Whitings – Source of Black Gold?. - UAE Algal mats & lime muds A link to Middle East carbonate source rock potential. C.G.St.C. Kendall, Xavier Jenson & Eugene Shinn. Departments of Geological Sciences, University of South Carolina, Jackson School of Geology, University of Texas Austin, - PowerPoint PPT Presentation
Whitings – Source of Black Gold? C.G.St.C. Kendall, Xavier C.G.St.C. Kendall, Xavier Jenson & Eugene Shinn Jenson & Eugene Shinn Departments of Geological Sciences, University Departments of Geological Sciences, University of South Carolina, of South Carolina, Jackson School of Geology, University of Texas Jackson School of Geology, University of Texas Austin, Austin, and Marine Science Center, University of South and Marine Science Center, University of South - UAE Algal mats & lime muds UAE Algal mats & lime muds A link to Middle East A link to Middle East carbonate source rock carbonate source rock potential potential
Departments of Geological Sciences, University of South Departments of Geological Sciences, University of South Carolina,Carolina,
Jackson School of Geology, University of Texas Austin,Jackson School of Geology, University of Texas Austin,and Marine Science Center, University of South Floridaand Marine Science Center, University of South Florida
-
UAE Algal mats & lime mudsUAE Algal mats & lime mudsA link to Middle East carbonate A link to Middle East carbonate
source rock potentialsource rock potential
Outline of Presentation• The HypothesisHypothesis• Overview of Arabian Gulf Reserves• Geological setting of Arabian Gulf• Modern lime mud & cyanobacteria
generation of Arabian Gulf• Bahamian Whitings Productivity,
Sequestration & Organic Matter• Geological setting of Arabian Gulf Oil
Fields & tie of hydrocarbon sequestered cyanobacterial remains in geologic section
• Significance of Russian source rock study
• Conclusions
Hypothesis
• Significant Holocene accumulations of Significant Holocene accumulations of cyanobacteria & lime mudcyanobacteria & lime mud in Arabian Gulf in Arabian Gulf axis & tidal zonesaxis & tidal zones
• These sediments have source rock These sediments have source rock potentialpotential
• Similar sediments have accumulated since Similar sediments have accumulated since TriassicTriassic
• Ancient carbonate muds are source of Ancient carbonate muds are source of significantsignificant petroleum reserves of petroleum reserves of Arabian Gulf regionArabian Gulf region
• The present is the key to the past!The present is the key to the past!
Oil Production - Arabian Gulf Productive hydrocarbon section older to West
[Paleozoic] & younger at Arabian Gulf Coast [Mesozoic] & youngest in East in Zagros Mts [ Upper Tertiary]. West to East production includes:•Infra-Cambrian Salt •Silurian and Ordovician clastics – Unaizah •Permian clastics & carbonates – Khuff •Upper Jurassic Carbonates - Arab & Tuwaik Mt Grp•Lwr Cretaceous Carbonates – Shuaiba & Thammama•Middle Cretaceous – Mishrif•Tertiary - AsmariMesozoic through Tertiary-Lime Mud Source
Proposed Concept Proposed Concept • Arabian Gulf Holocene cyanobacteria & Arabian Gulf Holocene cyanobacteria &
mud accumulations significant in axis & mud accumulations significant in axis & tidal zonestidal zones
• These sediments have source rocks These sediments have source rocks potentialpotential
• 4000 meters of similar sediments have 4000 meters of similar sediments have accumulated here since Triassicaccumulated here since Triassic
• Sequestered ancient carbonate muds are Sequestered ancient carbonate muds are source of the significant petroleum source of the significant petroleum reserves of Arabian Gulf regionreserves of Arabian Gulf region
• The present is the key to the past!The present is the key to the past!
Structural Provinces - Arabian Gulf
Zagros Fold Mts
Zagros Fold Mts
Mesozoic to Tertiary Mesozoic to Tertiary Foreland BasinForeland Basin
Pre-Cambrian Shield
Pre-Cambrian Shield
NASA ImageNASA Image
4,000 meters of4,000 meters ofMesozoic to TertiaryMesozoic to Tertiary
Isoprenoids• The alkane/acyclic isoprenoid fraction is the The alkane/acyclic isoprenoid fraction is the
main constituent of most crude oilsmain constituent of most crude oils• A large number of crude oils and rock A large number of crude oils and rock
extracts from Timan-Pechora basin (Russia) extracts from Timan-Pechora basin (Russia) suggest this fraction is direct product of suggest this fraction is direct product of liquefaction of biological debris preserved liquefaction of biological debris preserved essentially unaltered till oil generation.essentially unaltered till oil generation.
• Result is the primary biological provenance Result is the primary biological provenance of this fraction is preserved in the oil of this fraction is preserved in the oil fraction.fraction.
Hydrocarbon Source Hydrocarbon Source • Collister, Ehrlich, Mango, & Johnson (AAPG, Collister, Ehrlich, Mango, & Johnson (AAPG,
2004) propose primary organic materials convert 2004) propose primary organic materials convert to oil as dispersed alkanes & isoprenoids in rocksto oil as dispersed alkanes & isoprenoids in rocks
• Low TOC source or undermature rocks generate Low TOC source or undermature rocks generate significant oil if source carries sufficient special significant oil if source carries sufficient special kerogen derived from biological membranes is kerogen derived from biological membranes is unchanged till liquefaction unchanged till liquefaction
• Observations & experiments, mostly French labs, Observations & experiments, mostly French labs, show resistant organic membranes in form of show resistant organic membranes in form of biopolymers play this role. biopolymers play this role.
• Stable over a large range of conditions, survive Stable over a large range of conditions, survive early secondary bacterial attack & late-stage early secondary bacterial attack & late-stage breakdown with increasing thermal stress. breakdown with increasing thermal stress.
Evidence
• Significant Holocene accumulations of Significant Holocene accumulations of cyanobacteria & lime mudcyanobacteria & lime mud in Arabian Gulf in Arabian Gulf axis & tidal zonesaxis & tidal zones
• These sediments have source rocks These sediments have source rocks potentialpotential
• Similar sediments have accumulated since Similar sediments have accumulated since TriassicTriassic
• Ancient carbonate muds are source of Ancient carbonate muds are source of significantsignificant petroleum reserves of petroleum reserves of Arabian Gulf regionArabian Gulf region
• The present is the key to the past!The present is the key to the past!
BasinRamp
RestrictedShelf
OpenShelf
Carbonate Provinces - Arabian Gulf
Dust and Whiting response
Satellite scenes SW, to West coast of Arabian Gulf 12 July 2006, MODIS Rapid Response system site, Nasa http://rapidfire.sci.gsfc.nasa.gov
Weather Station Data
Temperatures - pink & MPH windspeed - black.Windspeeds over 25mph coincide with regional "Whiting"
blooms.
Arabian Gulf Arabian Gulf Factory producing carbonates Factory producing carbonates
& storing products of & storing products of cyanobacteria since Permiancyanobacteria since Permian
Arabian Gulf Arabian Gulf Factory producing carbonates Factory producing carbonates
& storing products of & storing products of cyanobacteria since Permiancyanobacteria since Permian
NASA ImageNASA Image
A big day for a bloom!!A big day for a bloom!!A big day for a bloom!!A big day for a bloom!!
Organics in the Gulf!Organics in the Gulf!Organics in the Gulf!Organics in the Gulf!
Nasa ImageNasa Image
Whitings common to-day and Whitings common to-day and common back in the Triassic!common back in the Triassic!Whitings common to-day and Whitings common to-day and common back in the Triassic!common back in the Triassic!
Organics in the Gulf!Organics in the Gulf!Organics in the Gulf!Organics in the Gulf!
Nasa ImageNasa Image
Wells and Illling - 1965• Among 1st to report ” Whitings” offshore from
Qatar precipitated in Persian Gulf.• Ascribed whitings to CO2 removal by
photosynthesis of phytoplankton. • Groot (1964) lab analysis of suspended sediment
• Lab experiments used NaCO3 to remove CO2 pptated aragonite from Gulf, but rates did not match instantaneous formation of “Whitings” but took 2 to three weeks.
Local Whiting Local Whiting Occurrences!Occurrences!
NASA satellite scene with very NASA satellite scene with very localized & diminished ‘Whitings’ localized & diminished ‘Whitings’ off UAE on Pearl Bank, offshore off UAE on Pearl Bank, offshore East Qatar, north flank of East Qatar, north flank of Bahrain shoal, and offshore from Bahrain shoal, and offshore from Saudi/Kuwaiti borderSaudi/Kuwaiti border
PG GulfMajor Source
DirectPrecipitation
Persian Gulf Facies DistributionPersian Gulf Facies Distribution
After Wilkinson & Drummond, 2004
Persian Gulf Mud DistributionPersian Gulf Mud Distribution
After Wilkinson & Drummond, 2004
The mud probably forms less than 1% of sediment signal since Mesozoic but forms a formidable source for
hydrocarbons of Gulf
Lime Mud Sequestered in Lime Mud Sequestered in Basin Axis & Tidal FlatsBasin Axis & Tidal Flats
in axial troughin axial trough& tidal flats & tidal flats
Lime mud Lime mud & organics& organics
sequesteredsequesteredin Mangrovein Mangrove
swampswamp tidal flatstidal flats
Shoaling Upward Inner Shelf Cycle
Shoaling UpShoaling UpCycleCycle
Abu Dhabi – Mud Flats
Abu Dhabi – Mud Flats
Earlier High Earlier High Energy BeachesEnergy Beaches
Earlier High Earlier High Energy BeachesEnergy Beaches
Supratidal Supratidal SabkhaSabkha
EvaporitesEvaporites
Supratidal Supratidal SabkhaSabkha
EvaporitesEvaporites
High IntertidalHigh IntertidalCyanobacterialCyanobacterial
FlatsFlats
High IntertidalHigh IntertidalCyanobacterialCyanobacterial
FlatsFlatsIntertidalIntertidal
CarbonateCarbonateFlatsFlats
IntertidalIntertidalCarbonateCarbonate
FlatsFlats
Tidal PondsTidal PondsTidal PondsTidal Ponds
Tidal Creek
Tidal Creek
Tidal Creek
Tidal Creek
Tidal PondTidal PondTidal PondTidal Pond
Tidal Creek &
Tidal Creek &
Cyanobacterial M
egapoygons
Cyanobacterial M
egapoygons
Tidal Creek &
Tidal Creek &
Cyanobacterial M
egapoygons
Cyanobacterial M
egapoygons
Cyanobacterial Peat
Cyanobacterial Peat
Cyanobacterial Peat
Cyanobacterial Peat
Crinkled Algal Mat
Crinkled Algal MatGypsum Mush
Gypsum MushCyanobacterial Peat
Cyanobacterial Peat
SURFACESURFACEANHYDRITEANHYDRITEPOLYGONSPOLYGONS
Anhydrite
Anhydrite
Anhydrite
Anhydrite
Intertidal Muds
Intertidal Muds
Intertidal Muds
Intertidal Muds
Cyanobacterial Peat
Cyanobacterial Peat
Cyanobacterial Peat
Cyanobacterial Peat
HALITE HALITE POLYGONSPOLYGONS
Anhydrite
Anhydrite
Anhydrite
Anhydrite
Washover Sediments
Washover Sediments
Washover Sediments
Washover Sediments
Cyanobacterial Peat
Cyanobacterial Peat
Cyanobacterial Peat
Cyanobacterial Peat
MICROTOME OFCYANOBACTERIAL
MATS
Modern Sources of Modern Sources of lime mudlime mud
• Isolated seas – Arabian GulfIsolated seas – Arabian Gulf• Wide platforms in nutrient Wide platforms in nutrient
deserts of tropical seas – deserts of tropical seas – BahamasBahamas
Bahamian Organic Productivity
• Whitings precipitate 1.35 metric tons per year
• 25% of Whiting is organic matter – mostly cyanobacteria and microalgae
• As much as 1.6% of surface sediment may contain organic matter
• Subsurface sediments preserve 1% TOC (up to 4%)
• 7Be (half-life 53 days) found in Whitings but absent in resuspended bottom sediment
Kramer, Swart, DeCarlo & Schosvbo, 2005
Bahamas Ocean Drilling Transect
Modern Sources of Modern Sources of lime mudlime mud
• Isolated seas – Arabian GulfIsolated seas – Arabian Gulf• Wide platforms in nutrient Wide platforms in nutrient
deserts of tropical seas – deserts of tropical seas – BahamasBahamas
Whitings
Whitings
LIME MUDLIME MUDACCUMULATESACCUMULATES
ON BANK, OFF BANK ON BANK, OFF BANK & TIDAL FLATS& TIDAL FLATS
WhitingWhiting
Aragonite NeedlesAragonite Needles2.5mm Long2.5mm Long
& 0.25 mm Wide& 0.25 mm Wide
Aragonite NeedlesAragonite Needles2.5mm Long2.5mm Long
& 0.25 mm Wide& 0.25 mm Wide
MAJOR SOURCEOF LIME MUD IN
BAHAMAS ISWHITINGS!
Sequestration in Downslope wedge
Sequestration on Tidal Flat
Bahamas – shoals source of mud
Rates of Accumulation• Short-lived isotopes determin accumulation
rates (Shinn et al., 2000). • Samples analyzed within 20 days of
collection using high-resolution gamma ray spectrometer for short-lived isotopes Be-7 & Th-234 with respective half lives of approx. 53 & 23 days.
• Active billowing Whitings had Be-7 & Th 234 but bottom sediment depleted.
• None of bottom sediment stirred by storms contained short-lived isotopes.
• Radiogenic elements adsorbed on sediment surface, or if epitaxial growth occurred, these short-lived isotopes would be present.
Bahamian Whitings Instant Precipitates• Whitings vivid white while water outside them is clear!
• Instantaneous chemical &/or biochemical aragonite precipitates.
• Many Whitings drift back & forth with tides over time continually raining sediment to bottom with no documented dispersal or end.
• Wane in intensity at slack tide to strengthen when tide reverses.
• Cloud (1961) followed a single Whiting for 48 hours while Shinn et al. (1989) followed Whitings for 24 hrs.
• Some persisted for 24 hrs over hard pellet sands with no mud stirred into suspension. Shinn et al. (1989) returned to same Whitings still drifting over pellet sand 2 days later & Robbins et al. (1997) documented persistence from satellite images.
• Artificial Whitings of stirred up bottom settled within 6 hours• Nearby natural Whitings persisted and did not dissipate • Whiting water pumped to settling tanks aboard boat settled
in 6 hrs.
Whiting Mud Sequestration• Hurricanes & winter storms export vast quantities of lime mud over
bank edge. • 7 weeks after Hurricane Andrew (1992), lime mud collected as
layers up to 5 cm thick over shallow ooid sands near bank edge (Shinn et al., 1993). Layers from slurries of lime mud exiting bank to Florida Straits & Tongue of Ocean.
• An up to 90m thick wedge of Holocene sediment at base of Bahama Bank slope (Wilber et al.,1990) represents 40 to 80% by volume of mud presently sequestered for entire bank.
• Vertical and lateral progradation rate of wedge is 11-15 m/ka and 80-110 m/ka, respectively (Wilber et al., 1990). Measures amount accumulated during last 6-8 ka and does not consider Whiting mud carried northward in Gulf Stream to distant locations and/or to dissolution.
• Ball et al. (1967) and Perkins and Enos (1968) report significant off-bank sediment transport in Florida following Hurricanes Donna and Betsy. Similar observations made and photographed in Florida by Shinn following Hurricane Andrew in 1992.
• Lime mud-laden sediment continues to spill off the platform for weeks following a hurricane. The Bahamian Bank has been submerged for the past 6-8 ka and is affected by a hurricane every 6 to 10 years. Overproduction, possibly far greater than 280%, is necessary to account for what is presently on the bank.
Organic Matter• Phytoplankton nucleae are cores to cells• Viable phytoplankton cyanobacterial cells in Whitings not
observed in bottom sediment - deteriorate quickly after deposition (Robbins and Blackwelder, 1992) .
• Aragonite needles adher to surface of living planktonic cyanobacteria indicates rapid precipitation within water column (Robbins & Blackwelder, 1992; Yates & Robbins, 1998; 1999; 2001).
• 25% of the 1.3 million metric tons ppted & suspended each year in Bahamas is organic matter, dropping to 1.8% of surface sediment. .
• Bahamian Bank Whitings & associated organic matter cover more limited areas swept off bank into deep water. Cores through Neogene western platform slope sediments preserve 1% TOC up to 4% (Kramer, Swart.
BasinBasin
RimRim
RestrictedShelf
RestrictedShelf
OpenShelf
OpenShelf
Bahamas Bahamas MorpholoMorpholo
gygy
Carbonate Mud Settings• Carbonate muds common through earth
history• Carbonates signaled by thick sections
adjacent to margins of recently pulled apart continental plates &/or in compressional terrains of colliding margins
• Carbonate muds collect in:– Lower portions of updip shallow water
cycles– Lower portions of downdip restricted
basins & basin slopes
Organic matterOrganic matter <1% <1% weight ofweight of HoloceneHolocene
Stratigraphic cross-section of Cretaceous Stratigraphic cross-section of Cretaceous Eastern Arabia (Alsharhan & Nairn 1986)Eastern Arabia (Alsharhan & Nairn 1986)
Tertiary Tertiary
Stratigraphic cross-section of NeogeneStratigraphic cross-section of NeogeneArabian Gulf (Alsharhan & Nairn 1986)Arabian Gulf (Alsharhan & Nairn 1986)
LimeLimeSourceSource
From International Petroleum EncyclopediaFrom International Petroleum Encyclopedia
LimeLimeSourceSource
ORGANIC MATTER HYPOTHESIS• The Arabian Gulf a sink of organic matter since
Triassic• As with modern Gulf much of this organic matter
related to multiple organic blooms through geological time
• Organic matter trapped in intertidal flat & basinal muds
• Dispersed organic matter in form of biological membranes, have simple chemical composition & structure, & so liquefy at a threshold temperature & do not require time & temperature history for maturation.
• A burst of oil generation produces transient overpressures resulting in liberation of oil by microfracturing and long-range migration through the resulting fractures.
• This ensures that large volumes of oil could be generated over a short time.
CONCLUSIONSCONCLUSIONS• Arabian Gulf Holocene cyanobacteria & mud Arabian Gulf Holocene cyanobacteria & mud
accumulations significant in axis & tidal accumulations significant in axis & tidal zoneszones
• These sediments have source rocks potentialThese sediments have source rocks potential• Similar sediments accumulated since TriassicSimilar sediments accumulated since Triassic• These ancient carbonate muds are source of These ancient carbonate muds are source of
the significant petroleum reserves of the significant petroleum reserves of Arabian Gulf regionArabian Gulf region
• The present is the key to the past!The present is the key to the past!
Now to Now to lunch!lunch!
West of Dhabaiya – Mangrove Swamp
Holocene tidal flats Holocene tidal flats are sequestering >1% are sequestering >1%
of weight as organic matter!of weight as organic matter!
