new data on the main components of organic matter, inorganic geochemistry, and stable isotopes al... more new data on the main components of organic matter, inorganic geochemistry, and stable isotopes along a north-south transect from the Cretaceous Western Interior Seaway (Portland-1 Colorado; Iona-1; Innes-1; Well X; Bouldin Creek outcrop - Eagle Ford Group, SW Texas, USA) and to the equatorial western Atlantic (ODP Sites 1260 and 1261) and Southern Ocean (ODP Site 1138)
This chapter summarizes geochronologic and other data for major Phanerozoic Large Igneous Provinc... more This chapter summarizes geochronologic and other data for major Phanerozoic Large Igneous Provinces (LIPs), Oceanic Anoxic Events (OAEs) and organic‐rich petroleum source rocks. It also evaluates the models that support or refute genetic links between the three groups. The evidence appears to favor genetic links between the three groups, however, additional high precision age and geochemical data are needed to validate several events. Furthermore, the chapter provides insights into the importance of LIPs in hydrocarbon exploration.
Centennial- to millennial-scale climate variations are often attributed to solar forcing or inter... more Centennial- to millennial-scale climate variations are often attributed to solar forcing or internal climate system variability, but recognition of such variations in the deep-time paleoclimate record is extremely rare. We present an exceptionally well-preserved, millimeter-scale laminated marlstone from a succession of precession-driven limestone-marlstone couplets deposited in the Western Interior Seaway (North America) immediately preceding and during the Cretaceous mid-Cenomanian event (ca. 96.5 Ma). Sedimentological, geochemical, and micropaleontological data indicate that individual pairs of light-dark laminae record alternations in the extent of water-column mixing and oxygenation. Principal component analysis of X-ray fluorescence element counts and a grayscale scan of a continuous thin section through the marlstone reveal variations with 80–100 yr, 200–230 yr, 350–500 yr, ~1650 yr, and 4843 yr periodicities. A substantial fraction of the data indicates an anoxic bottom wate...
Abstract Oceanic Anoxic Event 2 (OAE-2) occurred at the Cenomanian-Turonian boundary (∼94.1 Ma) a... more Abstract Oceanic Anoxic Event 2 (OAE-2) occurred at the Cenomanian-Turonian boundary (∼94.1 Ma) and was a time of profound global changes in ocean chemistry and the carbon cycle. This event was characterized by a positive carbon isotope excursion (CIE) caused by massive organic carbon burial, global greenhouse temperatures, ocean deoxygenation, and changes in ocean life driven by large igneous province (LIP) activity. LIPs throughout the Phanerozoic have had dynamic magma flux, with episodes of major eruptions interspersed with periods of relatively less intense eruptions. A possible trigger for LIP activity throughout the Phanerozoic has been attributed to extraterrestrial impacts because there are multiple contemporaneous occurrences of large craters, LIP activity, and mass extinctions in the geologic record. At the Cenomanian-Turonian boundary, there is a 25 km diameter (rim-to-rim) complex crater in NW Alberta, Canada known as the Steen River impact structure dated at 91 ± 7 Ma (Carrigy and Short, 1968). An alternative explanation for those craters found contemporaneous with LIP activity and mass extinctions is that they were created by large explosive events related to LIP activity. Explosive events associated with mantle plume incubation beneath cratonic lithosphere have been suggested to create geologic features commonly attributed to impacts (e.g., shocked quartz, microspherules, etc.). Currently, the trigger for LIP activity during OAE-2, as well as the duration of LIP activity and the temporal variation and magnitude of eruption rates are not well constrained. To address the issue of LIP eruption rates and the trigger for LIP activity, we examined osmium (Os) abundances and isotopes as well as highly siderophile element (HSE; for this study: Re, Ru, Pd, Os, Ir, Pt) abundance data from a continuous sedimentary section spanning OAE-2. The section is from the Eagle Ford Group in the Iona-1 core, deposited in the Cretaceous Western Interior Seaway (KWIS). We found three high Os concentration intervals with mantle-like initial Osi isotope (initial 187Os/188Os) values of ∼0.16. These intervals are interpreted to reflect high-flux LIP magmatic pulses. Between the pulses, lower Os abundances with more radiogenic Osi values of ∼0.20 are observed, which we interpret as low-flux LIP activity between the high-flux periods. This trend of high-and-low flux Os concentration pulses with mantle-like Osi values during the high flux periods is found in another KWIS core (USGS Portland #1) deposited to the north of Iona-1, and in core Deep Sea Drilling Project (DSDP) Site 530 Hole A (hereafter DSDP 530A; drilled off-shore Namibia in the Angola Basin) deposited in the Southern Hemisphere. Before and throughout the Iona-1 core OAE-2 interval, HSE abundance patterns indicate a mantle source for the unradiogenic Os, and are not consistent with an extraterrestrial impact trigger or contribution to LIP activity during OAE-2. This evidence for multiple high-flux pulses of LIP activity driving ocean deoxygenation has implications for the modern ocean, which is currently experiencing deoxygenation. These results provide new constraints on subsequent high-flux periods that extended the event. The first high-flux period started ∼60 Kyr after our selection of the onset of the CIE. The second and third high-flux periods started ∼270 and ∼400 Kyr after the onset of the CIE, respectively. After the third high-flux period, δ13Corg and Os isotope ratios shifted back to pre-excursion values over ∼585 kyr. In the Iona-1 core, OAE-2 lasted for 1.04 ± 0.12 Myr based on our selection of the CIE.
The Late Cretaceous Epoch was characterized major global perturbations in the carbon cycle, the m... more The Late Cretaceous Epoch was characterized major global perturbations in the carbon cycle, the most prominent occurring near the Cenomanian-Turonian (CT) transition marked by Oceanic Anoxic Event/OAE-2 at 94.9–93.7 Ma. The Cretaceous Western Interior Seaway (KWIS) was one of several epicontinental seas in which a complex water-mass evolution was recorded in widespread sedimentary successions. This contribution integrates new data on the main components of organic matter, geochemistry, and stable isotopes along a North-South transect from the KWIS to the equatorial western Atlantic and Southern Ocean. In particular, cored sedimentary rocks from the Eagle Ford Group of West Texas (~ 90–98 Ma) demonstrate subtle temporal and spatial variations in paleoenvironmental conditions and provide an important geographic constraint for interpreting water-mass evolution. High latitude (boreal-austral), equatorial tethyan and locally sourced Western Interior Seawa...
Since the beginning of the century, several authors have hypothesized and documented the presence... more Since the beginning of the century, several authors have hypothesized and documented the presence of bottom currents during the deposition of mudstones, including mudstones rich in organic matter, challenging the assumption that persistent low-energy conditions are necessary prerequisites for deposition of such sediments. More processes responsible for transport and deposition of mudstones mean also more processes acting contemporaneously in different parts of a basin. Without a precise and robust chronostratigraphic framework, however, it is not possible to characterize these differences. The new data reported here provide a profoundly different understanding of the controls on sedimentation in distal continental shelf platforms. To enhance the understanding of the different coeval environments of deposition coexisting in a muddy system, the Upper Cretaceous Eagle Ford Group, deposited on the Comanche carbonate platform, has been investigated by integrating sedimentology, mineralogy, geochemistry and palaeoecology, and creating age models in different physiographic sectors using biostratigraphy and geochronology. Data from two cores and 41 outcrops were analysed with a telescopic approach, from grain scale to basin scale. Nine temporal stages over a ca 8 Myr interval (ca 98 to 90 Ma) were defined in an area that spans 75 000 km2. Finally, the different environments of deposition recorded within each of the nine stages were interpreted. The construction of the chronostratigraphic framework also allowed: measuring the duration of a basin-wide gradational increase in energy in the water column (ca 1 Myr) and a hiatus confined into the shallower water sector (ca 2 Myr); determining the mean eruption frequency of volcanoes (ca 9 kyr); and the time of inundation of the Western Interior Seaway (975 to 97 1 Ma). The context, the outcrops– cores–logs correlations, the large data set (Appendix S1), the high-precision and well-calibrated constraints represent an unprecedented contribution for future regional facies models of organic-rich units and for improvements of key aspects in the industry of unconventional resources.
The English Basin is interpreted as a Mes~~Neoproterozoic, and Cambrian-age depocenter, forming a... more The English Basin is interpreted as a Mes~~Neoproterozoic, and Cambrian-age depocenter, forming a portion of the East Continent rift complex in areas of Kentucky and Indiana. Both proprietary and published seismic sections show a complex structural depocenter with a depth to crystalline basement exceeding 6100 m. Two boreholes penetrate the Proterozoic sequence of the depocenter and have strata similar in lithology to both the Precambrian Middle Run Formation (Centralia Group) described in Ohio and Kentucky and low-density clastic sediments of the overlying Marengo Formation.
Centennial-to millennial-scale climate variations are often attributed to solar forcing or intern... more Centennial-to millennial-scale climate variations are often attributed to solar forcing or internal climate system variability, but recognition of such variations in the deep-time paleoclimate record is extremely rare. We present an exceptionally well-preserved, millimeterscale laminated marlstone from a succession of precession-driven limestone-marlstone couplets deposited in the Western Interior Seaway (North America) immediately preceding and during the Cretaceous mid-Cenomanian event (ca. 96.5 Ma). Sedimentological, geochemical, and micropaleontological data indicate that individual pairs of light-dark laminae record alternations in the extent of water-column mixing and oxygenation. Principal component analysis of X-ray fluorescence element counts and a grayscale scan of a continuous thin section through the marlstone reveal variations with 80-100 yr, 200-230 yr, 350-500 yr, ∼1650 yr, and 4843 yr periodicities. A substantial fraction of the data indicates an anoxic bottom water variation with a pronounced 10,784 yr cycle. The centennial to millennial variations are reminiscent of those found in Holocene total solar irradiance variability, and the 10,784 yr anoxia cycle may be a manifestation of semi-precession-influenced Tethyan oxygen minimum zone waters entering the seaway.
new data on the main components of organic matter, inorganic geochemistry, and stable isotopes al... more new data on the main components of organic matter, inorganic geochemistry, and stable isotopes along a north-south transect from the Cretaceous Western Interior Seaway (Portland-1 Colorado; Iona-1; Innes-1; Well X; Bouldin Creek outcrop - Eagle Ford Group, SW Texas, USA) and to the equatorial western Atlantic (ODP Sites 1260 and 1261) and Southern Ocean (ODP Site 1138)
This chapter summarizes geochronologic and other data for major Phanerozoic Large Igneous Provinc... more This chapter summarizes geochronologic and other data for major Phanerozoic Large Igneous Provinces (LIPs), Oceanic Anoxic Events (OAEs) and organic‐rich petroleum source rocks. It also evaluates the models that support or refute genetic links between the three groups. The evidence appears to favor genetic links between the three groups, however, additional high precision age and geochemical data are needed to validate several events. Furthermore, the chapter provides insights into the importance of LIPs in hydrocarbon exploration.
Centennial- to millennial-scale climate variations are often attributed to solar forcing or inter... more Centennial- to millennial-scale climate variations are often attributed to solar forcing or internal climate system variability, but recognition of such variations in the deep-time paleoclimate record is extremely rare. We present an exceptionally well-preserved, millimeter-scale laminated marlstone from a succession of precession-driven limestone-marlstone couplets deposited in the Western Interior Seaway (North America) immediately preceding and during the Cretaceous mid-Cenomanian event (ca. 96.5 Ma). Sedimentological, geochemical, and micropaleontological data indicate that individual pairs of light-dark laminae record alternations in the extent of water-column mixing and oxygenation. Principal component analysis of X-ray fluorescence element counts and a grayscale scan of a continuous thin section through the marlstone reveal variations with 80–100 yr, 200–230 yr, 350–500 yr, ~1650 yr, and 4843 yr periodicities. A substantial fraction of the data indicates an anoxic bottom wate...
Abstract Oceanic Anoxic Event 2 (OAE-2) occurred at the Cenomanian-Turonian boundary (∼94.1 Ma) a... more Abstract Oceanic Anoxic Event 2 (OAE-2) occurred at the Cenomanian-Turonian boundary (∼94.1 Ma) and was a time of profound global changes in ocean chemistry and the carbon cycle. This event was characterized by a positive carbon isotope excursion (CIE) caused by massive organic carbon burial, global greenhouse temperatures, ocean deoxygenation, and changes in ocean life driven by large igneous province (LIP) activity. LIPs throughout the Phanerozoic have had dynamic magma flux, with episodes of major eruptions interspersed with periods of relatively less intense eruptions. A possible trigger for LIP activity throughout the Phanerozoic has been attributed to extraterrestrial impacts because there are multiple contemporaneous occurrences of large craters, LIP activity, and mass extinctions in the geologic record. At the Cenomanian-Turonian boundary, there is a 25 km diameter (rim-to-rim) complex crater in NW Alberta, Canada known as the Steen River impact structure dated at 91 ± 7 Ma (Carrigy and Short, 1968). An alternative explanation for those craters found contemporaneous with LIP activity and mass extinctions is that they were created by large explosive events related to LIP activity. Explosive events associated with mantle plume incubation beneath cratonic lithosphere have been suggested to create geologic features commonly attributed to impacts (e.g., shocked quartz, microspherules, etc.). Currently, the trigger for LIP activity during OAE-2, as well as the duration of LIP activity and the temporal variation and magnitude of eruption rates are not well constrained. To address the issue of LIP eruption rates and the trigger for LIP activity, we examined osmium (Os) abundances and isotopes as well as highly siderophile element (HSE; for this study: Re, Ru, Pd, Os, Ir, Pt) abundance data from a continuous sedimentary section spanning OAE-2. The section is from the Eagle Ford Group in the Iona-1 core, deposited in the Cretaceous Western Interior Seaway (KWIS). We found three high Os concentration intervals with mantle-like initial Osi isotope (initial 187Os/188Os) values of ∼0.16. These intervals are interpreted to reflect high-flux LIP magmatic pulses. Between the pulses, lower Os abundances with more radiogenic Osi values of ∼0.20 are observed, which we interpret as low-flux LIP activity between the high-flux periods. This trend of high-and-low flux Os concentration pulses with mantle-like Osi values during the high flux periods is found in another KWIS core (USGS Portland #1) deposited to the north of Iona-1, and in core Deep Sea Drilling Project (DSDP) Site 530 Hole A (hereafter DSDP 530A; drilled off-shore Namibia in the Angola Basin) deposited in the Southern Hemisphere. Before and throughout the Iona-1 core OAE-2 interval, HSE abundance patterns indicate a mantle source for the unradiogenic Os, and are not consistent with an extraterrestrial impact trigger or contribution to LIP activity during OAE-2. This evidence for multiple high-flux pulses of LIP activity driving ocean deoxygenation has implications for the modern ocean, which is currently experiencing deoxygenation. These results provide new constraints on subsequent high-flux periods that extended the event. The first high-flux period started ∼60 Kyr after our selection of the onset of the CIE. The second and third high-flux periods started ∼270 and ∼400 Kyr after the onset of the CIE, respectively. After the third high-flux period, δ13Corg and Os isotope ratios shifted back to pre-excursion values over ∼585 kyr. In the Iona-1 core, OAE-2 lasted for 1.04 ± 0.12 Myr based on our selection of the CIE.
The Late Cretaceous Epoch was characterized major global perturbations in the carbon cycle, the m... more The Late Cretaceous Epoch was characterized major global perturbations in the carbon cycle, the most prominent occurring near the Cenomanian-Turonian (CT) transition marked by Oceanic Anoxic Event/OAE-2 at 94.9–93.7 Ma. The Cretaceous Western Interior Seaway (KWIS) was one of several epicontinental seas in which a complex water-mass evolution was recorded in widespread sedimentary successions. This contribution integrates new data on the main components of organic matter, geochemistry, and stable isotopes along a North-South transect from the KWIS to the equatorial western Atlantic and Southern Ocean. In particular, cored sedimentary rocks from the Eagle Ford Group of West Texas (~ 90–98 Ma) demonstrate subtle temporal and spatial variations in paleoenvironmental conditions and provide an important geographic constraint for interpreting water-mass evolution. High latitude (boreal-austral), equatorial tethyan and locally sourced Western Interior Seawa...
Since the beginning of the century, several authors have hypothesized and documented the presence... more Since the beginning of the century, several authors have hypothesized and documented the presence of bottom currents during the deposition of mudstones, including mudstones rich in organic matter, challenging the assumption that persistent low-energy conditions are necessary prerequisites for deposition of such sediments. More processes responsible for transport and deposition of mudstones mean also more processes acting contemporaneously in different parts of a basin. Without a precise and robust chronostratigraphic framework, however, it is not possible to characterize these differences. The new data reported here provide a profoundly different understanding of the controls on sedimentation in distal continental shelf platforms. To enhance the understanding of the different coeval environments of deposition coexisting in a muddy system, the Upper Cretaceous Eagle Ford Group, deposited on the Comanche carbonate platform, has been investigated by integrating sedimentology, mineralogy, geochemistry and palaeoecology, and creating age models in different physiographic sectors using biostratigraphy and geochronology. Data from two cores and 41 outcrops were analysed with a telescopic approach, from grain scale to basin scale. Nine temporal stages over a ca 8 Myr interval (ca 98 to 90 Ma) were defined in an area that spans 75 000 km2. Finally, the different environments of deposition recorded within each of the nine stages were interpreted. The construction of the chronostratigraphic framework also allowed: measuring the duration of a basin-wide gradational increase in energy in the water column (ca 1 Myr) and a hiatus confined into the shallower water sector (ca 2 Myr); determining the mean eruption frequency of volcanoes (ca 9 kyr); and the time of inundation of the Western Interior Seaway (975 to 97 1 Ma). The context, the outcrops– cores–logs correlations, the large data set (Appendix S1), the high-precision and well-calibrated constraints represent an unprecedented contribution for future regional facies models of organic-rich units and for improvements of key aspects in the industry of unconventional resources.
The English Basin is interpreted as a Mes~~Neoproterozoic, and Cambrian-age depocenter, forming a... more The English Basin is interpreted as a Mes~~Neoproterozoic, and Cambrian-age depocenter, forming a portion of the East Continent rift complex in areas of Kentucky and Indiana. Both proprietary and published seismic sections show a complex structural depocenter with a depth to crystalline basement exceeding 6100 m. Two boreholes penetrate the Proterozoic sequence of the depocenter and have strata similar in lithology to both the Precambrian Middle Run Formation (Centralia Group) described in Ohio and Kentucky and low-density clastic sediments of the overlying Marengo Formation.
Centennial-to millennial-scale climate variations are often attributed to solar forcing or intern... more Centennial-to millennial-scale climate variations are often attributed to solar forcing or internal climate system variability, but recognition of such variations in the deep-time paleoclimate record is extremely rare. We present an exceptionally well-preserved, millimeterscale laminated marlstone from a succession of precession-driven limestone-marlstone couplets deposited in the Western Interior Seaway (North America) immediately preceding and during the Cretaceous mid-Cenomanian event (ca. 96.5 Ma). Sedimentological, geochemical, and micropaleontological data indicate that individual pairs of light-dark laminae record alternations in the extent of water-column mixing and oxygenation. Principal component analysis of X-ray fluorescence element counts and a grayscale scan of a continuous thin section through the marlstone reveal variations with 80-100 yr, 200-230 yr, 350-500 yr, ∼1650 yr, and 4843 yr periodicities. A substantial fraction of the data indicates an anoxic bottom water variation with a pronounced 10,784 yr cycle. The centennial to millennial variations are reminiscent of those found in Holocene total solar irradiance variability, and the 10,784 yr anoxia cycle may be a manifestation of semi-precession-influenced Tethyan oxygen minimum zone waters entering the seaway.
This contribution summarizes a decade of data acquisition, analysis, and interpretation of the Cr... more This contribution summarizes a decade of data acquisition, analysis, and interpretation of the Cretaceous Eagle Ford Group in West Texas by Shell, in collaboration with many academic institutions and independent industry consultants to demonstrate the value of integrated highresolution studies in mudstone analysis, useful for exploration of geo-resources, as well as refinement of greenhouse climate state earth systems evolution, and carbon cycle analyses.
Vashon Geology, the inaugural talk of a series of 7 Vashon 101 seminars, explores the geologic hi... more Vashon Geology, the inaugural talk of a series of 7 Vashon 101 seminars, explores the geologic history of Vashon, the glaciation that created the Island, and the resulting issues glacial deposits of sand, gravel and till have created. In addition, the presence of the Seattle and Tacoma Faults and their potential impacts on the Island are examined.
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