frondose biota did not occur until at least 30 Ma after the end of the Ediacaran period, registered by phylogenetic petalonamid Thaumaptilon from the Burgess Shale. Therefore, to paraphrase Mark Twain, reports of their earlier demise have been greatly exaggerated. Causes of their ultimate extinction should instead be sought in their total range and diversity dynamics. Overall, the Ediacaran–Cambrian transition shows extremely low numbers of recorded survivors, but diversity dynamics are dominated by the Cambrian explosion. In this context, recorded occurrences for the classically Ediacaran frondose biota are compatible with at least two extinction events, one within a possible mass extinction near the Cambrian boundary, and later, their ultimate extinction in, or after, the middle Cambrian (Miaolingian Series, Wuliuan Stage). There is, however, no correlative basis for a causal link between the Cambrian transition and the effective or final demise of the classically Ediacaran soft-bodied biota.

We report a new zircon U–Pb age of 1257 ± 6 Ma for the Punugodu granite (PG) pluton in the Eastern Dharwar Craton (EDC), Southern India. The Mesoproterozoic PG is alkali feldspar hypersolvus granite emplaced at shallow crustal level, as evident from the presence of rhyodacite xenoliths and hornfelsic texture developed in the metavolcanic country rocks of the Neoarchaean Nellore Schist Belt (NSB). Geochemically, the PG is metaluminous, ferroan and alkali-calcic, and is characterized by high SiO2 and Na2O + K2O, Ga/Al ratios >2.6, high-field-strength elements and rare earth element (REE) contents with low CaO, MgO and Sr, indicating its similarity to anorogenic, alkali (A-type) granite. The highly fractionated REE patterns with negative europium anomalies of PG reflect its evolved nature and feldspar fractionation. Mafic (MME) to hybrid (HME) microgranular enclaves represent distinct batches of mantle-derived magmas that interacted, mingled and undercooled within the partly crystalline PG host magma. Felsic microgranular enclaves (FME) having similar mineralogical and geochemical characteristics to the host PG most likely represent fragments of marginal rock facies of the PG pluton. The PG appears to be formed from an oceanic island basalt (OIB)-like source in an anorogenic, within-plate setting. The emplacement of PG (c. 1257 Ma) in the vicinity of Mesoproterozoic Kanigiri Ophiolite (c. 1334 Ma) shows an age gap of nearly 77 Ma, which probably suggests PG emplacement in an extensional environment along a terrain boundary at the western margin of the Neoarchaean NSB in the EDC.

Radiogenic strontium isotopes (87Sr/86Sr) of vein carbonates play a central role in the tectonometamorphic study of fold-and-thrust belts and accretionary wedges and have been used to document fluid sources and fluxes, for example, along major fault zones. In addition, the 87Sr/86Sr ratios of vein carbonates can trace the diagenetic to metamorphic evolution of pore fluids in accreted sediments. Here we present 87Sr/86Sr ratios of vein carbonates from the Infrahelvetic flysch units of the central European Alps (Glarus Alps, Switzerland), which were accreted to the North Alpine fold-and-thrust belt during the early stages of continental collision. We show that the vein carbonates trace the Sr isotopic evolution of pore fluids from an initial seawater-like signature towards the Sr isotopic composition of the host rock with increasing metamorphic grade. This relationship reflects the progressive equilibration of the pore fluid with the host rock and allows us to constrain the diagenetic to low-grade metamorphic conditions of deformation events, including bedding-parallel shearing, imbricate thrusting, folding, cleavage development, tectonic mélange formation and extension. The strontium isotope systematics of vein carbonates provides new insights into the prograde to early retrograde tectonic evolution of the Alpine fold-and-thrust belt and helps to understand the relative timing of deformation events.

Evidence of Late Triassic large tetrapods from the UK is rare. Here, we describe a track-bearing surface located on the shoreline near Penarth, south Wales, United Kingdom. The total exposed surface is c. 50 m long and c. 2 m wide, and is split into northern and southern sections by a small fault. We interpret these impressions as tracks, rather than abiogenic sedimentary structures, because of the possession of marked displacement rims and their relationship to each other with regularly spaced impressions forming putative trackways. The impressions are large (up to c. 50 cm in length), but poorly preserved, and retain little information about track-maker anatomy. We discuss alternative, plausible, abiotic mechanisms that might have been responsible for the formation of these features, but reject them in favour of these impressions being tetrapod tracks. We propose that the site is an additional occurrence of the ichnotaxon Eosauropus, representing a sauropodomorph trackmaker, thereby adding a useful new datum to their sparse Late Triassic record in the UK. We also used historical photogrammetry to digitally map the extent of site erosion during 2009–2020. More than 1 m of the surface exposure has been lost over this 11-year period, and the few tracks present in both models show significant smoothing, breakage and loss of detail. These tracks are an important datapoint for Late Triassic palaeontology in the UK, even if they cannot be confidently assigned to a specific trackmaker. The documented loss of the bedding surface highlights the transient and vulnerable nature of our fossil resources, particularly in coastal settings, and the need to gather data as quickly and effectively as possible.

Bedding-perpendicular joints striking parallel (longitudinal) and perpendicular (transverse) to both the axis of the hosting anticline and the trend of the foredeep-belt system are widely recognized in fold-and-thrust belts. Their occurrence has been commonly attributed to folding-related processes, such as syn-folding outer-arc extension, although they can also be consistent with a pre-folding foredeep-related fracturing stage. Here we report the pre-folding fracture pattern affecting the Pietrasecca Anticline, in the central Apennines (Italy), resolved by a detailed field structural analysis. Field observations, scan-lines and interpretation of virtual outcrops were used to study the intensity, distribution and the orientations of fracture pattern along the anticline. The fracture pattern of the Pietrasecca Anticline consists of longitudinal and transverse joints, oriented approximately perpendicular to bedding, and of a pre-folding longitudinal pressure-solution cleavage set, which is oblique to bedding regardless of the bedding dip. Cross-cutting relationships show that joints predated the development of the pressure-solution cleavage. Furthermore, joint intensity does not relate to the structural position along the anticline. Taken together, these observations suggest that jointing occurred in a foredeep environment before the Pietrasecca Anticline growth. Our work further demonstrates that joints striking parallel and orthogonal to the main fold axis do not necessarily represent syn-folding deformation structures.

In this study, we present a new granular rock-analogue material (GRAM) with a dynamic scaling suitable for the simulation of fault and fracture processes in analogue experiments. Dynamically scaled experiments allow the direct comparison of geometrical, kinematical and mechanical processes between model and nature. The geometrical scaling factor defines the model resolution, which depends on the density and cohesive strength ratios of model material and natural rocks. Granular materials such as quartz sands are ideal for the simulation of upper crustal deformation processes as a result of similar nonlinear deformation behaviour of granular flow and brittle rock deformation. We compared the geometrical scaling factor of common analogue materials applied in tectonic models, and identified a gap in model resolution corresponding to the outcrop and structural scale (1–100 m). The proposed GRAM is composed of quartz sand and hemihydrate powder and is suitable to form cohesive aggregates capable of deforming by tensile and shear failure under variable stress conditions. Based on dynamical shear tests, GRAM is characterized by a similar stress–strain curve as dry quartz sand, has a cohesive strength of 7.88 kPa and an average density of 1.36 g cm−3. The derived geometrical scaling factor is 1 cm in model = 10.65 m in nature. For a large-scale test, GRAM material was applied in strike-slip analogue experiments. Early results demonstrate the potential of GRAM to simulate fault and fracture processes, and their interaction in fault zones and damage zones during different stages of fault evolution in dynamically scaled analogue experiments.