Ihsan Al-aasm - Academia.edu (original) (raw)

Papers by Ihsan Al-aasm

Research paper thumbnail of Origin of Authigenic Carbonates in Eocene to Quaternary Sediments from the Arctic Ocean and Norwegian-Greenland Sea

Proceedings of the Ocean Drilling Program, Dec 1, 1996

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Research paper thumbnail of Hydrothermal Dolomitization of the Mississippian Upper Debolt Formation, Sikanni Gas Field, Northeastern British Columbia, Canada

Bulletin of Canadian Petroleum Geology, Sep 1, 1997

The Mississippian carbonates of the Upper Debolt Formation, Sikanni Field, British Columbia, are ... more The Mississippian carbonates of the Upper Debolt Formation, Sikanni Field, British Columbia, are gas-producing, fractured and brecciated, dolomitized rocks. These rocks have undergone complex diagenetic changes, represented mainly by various generations of ...

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Research paper thumbnail of Fluid compartmentalization and dolomitization in the Cambrian and Ordovician successions of the Huron Domain, Michigan Basin

Marine and Petroleum Geology, Apr 1, 2018

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Research paper thumbnail of Neomorphism: A Tale of Divergence from Two Mississippian Dolomites

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Research paper thumbnail of Stratigraphy, Stable Isotopes, and Hydrocarbon Potential of the Aptian Shuaiba Formation, U.A.E

SEPM (Society for Sedimentary Geology) eBooks, 2000

... of the United Arab Emirates (UAE), forms one of t.he most important petroleum reservoirs in .... more ... of the United Arab Emirates (UAE), forms one of t.he most important petroleum reservoirs in ... 69, Copyright © 2000 SEPM (Society for Sedimentary Geology), ISBN 1-56576-O75-1, p. 299 ... These samples came from both onshore and offshore fields in the UAE, including producing ...

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Research paper thumbnail of Some Reflections on Refluxion: The Wabamun “Crossfield Zone” Reservoirs as Classic Examples

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Research paper thumbnail of Dolomitization of Mississippian Carbonates of Western Canada Sedimentary Basin: Petrologic and Geochemical Constraints

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Research paper thumbnail of Big Gas in Hydrothermal Chert-hosted Reservoirs: Is Parkland, B.C. Unique?

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Research paper thumbnail of The Effect of Hydrothermal Fluid Flow on Early Diagenetic Dolomitization: An Example from the Devonian Slave Point Formation, Northwest Alberta, Canada

The Middle Devonian carbonates of the Slave Point Formation, Hamburg field, northwestern Alberta,... more The Middle Devonian carbonates of the Slave Point Formation, Hamburg field, northwestern Alberta, are composed mainly of stromatoporoid and Amphipora floatstones and rudstones, with interbedded mudstone and grainstone facies characteristic of deposition in open to slightly restricted marine platform environments. These carbonates have undergone a complex diagenetic history, from shallow to deep burial, as represented by fracturing, calcite cementation, silicification, and dolomitization. Petrographically, four different types of dolomite have been identified (from early to late): (1) fine-crystalline matrix dolomite; (2) pseudomorphic dolomite; (3) medium-crystalline pervasive dolomite; and (4) saddle dolomite. Fine-crystalline dolomite (5– 50 m) replaces the mud matrix and slightly penetrates the edges of allochems. It occurred in mud-supported facies and was precipitated by marine fluids. Oxygen isotope values range from 11.62 to 9.34 (Peedee belemnite), lower than postulated values for Devonian carbonates. The enriched 87Sr/86Sr isotope value from this phase (0.71002) suggests that later diagenetic fluids may have recrystallized this dolomite. Pseudomorphic dolomite (50–100 m) replaces crinoids and occurs as single, large dolomite crystals. Its oxygen and carbon isotopic values range from 10.58 to 9.65 and +4.24 to +4.49, respectively. Medium-crystalline pervasive dolomite (10–100 m) occurs along dissolution seams and obliterates all previous fabrics. It is proposed that this medium-crystalline dolomite formed during shallow to intermediate burial because of its association with dissolution seams and high iron content. The range of oxygen isotope values for this dolomite (11.74 to 9.5) suggests precipitation from a warm fluid, possibly in a burial environment, and/or later recrystallization by hydrothermal fluids. The relatively wide range of carbon isotope values (+1.19 to +4.49) and enriched strontium isotope ratio (0.710020) suggests recrystallization. Saddle dolomite (250–2000 m) partially to completely occludes void spaces (both fractures and vugs) and also occurs as a minor replacement mineral. The oxygen isotope values for saddle dolomite (13.95 to 11.97), as well as the nonradiogenic to enriched strontium isotope ratios for saddle dolomite (0.70494 to 0.710351), and the fluid-inclusion data (homogenization temperature, Th, range between 125 and 161C and estimated salinity, between 22.2 and 24.7 wt.% NaCl equivalent) indicate precipitation from hot, highly saline, hydrothermal fluids, which were probably expelled tectonically during the Late Devonian–Mississippian Antler thrust belt development.

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Research paper thumbnail of Diagenetic Evolution of Upper Jurassic-Lower Cretaceous Berdiga Formation, NE Turkey: Petrographic and Geochemical Evidence

Paleobiodiversity and Tectono-Sedimentary Records in the Mediterranean Tethys and Related Eastern Areas, 2019

Upper Jurassic-lower Cretaceous Berdiga Formation crops out extensively in NE Turkey. The host ca... more Upper Jurassic-lower Cretaceous Berdiga Formation crops out extensively in NE Turkey. The host carbonates at Eski Gumushane section are pervasively dolomitized by fabric-destructive and fabric-preserving replacive dolomites (RD). These dolomites are Ca-rich and non-stoichiometric (Ca56-58Mg42-44). They have highly variable but low δ18O (−11.38 to −4.05‰ V-PDB) and δ13C (0.69 to 3.13‰V-PDB) values, radiogenic 87Sr/86Sr ratios (0.70753 to 0.70884), extremely high Fe (2727–21053 ppm) and Mn (1548–27726 ppm) contents. Microcrystalline quartz cement, dolomite cement and the scattered euhedral pyrite minerals (average 5 μm) are also observed in the dissolution porosity of replacive dolomites. This study demonstrates that these carbonates have undergone a complex diagenetic history from shallow to deep burial associated with syn-sedimentary extensional tectonic activity during the Albian–Aptian and later with the hydrothermal emplacement of the polymetallic mineralization during the Eocene.

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Research paper thumbnail of Paleoclimatic, paleogeographic and burial-history controls on the diagenetic evolution of reservoir sandstones: evidence from the Early Cretaceous Serraria Sandstones in the Sergipe-Alagoas Basin, NE Brazil

Paleoclimatic, paleogeographic and burial-history controls on the diagenetic evolution of reservo... more Paleoclimatic, paleogeographic and burial-history controls on the diagenetic evolution of reservoir sandstones: evidence from the Early Cretaceous Serraria Sandstones in the Sergipe-Alagoas Basin, NE Brazil

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Research paper thumbnail of Paleomagnetic dating of diagenetic events in Paleozoic carbonate reservoirs of the Western Canada Sedimentary Basin

Paragenetic sequences for sedimentary rocks provide information on their geologic histories by es... more Paragenetic sequences for sedimentary rocks provide information on their geologic histories by establishing the order of diagenetic events such as compaction, mineral replacement, mineralization, fracturing and porosity evolution. Thus, a paragenetic sequence can be used to determine the age of a specific diagenetic event relative to other events. It is much more difficult to get an absolute age for that event. Direct radiometric dating of a specific mineral in the sequence will provide an absolute age date for the mineral, and the minimum and maximum age for the diagenetic events preceding and following, respectively. However, only a few studies have used radiometric techniques, either due to limitations of the techniques themselves or to a scarcity of datable minerals. Most studies of this type have been carried out on illite, calcite, glauconite, potassium feldspar and sphalerite, using Rb-Sr, U-Pb, 40Ar/39Ar, or Th-U-Pb techniques (e.g. Hearn et al. 1987; Smith et al. 1991; Dani...

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Research paper thumbnail of Dolomitization of Mississippian Carbonates in the Shell Waterton Gas Field, Southwestern Alberta: Insights from Paleomagnetism, Petrology and Geochemistry

Bulletin of Canadian Petroleum Geology, 1998

Petrology, geochemistry and paleomagnetism have been collectively used to examine the process and... more Petrology, geochemistry and paleomagnetism have been collectively used to examine the process and timing of both dolomitization and hydrocarbon migration in carbonates from the Mississippian Mount Head Formation of the Shell Waterton gas field in the foothills of the Rocky Mountains of southwestern Alberta. Plugs were sampled from three unoriented drill cores and their azimuths were measured with respect to a master orientation line (MOL) on fitted segments of each core to provide the relative orientation between specimens from different plugs. The MOL azimuth was obtained by: 1) comparison of features observed in the core with those observed in the oriented Formation Micro-Scanner (FMS) logs; and, 2) aligning the low temperature magnetization direction with the present Earth's magnetic field (PEMF). Both methods gave similar results, showing that paleomagnetism can be an effective and inexpensive alternative for orienting drill core for which FMS logs are not available. Thermal...

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Research paper thumbnail of Paleomagnetism, Petrology and Geochemistry of Mississippian Dolomites from the Shell Waterton Gas Field, Southwestern Alberta

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Research paper thumbnail of Dating penecontemporaneous dolomitization in carbonate reservoirs: Paleomagnetic, petrographic, and geochemical constraints

AAPG Bulletin, 2003

The predominant dolomitization in the Mississippian Debolt Formation, Western Canada sedimentary ... more The predominant dolomitization in the Mississippian Debolt Formation, Western Canada sedimentary basin was hypothesized to be early in three gas fields, based on stable oxygen and carbon isotopic values and on strontium isotope ratios that are similar to postulated Mississippian dolomite values and seawater ratios, respectively. As the absolute age could not be determined by this method, paleomagnetism was used to place constraints on the age of the dolomitization. The magnetic analyses on Debolt specimens from the same wells revealed three magnetization components that could be tied to geologic/diagenetic events: (1) a low-temperature ( 350 degreesC) and coercivity (>80 mT) C component of primary or early diagenetic origin that is found mostly in the fine-grained limestone and dolomitic muds. The preservation of a primary or early diagenetic magnetization, combined with the preservation of primary isotopic values, indicates that little or no extrabasinal fluid flow is likely to ...

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Research paper thumbnail of Diagenetic History and Isotope Geochemistry of Pabdeh Formation in Dezful Embayment (Zagros Basin) SW Iran

GEO 2010, 2010

Pabdeh Formation (upper Eocene-Oligocene) is a carbonate dominated sedimentary package with shale... more Pabdeh Formation (upper Eocene-Oligocene) is a carbonate dominated sedimentary package with shale -marl intervals. This Formation was studied the type section (Kuh-E-Gurpi) and four boreholes located in Dezful Embayment (Zagros Basin). The Pabdeh Formation comprises three depositional sequences bounded by Type I sequence boundary in lower part and both Type I and type II sequence boundaries in upper part. Uppermost sequence encompassed a subsea marine phreatic diagenetic environment, whereas sequence one and two evidently experienced burial diagenesis with moderately reducing conditions in a relatively enclosed system. Sr87/ Sr86 ratios represents a sharp separations between sequence two and three, whereas low Rb content of these samples suggesting these sediments are not affected by meteoric fluids in an open system. A double behaviour is expected from the Pabdeh Formation as the lithology are combination of carbonates and shale alternations, as shales could be considered as potential source rocks, whereas grainstones of tempestite facies have reservoir characteristics. Hence change of stratigraphic trap exploration is a scenario for these facies changes within the Pabdeh Formation. Furthermore, extensive fracturing in upper parts of second sequence implies reservoir porosity development in these parts. Evidences of meteoric water flushing implies in third (last) sequence, leads porosity development in this sequence.

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Research paper thumbnail of Recognition of Palaeoexposure Surfaces within Cenomanian-Turonian Strata of Southwesterrn Iran: Implications for Reservoir Characteristics

GEO 2010, 2010

Recognition of Palaeoexposure Surfaces within Cenomanian-Turonian Strata of Southwesterrn Iran: I... more Recognition of Palaeoexposure Surfaces within Cenomanian-Turonian Strata of Southwesterrn Iran: Implications for Reservoir Characteristics. Elham Hajikazemi 1 ; Ihsan S. Al-Aasm 1 ; Mario Coniglio 2. ... Geological Magazine 143, 561-608. ...

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Research paper thumbnail of Sequence Stratigraphy of Pabdeh Formation in Dezful Embayment (Zagros Basin) SW Iran

GEO 2010, 2010

Pabdeh Formation (upper Eocene-Oligocene) is a carbonate dominated sedimentary package with shale... more Pabdeh Formation (upper Eocene-Oligocene) is a carbonate dominated sedimentary package with shale -marl intervals. This Formation was studied the type section (Kuh-E-Gurpi) and four boreholes located in Dezful Embayment (Zagros Basin). The Pabdeh Formation comprises three depositional sequences bounded by Type I sequence boundary in lower part and both Type I and type II sequence boundaries in upper part. Uppermost sequence encompassed a subsea marine phreatic diagenetic environment, whereas sequence one and two evidently experienced burial diagenesis with moderately reducing conditions in a relatively enclosed system. Sr87/ Sr86 ratios represents a sharp separations between sequence two and three, whereas low Rb content of these samples suggesting these sediments are not affected by meteoric fluids in an open system. A double behaviour is expected from the Pabdeh Formation as the lithology are combination of carbonates and shale alternations, as shales could be considered as potential source rocks, whereas grainstones of tempestite facies of TST and HST in second sequence have reservoir characteristics. Hence change of stratigraphic trap exploration is a scenario for these facies changes within the Pabdeh Formation. Furthermore, extensive fracturing in upper parts of second sequence (late HST) implies reservoir porosity development in these parts. Evidences of meteoric water flushing implies in third (last) sequence, leads porosity development in this sequence.

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Research paper thumbnail of Palaeo‐Exposure Surfaces in the Aptian Dariyan Formation, Offshore SW Iran: Geochemistry and Reservoir Implications

Journal of Petroleum Geology, 2018

Palaeo‐exposure surfaces within and at the top of the carbonate‐dominated Aptian Dariyan Formatio... more Palaeo‐exposure surfaces within and at the top of the carbonate‐dominated Aptian Dariyan Formation have been poorly studied in the Iranian sector of the Persian Gulf. This paper presents an integrated sedimentological and geochemical study of the Dariyan Formation at four oil and gas fields located in the western, central and eastern parts of the Gulf. Facies stacking patterns in general indicate shallowing‐upwards trends toward the exposure surfaces, which are interpreted to correspond to unconformities.The Dariyan Formation in the study area is divided into upper and lower carbonate units by a deep‐water, high‐gamma shale‐marl interval. At fields in the western and central Gulf, significant diagenetic changes were recorded in the top of the upper carbonate unit, including meteoric dissolution and cementation, brecciation and paleosol formation. An exposure surface is also present at the top of the lower carbonate unit in all the fields in the study area, and is associated with met...

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Research paper thumbnail of Petrologic and geochemical attributes of calcite cementation, dolomitization and dolomite recrystallization: an example from the Mississippian Pekisko Formation, west-central Alberta

Bulletin of Canadian Petroleum Geology, 2017

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Research paper thumbnail of Origin of Authigenic Carbonates in Eocene to Quaternary Sediments from the Arctic Ocean and Norwegian-Greenland Sea

Proceedings of the Ocean Drilling Program, Dec 1, 1996

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Research paper thumbnail of Hydrothermal Dolomitization of the Mississippian Upper Debolt Formation, Sikanni Gas Field, Northeastern British Columbia, Canada

Bulletin of Canadian Petroleum Geology, Sep 1, 1997

The Mississippian carbonates of the Upper Debolt Formation, Sikanni Field, British Columbia, are ... more The Mississippian carbonates of the Upper Debolt Formation, Sikanni Field, British Columbia, are gas-producing, fractured and brecciated, dolomitized rocks. These rocks have undergone complex diagenetic changes, represented mainly by various generations of ...

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Research paper thumbnail of Fluid compartmentalization and dolomitization in the Cambrian and Ordovician successions of the Huron Domain, Michigan Basin

Marine and Petroleum Geology, Apr 1, 2018

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Research paper thumbnail of Neomorphism: A Tale of Divergence from Two Mississippian Dolomites

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Research paper thumbnail of Stratigraphy, Stable Isotopes, and Hydrocarbon Potential of the Aptian Shuaiba Formation, U.A.E

SEPM (Society for Sedimentary Geology) eBooks, 2000

... of the United Arab Emirates (UAE), forms one of t.he most important petroleum reservoirs in .... more ... of the United Arab Emirates (UAE), forms one of t.he most important petroleum reservoirs in ... 69, Copyright © 2000 SEPM (Society for Sedimentary Geology), ISBN 1-56576-O75-1, p. 299 ... These samples came from both onshore and offshore fields in the UAE, including producing ...

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Research paper thumbnail of Some Reflections on Refluxion: The Wabamun “Crossfield Zone” Reservoirs as Classic Examples

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Research paper thumbnail of Dolomitization of Mississippian Carbonates of Western Canada Sedimentary Basin: Petrologic and Geochemical Constraints

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Research paper thumbnail of Big Gas in Hydrothermal Chert-hosted Reservoirs: Is Parkland, B.C. Unique?

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Research paper thumbnail of The Effect of Hydrothermal Fluid Flow on Early Diagenetic Dolomitization: An Example from the Devonian Slave Point Formation, Northwest Alberta, Canada

The Middle Devonian carbonates of the Slave Point Formation, Hamburg field, northwestern Alberta,... more The Middle Devonian carbonates of the Slave Point Formation, Hamburg field, northwestern Alberta, are composed mainly of stromatoporoid and Amphipora floatstones and rudstones, with interbedded mudstone and grainstone facies characteristic of deposition in open to slightly restricted marine platform environments. These carbonates have undergone a complex diagenetic history, from shallow to deep burial, as represented by fracturing, calcite cementation, silicification, and dolomitization. Petrographically, four different types of dolomite have been identified (from early to late): (1) fine-crystalline matrix dolomite; (2) pseudomorphic dolomite; (3) medium-crystalline pervasive dolomite; and (4) saddle dolomite. Fine-crystalline dolomite (5– 50 m) replaces the mud matrix and slightly penetrates the edges of allochems. It occurred in mud-supported facies and was precipitated by marine fluids. Oxygen isotope values range from 11.62 to 9.34 (Peedee belemnite), lower than postulated values for Devonian carbonates. The enriched 87Sr/86Sr isotope value from this phase (0.71002) suggests that later diagenetic fluids may have recrystallized this dolomite. Pseudomorphic dolomite (50–100 m) replaces crinoids and occurs as single, large dolomite crystals. Its oxygen and carbon isotopic values range from 10.58 to 9.65 and +4.24 to +4.49, respectively. Medium-crystalline pervasive dolomite (10–100 m) occurs along dissolution seams and obliterates all previous fabrics. It is proposed that this medium-crystalline dolomite formed during shallow to intermediate burial because of its association with dissolution seams and high iron content. The range of oxygen isotope values for this dolomite (11.74 to 9.5) suggests precipitation from a warm fluid, possibly in a burial environment, and/or later recrystallization by hydrothermal fluids. The relatively wide range of carbon isotope values (+1.19 to +4.49) and enriched strontium isotope ratio (0.710020) suggests recrystallization. Saddle dolomite (250–2000 m) partially to completely occludes void spaces (both fractures and vugs) and also occurs as a minor replacement mineral. The oxygen isotope values for saddle dolomite (13.95 to 11.97), as well as the nonradiogenic to enriched strontium isotope ratios for saddle dolomite (0.70494 to 0.710351), and the fluid-inclusion data (homogenization temperature, Th, range between 125 and 161C and estimated salinity, between 22.2 and 24.7 wt.% NaCl equivalent) indicate precipitation from hot, highly saline, hydrothermal fluids, which were probably expelled tectonically during the Late Devonian–Mississippian Antler thrust belt development.

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Research paper thumbnail of Diagenetic Evolution of Upper Jurassic-Lower Cretaceous Berdiga Formation, NE Turkey: Petrographic and Geochemical Evidence

Paleobiodiversity and Tectono-Sedimentary Records in the Mediterranean Tethys and Related Eastern Areas, 2019

Upper Jurassic-lower Cretaceous Berdiga Formation crops out extensively in NE Turkey. The host ca... more Upper Jurassic-lower Cretaceous Berdiga Formation crops out extensively in NE Turkey. The host carbonates at Eski Gumushane section are pervasively dolomitized by fabric-destructive and fabric-preserving replacive dolomites (RD). These dolomites are Ca-rich and non-stoichiometric (Ca56-58Mg42-44). They have highly variable but low δ18O (−11.38 to −4.05‰ V-PDB) and δ13C (0.69 to 3.13‰V-PDB) values, radiogenic 87Sr/86Sr ratios (0.70753 to 0.70884), extremely high Fe (2727–21053 ppm) and Mn (1548–27726 ppm) contents. Microcrystalline quartz cement, dolomite cement and the scattered euhedral pyrite minerals (average 5 μm) are also observed in the dissolution porosity of replacive dolomites. This study demonstrates that these carbonates have undergone a complex diagenetic history from shallow to deep burial associated with syn-sedimentary extensional tectonic activity during the Albian–Aptian and later with the hydrothermal emplacement of the polymetallic mineralization during the Eocene.

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Research paper thumbnail of Paleoclimatic, paleogeographic and burial-history controls on the diagenetic evolution of reservoir sandstones: evidence from the Early Cretaceous Serraria Sandstones in the Sergipe-Alagoas Basin, NE Brazil

Paleoclimatic, paleogeographic and burial-history controls on the diagenetic evolution of reservo... more Paleoclimatic, paleogeographic and burial-history controls on the diagenetic evolution of reservoir sandstones: evidence from the Early Cretaceous Serraria Sandstones in the Sergipe-Alagoas Basin, NE Brazil

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Research paper thumbnail of Paleomagnetic dating of diagenetic events in Paleozoic carbonate reservoirs of the Western Canada Sedimentary Basin

Paragenetic sequences for sedimentary rocks provide information on their geologic histories by es... more Paragenetic sequences for sedimentary rocks provide information on their geologic histories by establishing the order of diagenetic events such as compaction, mineral replacement, mineralization, fracturing and porosity evolution. Thus, a paragenetic sequence can be used to determine the age of a specific diagenetic event relative to other events. It is much more difficult to get an absolute age for that event. Direct radiometric dating of a specific mineral in the sequence will provide an absolute age date for the mineral, and the minimum and maximum age for the diagenetic events preceding and following, respectively. However, only a few studies have used radiometric techniques, either due to limitations of the techniques themselves or to a scarcity of datable minerals. Most studies of this type have been carried out on illite, calcite, glauconite, potassium feldspar and sphalerite, using Rb-Sr, U-Pb, 40Ar/39Ar, or Th-U-Pb techniques (e.g. Hearn et al. 1987; Smith et al. 1991; Dani...

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Research paper thumbnail of Dolomitization of Mississippian Carbonates in the Shell Waterton Gas Field, Southwestern Alberta: Insights from Paleomagnetism, Petrology and Geochemistry

Bulletin of Canadian Petroleum Geology, 1998

Petrology, geochemistry and paleomagnetism have been collectively used to examine the process and... more Petrology, geochemistry and paleomagnetism have been collectively used to examine the process and timing of both dolomitization and hydrocarbon migration in carbonates from the Mississippian Mount Head Formation of the Shell Waterton gas field in the foothills of the Rocky Mountains of southwestern Alberta. Plugs were sampled from three unoriented drill cores and their azimuths were measured with respect to a master orientation line (MOL) on fitted segments of each core to provide the relative orientation between specimens from different plugs. The MOL azimuth was obtained by: 1) comparison of features observed in the core with those observed in the oriented Formation Micro-Scanner (FMS) logs; and, 2) aligning the low temperature magnetization direction with the present Earth's magnetic field (PEMF). Both methods gave similar results, showing that paleomagnetism can be an effective and inexpensive alternative for orienting drill core for which FMS logs are not available. Thermal...

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Research paper thumbnail of Paleomagnetism, Petrology and Geochemistry of Mississippian Dolomites from the Shell Waterton Gas Field, Southwestern Alberta

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Research paper thumbnail of Dating penecontemporaneous dolomitization in carbonate reservoirs: Paleomagnetic, petrographic, and geochemical constraints

AAPG Bulletin, 2003

The predominant dolomitization in the Mississippian Debolt Formation, Western Canada sedimentary ... more The predominant dolomitization in the Mississippian Debolt Formation, Western Canada sedimentary basin was hypothesized to be early in three gas fields, based on stable oxygen and carbon isotopic values and on strontium isotope ratios that are similar to postulated Mississippian dolomite values and seawater ratios, respectively. As the absolute age could not be determined by this method, paleomagnetism was used to place constraints on the age of the dolomitization. The magnetic analyses on Debolt specimens from the same wells revealed three magnetization components that could be tied to geologic/diagenetic events: (1) a low-temperature ( 350 degreesC) and coercivity (>80 mT) C component of primary or early diagenetic origin that is found mostly in the fine-grained limestone and dolomitic muds. The preservation of a primary or early diagenetic magnetization, combined with the preservation of primary isotopic values, indicates that little or no extrabasinal fluid flow is likely to ...

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Research paper thumbnail of Diagenetic History and Isotope Geochemistry of Pabdeh Formation in Dezful Embayment (Zagros Basin) SW Iran

GEO 2010, 2010

Pabdeh Formation (upper Eocene-Oligocene) is a carbonate dominated sedimentary package with shale... more Pabdeh Formation (upper Eocene-Oligocene) is a carbonate dominated sedimentary package with shale -marl intervals. This Formation was studied the type section (Kuh-E-Gurpi) and four boreholes located in Dezful Embayment (Zagros Basin). The Pabdeh Formation comprises three depositional sequences bounded by Type I sequence boundary in lower part and both Type I and type II sequence boundaries in upper part. Uppermost sequence encompassed a subsea marine phreatic diagenetic environment, whereas sequence one and two evidently experienced burial diagenesis with moderately reducing conditions in a relatively enclosed system. Sr87/ Sr86 ratios represents a sharp separations between sequence two and three, whereas low Rb content of these samples suggesting these sediments are not affected by meteoric fluids in an open system. A double behaviour is expected from the Pabdeh Formation as the lithology are combination of carbonates and shale alternations, as shales could be considered as potential source rocks, whereas grainstones of tempestite facies have reservoir characteristics. Hence change of stratigraphic trap exploration is a scenario for these facies changes within the Pabdeh Formation. Furthermore, extensive fracturing in upper parts of second sequence implies reservoir porosity development in these parts. Evidences of meteoric water flushing implies in third (last) sequence, leads porosity development in this sequence.

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Research paper thumbnail of Recognition of Palaeoexposure Surfaces within Cenomanian-Turonian Strata of Southwesterrn Iran: Implications for Reservoir Characteristics

GEO 2010, 2010

Recognition of Palaeoexposure Surfaces within Cenomanian-Turonian Strata of Southwesterrn Iran: I... more Recognition of Palaeoexposure Surfaces within Cenomanian-Turonian Strata of Southwesterrn Iran: Implications for Reservoir Characteristics. Elham Hajikazemi 1 ; Ihsan S. Al-Aasm 1 ; Mario Coniglio 2. ... Geological Magazine 143, 561-608. ...

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Research paper thumbnail of Sequence Stratigraphy of Pabdeh Formation in Dezful Embayment (Zagros Basin) SW Iran

GEO 2010, 2010

Pabdeh Formation (upper Eocene-Oligocene) is a carbonate dominated sedimentary package with shale... more Pabdeh Formation (upper Eocene-Oligocene) is a carbonate dominated sedimentary package with shale -marl intervals. This Formation was studied the type section (Kuh-E-Gurpi) and four boreholes located in Dezful Embayment (Zagros Basin). The Pabdeh Formation comprises three depositional sequences bounded by Type I sequence boundary in lower part and both Type I and type II sequence boundaries in upper part. Uppermost sequence encompassed a subsea marine phreatic diagenetic environment, whereas sequence one and two evidently experienced burial diagenesis with moderately reducing conditions in a relatively enclosed system. Sr87/ Sr86 ratios represents a sharp separations between sequence two and three, whereas low Rb content of these samples suggesting these sediments are not affected by meteoric fluids in an open system. A double behaviour is expected from the Pabdeh Formation as the lithology are combination of carbonates and shale alternations, as shales could be considered as potential source rocks, whereas grainstones of tempestite facies of TST and HST in second sequence have reservoir characteristics. Hence change of stratigraphic trap exploration is a scenario for these facies changes within the Pabdeh Formation. Furthermore, extensive fracturing in upper parts of second sequence (late HST) implies reservoir porosity development in these parts. Evidences of meteoric water flushing implies in third (last) sequence, leads porosity development in this sequence.

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Research paper thumbnail of Palaeo‐Exposure Surfaces in the Aptian Dariyan Formation, Offshore SW Iran: Geochemistry and Reservoir Implications

Journal of Petroleum Geology, 2018

Palaeo‐exposure surfaces within and at the top of the carbonate‐dominated Aptian Dariyan Formatio... more Palaeo‐exposure surfaces within and at the top of the carbonate‐dominated Aptian Dariyan Formation have been poorly studied in the Iranian sector of the Persian Gulf. This paper presents an integrated sedimentological and geochemical study of the Dariyan Formation at four oil and gas fields located in the western, central and eastern parts of the Gulf. Facies stacking patterns in general indicate shallowing‐upwards trends toward the exposure surfaces, which are interpreted to correspond to unconformities.The Dariyan Formation in the study area is divided into upper and lower carbonate units by a deep‐water, high‐gamma shale‐marl interval. At fields in the western and central Gulf, significant diagenetic changes were recorded in the top of the upper carbonate unit, including meteoric dissolution and cementation, brecciation and paleosol formation. An exposure surface is also present at the top of the lower carbonate unit in all the fields in the study area, and is associated with met...

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Research paper thumbnail of Petrologic and geochemical attributes of calcite cementation, dolomitization and dolomite recrystallization: an example from the Mississippian Pekisko Formation, west-central Alberta

Bulletin of Canadian Petroleum Geology, 2017

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