3. Depositional environments - Forsiden - Universitetet i Oslo

1 3. Depositional environments Graduate programm Introduction to Sedimentology 2013-11-15 Classification: Internal 2 - Classification: Internal 2011-04-01 Sedimentology: Weathering Erosjon Deposition Mountain/rocks are broken down Weathering Sediments are dumped in a low lying area (ocean/sea) Deposition Sediments are transported by air, water and ice Erosion Layer after layer is deposited due to the weight, the ocean floor sinks and more space is made Stratigraphy Due to the pressure, the sediments become compressed and hard A rock is born Small pieces of rock collectively called: Sediments Low lying area in ocean & sea where sediments end up is called a Basin 3 - Classification.

2 Internal 2011-04-01 Petroleum geology: Essentials ProducabilityPermeability2)Producability Permeability2)StoragePorosity1)StoragePo rosity1)TIMING Petroleum system Mature Source Rock Reservoir Rock Cap Rock and Trap Migration 150 C 65 C Oil Window ~100 Myr 4 - Classification: Internal 2011-04-01 Tectonic: Types of Faults Normal Fault Strike-slip Fault Thrust/Reverse fault Depositional environments 5 - Classification: Internal 2011-04-01 6 - Classification: Internal 2011-04-01 Depositional environments 2013-11-15 9 Classification: Internal Continental Glacial Fluvial Deserts Shallow and marginal marine Deltaic Linear shorelines (Barrier, non-Barrier) Estuaries Deep marine Offshore (continental slope) Deep marine (basin floor) glacial aeolian lakes Examples: Peon, Norway Sequence stratigraphy 2013-11-15 10 Classification: Internal Fluvial Depositional environment facies associations 2013-11-15 18 Classification.

3 Internal Channel fill Floodplain Levee Crevasse splay channel floodplain levee Flooded floodplain levee channel Crevasse splay 2013-11-15 19 Classification: Internal Fluvial planforms Meandering, braided and anastomosing river planform Note! Channel belt versus individual streams and bars Meandering Braided Anastomosing 2013-11-15 23 Classification: Internal Channel fill of meandering rivers Lateral accretion Donselaar 2013-11-15 24 Classification: Internal Emery and Myers 1995 Channel fill of anastomosing rivers Isolated channel fills Aggarading vertically Gravel to silt Planar tabular cross beds Downstream dune migration Small LA sequences Makaske, 2001 Makaske, 2001 Makaske, 2001 Crevasse splay 2013-11-15 26 Classification.

4 Internal Breach of natural levee Rapid deposition on floodplain Sheet-like sandstone/siltstone bodies Mudstone interbeds Levee Floodplain River channel Breaker point Crevasse channel Crevasse splay Huesca, Spain, A. Kulikova, 2013 River avulsion 2013-11-15 28 Classification: Internal Regional new channel is established Local meander cut-off ox-bow lake Regional avulsion Local avulsion Taquari DFS, Pantanal Basin, Brazil (image FSRG, Buehler et al., 2011) Note! Channel belt versus individual streams and bars Sandstone body types 2013-11-15 30 Classification: Internal Channel fill: Ribbon-like Isolated lenses bars Sheet-like Floodplain.

5 Ribbon-like Thin sheet-like Amalgamated sandstone bodies Combinatin of above Point bars develop perpendicular to river flow direction Lateral restricted sandstone Poor vertical connectivity Longitudinal bars develop parallel to river flow direction Multistory/ multilateral sheet sandstones Good vertical and lateral connectivity Hirst, 1991 2013-11-15 31 Classification: Internal Sinuous, meandering stream Model 4 Model 4 Point bars - perpendicular to flow direction Lateral restricted sandstone Poor vertical connectivity Highly mobile braided stream Longitudinal bars - parallel to flow direction Multistory/multilateral sheet-like sandstones Good vertical and lateral connectivity Sandstone body types Depositional environments 2013-11-15 36 Classification.

6 Internal glacial aeolian lakes Continental Glacial Fluvial Deserts Shallow and marginal marine Deltaic Linear shorelines (Barrier, non-Barrier) Estuaries Deep marine Offshore (continental slope) Deep marine (basin floor) Examples: Lomvi, Norway, Rotligent,, UK 2013-11-15 37 Classification: Internal Desert Depositional environment Aeolian blown sands Ephemeral lakes/rivers Alluvial fans Nichols, 1999 2013-11-15 38 Classification: Internal Alluvial fans: types Gravity flow Sheetflood Channelised Corase-grained deposits Horiz. & cross bedding Debri flow Channelised Nichols, 1999 Nichols, 1999 2013-11-15 42 Classification: Internal Dune and interdune facies association Metz et al.

7 , JSR, 2009 High water table no aeolian reworking in wet interdune areas interdune dune interdune dune Depositional environments 2013-11-15 45 Classification: Internal Continental Glacial Fluvial Deserts Shallow and marginal marine Deltaic Linear shorelines (Barrier, non-Barrier) Estuaries Deep marine Offshore (continental slope) Deep marine (basin floor) barrier Examples: Brent, Cook, Upper Tilje (?), Norway 2013-11-15 46 Classification: Internal Delta Classification Mississippi Galloway, 1975 Fluvial-dominated delta subenvironments 2013-11-15 47 Classification: Internal Mississippi Prodelta: Suspended fine-grained sediments Plums into deeper water Delta plain: Various channel fills Crevasse splays Floodplain facies (peat) Interdistributary bay: Low energy Similar to floodplain Bay fill by crevasse splays bay Distributary channel: Similar to fluvial channel Subaqueous levees Mouth bars.

8 Proximal sandy bars Not continuous Tabular horizontal and cross-bedding Stets & Schafer, 2009 Low wave and tide energy Deacrese of velosity at the sea front Mouth bar distributive pattern Decrease grains side with depth Delta lobe switching 2013-11-15 48 Classification: Internal Each distributary fills the space and migrates to another location Nichols, 1999 2013-11-15 49 Classification: Internal Wave-dominated delta subenvironments Prodelta: Suspended fine-grained sediments Plums into deeper water Delta plain: Various channel fills Crevasse splays Floodplain facies Distributary channel: Similar to fluvial channel No subaqueous levees Do not prograde into the sea Mouth bars: Proximal sandy bars Wave/tides reworking Tabular horizontal and cross-bedding Coastal sandy bars: Sandy beaches Continuous Sand of mouth bars reworked by oblique waves High wave energy Difference: Channel do not prograde Sandy coastal bars Well-sorted sand MSN Map Paraibo delta, Brazil 2013-11-15 50 Classification.

9 Internal Tide-dominated delta subenvironments Prodelta: Suspended fine-grained sediments Plums into deeper water Upper delta plain (non tidal): Various channel fills Crevasse splays Floodplain facies Lower delta plain (tidal): Tidal flats Periodically flooding with tides Mangroove Tidal sand bars: Tide modifies mouth bars Elongate bars Bidirectional cross-bedding Mud drapes Tidal channels: Affected tides Stagnation periods High tidal range Difference: Channel affected by tides Tidal sandy bars Tidal indicators Ganges Delta, Bangladesh / India 2013-11-15 51 Classification: Internal Delta progradation All types of deltas are progradational in nature Produce shallowing vertical facies succession B A well well log prodelta delta front delta plain A B River-dominated Delta plain Distributary Channel Mouth bar Delta front Prodelta Nichols, 1999 Depositional environments 2013-11-15 53 Classification.

10 Internal Continental Glacial Fluvial Deserts Shallow and marginal marine Deltaic Linear shorelines (Barrier, non-Barrier) Estuaries Deep marine Offshore (continental slope) Deep marine (basin floor) barrier Examples: Rannoch/Etive/Tarbert (Brent Gr), Upper Ile, Norway Wave-dominated linear shoreline (non-barrier) 2013-11-15 54 Classification: Internal Beach (foreshore, backshore, dunes) low angle/horizontal bedding Shorface (above Fairweather wave base) dunes, cross bedding Offshore transition (above Storm wave base) hummocky cross stratfication 2013-11-15 55 Classification: Internal Wave-dominated linear shoreline with barrier islands Abundant sediment supply Longshore current Small tidal range Tidal flat, marsh - small tidal range Lagoon shallow, suspended material from the sea and coastal plain, evaporites Washovers thin layers of sand in lagoon Beach (foresho)