Use of clay fabric to distinguish turbiditic and hemipelagic siltstones and silts

O’Brien, Neal R.; Nakazawa, Keiji; Tokuhashi, Shuichi

doi:10.1111/j.1365-3091.1980.tb01157.x

Cited by 62 publications

(10 citation statements)

References 21 publications

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“…8a, b), which indicates a rapid deposition from event-driven density currents (O'Brien et al . 1980). The presence of authigenic glauconite as ultrafine-grained (1–3 μm) spheres in mudstones (Fig.…”

Section: Discussionmentioning

confidence: 99%

New Wiwaxia material from the Tsinghsutung Formation (Cambrian Series 2) of Eastern Guizhou, China

et al. 2013

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Wiwaxia is an extinct early metazoan with uncertain affinities, which is well represented in strata of Cambrian Series 2-3 age. Well-preserved representatives of Wiwaxia are known from the Burgess Shale Biota and the Kaili Biota. Here, new material of Wiwaxia corrugata (Matthew, 1899) is reported from the upper part of the Tsinghsutung Formation (Cambrian Series 2) near Balang Village, Guizhou Province, China. These specimens have a close evolutionary relationship to Wiwaxia taijiangensis Zhao, Qian & Lee, 1994 from the overlying Kaili Formation. New Wiwaxia material from the Tsinghsutung Formation and observations of specimens with articulated individuals from the Kaili Formation suggest that Wiwaxia taijiangensis should be a junior synonym of W. corrugata. A new study indicates that W. corrugata has a wide geographic distribution, a short geological history and evolutionary uniqueness and provides new data on taphonomy of this genus.

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Section: Discussionmentioning

confidence: 99%

New Wiwaxia material from the Tsinghsutung Formation (Cambrian Series 2) of Eastern Guizhou, China

et al. 2013

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“…Facies 1: hemipelagites. The fine-grained, matrix-supported texture of this facies and the symmetrical skewness values (Brackenridge et al, 2018) suggest hemipelagic sedimentation from deposition by suspension fallout and lateral advection (Hesse, 1975;O'Brien et al, 1980;Martins, 2003). This interpretation is supported by the dominant presence of detrital grains; high peaks in fine-grained detrital input (Ti/Ca) and high PC1 loading further evidence a hemipelagic origin.…”

Section: Sedimentary Facies Interpretationmentioning

confidence: 95%

Contourite characterization and its discrimination from other deep‐water deposits in the Gulf of Cadiz contourite depositional system

et al. 2020

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Despite numerous efforts to properly differentiate between contourites and other deep-water deposits in cores and outcrops, reliable diagnostic criteria are still lacking. The co-occurrence of downslope and along-slope sedimentary processes makes it particularly difficult to differentiate these relatively homogeneous deposits. The main aim of this paper is to identify differences in deep-water sediments based on Principal Component Analysis of grain size and geochemistry, sedimentary facies, and reinforced by microfacies and ichnofacies. The sediments studied were obtained from two International Ocean Drilling Program Expedition 339 sites in mounded and sheeted drifts in the Gulf of Cadiz. The statistical approach led to the discernment of hemipelagites, silty contourites, sandy contourites, bottom current reworked sands, fine-grained turbidites and debrites over a range of depositional and physiographic elements. These elements are linked to contourite drifts, the drift-channel transition, the contourite channel and distal upper slope. When bottom currents or gravity-driven flows are not the dominant depositional process, marine productivity and continental input settling forms the main depositional mechanism in deep-water environments. This is reflected by a high variability of the first principal component in hemipelagic deposits. The stacked principal component variability of these deposits evidences that the contourite drift and the adjacent contourite channel were influenced by the interrelation of hemipelagic, gravitational and bottom current induced depositional processes. This interrelation questions the paradigm that a drift is made up solely of muddy sediments. The interrelation of sedimentary processes is a consequence of the precession-driven changes in the intensity of the Mediterranean Outflow Water related to Mediterranean climate variability, which are punctuated by millennial-scale variability. Associated vertical and lateral shifts of the Mediterranean Outflow Water, and therefore of its interface with the East North Atlantic Central Water, controlled sediment input and favoured turbulent sediment transport in the middle slope. During 987

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“…Densite mud typically has higher organic carbon contents, and a greater component that was originally terrigenous (Fig. 6E; Hesse, 1975; Piper, 1978; O’Brien et al. , 1980; Talling et al.…”

Section: Part 2: Depositional Processes and Deposit Typesmentioning

confidence: 99%

Subaqueous sediment density flows: Depositional processes and deposit types

et al. 2012

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Submarine sediment density flows are one of the most important processes for moving sediment across our planet, yet they are extremely difficult to monitor directly. The speed of long run‐out submarine density flows has been measured directly in just five locations worldwide and their sediment concentration has never been measured directly. The only record of most density flows is their sediment deposit. This article summarizes the processes by which density flows deposit sediment and proposes a new single classification for the resulting types of deposit. Colloidal properties of fine cohesive mud ensure that mud deposition is complex, and large volumes of mud can sometimes pond or drain‐back for long distances into basinal lows. Deposition of ungraded mud (TE‐3) most probably finally results from en masse consolidation in relatively thin and dense flows, although initial size sorting of mud indicates earlier stages of dilute and expanded flow. Graded mud (TE‐2) and finely laminated mud (TE‐1) most probably result from floc settling at lower mud concentrations. Grain‐size breaks beneath mud intervals are commonplace, and record bypass of intermediate grain sizes due to colloidal mud behaviour. Planar‐laminated (TD) and ripple cross‐laminated (TC) non‐cohesive silt or fine sand is deposited by dilute flow, and the external deposit shape is consistent with previous models of spatial decelerating (dissipative) dilute flow. A grain‐size break beneath the ripple cross‐laminated (TC) interval is common, and records a period of sediment reworking (sometimes into dunes) or bypass. Finely planar‐laminated sand can be deposited by low‐amplitude bed waves in dilute flow (TB‐1), but it is most likely to be deposited mainly by high‐concentration near‐bed layers beneath high‐density flows (TB‐2). More widely spaced planar lamination (TB‐3) occurs beneath massive clean sand (TA), and is also formed by high‐density turbidity currents. High‐density turbidite deposits (TA, TB‐2 and TB‐3) have a tabular shape consistent with hindered settling, and are typically overlain by a more extensive drape of low‐density turbidite (TD and TC,). This core and drape shape suggests that events sometimes comprise two distinct flow components. Massive clean sand is less commonly deposited en masse by liquefied debris flow (DCS), in which case the clean sand is ungraded or has a patchy grain‐size texture. Clean‐sand debrites can extend for several tens of kilometres before pinching out abruptly. Up‐current transitions suggest that clean‐sand debris flows sometimes form via transformation from high‐density turbidity currents. Cohesive debris flows can deposit three types of ungraded muddy sand that may contain clasts. Thick cohesive debrites tend to occur in more proximal settings and extend from an initial slope failure. Thinner and highly mobile low‐strength cohesive debris flows produce extensive deposits restricted to distal areas. These low‐strength debris flows may contain clasts and travel long distances (DM‐2), or result from more l...

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Use of clay fabric to distinguish turbiditic and hemipelagic siltstones and silts

Cited by 62 publications

References 21 publications

New Wiwaxia material from the Tsinghsutung Formation (Cambrian Series 2) of Eastern Guizhou, China

New Wiwaxia material from the Tsinghsutung Formation (Cambrian Series 2) of Eastern Guizhou, China

Contourite characterization and its discrimination from other deep‐water deposits in the Gulf of Cadiz contourite depositional system

Subaqueous sediment density flows: Depositional processes and deposit types

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