Sedimentary Basins & Sedimentary Basins & Petroleum GeologyPetroleum Geology

Controls on large-scale Controls on large-scale sedimentationsedimentation

Sedimentary processes are controlled, on large scales, Sedimentary processes are controlled, on large scales, by:by:

Climate Climate determines: determines:

weathering rates, weathering rates, precipitation & run-off (sed. transportation), precipitation & run-off (sed. transportation), environments environments

Tectonic settingTectonic setting determines: determines:

relief relief time for sed. transport time for sed. transport types of environments types of environments types of sedimentary basins types of sedimentary basins source rock type source rock type

What is a sedimentary basin?What is a sedimentary basin? A low area on the Earth’s surface relative to surroundings A low area on the Earth’s surface relative to surroundings

e.g. deep ocean basin (5-10 km deep), intramontane basin (2-3 km e.g. deep ocean basin (5-10 km deep), intramontane basin (2-3 km a.s.l.) a.s.l.)

May be of May be of tectonictectonic (or (or erosionalerosional origin) origin) A receptacle for sedimentation; erosion may also be important A receptacle for sedimentation; erosion may also be important Sedimentation may be interrupted - unconformities Sedimentation may be interrupted - unconformities Basins may be small (kms2) or large (106+ km2) Basins may be small (kms2) or large (106+ km2) Basins may be simple or composite (sub-basins) Basins may be simple or composite (sub-basins) Basins may change in size & shape due to: Basins may change in size & shape due to:

erosion erosion sedimentation sedimentation tectonic activity tectonic activity eustatic sea-level changes eustatic sea-level changes

Basins may overlap each other in time Basins may overlap each other in time

The Evolution of Sedimentary The Evolution of Sedimentary BasinsBasins

The evolution of sedimentary basins may The evolution of sedimentary basins may include: include: tectonic activity (initiation, termination) tectonic activity (initiation, termination) magmatic activity magmatic activity metamorphism metamorphism

as well as sedimentation as well as sedimentation all may be contemporaneous all may be contemporaneous Basins may develop on oceanic crust, Basins may develop on oceanic crust,

island arc crust, or continental crust island arc crust, or continental crust

Basins may be sedimentary basins Basins may be sedimentary basins sedimentary fill is relatively undeformed, sedimentary fill is relatively undeformed, basin margin facies are preserved basin margin facies are preserved

OR, OR, structuralstructural (remnants of) (remnants of) basinsbasins sedimentary fill is deformed sedimentary fill is deformed dips > original depositional slopesdips > original depositional slopesbasin margin facies are eroded basin margin facies are eroded

Components of a basinComponents of a basin

Axial elements of sedimentary basins: Axial elements of sedimentary basins: Basin axisBasin axis is the lowest point on the is the lowest point on the

basement surface basement surface Topographic axisTopographic axis is the lowest point on the is the lowest point on the

depositional surface depositional surface DepocentreDepocentre is the point of thickest sediment is the point of thickest sediment

accumulation accumulation

What type of basin do we have?What type of basin do we have?

Depends on the structural setting of the Depends on the structural setting of the basinbasin

Many types, corresponding to different Many types, corresponding to different locationslocationsDivergent plate margin basinsDivergent plate margin basinsConvergent plate margin basinsConvergent plate margin basins

Divergent plate margin Divergent plate margin basinsbasins

Continental Rift Zones (Narrow)Continental Rift Zones (Narrow) Aulacogene BasinsAulacogene Basins

Continental Rift ZonesContinental Rift Zones Oceanic Rift BasinsOceanic Rift Basins

Open Ocean Passive-Margin BasinsOpen Ocean Passive-Margin Basins

Continental Rift Zones (Narrow)Continental Rift Zones (Narrow)

Origin Origin large scale mantle convection large scale mantle convection regional updoming ± regional basaltic (flood) regional updoming ± regional basaltic (flood)

volcanism volcanism extensional failure of crust extensional failure of crust

listric normal fault system listric normal fault system subsided/rotated half grabens subsided/rotated half grabens

widening to form central rift graben widening to form central rift graben may: may:

rupturing of crust rupturing of crust spreading ridge, oceanic basin spreading ridge, oceanic basin

Continental Rift Zones (Narrow)Continental Rift Zones (Narrow) two associated basin types two associated basin types

central rift graben basin central rift graben basin rim basins rim basins

environments & facies environments & facies alluvial fan, fluvial, lake alluvial fan, fluvial, lake volcanism volcanism

initial (flood) basaltic (arch phase) initial (flood) basaltic (arch phase) lavas lavas

intra-rift bimodal volcanism intra-rift bimodal volcanism basalt-rhyolite lavas & pyroclastics basalt-rhyolite lavas & pyroclastics often peralkaline often peralkaline calderas, stratovolcano, shields calderas, stratovolcano, shields mantle magmas melt crust mantle magmas melt crust

Continental Rift Zones (Narrow)Continental Rift Zones (Narrow) Sediment compositions Sediment compositions

mixed provenance mixed provenance exposed crustal rocks at rift margin exposed crustal rocks at rift margin contemporaneous volcanic sources contemporaneous volcanic sources

Examples Examples East Africa rift zone East Africa rift zone Rio Grande rift; Rhine graben Rio Grande rift; Rhine graben

May be subsequently deformed by May be subsequently deformed by compressional deformation compressional deformation e.g. Proterozoic Mt. Isa rift e.g. Proterozoic Mt. Isa rift Devono-Carb. Mt. Howitt province, Victoria Devono-Carb. Mt. Howitt province, Victoria

Aulacogene BasinsAulacogene Basins Narrow continental rifts which do not evolve into spreading ridge Narrow continental rifts which do not evolve into spreading ridge

oceanic basins. oceanic basins. e.g North Sea basins, Europe; Gippsland Basin, Bass Basin. e.g North Sea basins, Europe; Gippsland Basin, Bass Basin.

Dominated by initial alluvial fan, fluvial, lake facies; up to 4 km thick. Dominated by initial alluvial fan, fluvial, lake facies; up to 4 km thick. May extend through May extend through

crustal subsidence & extension crustal subsidence & extension marine transgression; no oceanic crust marine transgression; no oceanic crust coastal plain rivers, coal swamp shoreline, shelf & slope environment coastal plain rivers, coal swamp shoreline, shelf & slope environment

(e.g. Gippsland, Bass basins (e.g. Gippsland, Bass basins Provenance Provenance

continental, mixed continental, mixed plutonic, metasedimentary, metavolcanic, contemporaneous volcanic plutonic, metasedimentary, metavolcanic, contemporaneous volcanic ± marine carbonates± marine carbonates

Continental Rift ZonesContinental Rift Zones OriginOrigin

regionally extensive mantle convection regionally extensive mantle convection = ? driven by subduction oceanic spreading ridge under continent = ? driven by subduction oceanic spreading ridge under continent e.g. ?Western U.S.A. e.g. ?Western U.S.A.

Extensional failure of crust Extensional failure of crust complex lystric fault system complex lystric fault system

down to 15 km, Western U.S.A. down to 15 km, Western U.S.A. uprise of mantle + metamorphic core complexes - regional uplift, up to 2-3 km uprise of mantle + metamorphic core complexes - regional uplift, up to 2-3 km widespread volcanism in complex multiple graben rift basins widespread volcanism in complex multiple graben rift basins

Environments and faciesEnvironments and facies alluvial fan, fluvial, lacustrine alluvial fan, fluvial, lacustrine

VolcanismVolcanism flood basalts, bimodal basalt-rhyolite-andesite: lavas & pyroclastics flood basalts, bimodal basalt-rhyolite-andesite: lavas & pyroclastics tholeiitic, alkaline, calc-alkaline: lavas & pyroclastics. tholeiitic, alkaline, calc-alkaline: lavas & pyroclastics.

ProvenanceProvenance mixed crustal sources mixed crustal sources contemporaneous volcanic sourcescontemporaneous volcanic sources

Oceanic Rift BasinsOceanic Rift Basins Initially narrow (e.g. Red Sea) Initially narrow (e.g. Red Sea) may evolve into open oceanic basins may evolve into open oceanic basins

OriginOrigin narrow continental rifts evolve narrow continental rifts evolve break-up break-up oceanic spreading ridge oceanic spreading ridge oceanic crust in axial basins oceanic crust in axial basins continental crust at basin margin continental crust at basin margin

Environments & faciesEnvironments & facies alluvial fans, fan deltas, shoreline narrow shelf, slope, abyssal plain alluvial fans, fan deltas, shoreline narrow shelf, slope, abyssal plain

VolcanismVolcanism MORB tholeiitic oceanic crust MORB tholeiitic oceanic crust Lavas, hyaloclastite Lavas, hyaloclastite

ProvenanceProvenance mixed continental mixed continental contemporaneous volcanics contemporaneous volcanics shelf carbonate, evaporites shelf carbonate, evaporites oceanic carbonate, evaporites oceanic carbonate, evaporites oceanic pelagic, hemi-pelagic oceanic pelagic, hemi-pelagic

Open Ocean Passive-Margin Open Ocean Passive-Margin BasinsBasins

Evolve from oceanic rift basins Evolve from oceanic rift basins Become passive margin basins when MOR’s - large, wide ocean Become passive margin basins when MOR’s - large, wide ocean

basins. basins. Half graben system evolves into coastal plain-continental shelf & Half graben system evolves into coastal plain-continental shelf &

slope slope oceanic abyssal plain system oceanic abyssal plain system

Volcanism Volcanism none expected after break-up none expected after break-up perhaps intraplate hot spot volcanism perhaps intraplate hot spot volcanism

Sedimentation & provenance Sedimentation & provenance as for oceanic rift basin as for oceanic rift basin + well developed shelf-slope seds (± carbonate seds.) + well developed shelf-slope seds (± carbonate seds.)

Tectonics Tectonics post-break-up thermal & later isostatic subsidence of continental margin post-break-up thermal & later isostatic subsidence of continental margin

transgression transgression

Convergent Plate Margin Convergent Plate Margin BasinsBasins

Continental Margin Arc-Subduction Continental Margin Arc-Subduction Associated BasinsAssociated Basins

Origin Origin oceanic plate being subducted under continental oceanic plate being subducted under continental

margin margin trench, accretionary prism, continental margin trench, accretionary prism, continental margin

volcanic arc volcanic arc E.g. Andes, Cascades arc E.g. Andes, Cascades arc

Volcanism Volcanism calc-alkaline arc volcanism calc-alkaline arc volcanism

andesites, dacites, rhyolites, rhyodacites, minor basalts andesites, dacites, rhyolites, rhyodacites, minor basalts hydrous fluids from subducting lab melt mantle above, & both hydrous fluids from subducting lab melt mantle above, & both

then melt the base of the crust then melt the base of the crust lavas + pyroclasticslavas + pyroclastics

Continental Margin Arc-Subduction Continental Margin Arc-Subduction Associated BasinsAssociated Basins

Basin types: environments & facies Basin types: environments & facies Trench basin Trench basin

deep marine deep marine turbidites, pelagic seds. turbidites, pelagic seds.

Forearc basin Forearc basin perched on "scraped off", imbricate thrust faulted, accretionary prism perched on "scraped off", imbricate thrust faulted, accretionary prism alluvial fan, fluvial, shoreline shelf, deep turbidite fans alluvial fan, fluvial, shoreline shelf, deep turbidite fans

Back arc-foreland basin Back arc-foreland basin lies behind arc lies behind arc at foot of craton directed fold & thrust belt if present at foot of craton directed fold & thrust belt if present alluvial fan, fluvial, lakes alluvial fan, fluvial, lakes

Intra-arc Intra-arc arc volcanoes often lie in major graben arc volcanoes often lie in major graben alluvial fan, fluvial, lakealluvial fan, fluvial, lake

Continental Margin Arc-Subduction Continental Margin Arc-Subduction Associated BasinsAssociated Basins

Sediment compositions Sediment compositions TrenchTrench

metasedimentary debris eroded off accretionary prism metasedimentary debris eroded off accretionary prism v. minor volcanic debris v. minor volcanic debris pelagic sed. pelagic sed.

Forearc basinForearc basin voluminous volcanic debris voluminous volcanic debris

Back-arc basinBack-arc basin arc & thrust belt derived arc & thrust belt derived mixed volc., meta-sed., metamorphic, plutonic mixed volc., meta-sed., metamorphic, plutonic

Intra-arc basinsIntra-arc basins: lavas, volcanic seds, pyroclastics: lavas, volcanic seds, pyroclastics

Island Arc-Subduction Associated Island Arc-Subduction Associated BasinsBasins

E.g. Marianas, Tonga-Kermadec arcs E.g. Marianas, Tonga-Kermadec arcs Origin Origin

oceanic plate is subducted under another oceanic plate oceanic plate is subducted under another oceanic plate trench, accretionary prism, volcanic island arc trench, accretionary prism, volcanic island arc volcanic arc on oceanic lithosphere volcanic arc on oceanic lithosphere back arc basin(s) originate by rifting of arc block, development of back arc basin(s) originate by rifting of arc block, development of

small spreading ridge small spreading ridge widening basin; oceanic crust widening basin; oceanic crust

arc block migrates trenchward as subducting plate "rolls back". arc block migrates trenchward as subducting plate "rolls back". Volcanism Volcanism

island arc tholeiitic volcanics island arc tholeiitic volcanics basalts, basaltic andesites basalts, basaltic andesites

back arc basin tholeiitic crust back arc basin tholeiitic crust

Island Arc-Subduction Associated Island Arc-Subduction Associated BasinsBasins

Basin types, environments, facies, provenance Basin types, environments, facies, provenance Trench basinTrench basin

turbidites, pelagic sediments turbidites, pelagic sediments metasedimentary sed. from accretionary prism metasedimentary sed. from accretionary prism arc derived volcanic sediment arc derived volcanic sediment

Fore-arc basinFore-arc basin on accretionary prism on accretionary prism volcanic seds., carbonates volcanic seds., carbonates turbidites turbidites

Back arc basinBack arc basin arc derived volcaniclastic turbidite apron arc derived volcaniclastic turbidite apron pelagic sediments, especially where basin is large pelagic sediments, especially where basin is large

no continental derived sediment no continental derived sediment only rare silicic volcanism only rare silicic volcanism

Continental Collision Belts & BasinsContinental Collision Belts & Basins

E.g. Himalayan mountain chain, European Alps E.g. Himalayan mountain chain, European Alps

Origin Origin long term subduction of oceanic plate under continental margin, will bring long term subduction of oceanic plate under continental margin, will bring

"passenger" continent into collision with arc host continent. "passenger" continent into collision with arc host continent. oceanic basin closes during collision oceanic basin closes during collision subducting continent under thrust over-riding continent subducting continent under thrust over-riding continent uplift, mountain range, double continental crust thickness uplift, mountain range, double continental crust thickness

VolcanismVolcanism subduction related volcanism stop at collision, when subduction stop subduction related volcanism stop at collision, when subduction stop granitoid plutonism may occur due to extremely thickened crust granitoid plutonism may occur due to extremely thickened crust

magmas won't rise because of compressional stress field magmas won't rise because of compressional stress field Basin types, environments, facies provenance Basin types, environments, facies provenance

foreland basin at foot of fold & thrust belt foreland basin at foot of fold & thrust belt subject to isostatic subsidence subject to isostatic subsidence huge sediment flux off mountain belt huge sediment flux off mountain belt alluvial fan, braided river, meandering river, lake environments & facies alluvial fan, braided river, meandering river, lake environments & facies metasedimentary, met. (include high grade plutonic, reflecting deep crustal metasedimentary, met. (include high grade plutonic, reflecting deep crustal

erosion)erosion)

Continental Strike-Slip BasinsContinental Strike-Slip Basins E.g. California borderland basins associated with San E.g. California borderland basins associated with San

Andreas strike-slip fault system Andreas strike-slip fault system Origin Origin

strike-slip along non-linear faults strike-slip along non-linear faults opening "holes" or basins at fault jogs or bends opening "holes" or basins at fault jogs or bends

Volcanism Volcanism usually none, unless "accidental" intraplate usually none, unless "accidental" intraplate

Basin types, environments, facies, provenance Basin types, environments, facies, provenance "pull-apart" or strike-slip basins "pull-apart" or strike-slip basins alluvial fans, rivers, lakes alluvial fans, rivers, lakes alluvial, lacustrine, coal, ?evaporite seds. alluvial, lacustrine, coal, ?evaporite seds. provenance: whatever is being eroded from exposed crust provenance: whatever is being eroded from exposed crust

Stable Continental Interior BasinsStable Continental Interior Basins

E.g. Lake Eyre Basin E.g. Lake Eyre Basin Intracratonic (= within stable continental Intracratonic (= within stable continental

crustal mass) crustal mass) Long term stability Long term stability Flat topography Flat topography River, desert, lake environments & facies River, desert, lake environments & facies Mature basement derived sed. ± Mature basement derived sed. ±

evaporites evaporites