Speleothem carbon and oxygen isotopic records from Onondaga Cave, south-central Missouri, and Bec... more Speleothem carbon and oxygen isotopic records from Onondaga Cave, south-central Missouri, and Beckham Creek Cave, north-central Arkansas, are compared with the Cupola Pond and Oldfield Swamp pollen series from southeastern Missouri and the Rodgers Shelter and Modoc Shelter vertebrate biostratigraphic sequences from central Missouri and southwestern Illinois. Similar, and roughly contemporaneous, shifts between deciduous forest and steppe indicators throughout the Holocene are revealed in each database. ...
A latitudinal gradient in meteoric N 18 O compositions compiled from paleosol sphaerosiderites th... more A latitudinal gradient in meteoric N 18 O compositions compiled from paleosol sphaerosiderites throughout the Cretaceous Western Interior Basin (KWIB) (34^75 ‡N paleolatitude) exhibits a steeper, more depleted trend than modern (predicted) values (3.0x [34 ‡N latitude] to 9.7x [75 ‡N] lighter). Furthermore, the sphaerosiderite meteoric N 18 O latitudinal gradient is significantly steeper and more depleted (5.8x [34 ‡N] to 13.8x [75 ‡N] lighter) than a predicted gradient for the warm mid-Cretaceous using modern empirical temperature^N 18 O precipitation relationships. We have suggested that the steeper and more depleted (relative to the modern theoretical gradient) meteoric sphaerosiderite N 18 O latitudinal gradient resulted from increased air mass rainout effects in coastal areas of the KWIB during the mid-Cretaceous. The sphaerosiderite isotopic data have been used to constrain a mass balance model of the hydrologic cycle in the northern hemisphere and to quantify precipitation rates of the equable 'greenhouse' Albian Stage in the KWIB. The mass balance model tracks the evolving isotopic composition of an air mass and its precipitation, and is driven by latitudinal temperature gradients. Our simulations indicate that significant increases in Albian precipitation (34^52%) and evaporation fluxes (76^96%) are required to reproduce the difference between modern and Albian meteoric siderite N 18 O latitudinal gradients. Calculations of precipitation rates from model outputs suggest mid^high latitude precipitation rates greatly exceeded modern rates (156^220% greater in mid latitudes [2600^3300 mm/yr], 99% greater at high latitudes [550 mm/yr]). The calculated precipitation rates are significantly different from the precipitation rates predicted by some recent general circulation models (GCMs) for the warm Cretaceous, particularly in the mid to high latitudes. Our mass balance model by no means replaces GCMs. However, it is a simple and effective means of obtaining quantitative data regarding the mid-Cretaceous hydrologic cycle in the KWIB. Our goal is to encourage the incorporation of isotopic tracers into GCM simulations of the mid-Cretaceous, and to show how our empirical data and mass balance model estimates help constrain the boundary conditions. ß
Abstract For many decades researchers have attempted to clarify the factors controlling the preci... more Abstract For many decades researchers have attempted to clarify the factors controlling the precipitation of calcium carbonate polymorphs and the incorporation of Mg into calcite precipitating in natural systems. In this study a novel experimental approach delineates the role of instantaneous supersaturation and solution Mg/Ca ratio in calcium carbonate mineralogy and composition. The results of this study show that in solutions with different Mg/Ca ratios, the transition between the aragonite and the calcite+ aragonite precipitation ...
This paper presents the biotic, sedimentary, geomorphic, and climatic history of the upper part o... more This paper presents the biotic, sedimentary, geomorphic, and climatic history of the upper part of the Roberts Creek Basin, northeastern Iowa for the late-glacial and Holocene, and compares these records with a CO isotopic sequence from Coldwater Cave, 60 km northwest of Roberts Creek. The biotic record (pollen, vascular plant and bryophyte macrofossils, and insects) is preserved in floodplain alluvium that underlies three constructional surfaces separated by low scarps. Each surface is underlain by a ...
Page 1. Kansas Interdisciplinary Carbonates Consortium Proposal – June 2012 108 Carbonate Cementa... more Page 1. Kansas Interdisciplinary Carbonates Consortium Proposal – June 2012 108 Carbonate Cementation in Meteoric Phreatic Systems: Morphology, Distribution, and Rates Luis A. Gonzalez, Jennifer Roberts, Robert H. Goldstein STATUS: Long-term project in progress TIMING: Significant results to be reported – Results currently available to membership FUNDING: Currently none, earlier work funded by Shell.
6.1 Abstract Organic carbon is oxidized by microorganisms that use a series of terminal electron ... more 6.1 Abstract Organic carbon is oxidized by microorganisms that use a series of terminal electron acceptors defined by free energy yield and availability. Methanogenesis by highly specialized Archea occurs once the availability of these electron acceptors is diminished beyond a thermodynamic threshold which renders the energy yield to low to sustain microbial respiration.
Abstract Tham Khuyen Cave (Lang Son Province, northern Vietnam) is one of the more significant si... more Abstract Tham Khuyen Cave (Lang Son Province, northern Vietnam) is one of the more significant sites to yield fossil vertebrates in east Asia. During the mid-1960s, excavation in a suite of deposits produced important hominoid dental remains of middle Pleistocene age. We undertake more rigorous analyses of these sediments to understand the fluvial dynamics of Pleistocene cave infilling as they determine how skeletal elements accumulate within Tham Khuyen and other east Asian sites.
The Hualapai basin, northwestern Arizona, contains one of the thickest known, nonmarine halite de... more The Hualapai basin, northwestern Arizona, contains one of the thickest known, nonmarine halite deposits in a continental rift. The basin is a large half-graben in the hanging wall of a listric normal fault along the eastern margin of the Basin and Range province. Seismic reflection and drill-hole data indicate that the little-deformed halite is 2.5 km thick in the central part of the basin, approaches in volume, and has a three-dimensional lenticularwedge geometry.
Stable isotopic data of carbonates suggest diagenefic modification under a meteoric and meteoric-... more Stable isotopic data of carbonates suggest diagenefic modification under a meteoric and meteoric-marine mixing environments for sediments above 915 m. A fracture zone near 915 m coincides with an abrupt shift in• 5180 compositions indicating the presence of hotter fluids during alteration of these sediments. The depleted õ13C signatures occurring above a fault at! 220 m are suggestive of isotopically light gaseous hydrocarbons migrating through the fault and being oxidized as they dispersed through the sediment column.
Abstract Carbonate d 13 C profiles of a mid-Caradoc carbon isotope excursion are compared between... more Abstract Carbonate d 13 C profiles of a mid-Caradoc carbon isotope excursion are compared between three exposed stratigraphic sections: the McGregor Quarry in Clayton County, Iowa, the Dickeyville North Roadcut section in Grant County, Wisconsin, and the Eureka Roadcut section in St. Louis County, Missouri.
Abstract Quantitative estimates of increased heat transfer by atmospheric H 2 O vapor during the ... more Abstract Quantitative estimates of increased heat transfer by atmospheric H 2 O vapor during the Albian greenhouse warming suggest that the intensified hydrologic cycle played a greater role in warming high latitudes than at present and thus represents a viable alternative to oceanic heat transport.
Abstract Sphaerosiderite, a morphologically distinct millimeter-scale spherulitic siderite (FeCO ... more Abstract Sphaerosiderite, a morphologically distinct millimeter-scale spherulitic siderite (FeCO 3), forms predominantly in wetland soils and sediments, and is common in the geologic record. Ancient sphaerosiderites are found in paleosol horizons within coal-bearing stratigraphic intervals and, like their modern counterparts, are interpreted as having formed in water-saturated environments.
Abstract Isotopic analyses of three stalagmites from Cold Water Cave, northeast Iowa, United Stat... more Abstract Isotopic analyses of three stalagmites from Cold Water Cave, northeast Iowa, United States, reveal nearly identical δ 13 C trends from ca. 7 to 2 ka. However, δ 18 O patterns differ by as much as 3‰ from 5.7 to 3.2 ka. These disparate δ 18 O values reflect evaporative 18 O enrichment in meteoric water prior to infiltration, suggesting that previously calculated temperatures based on a single Cold Water Cave stalagmite overestimated middle Holocene warming.
Abstract We present a 23 yr stalagmite record (1977–2000) of oxygen isotope variation, associated... more Abstract We present a 23 yr stalagmite record (1977–2000) of oxygen isotope variation, associated with 11 tropical cyclones (TCs), from Actun Tunichil Muknal cave in central Belize. High-resolution microsampling yielded a record of monthly to weekly temporal resolution that contains abrupt decreases (negative excursions) in calcite δ 18 O values that correspond with recent TC rain events nearby.
Abstract We compare four emerging approaches to reconstructing Holocene vegetation and climate fr... more Abstract We compare four emerging approaches to reconstructing Holocene vegetation and climate from south of the glacial border in northeastern Iowa, United States. Pollen, plant macrofossils, carbon isotopic (δ 13 C) values from alluvial organic matter, and carbon isotopic values in stalagmites from a nearby cave all show similar paleovegetational and paleoclimatic trends during the Holocene. Pollen and plant macrofossils show a rapid change from forest to prairie about 6000 cal.
Purpose Isla de Mona (Figure 1) and Isla Monito are uplifted and faulted carbonate plateaus that ... more Purpose Isla de Mona (Figure 1) and Isla Monito are uplifted and faulted carbonate plateaus that expose sections of the only known Miocene-Pliocene reef complex in the Caribbean. The excellent 3D exposures on these two islands allow for detailed facies mapping and sampling of this unique reef complex. The upper units of the reef complex have been extensively karstified (Figure 2) and the lowermost units densely dolomitized (Figure 3).
The carbon isotopic compositions of six stalagmites from five caves in the Ozark Highlands of cen... more The carbon isotopic compositions of six stalagmites from five caves in the Ozark Highlands of central and southern Missouri and northern Arkansas provide a detailed record of early and late Holocene vegetation dynamics. A rapid decrease in speleothem∂ 13C values between∼ 9500 and∼ 8200yr BP indicates a period of increased C3 vegetation, suggesting cool and/or moist conditions relative to the earliest Holocene and the prairie-dominated middle Holocene.
Abstract We report a large, positive, carbon isotope excursion in the Kinderhookian Stage of the ... more Abstract We report a large, positive, carbon isotope excursion in the Kinderhookian Stage of the Lower Mississippian in North America and propose that the excursion is linked to the Antler orogeny. The δ 13 C excursion reaches+ 7.1‰ in the upper part of the Joana Limestone in southeast Nevada and correlates with peaks recognized in Europe and elsewhere in North America.
Abstract We present a paleolatitudinal precipitation reconstruction for the greenhouse setting of... more Abstract We present a paleolatitudinal precipitation reconstruction for the greenhouse setting of mid-latitude North America based on the oxygen isotopic composition of sphaerosiderites found in middle Cretaceous wetland paleosols. Our reconstructed middle Cretaceous δ 18 O values of precipitation are∼ 4‰ less than values from comparable modern low-elevation coastal settings free of monsoons.
Speleothem carbon and oxygen isotopic records from Onondaga Cave, south-central Missouri, and Bec... more Speleothem carbon and oxygen isotopic records from Onondaga Cave, south-central Missouri, and Beckham Creek Cave, north-central Arkansas, are compared with the Cupola Pond and Oldfield Swamp pollen series from southeastern Missouri and the Rodgers Shelter and Modoc Shelter vertebrate biostratigraphic sequences from central Missouri and southwestern Illinois. Similar, and roughly contemporaneous, shifts between deciduous forest and steppe indicators throughout the Holocene are revealed in each database. ...
A latitudinal gradient in meteoric N 18 O compositions compiled from paleosol sphaerosiderites th... more A latitudinal gradient in meteoric N 18 O compositions compiled from paleosol sphaerosiderites throughout the Cretaceous Western Interior Basin (KWIB) (34^75 ‡N paleolatitude) exhibits a steeper, more depleted trend than modern (predicted) values (3.0x [34 ‡N latitude] to 9.7x [75 ‡N] lighter). Furthermore, the sphaerosiderite meteoric N 18 O latitudinal gradient is significantly steeper and more depleted (5.8x [34 ‡N] to 13.8x [75 ‡N] lighter) than a predicted gradient for the warm mid-Cretaceous using modern empirical temperature^N 18 O precipitation relationships. We have suggested that the steeper and more depleted (relative to the modern theoretical gradient) meteoric sphaerosiderite N 18 O latitudinal gradient resulted from increased air mass rainout effects in coastal areas of the KWIB during the mid-Cretaceous. The sphaerosiderite isotopic data have been used to constrain a mass balance model of the hydrologic cycle in the northern hemisphere and to quantify precipitation rates of the equable 'greenhouse' Albian Stage in the KWIB. The mass balance model tracks the evolving isotopic composition of an air mass and its precipitation, and is driven by latitudinal temperature gradients. Our simulations indicate that significant increases in Albian precipitation (34^52%) and evaporation fluxes (76^96%) are required to reproduce the difference between modern and Albian meteoric siderite N 18 O latitudinal gradients. Calculations of precipitation rates from model outputs suggest mid^high latitude precipitation rates greatly exceeded modern rates (156^220% greater in mid latitudes [2600^3300 mm/yr], 99% greater at high latitudes [550 mm/yr]). The calculated precipitation rates are significantly different from the precipitation rates predicted by some recent general circulation models (GCMs) for the warm Cretaceous, particularly in the mid to high latitudes. Our mass balance model by no means replaces GCMs. However, it is a simple and effective means of obtaining quantitative data regarding the mid-Cretaceous hydrologic cycle in the KWIB. Our goal is to encourage the incorporation of isotopic tracers into GCM simulations of the mid-Cretaceous, and to show how our empirical data and mass balance model estimates help constrain the boundary conditions. ß
Abstract For many decades researchers have attempted to clarify the factors controlling the preci... more Abstract For many decades researchers have attempted to clarify the factors controlling the precipitation of calcium carbonate polymorphs and the incorporation of Mg into calcite precipitating in natural systems. In this study a novel experimental approach delineates the role of instantaneous supersaturation and solution Mg/Ca ratio in calcium carbonate mineralogy and composition. The results of this study show that in solutions with different Mg/Ca ratios, the transition between the aragonite and the calcite+ aragonite precipitation ...
This paper presents the biotic, sedimentary, geomorphic, and climatic history of the upper part o... more This paper presents the biotic, sedimentary, geomorphic, and climatic history of the upper part of the Roberts Creek Basin, northeastern Iowa for the late-glacial and Holocene, and compares these records with a CO isotopic sequence from Coldwater Cave, 60 km northwest of Roberts Creek. The biotic record (pollen, vascular plant and bryophyte macrofossils, and insects) is preserved in floodplain alluvium that underlies three constructional surfaces separated by low scarps. Each surface is underlain by a ...
Page 1. Kansas Interdisciplinary Carbonates Consortium Proposal – June 2012 108 Carbonate Cementa... more Page 1. Kansas Interdisciplinary Carbonates Consortium Proposal – June 2012 108 Carbonate Cementation in Meteoric Phreatic Systems: Morphology, Distribution, and Rates Luis A. Gonzalez, Jennifer Roberts, Robert H. Goldstein STATUS: Long-term project in progress TIMING: Significant results to be reported – Results currently available to membership FUNDING: Currently none, earlier work funded by Shell.
6.1 Abstract Organic carbon is oxidized by microorganisms that use a series of terminal electron ... more 6.1 Abstract Organic carbon is oxidized by microorganisms that use a series of terminal electron acceptors defined by free energy yield and availability. Methanogenesis by highly specialized Archea occurs once the availability of these electron acceptors is diminished beyond a thermodynamic threshold which renders the energy yield to low to sustain microbial respiration.
Abstract Tham Khuyen Cave (Lang Son Province, northern Vietnam) is one of the more significant si... more Abstract Tham Khuyen Cave (Lang Son Province, northern Vietnam) is one of the more significant sites to yield fossil vertebrates in east Asia. During the mid-1960s, excavation in a suite of deposits produced important hominoid dental remains of middle Pleistocene age. We undertake more rigorous analyses of these sediments to understand the fluvial dynamics of Pleistocene cave infilling as they determine how skeletal elements accumulate within Tham Khuyen and other east Asian sites.
The Hualapai basin, northwestern Arizona, contains one of the thickest known, nonmarine halite de... more The Hualapai basin, northwestern Arizona, contains one of the thickest known, nonmarine halite deposits in a continental rift. The basin is a large half-graben in the hanging wall of a listric normal fault along the eastern margin of the Basin and Range province. Seismic reflection and drill-hole data indicate that the little-deformed halite is 2.5 km thick in the central part of the basin, approaches in volume, and has a three-dimensional lenticularwedge geometry.
Stable isotopic data of carbonates suggest diagenefic modification under a meteoric and meteoric-... more Stable isotopic data of carbonates suggest diagenefic modification under a meteoric and meteoric-marine mixing environments for sediments above 915 m. A fracture zone near 915 m coincides with an abrupt shift in• 5180 compositions indicating the presence of hotter fluids during alteration of these sediments. The depleted õ13C signatures occurring above a fault at! 220 m are suggestive of isotopically light gaseous hydrocarbons migrating through the fault and being oxidized as they dispersed through the sediment column.
Abstract Carbonate d 13 C profiles of a mid-Caradoc carbon isotope excursion are compared between... more Abstract Carbonate d 13 C profiles of a mid-Caradoc carbon isotope excursion are compared between three exposed stratigraphic sections: the McGregor Quarry in Clayton County, Iowa, the Dickeyville North Roadcut section in Grant County, Wisconsin, and the Eureka Roadcut section in St. Louis County, Missouri.
Abstract Quantitative estimates of increased heat transfer by atmospheric H 2 O vapor during the ... more Abstract Quantitative estimates of increased heat transfer by atmospheric H 2 O vapor during the Albian greenhouse warming suggest that the intensified hydrologic cycle played a greater role in warming high latitudes than at present and thus represents a viable alternative to oceanic heat transport.
Abstract Sphaerosiderite, a morphologically distinct millimeter-scale spherulitic siderite (FeCO ... more Abstract Sphaerosiderite, a morphologically distinct millimeter-scale spherulitic siderite (FeCO 3), forms predominantly in wetland soils and sediments, and is common in the geologic record. Ancient sphaerosiderites are found in paleosol horizons within coal-bearing stratigraphic intervals and, like their modern counterparts, are interpreted as having formed in water-saturated environments.
Abstract Isotopic analyses of three stalagmites from Cold Water Cave, northeast Iowa, United Stat... more Abstract Isotopic analyses of three stalagmites from Cold Water Cave, northeast Iowa, United States, reveal nearly identical δ 13 C trends from ca. 7 to 2 ka. However, δ 18 O patterns differ by as much as 3‰ from 5.7 to 3.2 ka. These disparate δ 18 O values reflect evaporative 18 O enrichment in meteoric water prior to infiltration, suggesting that previously calculated temperatures based on a single Cold Water Cave stalagmite overestimated middle Holocene warming.
Abstract We present a 23 yr stalagmite record (1977–2000) of oxygen isotope variation, associated... more Abstract We present a 23 yr stalagmite record (1977–2000) of oxygen isotope variation, associated with 11 tropical cyclones (TCs), from Actun Tunichil Muknal cave in central Belize. High-resolution microsampling yielded a record of monthly to weekly temporal resolution that contains abrupt decreases (negative excursions) in calcite δ 18 O values that correspond with recent TC rain events nearby.
Abstract We compare four emerging approaches to reconstructing Holocene vegetation and climate fr... more Abstract We compare four emerging approaches to reconstructing Holocene vegetation and climate from south of the glacial border in northeastern Iowa, United States. Pollen, plant macrofossils, carbon isotopic (δ 13 C) values from alluvial organic matter, and carbon isotopic values in stalagmites from a nearby cave all show similar paleovegetational and paleoclimatic trends during the Holocene. Pollen and plant macrofossils show a rapid change from forest to prairie about 6000 cal.
Purpose Isla de Mona (Figure 1) and Isla Monito are uplifted and faulted carbonate plateaus that ... more Purpose Isla de Mona (Figure 1) and Isla Monito are uplifted and faulted carbonate plateaus that expose sections of the only known Miocene-Pliocene reef complex in the Caribbean. The excellent 3D exposures on these two islands allow for detailed facies mapping and sampling of this unique reef complex. The upper units of the reef complex have been extensively karstified (Figure 2) and the lowermost units densely dolomitized (Figure 3).
The carbon isotopic compositions of six stalagmites from five caves in the Ozark Highlands of cen... more The carbon isotopic compositions of six stalagmites from five caves in the Ozark Highlands of central and southern Missouri and northern Arkansas provide a detailed record of early and late Holocene vegetation dynamics. A rapid decrease in speleothem∂ 13C values between∼ 9500 and∼ 8200yr BP indicates a period of increased C3 vegetation, suggesting cool and/or moist conditions relative to the earliest Holocene and the prairie-dominated middle Holocene.
Abstract We report a large, positive, carbon isotope excursion in the Kinderhookian Stage of the ... more Abstract We report a large, positive, carbon isotope excursion in the Kinderhookian Stage of the Lower Mississippian in North America and propose that the excursion is linked to the Antler orogeny. The δ 13 C excursion reaches+ 7.1‰ in the upper part of the Joana Limestone in southeast Nevada and correlates with peaks recognized in Europe and elsewhere in North America.
Abstract We present a paleolatitudinal precipitation reconstruction for the greenhouse setting of... more Abstract We present a paleolatitudinal precipitation reconstruction for the greenhouse setting of mid-latitude North America based on the oxygen isotopic composition of sphaerosiderites found in middle Cretaceous wetland paleosols. Our reconstructed middle Cretaceous δ 18 O values of precipitation are∼ 4‰ less than values from comparable modern low-elevation coastal settings free of monsoons.
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