sand body characterisation in tidal marine settings ... · sandstone 3 0.23 0.07 64.42 175.75 0.11...
TRANSCRIPT
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Sand Body Characterisation in Tidal Marine
Settings – Examples from the Malay Basin
Dr. M. Johansson
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MODERN DAY DELTAS
Sundarbans, Bangladesh
Volga River Delta, Caspian Sea
Rajang River Delta, Sarawak
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SCHEMATIC MAP OF TIDE DOMINATED DELTA
From Dalrymple & Choi 2007 (Earth Science Reviews 81 135-175)
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SUNDA SHELF
Lower Glacial Maximum 21K BP
Mesozoic Sundaland
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Depositional Environment
Journal of Sedimentary Research, 2017, v. 87, 17–40Research ArticleDOI: http://dx.doi.org/10.2110/jsr.2016.88
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TIDAL SHOAL CORE
MS & MF-:Microfractures; SC-Synaeresis Cracks:SR- Shear Rotation; RS-Reactivation Surfaces;
Gy- Gyrolithes burrow; J-J shaped burrows; MC-mud filled cracks; Rp-Ripple Structures; Scl-clay
lam Sst; Sba-bioturbated Sst; Pa – Paleophycus burrows; Sl- lam Sst
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FACIES CLASSIFICATION SCHEME
Core Description Facies Facies Described from the Image
Core Facies Image FaciesPetrophysical
Facies
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Rock Type PHIT BFV T2LM KTIM Frequency Facies Code Facies Description Core Photo
1 0.26 0.04 376.22 1361.39 0.08
Sb Bioturbated Sandstone
2 0.25 0.04 105.07 937.01 0.07 Sltb Bioturbated Silty Sandstone
SlHorizontally Laminated
Sandstone
3 0.23 0.07 64.42 175.75 0.11
SrxRipple Cross-Laminated
sandstone
Scl Clay Laminated Sandstone
4 0.21 0.10 27.57 19.19 0.14SG
Glaugonite Calcite Cemented
Sandstone
5 0.21 0.12 21.90 15.36 0.20 Ssltb Bioturbated Silty Sandstone
SltrxRipple Cross-Laminated
Silty Sandstone
SrxrtSandstone Ripple Cross-
laminated with Rootlets
DmpDolomite horizon with Small
Pisoids
Msb Sandy Biouturbated Shale
Msl Sandy Laminated Shale
6 0.14 0.13 4.02 0.05 0.39 Mslt Silty-Shale (Mslt)
Msltb Silty Bioturbated Shale
Msrt Mudstone with Rootlets
RL Regressive Lag Deposit
Grain-size Analysis from CMR
Cross-Bedded SandstoneSsx
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clay vfslt fslt mslt cslt vfsd fsd msd csd vcsdgrvl
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clay vfslt fslt mslt cslt vfsd fsd msd csd vcsdgrvl
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clay vfslt fslt mslt cslt vfsd fsd msd csd vcsdgrvl
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clay vfslt fslt mslt cslt vfsd fsd msd csd vcsdgrvl
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clay vfslt fslt mslt cslt vfsd fsd msd csd vcsdgrvl
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clay vfslt fslt mslt cslt vfsd fsd msd csd vcsdgrvl
Way up
PETROPHYSICAL FACIES
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CROSS-SECTIONAL
DISTRIBUTION
Journal of Sedimentary Research, 2017, v. 87, 17–40Research ArticleDOI: http://dx.doi.org/10.2110/jsr.2016.88
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R.W. Dalrymple, K. Choi / Earth-Science Reviews 81 (2007) 135–174
VERTICAL DISTRIBUTION
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DISTRIBUTARY CHANNEL
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CHARACTERISTIC FEATURES OF DISTRIBUTARY
CHANNELS•Fining-up Grain-size
•High-angle cross-bedding
•Dominance of clean sand
•Paleosols evident with rootlets
•Abundance of calcite cement layers
Average Sand Body Average Thickness 25m thick
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TIDAL CHANNELS
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CHARACTERISTIC FEATURES OF TIDAL CHANNELS
•Coarsening-up grain size
•Cross-bedding (Hummocky Cross-Stratification)
•Dominance of Heterolithic facies or clay drapes
•Fine –medium grain sand
•Calcite Cements
Average Sand Body Average Thickness 3m thick
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DISTRIBUTARY CHANNEL
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CHARACTERISTIC FEATURES OF MOUTH BARS•Coarsening-up Grain-size
•Low-angle cross-bedding (Ripples)
•Dominance of Clean sand
•Rootlets at top of sand
•Little to no Calcite Cement
Average Sand Body Average Thickness 15m thick
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FACIES TRANSITION
Mouth bar
Tidal Channel
Estuarine Channel
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Controls on Sinuosity
- slope gradient
- bed resistance
- Sediment supply
- Flow RegimeSundarbans, Bangladesh
2km
2km 2km
HORIZONTAL DISTRIBUTION
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TYPES OF SINUOSITY AND CHANNEL
WIDTH
2km
2km 2km
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SIGNIFICANCE OF RESISTANCE ON
SINUOSITY
Generic theory for channel sinuosity Eli D. Lazarus and José Antonio Constantinehttps://doi.org/10.1073/pnas.1214074110
Resistance-dominated surfaces produce
channels with higher sinuosity than those of
slope-dominated surfaces because increased
resistance impedes downslope flow.
Straightened river after vegetation
cover is removed
https://doi.org/10.1073/pnas.1214074110
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TYPES OF SINUOSITY
AND SAND/MUD RATIO
2km
2km
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CONCLUSION
• Understanding the tidal marine-estuarine processes is critical to
understanding the nature of sandstone processes
•The relationship between sinuosity and facies, could provide a useful
exploratory tool
•Distinct sand bodies and palaeocurrents can be identified and placed in an
estuarine Geological model
•The combination of core, image logs, elemental spectroscopy and NMR
identified robust depofacies, lithofacies and rock types simplify complex
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Any Questions?