Sole Marks Research Articles

Flow‐induced interfacial deformation structures (FIDS): Implications for the interpretation of palaeocurrents, flow dynamics and substrate rheology

ABSTRACTSole structures on the base of turbidites, and other bed types, are typically classified into scour marks and tool marks, such as flutes, grooves, skim marks and prod marks. Yet, there are a range of other common sole marks that are unrelated to scouring or tools, and whose origin is poorly understood. Prominent among these sole structures are longitudinal ridges and furrows, and ‘dinosaur leather’ structures associated with mud ripples. Herein, these features are described and it is argued that they are the product of deformation of the substrate during a sediment gravity flow event. In these flow‐induced interfacial deformation structures (FIDS), a soft cohesive substrate undergoes deformation in response to a buoyant force induced by the denser basal component of an overriding flow, and the flow interacts with this buoyant deformation through shear to remould the substrate. Variations in the relative strength of these buoyant and shear‐induced forces explain the wide range of FIDS that can form. This FIDS model reinterprets the formation of longitudinal ridges and furrows, which have previously been classified as scour marks, and explains their distinctive spatial patterns. Furthermore, the new model builds on the seminal work of Dżułyński and colleagues in the 1960s and 1970s, who identified that these structures contain key palaeocurrent information, and it is argued that such information is largely under‐utilized. Importantly, alongside their utility as palaeocurrent indicators, FIDS provide insights into the rheology of the substrate at the time of their formation, and thus the nature of basal flow conditions in the formative flows.

Assessment the Subbottom Sedimentary Situation for Khor Abdullah, NW Arabian Gulf Using Sedimentary Coring Analysis and Sub-Bottom Profile Technique

The Coring Analysis and Sub-Bottom Profile technique are effective tools for assessing the sedimentary development of the bottoms, in this study these methods were used to assess the Sub bottom Sedimentary Situation for Khor Abdullah, NW Arabian Gulf. Two marine core sediments were studied at a depth of 40 m. Detailed grain-size analysis was carried out on 86 samples from cores. In addition, many sedimentary structures were diagnosed, such as load structures, wavy bedding, interfingered, peat layers, sole marks, and others. The environments and the transgression and regression of the sea were detected and interpreted on the basis of these analyzes, which were also attributed to the presence of the fauna in some beds.

Resolving tsunami wave dynamics: Integrating sedimentology and numerical modelling

AbstractTsunamis are a major hazard along many of the world's coastlines. To understand the impact of these events, a sufficiently long record of previous events is needed, which can be provided by their sedimentary deposits. A number of past events have left extensive sedimentary deposits that can be used to understand the hydrodynamics of the tsunami. The ca 8.15 ka Storegga submarine slide was a large, tsunamigenic mass movement off the coast of Norway. The resulting tsunami had estimated run‐up heights of around 10 to 20 m on the Norwegian coast, over 30 m in Shetland and 3 to 6 m on the Scottish mainland coast. New cores were taken from the Ythan Valley in North‐East Scotland, where Storegga tsunami deposits have previously been found. High‐resolution sedimentary analyses of the cores, combined with statistical (changepoint) analysis, shows signatures of multiple waves. Moreover, detailed CT scans of the erosional basal surface reveal sole marks called skim marks. Taken in conjunction with the grain size and sedimentary fabric characteristics of the tsunami deposits, this indicates that the flow exhibited a high‐concentration basal component, with an initial semi‐cohesive phase and that deposition was dominantly capacity driven. A multiple wave hypothesis is tested by creating a high‐resolution numerical model (metre‐scale) of the wave inundation, coupled to a previously published regional model. The inundation model confirms that multiple waves passed over the site in agreement with the sedimentological analysis. The sensitivity of the model to the reconstructed palaeocoastal geomorphology is quantitatively explored. It is concluded that local palaeogeomorphological reconstruction is key to understanding the hydrodynamics of a tsunami wave group in relation to its sedimentary deposit. Combining sedimentological data with high‐resolution inundation modelling is a powerful tool to help interpret the sedimentary record of tsunami events and hence to improve knowledge of their risks.

Controls on sedimentation in a deep‐water foredeep: Central Pindos foreland basin, western Greece

AbstractThis study provides a sedimentological, stratigraphic and palaeocurrent investigation of Upper Eocene to Lower Oligocene deep‐sea fan deposits found in the central part of the Pindos foreland basin in western Greece. According to facies analysis, the examined succession at Amfilochia area has 13 sedimentary facies and 10 facies and sub‐facies associations. Depositional elements include abyssal plain pelagics, outer fan, inner fan, and slope deposits. Outer fan sediments are classified as lobe‐axis, lobe‐off‐axis, lobe‐fringe, and distant lobe‐fringe deposits, while inner fan sediments are classified as channel‐fill, crevasse‐splay, internal and external levee deposits. The stratigraphic study shows an upward shift from abyssal plain pelagics to outer, inner fan, and finally slope deposits, implying submarine fan system progradation and progressive infilling of a deep‐water sediment depocentre. The sediments were deposited in the foredeep of the Pindos foreland system and correspond to the system's underfilled stage, when sedimentation was unable to exceed the accommodation provided by lithospheric flexure. They point to deposition near the onset of the Pindos orogen, after the closure of the Pindos basin because of the collision of the Apulian with the Pelagonian microplate during the Cretaceous‐Palaeogene period. Palaeocurrent data from sole marks show bipolar directions associated with two distinct spreading sub‐marine fan deposits. As a result, the study region was split into Upper (major SE‐direction flow) and Lower (major NW‐direction flow) parts, indicating that axial flows were predominant during sediment deposition. However, as the deposition of the elements continued, the progradation of both systems constrained the space accommodation because of the increased basin sediment supply and forced an increase in the degree of basin confinement that changed the compensational to aggradational stacking pattern. The goals of this research are to develop an updated facies model for these deep‐sea fans as well as a robust correlation framework for the various stratigraphic units in the central Pindos foreland basin. This research also connects the stratigraphic development of deep‐sea fan deposits to the evolutionary phases of the Pindos foreland system, providing fresh insights into the palaeogeographic circumstances in the Pindos foreland basin.

Sole marks reveal deep-marine depositional process and environment: Implications for flow transformation and hybrid-event-bed models

ABSTRACTDeposits of sediment gravity flows in the Aberystwyth Grits Group (Silurian, west Wales, United Kingdom) display evidence that sole marks are suitable for reconstructing depositional processes and environments in deep-marine sedimentary successions. Based on drone imagery, 3D laser scanning, high-resolution sedimentary logging, and detailed descriptions of sole marks, an outcrop 1600 m long between the villages of Aberarth and Llannon was subdivided into seven lithological units, representing: a) mudstone-poor, coarse-grained and thick-bedded submarine channel fills, dominated by the deposits of erosive high-density turbidity currents with flute marks; b) mudstone-rich levee deposits with thin-bedded, fine-grained sandstones formed by low-density turbidity currents that scoured the bed to form flute marks; c) channel–lobe transition-zone deposits, dominated by thick beds, formed by weakly erosive, coarse-grained hybrid events, with pronounced mudstone-rich or sandstone-dominated debritic divisions and groove marks below basal turbiditic divisions, and with subordinate amounts of turbidites and debris-flow deposits; d) tabular, medium- to thick-bedded turbiditic sandstones with flute marks and mixed sandstone–mudstone hybrid event beds mainly with groove marks, interpreted as submarine lobe-axis (or off-axis) deposits; and e) tabular, thin- to medium-bedded, fine-grained, mainly turbiditic sandstones mostly with flute marks, formed in a lobe-fringe environment. Both lobe environments also comprised turbidites with low-amplitude bed waves and large ripples, which are interpreted to represent transient-turbulent flows. The strong relationship between flute marks and turbidites agrees with earlier predictions that turbulent shear flows are essential for the formation of flute marks. Moreover, the observation as part of this study that debris-flow deposits are exclusively associated with groove marks signifies that clay-charged, laminar flows are carriers for tools that are in continuous contact with the bed. A new process model for hybrid event beds, informed by the dominance of tool marks, in particular grooves, below the basal sand division (H1 division of Haughton et al. 2009) and by the rapid change from turbidites in the channel to hybrid event beds in the channel–lobe transition zone, is proposed. This model incorporates profound erosion of clay in the channel by the head of a high-density turbidity current and subsequent transformation of the head into a debris flow following rapid lateral flow expansion at the mouth of the channel. This debris flow forms the groove marks below the H1 division in hybrid event beds. A temporal increase in cohesivity in the body of the hybrid event is used to explain the generation of the H1, H2, and H3 divisions (sensuHaughton et al. 2009) on top of the groove surfaces, involving a combination of longitudinal segregation of bedload and vertical segregation of suspension load. This study thus demonstrates that sole marks can be an integral part of sedimentological studies at different scales, well beyond their traditional use as indicators of paleoflow direction or orientation.

Cretaceous Forearc Sedimentation and Contemporary Basin Tectonics in Northwestern Borneo: New Sedimentological Insights from Pedawan Formation, Kuching Zone, East Malaysia

Sedimentary successions developed at the destructive plate margin settings are extremely important as they bear valuable record of contemporary basin tectonics and consequent sedimentation. Intense deformation and metamorphism often obliterate the primary sedimentary texture and structures of the sedimentary successions formed at destructive plate margins. However, sedimentological analysis of young unmetamorphosed forearc successions provides rare opportunity to infer the interplay between tectonics and sedimentation. Therefore, a process-based sedimentological facies analysis and provenance studies of the Cretaceous Pedawan Formation in the Kuching Zone, Borneo, have been undertaken for the first time. The sandstones are compositionally and texturally immature. They are normally graded with sole marks and have erosional lower contacts with mudstones and generally have gradational upper contacts. The massive sandstones, parallel-laminated sandstones, and the combination of rippled sandstones with thin mudstones are interpreted as turbidites. The lack of wave-generated structures, including hummocky cross stratification, indicates that deposition took place below storm wave base, possibly in a shelf setting. The lower part of the Pedawan Formation is mudstone dominated, and the upper part progressively becomes sandstone dominated. The Pedawan Formation bears several penecontemporaneously deformed horizons sandwiched between laterally persistent undeformed beds. Deformation structures include folds with reclined to recumbent geometry and layer-confined normal and reverse faults. We have interpreted these deformed horizons as seismites. Modal analyses of the sandstones indicate recycled orogenic as well as arc provenance and thus indicate mixing of recycled orogenic sediments with arc-derived volcanic material. The sedimentary facies characteristics of the Pedawan Formation in combination with numerous penecontemporaneous deformation features at selected stratigraphic levels indicate that the turbidites formed in a seismically active deepwater depositional setting as part of a long-lived subduction complex in eastern Sundaland during which several crustal fragments were accreted to Borneo.

Aseismic and seismic impact on development of soft-sediment deformation structures in deep-marine sand-shaly Crocker fan in Sabah, NW Borneo

Soft-sediment deformation structures are present within the deep-marine fan of the West Crocker Formation, Sabah Basin, NW Borneo. Focus of this study is to highlight the impact of seismic and aseismic activities on the development of these structures and their distribution in deep-marine fan. Twenty-nine types of deformation structures were identified during the study of twelve exposed sections. These structures were grouped into five categories: i) water-escape structures, ii) sole marks, iii) clastic intrusions, iv) deformed laminations, and v) syn-depositional brittle and ductile deformation structures. The sediment deformation is interpreted to be caused either by aseismic processes like slope failure, gravity collapse, sediment overloading, density gradient, seismic induced mechanisms such as earthquakes, tectonic uplift, or combined effect of seismic and aseismic events. These structures are classified based on type of features developed during semi-consolidated phase of rock deposition. The seismite structures i.e., clastic intrusions, deformed laminations, and syn-depositional structures are correlated with active collisional tectonics during the Late Paleogene times in the Sabah Basin. In the present work, a generalized conceptual model has also been proposed for the development of soft-sediment deformation structures in a submarine fan environment. Dewatering structurers and rapid sedimentation features are associated with inner fan, load and flame structures are present within middle fan, while contorted layers, slumps and mass-transport deposits are linked with distal fan settings.

Stratigraphic and paleogeographic development of a deep-marine foredeep: Central Pindos foreland basin, western Greece

This research presents a sedimentological, stratigraphic and paleocurrent analysis of the Upper Eocene to Lower Oligocene submarine fan deposits that occur in the central part of Pindos foreland basin, western Greece. Facies analysis suggests that the studied succession includes thirteen sedimentary facies and ten facies and sub-facies associations. The environments of deposition comprise abyssal plain, outer fan and inner fan deposits. Outer fan sediments are subdivided into lobe-axis, lobe off-axis, lobe-fringe and distal lobe-fringe deposits whereas, inner fan deposits include channel-fill, crevasse-splay, internal and external levee deposits. The stratigraphic analysis documents an upward transition from abyssal plain to outer and eventually to inner fan deposits suggesting progradation of the submarine fan system and progressive infilling of a deep-water sediment depocenter. The sediments were accumulated in the foredeep province of the Pindos foreland system and correspond to the underfilled stage of the system. They suggest deposition close to the onset of Pindos orogen, when sedimentation was unable to exceed the accommodation space created by lithospheric flexure. Paleocurrent data from sole marks reveal a NE-SW direction, suggesting that axial flows were dominant during the sediment deposition. The objectives of this study are to provide an updated facies model for these submarine fans and offer a robust correlation framework for the different stratigraphic units in the central Pindos foreland basin. Further, this study links for the first time the stratigraphic evolution of the deep-sea fan deposits with the evolutionary stages of the Pindos foreland system and provides new insights into the paleogeographic conditions in the Pindos foreland basin.

Trademark protection of single-colour trademarks: a study of the Chinese Louboutin case

In December 2018, Beijing Higher Court released the final decision associated with Christian Louboutin's trademark registration of the famous Red Sole Mark, holding that the mark should be categorized as a single-colour mark applied to a specific portion of the good and it could be registered as a trademark in China. This decision is the first Chinese judicial opinion associated with trademark registrability of a single-colour mark applied to a specific portion of the good, and therefore it plays a significant role in future trademark protection of single-colour trademarks.

An integrated process‐based model of flutes and tool marks in deep‐water environments: Implications for palaeohydraulics, the Bouma sequence and hybrid event beds

AbstractFlutes and tool marks are commonly observed sedimentary structures on the bases of sandstones in deep‐water successions. These sole structures are universally used as palaeocurrent indicators but, in sharp contrast to most sedimentary structures, they are not used in palaeohydraulic reconstructions or to aid prediction of the spatial distribution of sediments. Since Kuenen's famous 1953 paper, flutes and tool marks in deep‐water systems have been linked to turbidity currents, as reflected in the standard Bouma sequence taught to generations of geologists. Yet, these structures present a series of unaddressed enigmas. Detailed field studies in the 1960s and early 1970s observed that flutes are typically associated with thicker, more proximal beds, whilst tools are generally prevalent in thinner, more distal, beds. Additionally, flutes and tool marks are rarely observed on the same surfaces, and flutes are seen to change downstream from larger wider parabolic to smaller narrower spindle‐shaped forms. No model has been proposed that explains these field‐based observations. This contribution undertakes a radical re‐examination of the formative flow conditions of flutes and tool marks, and demonstrates that they are the products of a wide range of sediment gravity flows, from turbulent flows, through transitional clay‐rich flows, to debris flows. Flutes are not solely the product of turbulent flows, but can continue to form in transitional flows. Grooves are shown to be formed bydebris flows, slumps and slides, not turbidity currents, and in many cases the debris flows are linked to the debritic component of hybrid flows. Discontinuous tool marks, including skim (bounce) marks, prod marks and skip marks, are shown to be formed by transitional mud‐rich flows. Consequently, the observed spatial distribution of flutes and tool marks can be explained by a progressive increase in flow cohesivity downstream. This model of flutes and tool marks dovetails with models of hybrid flows that predict such a longitudinal increase in flow cohesivity. However, some deposits show grooves preferentially associated with BoumaTAbeds, and these are likely formed by flows transforming from higher to lower cohesion, and are present in basins where hybrid beds are absent or rare. The recognition that sole structures may haveno genetic linkto the later overlying turbidity current deposits, and can be formed by a wide range of flow types, indicates that the existing pictorial description of the Bouma sequenceis incorrect. A modified Bouma sequence is proposed here that addresses these points. In utilizing the advances in fluid dynamics since Kuenen's pioneering research, this study demonstrates that it is possible to use flutes and tool marks to interpret flow type at the point of formation, the nature of flow transformations, and the mechanics of the basal layer. These advances suggest that it is then possible to predict the nature of deposit type down‐dip. This new understanding, in combination with further testing in outcrop of the proposed relationships between sole marks and palaeohydraulics, opens up a wealth of possibilities for improving the understanding of deep‐water clastic environments, with implications for developing more complete facies models, assessing subaqueous geohazards and the resilience of seafloor infrastructure, and advancing our understanding of deep‐water sediments as archives of palaeoenvironmental change.

Phanerozoic shallow marine sole marks and substrate evolution

Research Article| August 01, 2018 Phanerozoic shallow marine sole marks and substrate evolution Lidya G. Tarhan Lidya G. Tarhan * 1Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06511, USA *E-mail: lidya.tarhan@yale.edu Search for other works by this author on: GSW Google Scholar Geology (2018) 46 (9): 755–758. https://doi.org/10.1130/G45055.1 Article history received: 19 Apr 2018 rev-recd: 29 Jun 2018 accepted: 04 Jul 2018 first online: 01 Aug 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation Lidya G. Tarhan; Phanerozoic shallow marine sole marks and substrate evolution. Geology 2018;; 46 (9): 755–758. doi: https://doi.org/10.1130/G45055.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyGeology Search Advanced Search Abstract The presence of erosive sole structures such as tool and flute marks in the sedimentary record can be used to interpret flow dynamics of ancient storm-dominated settings, as well as seafloor sediment properties. The formation and preservation of these structures require a hydroplastic and cohesive substrate. Therefore, the temporal distribution of these structures can be employed to track secular changes in seafloor rheology, which can significantly alter early diagenetic processes and thus shape global biogeochemical cycling. Herein I present a global compilation of Phanerozoic shallow marine successions bearing erosive sole structures, derived from assessment of the sedimentological, tectonic, and paleontological literature. The frequency of sole mark preservation in shallow marine environments has dramatically declined through the Phanerozoic. This first-order trend suggests that the rheological nature of the seafloor has experienced major secular transformations over the past 541 m.y. This record provides evidence for a marked decrease in sediment cohesion and increase in sediment porosity of the uppermost seafloor sediment column through time. I attribute this change in seafloor sedimentary properties to increases in the extent of bioturbation through the Phanerozoic, because the activity of sediment-mixing infauna dramatically increases the fluid content of the shallow sediment pile, decreasing the hydroplasticity necessary for sole mark formation and preservation. The gradual decline in the frequency of abiogenic sole marks in shallow marine successions through the Phanerozoic indicates that the development of bioturbation has been a similarly protracted process. You do not currently have access to this article.

Soft-sediment deformation structures induced by rapid sedimentation in Early Cretaceous turbidites, Lingshan Island, eastern China

Turbidites of the Early Cretaceous Lingshandao Formation on Lingshan Island, eastern China, show numerous soft-sediment deformation structures. The turbidites accumulated in a rift basin plain on the distal part of a low-energy fan, together with autochthonous fine-grained sediments that settled from suspension. Occasionally, sets of both types of sediments slumped down the basin slope. The turbidites were studied in two sections. Paleocurrent directions, measured from sole marks at the base of the sandy turbidites, indicate a slope from SE to NW; this is consistent with the dip direction of the axial planes of the major slump folds. Among the numerous types of soft-sediment deformation structures that are present, two types are of special interest because of their specific genesis, viz. rip-up clasts and dome structures. It appears that rapid sedimentation must be considered as the main trigger behind these deformations: the rapid accumulation of particularly the sandy turbidites resulted in overloading of the underlying beds and then consequently in an increase in their pore-water pressure that induced liquefaction and fluidization, which triggered the formation of the rip-up clasts and dome structures. The downslope movement of freshly deposited turbidites after slope failure over the inclined sedimentary surface induced shear stresses, which resulted in the complication of the rip-up clasts and the preferred orientation of some dome structures. Both the dip directions of the axial planes of some of the dome structures and microfolds within the rip-up clasts are consistent with the paleocurrent direction indicated by the sole marks and the slump folds.

Indication of calcareous tempestite inside the Qulqula Group in the Zagros Suture Zone, KRI

This sedimentological study focuses on carbonate storm deposits (calcareous tempestites) have been recognized for Qulqula platform in the Zagros Suture Zone outcropping at Sharbazher area in the northeastern Sulaimani City. This deposits are recorded between the oolitic limestone and calcareous turbidities in the Qulqula Group for the first time. These offer the first indication of event sedimentation in the Qulqula domain. Calcareous tempestites deposited on subsided eastern Arabian continental margin at initial stage of continental rifting, most possibly during Early Late Triassic to Early Jurassic. It is mostly encompasscalcarenite beds and indicating by some storm generated criteria such as: hummocky cross-stratification, parallel lamination, symmetrical wave-ripples, normally graded flat pebble conglomerate, and sole mark (flute caste, load cast, groove mark). Moreover, found Cruziana and Skolithos trace fossils with these calcarenite beds. Finally, for paleogeographic configuration of Qulqula carbonate platform, facies-depth connections on carbonate ramp model build up as shallowing-upward cycles from calcareous turbidities which deposited in distal part of outer ramp and carbonate distally steepened ramp to calcareous tempestites in mid ramp to oolitic limestone were formed in high-energy inner carbonate ramp.

Current‐aligned dewatering sheets and ‘enhanced’ primary current lineation in turbidite sandstones of the Marnoso‐arenacea Formation

AbstractTurbidite sandstones of the Miocene Marnoso‐arenacea Formation (northern Apennines, Italy) display centimetre to decimetre long, straight to gently curved, 0·5 to 2·0 cm regularly spaced lineations on depositional (stratification) planes. Sometimes these lineations are the planform expression of sheet structures seen as millimetre to centimetre long vertical ‘pillars’ in profile. Both occur in the middle and upper parts of medium‐grained and fine‐grained sandstone beds composed of crude to well‐defined stratified facies (including corrugated, hummocky‐like, convolute, dish‐structured and dune stratification) and are aligned sub‐parallel to palaeoflow direction as determined from sole marks often in the same beds. Outcrops lack a tectonic‐related fabric and therefore these structures may be confidently interpreted to be sedimentary in origin. Lineations resemble primary current lineations formed by the action of turbulence during bedload transport under upper stage plane bed conditions. However, they typically display a larger spacing and micro‐topography compared to classic primary current lineations and are not associated with planar‐parallel, finely laminated sandstones. This type of ‘enhanced lineation’ is interpreted to develop by the same process as primary current lineations, but under relatively high near‐bed sediment concentrations and suspended load fallout rates, as supported by laboratory experiments and host facies characteristics. Sheets are interpreted to be dewatering structures and their alignment to palaeoflow (only noted in several other outcrops previously) inferred to be a function of vertical water‐escape following the primary depositional grain fabric. For the Marnoso‐arenacea beds, sheet orientation may be linked genetically to the enhanced primary current lineation structures. Current‐aligned lineation and sheet structures can be used as palaeoflow indicators, although the directional significance of sheets needs to be independently confirmed. These indicators also aid the interpretation of dewatered sandstones, suggesting sedimentation under a traction‐dominated depositional flow – with a discrete interface between the aggrading deposit and the flow – as opposed to under higher concentration grain or hindered‐settling dominated regimes.

Sole markings of extraordinary size and variety in Crocker sandstones of Sabah

Sole markings of extraordinary size and variety in Crocker sandstones of Sabah

Attribute of trace fossils of Laisong flysch sediments, Manipur, India

The depositional basin in which the Late Eocene–Early Oligocene Laisong flysch sediments Barail Group, Manipur region (Indo-Myanmar ranges) have been deposited is generally considered to be of deep marine environment. However, field observation indicates the presence of many shallow environment signature characteristics of marginal to sublittoral marine settings, in addition to the general occurrence of deep marine turbidites. To address this aspect, ichnological analyses of the Laisong Formation has been attempted for elucidating palaeoenvironmental setting prevalent during the deposition of these sediments. Presence of 36 ichnospecies belonging to 33 ichnogenera has so far been identified. The ichnospecies may be grouped into different ichnofacies such as Skolithos–Cruziana mixed ichnofacies, Cruziana ichnofacies, Skolithos ichnofacies, Zoophycos ichnofacies, Nereites ichnofacies and Teredolites ichnofacies which decrease in abundance in this order of sequence with Skolithos–Cruziana mixed ichnofacies being the most dominant. The above-mentioned ichnofacies are found associated with sedimentary structures such as large sole marks, parallel laminations, massive and structureless beds, rip-up clasts, etc., which are characteristics of submarine fan deposits below the storm wave base and current ripples, herringbone structures, hummocky cross stratifications, pot casts, rain prints, etc., that marked shallow marginal marine setting such as tidal flats, deltas and shoreface. With such observations it is very likely that the Laisong sediments were formed in a tectonically active basin with varied bathymetric ranges indicating alternate transgressive and regressive nature.

The Monotis–Dactylioceras Bed in the Posidonienschiefer Formation (Toarcian, southern Germany): condensed section, tempestite, or tsunami-generated deposit?

The Monotis–Dactylioceras Bed in the Toarcian Posidonienschiefer Formation is a conspicuous shell accumulation, which was used as marble in the late eighteenth century of Bavaria. The shell bed is characterized by left valves of the bivalve Meleagrinella substriata (von Munster) and local accumulations of the ammonite Dactylioceras athleticum (Simpson), and has previously been considered to reflect a regression or a storm event. Indeed, three different interpretations of the bed appear possible: (1) condensed section, (2) tempestite, or (3) tsunami deposit. New observations, specifically swaley cross-stratification and sole marks, point to an event-like formation of the bed. While most of the observations are consistent with the formation by a storm event, the singular occurrence within the 4.4 Ma lasting Lower Toarcian, which spanned about 4.4 Ma, and the inverse grading of the shells point to a possible tsunami origin. The latter hypothesis is supported by contemporaneous seismites in the western Tethyan realm, and micrite injections in strata below the Monotis–Dactylioceras bed, which may reflect quake-induced sediment liquefaction.

New marine evidence for a Late Wisconsinan ice stream in Amundsen Gulf, Arctic Canada

Amundsen Gulf and adjoining Dolphin and Union Strait and Coronation Gulf form the southwestern end of the Northwest Passage adjacent to the Beaufort Sea. Extensive high resolution multibeam sonar imagery and sub-bottom profiles of the seabed have been acquired, primarily in Amundsen Gulf, by ArcticNet and the Ocean Mapping Group at the University of New Brunswick. These data reveal a variety of seabed landforms including mega-scale glacial ridge and groove lineations, drumlins, moraines, iceberg scours, bedrock outcrops, and discontinuous sediment deposits of variable thickness. The lineations are widespread, especially in southeastern Amundsen Gulf. They resemble modern and paleo bedforms reported from Antarctica, Svalbard, Greenland and other Canadian Arctic channels, where they have been ascribed to ice streams.The glacial sole marks on the seabed in Amundsen Gulf and regional data from the adjacent mainland and islands outline the configuration of a glacial ice stream from the Laurentide Ice Sheet that occupied Amundsen Gulf and adjoining waterways during the Late Wisconsinan. Part of the northwestward flowing ice stream was deflected around the Colville Mountains on Victoria Island and rejoined the main ice stream in Amundsen Gulf by way of Prince Albert Sound. The grounded Amundsen Gulf ice stream extended northwestward to the outer slope in the Beaufort Sea where it was buttressed by Arctic Shelf Ice. Maximum ice stream extent is inferred to have been coincident with the Late Glacial Maximum. Multi-sequence ice-contact sediments and stratigraphic relations with glaciomarine sediments indicate that several ice advances and retreats occurred in the northwestern part of the gulf. Final retreat from the maximum position began prior to 13,000 cal yr BP and terrestrial dates indicate that the retreating ice front had reached Dolphin and Union Strait by about 12.5 cal ka BP.

The use of the terms trace, mark and structure

Mark, trace and structure have been in consistently used in ichnology for many years; we wish to clarify the origins and to prescribe correct usage of these terms. The origins of the words are ancient and complex; in the twentieth century they were given clear definitions as ichnologic terms. Seilacher (1953) de fined a mark (German Marke ) as a physical (abiogenic) sedimentary structure, as in the common terms sole mark, flute mark, but not bite mark or scratch mark . Trace has been defined many times; we recommend the consensus definition of Bertling et al. (2006) as “a morphologically recurrent structure resulting from the life activity of an individual organism (or homotypic or ganisms) modifying the substrate”; this in cludes dwelling trace, feeding trace, bite trace . Structure , as implied in another consensus paper (Frey, 1973), is a neutral term for geologic patterns resulting from either biogenic or abiogenic processes. Use of the three terms in a clear consistent manner will aid communication both among ichnologists and between ichnologists and their colleagues in other fields.

The palaeogeographical background of Late Devonian storm events in the western part of the Holy Cross Mountains (Poland)

Abstract Late Devonian coarse-grained carbonate deposits in the Holy Cross Mountains were studied for possible storm depositional systems and catastrophic tsunami events, as it must be assumed that the investigated area was strongly affected by tropical hurricanes generated in the open ocean North of Gondwana. This assumption appears consistent with diagnostic features of carbonate tempestites at several places in the Holy Cross Mountains. Sedimentary structures and textures that indicate so are, among other evidence, erosional bases with sole marks, graded units, intra- and bioclasts, different laminations and burrowing at the tops of tempestite layers. It has been suggested before that a tsunami occurred during the Late Devonian, but the Laurussian shelf had an extensional regime at the time, which excludes intensive seismic activity. The shelf environment also excluded the generation of tsunami waves because the depth was too shallow. Additionally, the Holy Cross Mountains region was surrounded in the Devonian by shallow-marine and stable elevated areas: the Nida Platform, the Opatkowice Platform and the Cracow Platform to the South, and the elevated Lublin-Lviv area to the NE. Thus, tsunami energy should have been absorbed by these regions if tsunamites would have occurred.