Time-series analysis of a heterolithic, ripple-laminated deposit (Early Jurassic, Tilje Formation) and implications for reservoir modelling

Nordahl, Kjetil; Martinius, Allard W.; Kritski, A.

doi:10.1016/j.margeo.2006.10.019

Cited by 14 publications

(4 citation statements)

References 37 publications

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“…However, in general, the wavelet transform can be applied to any type of signal including those collected in space domain. The method is particularly effective in detecting the periodic structure hidden in a data set, and was proven to be an effective tool for studying small‐scale (millimetre to centimetre) sedimentary cyclicity in core (Nordahl et al. , 2006).…”

Section: Tide‐induced Periodicity In Fluvial Bedform Migrationmentioning

confidence: 99%

Tide‐influenced fluvial bedforms and tidal bore deposits (Late Jurassic Lourinhã Formation, Lusitanian Basin, Western Portugal)

Martinius

Gowland²

2010

Sedimentology

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125

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In a sedimentological sense a fluvial to tidal transition zone can be defined in rivers as a zone that separates the upstream fluvial from the downstream estuarine zone. Characteristic sedimentary structures within this zone are notoriously difficult to recognize. This study demonstrates the influence of tidal modulation within the most proximal part of the fluvial-tidal transition zone (i.e. the 'backwater zone') of an ancient fluvial system. Criteria have been established to differentiate between purely fluvial facies and those modulated by tidal energy. The stratigraphic interval from which the data were derived is the Lourinhã Formation (Late Jurassic) of the Lusitanian Basin, WesternPortugal. An analysis of sedimentary features at four key localities has identified a temporal spectrum of tidal influence ranging from the daily modulation of fluvial flows to the effects of tidal bore passage. A combination of quantitative and qualitative data reveals systematic changes in the internal architecture of dune-scale bedforms deposited in a channel-floor setting. The key co-occurring features are: (i) increasing-decreasing organic particle concentration; (ii) increasing-decreasing bottomset thickness; (iii) increasingdecreasing foreset dip and shape (from convex to concave); and (iv) increasingdecreasing brinkpoint height. Collectively, these features are interpreted as having been produced by successive fluctuations in flow regime conditions from lower (during flood tidal retardation) to higher (during ebb tidal drawdown) current velocities. Bedforms showing these features occur in both meandering fluvial channels and straighter distributary systems. In addition, several examples of a specific type of stepped erosion surface and draping sediment have been recognized, the interpretation of which strongly suggests generation by the passage of tidal bores. If this interpretation is correct, then it represents one of the first published examples of tidal bore propagation in ancient fluvial systems. Palaeoclimatic evidence (cellular analysis of woody tissue, palaeosol character and plate reconstruction) indicates a warm, seasonal, winter wet to summer dry climate during deposition of the Lourinhã Formation. From this evidence it is suggested that tidal modulation and tidal bore effects are more likely to develop in the 'dry season', when fluvial flow in the main river channels was reduced.

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Section: Tide‐induced Periodicity In Fluvial Bedform Migrationmentioning

confidence: 99%

Tide‐influenced fluvial bedforms and tidal bore deposits (Late Jurassic Lourinhã Formation, Lusitanian Basin, Western Portugal)

Martinius

Gowland²

2010

Sedimentology

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125

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“…The accurate interpretation of the balance between processes in ancient FMTZs will help to distinguish between different types of ancient delta system and to improve prediction of the facies distribution and architecture. Accurate assessment of the degree of tidal influence has fundamental implications for the appraisal of hydrocarbon reservoirs because deltas show significant differences in sandbody morphology and depositional architecture (Reynolds, ) and facies‐scale characteristics (Martinius et al ., ; Nordahl et al ., ) depending on the relative strength of different processes. The aim of this contribution is to provide criteria to assess the relative balance between tidal and fluvial processes in ancient systems using reconstructed architecture and facies associated with the FMTZ from the Lajas Formation.…”

Section: Introductionmentioning

confidence: 97%

“…Wave process is not considered for this study because the sedimentary structures suggest that wave process is negligible in the studied deposits. and facies-scale characteristics (Martinius et al, 2005;Nordahl et al, 2006) depending on the relative strength of different processes. The aim of this contribution is to provide criteria to assess the relative balance between tidal and fluvial processes in ancient systems using reconstructed architecture and facies associated with the FMTZ from the Lajas Formation.…”

Section: Introductionmentioning

confidence: 99%

Recognition criteria, characteristics and implications of the fluvial to marine transition zone in ancient deltaic deposits (Lajas Formation, Argentina)

et al. 2016

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The seaward end of modern rivers is characterized by the interactions of marine and fluvial processes, a tract known as the fluvial to marine transition zone, which varies between systems due to the relative strength of these processes. To understand how fluvial and tidal process interactions and the fluvial to marine transition zone are preserved in the rock record, large‐scale outcrops of deltaic deposits of the Middle Jurassic Lajas Formation (Neuquén Basin, Argentina) have been investigated. Fluvial–tidal indicators consist of cyclically distributed carbonaceous drapes in unidirectional, seaward‐oriented cross‐stratifications, which are interpreted as the result of tidal modulation of the fluvial current in the inner part of the fluvial to marine transition zone. Heterolithic deposits with decimetre‐scale interbedding of coarser‐grained and finer‐grained facies with mixed fluvial and tidal affinities are interpreted to indicate fluvial discharge fluctuations (seasonality) and subordinate tidal influence. Many other potential tidal indicators are argued to be the result of fluvial–tidal interactions with overall fluvial dominance or of purely fluvial processes. No purely tidal or tide‐dominated facies were recognized in the studied deposits. Moreover, fluvial–tidal features are found mainly in deposits interpreted as interflood (forming during low river stage) in distal (delta front) or off‐axis (interdistributary) parts of the system. Along major channel axes, the interpreted fluvial to marine transition zone is mainly represented by the fluvial‐dominated section, whereas little or no tide‐dominated section is identified. The system is interpreted to have been hyposynchronous with a poorly developed turbidity maximum. These conditions and the architectural elements described, including major and minor distributary channels, terminal distributary channels, mouth bars and crevasse mouth bars, are consistent with an interpretation of a fluvial‐dominated, tide‐influenced delta system and with an estimated short backwater length and inferred microtidal conditions. The improved identification of process interactions, and their preservation in ancient fluvial to marine transition zones, is fundamental to refining interpretations of ancient deltaic successions.

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“…() to describe clay‐dominated coats on sand grains that developed in the Gironde Estuary. This mud‐rich macrotidal estuary has heterolithic point bars and tidal sand bars several kilometres long, and therefore comparable sizes to ancient estuarine reservoir geobodies as observed in the Permian Cape Hay Formation, in the Early Jurassic Tilje Formation (Norway), in the Early Cretaceous Sego Formation (Colorado, United States) or in the Cretaceous McMurray Formation (Alberta, Canada; Martinius et al ., ; Nordhal et al ., ; Musial et al ., ; Aschoff et al ., ; Saïag et al ., ).…”

Section: Introductionmentioning

confidence: 98%

Detrital clay grain coats in estuarine clastic deposits: origin and spatial distribution within a modern sedimentary system, the Gironde Estuary (south‐west France)

et al. 2018

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Porosity and permeability may be preserved in deep sandstone reservoirs by clay coating (mainly chlorite) which limits quartz overgrowths. Chloritization around quartz grains results mainly from mineralogical transformations of pre-existing clays. It is fundamental to study those clay precursors to better understand and predict the location and distribution of clay coatings in subsurface sandstones for petroleum or geothermal prospecting. This paper reports a high-resolution analysis of the composition, distribution and fabric of clays along a modern estuary, the Gironde (south-west France). The scale of the study ranges from thin sections, through sand bar bodies, up to the entire estuary. Results show that clays are detrital and deposited at the same time as sand grains despite strong hydrodynamic conditions. Clays bind to medium-grained sands forming detrital clay grain coats. On average, 26% of detrital sand grains are coated along the entire length of the estuary. Coat thickness varies from 1 lm to more than 200 lm, and coat coverage exceeds 30% in some samples. The turbidity maximum zone position (surface water turbidity from 1 to 10 g l À1 ) in the estuary, which is controlled by seasonal variations in hydrodynamic processes, significantly impacts the location of the maximum clay content and the abundance of coated grains in sandy facies along the estuary. Flocculation in the water column results in the accumulation of suspended matter and contributes to the high turbidity in the estuary. Exopolymeric substances produced by diatoms are observed both in the field and by cryo-scanning electron microscopy, suggesting that they may play a major role in binding detrital clay around sand grains. Finally, tidal bars and heterolithic point bars in the estuary funnel and estuarine channels are prime sedimentological targets for finding clay coatings and potentially good reservoir quality in deeply buried sandstones.

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Time-series analysis of a heterolithic, ripple-laminated deposit (Early Jurassic, Tilje Formation) and implications for reservoir modelling

Cited by 14 publications

References 37 publications

Tide‐influenced fluvial bedforms and tidal bore deposits (Late Jurassic Lourinhã Formation, Lusitanian Basin, Western Portugal)

Tide‐influenced fluvial bedforms and tidal bore deposits (Late Jurassic Lourinhã Formation, Lusitanian Basin, Western Portugal)

Recognition criteria, characteristics and implications of the fluvial to marine transition zone in ancient deltaic deposits (Lajas Formation, Argentina)

Detrital clay grain coats in estuarine clastic deposits: origin and spatial distribution within a modern sedimentary system, the Gironde Estuary (south‐west France)

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