contributed to the section on CCR risks to people. Walt Kelly wrote the section on CCR Risks to G... more contributed to the section on CCR risks to people. Walt Kelly wrote the section on CCR Risks to Groundwater. Alison Stodola wrote the section on CCR Risks to the Environment. Scott Elrick and Laura Keefer wrote the section on geological and hydrologic factors. Nandakishore Rajagopalan wrote the section on beneficial use of CCR, with contributions from Veronica Hemrich. Randy Locke and Trish Barker coordinated overall report development and editing. Randy Locke and Laura Keefer developed the recommendations.
2011 GSA Annual Meeting in Minneapolis (9–12 October 2011). Paper No. 249-18, Presentation Time: ... more 2011 GSA Annual Meeting in Minneapolis (9–12 October 2011). Paper No. 249-18, Presentation Time: 9:00 AM-6:00 PM. REVISED UPPER PENNSYLVANIAN STRATIGRAPHY OF ILLINOIS BASIN WITH REGIONAL CORRELATIONS. ...
Here I provide critical notes on a multiauthored paper purported to show the absence of a major g... more Here I provide critical notes on a multiauthored paper purported to show the absence of a major gap in the Upper Pennsylvanian stratigraphic succession in North America (and, by inference, in northern Western Europe). It is observed that intellectually satisfying explanations for the discontinuities in the North American successions, having recourse to climate-driven alterations, do not take into account that the more continuous succession in northwestern Spain only shows gradual changes in floral composition. Inaccuracies in the use of scientific literature are pointed out. Perhaps, there are few experiences so satisfying as to see complacency disturbed, and to bring a large continental area, like North America, in contact with a wider world. The closing of the ranks, as exemplified by Falcon-Lang et al. (2011), is a very human response to new information from outside brought to bear on a large continental area where the general assumption has been that size guaranteed completeness of record. Of course, not everyone subscribed to this notion. David White’s papers on the Carboniferous of eastern North America show an awareness of certain comparisons with North and Central European successions that imply changes in stratigraphic development attributed to climatic changes, the suddenness of which inspire doubts about the continuity of the stratigraphic record. Darrah (1969, p. 26) mentioned ‘‘a marked floral break’’ in mid-Conemaugh of the Appalachian succession, and Kosanke and Cecil (1996) also observed a floral break. It may be helpful from a historical perspective that the present writer, after a couple of decades involvement with the International Union of Geological Sciences (IUGS) Subcommission on Carboniferous Stratigraphy (as Secretary and Chairman) was engaged for a report (unpublished) analyzing the Carboniferous (Pennsylvanian) stratigraphy of the British, northern French, Belgian, Dutch and West German areas surrounding the southern North Sea. This involved a revision of borehole material in the Netherlands and the examination of borehole samples in West Germany, in close cooperation with H.W.J. van Amerom. A major conclusion was the recognition of a sizeable lowangle unconformity, with physical evidence including secondary reddening, between lower Rotliegend and various different levels of upper Westphalian strata. The size of the unconformity could only be grasped by the recognition that most of Stephanian time was missing. The date of the unpublished report was 1985. This knowledge was available (privately) when P.C. Lyons (U.S. Geological Survey, Reston) organized a joint fieldtrip in the Appalachians in 1995, primarily with the aim to establish the level at which the Westphalian-Stephanian boundary could be recognized in the Appalachian succession. This had been assumed to lie close to the Middle
Interregional correlation of the marine zones of major cyclothems between North America and easte... more Interregional correlation of the marine zones of major cyclothems between North America and eastern Europe does not support assertions that a major stratigraphic gap exists between the traditional regional Desmoinesian and Missourian stages in North America. Such a gap was previously proposed to explain an abrupt change in megafloral assemblages in the northern Appalachian Basin and by extension across all of North America. Conodont-based correlation from the essentially complete low-shelf Midcontinent succession (distal from the highstand shoreline), through the mid-shelf Illinois Basin, to the high shelf of the Appalachian Basin (proximal to highstand shoreline) demonstrates that all major ,400 kyr cyclothem groupings in the Midcontinent are recognizable in the Illinois Basin. In the Appalachian Basin, however, the grouping at the base of the Missourian is represented only by paleosols and localized coal. The immediately preceding grouping was removed very locally by paleovalley incision, as is evident at the 7-11 Mine, Columbiana County, Ohio, from which the original megafloral data were derived. At the few localities where incised paleodrainage exists, there may be a gap of ,1000 kyr, but a gap of no more than ,600 kyr occurs elsewhere in the Appalachian Basin at that level and its magnitude progressively decreases westward into the Illinois (,300 kyr) and Midcontinent (,200 kyr) Basins. Thus, while a gap is present near the Desmoinesian-Missourian boundary in North America, it is typically more than an order of magnitude smaller than that originally proposed and is similar to the gaps inferred at sequence boundaries between cyclothems at many horizons in the Pennsylvanian of North America.
Proceedings of the Tidalites 2012 conference, 2016
Roof facies of widespread, Pennsylvanian Period, economically important coals in the Eastern Inte... more Roof facies of widespread, Pennsylvanian Period, economically important coals in the Eastern Interior Coal Basin (Illinois Basin) commonly exhibit evidence of extensive and cataclysmic tidal sedimentation during rapid marine-flooding events. Upright Trees and smaller plants were covered and entombed by swiftly deposited, thin-bedded and laminated mud and sand. This facies has historically been interpreted as fluvialstyle cross bedding. Detailed examination clearly shows that these facies consist of inclined heterolith stratifications (IHS). Entire forests of upright trunks have been documented in the roof strata of surface and underground coal mines. Detailed sedi mentological analyses of mine-roof facies indicate a pervasive and significant tidal influence. In some cases, daily and semi-monthly tidal periods have been preserved within laminated facies ('tidal rhythmites'). Based upon modern analogues, the tidal facies are indicative of hypertidal conditions. The hyper-dynamic tidal regime resulted in rapid sediment accumulation, particularly along pre-existing drainages within the ancient coastal swamp. Stratigraphic successions indicate a recurring pattern of very rapid change from widespread coal-swamp conditions to tidally-influenced deposi tion. The repetition of these stratigraphic phenomena throughout the Pennsylvanian Period suggests significant external controls on sea-level, probably related to Gondwanan deglaciations and resultant large-scale meltwater pulses. Despite the rapid changes of sea-level rise, the hypertidal depositional dynamics resulted in conditions whereby inundated coastal forests were buried by tidally influenced sedimentation.
The Pennsylvanian-Permian transition has been inferred to be a time of significant glaciation in ... more The Pennsylvanian-Permian transition has been inferred to be a time of significant glaciation in the Southern Hemisphere, the effects of which were manifested throughout the world. In the equatorial regions of Pangea, the response of terrestrial ecosystems was highly variable geographically, reflecting the interactions of polar ice and geographic patterns on atmospheric circulation.In general, however, there was a drying trend throughout most of the western and central equatorial belt.In western Pangea, the climate proved to be considerably more seasonally dry and with much lower mean annual rainfall than in areas in the more central and easterly portions of the supercontinent.Here we describe lower Permian (upper Asselian) fossil plant assemblages from the Community Pit Formation in Prehistoric Trackways National Monument near Las Cruces, south-central New Mexico, U.S.A. The fossils occur in sediments within a 140-m-wide channel that was incised into indurated marine carbonates. The channel filling can be divided into three phases.A basal channel, limestone conglomerate facies contains allochthonous trunks of walchian conifers. A middle channel fill is composed of micritic limestone beds containing a brackish-to-marine fauna with carbon, oxygen and strontium isotopic composition that provide independent support for salinity inferences.The middle limestone also contains a (par)autochthonous adpressed megaflora co-dominated by voltzian conifers and the callipterid Lodevia oxydata.The upper portions of the channel are filled with muddy, gypsiferous limestone that lacks plant fossils.This is the geologically oldest occurrence of voltzian conifers. It also is the westernmost occurrence of L. oxydata, a rare callipterid known only from the Pennsylvanian-Permian transition in Poland, the Appalachian Basin and New Mexico.The presence of in situ fine roots within these channel-fill limestone beds and the taphonomic constraints on the incorporation of aerial plant remains into a lime mudstone indicate 3 that the channel sediments were periodically colonized by plants, which suggests that these species were tolerant of salinity, making these plants one of, if not the earliest unambiguous mangroves.
In the first phase of the program, March 1996-April 2000, we are estimating strong ground motions... more In the first phase of the program, March 1996-April 2000, we are estimating strong ground motions at each critical site. These estimates are obtained by using an integrated geological, seismological, geophysical, and geotechnical approach, bringing together the unique capabilities of the campus and Laboratory personnel. This program is also designed to maximize student participation. Many of the site-specific results are also applicable to risk evaluation of other sites on the respective campuses. In the next phase, the program is planning to extend the integrated studies of strong ground motion effects to other interested UC campuses which are potentially at risk from damaging earthquakes. This report describes the initial seismic source and site characterization studies performed for the UC San Diego campus where a new seismic station has been installed. The Principal Investigator at San Diego is Professor Bernard Minster. The Campus Earthquake Program is funded from several additional sources, which leverage the core support provided by the Office of the President and which are gratefully acknowledged. These sources included the University Relations Program at LLNL, directed by Dr. Claire Max, and the offices of the appropriate Vice-Chancellors on the various campuses. At UC San Diego, the Senior Vice-Chancellor for Academic Affairs was Marjorie Caserio and is now Marsha Chandler, the Vice-Chancellor for Resource Management and Planning is John A. Woods, and the Assistant Vice-Chancellor for Design and Construction is Boone Hellmann.
The morphology, mineralogy, and stratigraphic and lateral distribution of paleosols in Pennsylvan... more The morphology, mineralogy, and stratigraphic and lateral distribution of paleosols in Pennsylvanian (Moscovian-Gzhelian; Atokan-Virgilian) mixed marine and terrestrial coal-bearing strata (i.e., cyclothems) in the Illinois basin (IB) are presented in order to determine the dominant pedogenic processes within a cyclic sedimentary depositional framework. Paleosol morphologies range from weakly developed horizons with evidence of rooting and little to no pedogenic structure, to horizons with well-developed pedogenic slickensides, angular blocky structure, and carbonate nodules and tubules. The majority of paleosols in strata from the basin interior preserve (1) low chroma (gley) colors, (2) identifiable fossil plant organic matter that increases in abundance upward in the profiles toward the interpreted paleo-surface, and (3) calcite, sphaerosiderite, and pyrite cements and nodules. In contrast, paleosols in strata from the northern margin of the basin display high chroma colors and calcite cements and less fossil organic matter, sphaerosiderite, and pyrite cements. These observations indicate that paleosols from the basin interior underwent a multi-phase pedogenic and shallow burial history characterized by an initial better-drained, oxygenated stage under seasonal precipitation, followed by a poorly drained, reducing stage, while paleosols from the northern margin of the basin experienced overall more oxygenated conditions throughout their pedogenic development. X-ray diffraction analysis of the , 2 mm size fraction of paleosol matrix in IB paleosols indicates a mineralogical composition dominated by kaolinite, randomly interstratified (R0) and ordered (R1) illite-smectite (I/S), and subordinate amounts of chlorite. These combined observational and mineralogical datasets indicate that significant changes in paleohydrology were largely responsible for the development of Pennsylvanian soil profiles in the IB.
Peat-swamp vegetation of the late Middle Pennsylvanian differed markedly from that of the Late Pe... more Peat-swamp vegetation of the late Middle Pennsylvanian differed markedly from that of the Late Pennsylvanian. Dominating the former was a variety of arborescent lycopsids, medullosan pteridosperms, and increasing numbers of marattialean tree ferns. In contrast, marattialean tree ferns and medullosan pteridosperms were dominant in the Late Pennsylvanian whereas lycopsids were of lesser importance, although much species turnover occurred in each of these groups. The most severe turnover was among the lycopsids; the Sigillariaceae were the only major lycopsid lineage to survive, thrive, and attain wide distribution throughout Euramerica, represented almost exclusively by Sigillaria brardii Brongniart (possibly a species complex). The nature of the ecological transition that brought the marattialean vegetation to dominance is not well understood, even though the pattern has been documented across Euramerica. In a study of terminal peat-swamp vegetation preserved at the coal-bed to roof-shale transition in three major late Middle Pennsylvanian age coals of the Illinois Basin, USA, we have identified two major plant assemblages. The first, preserved at the coal-to-roof transitional interface, is autochthonous to minimally parautochthonous and appears to have been buried rapidly during the introduction of sediment to the swamp habitat, burying the vegetation close to its site of growth. This vegetation is similar in taxonomic composition to that documented from the peat swamp (based on coal balls), although the quantitative abundances of the dominant species are different from most coal-ball assemblages. In contrast, the second major plant assemblage occurs in tidal channels that traversed actively developing mudflats flanking major estuaries on the lowland landscape. These channels primarily contain the arborescent lycopsid Sigillaria Brongniart with scattered remains of marattialean tree fern and pteridosperm foliage. This second assemblage more closely resembles the peat-swamp flora of the Late Pennsylvanian than that of the Middle Pennsylvanian and may presage this younger flora. The pattern suggests that following the ecological disruption during the Middle-Late Pennsylvanian transition, vegetation formerly dominant in Middle Pennsylvanian clastic-swamp habitats colonized the Late Pennsylvanian peat swamps and surrounding swampy lowlands. This clastic-swamp vegetation thus appears to have harbored lineages (even if not individual species) that survived the turnover and were then able to move into the disrupted landscape from which the formerly dominant forms had been removed.
in southwestern San Miguel County, New Mexico, the upper paleozoic Sangre de Cristo Formation is ... more in southwestern San Miguel County, New Mexico, the upper paleozoic Sangre de Cristo Formation is ~300 m thick. Most of the lower-middle parts of the formation are poorly exposed, but the base of the formation crops out as extrabasinal conglomerate resting with evident disconformity on the Middle pennsylvanian porvenir Formation. the upper 160 m of the Sangre de Cristo Formation are continuously exposed, and are mostly red-bed, non-fissile mudstone, and less common sandstone, conglomerate and calcrete. the contact of yeso Group strata on Sangre de Cristo Formation strata is very similar to the conformable abo-yeso contact to the south. Most of the sandstones of the Sangre de Cristo Formation are subarkose to arkose, and a few sandstones and pebbly sandstones containing abundant reworked carbonate grains are classified as lithic arenites. trace fossils of invertebrates and vertebrates (mostly arthropod and tetrapod walking traces) are locally common in the upper part of the Sangre de ...
contributed to the section on CCR risks to people. Walt Kelly wrote the section on CCR Risks to G... more contributed to the section on CCR risks to people. Walt Kelly wrote the section on CCR Risks to Groundwater. Alison Stodola wrote the section on CCR Risks to the Environment. Scott Elrick and Laura Keefer wrote the section on geological and hydrologic factors. Nandakishore Rajagopalan wrote the section on beneficial use of CCR, with contributions from Veronica Hemrich. Randy Locke and Trish Barker coordinated overall report development and editing. Randy Locke and Laura Keefer developed the recommendations.
2011 GSA Annual Meeting in Minneapolis (9–12 October 2011). Paper No. 249-18, Presentation Time: ... more 2011 GSA Annual Meeting in Minneapolis (9–12 October 2011). Paper No. 249-18, Presentation Time: 9:00 AM-6:00 PM. REVISED UPPER PENNSYLVANIAN STRATIGRAPHY OF ILLINOIS BASIN WITH REGIONAL CORRELATIONS. ...
Here I provide critical notes on a multiauthored paper purported to show the absence of a major g... more Here I provide critical notes on a multiauthored paper purported to show the absence of a major gap in the Upper Pennsylvanian stratigraphic succession in North America (and, by inference, in northern Western Europe). It is observed that intellectually satisfying explanations for the discontinuities in the North American successions, having recourse to climate-driven alterations, do not take into account that the more continuous succession in northwestern Spain only shows gradual changes in floral composition. Inaccuracies in the use of scientific literature are pointed out. Perhaps, there are few experiences so satisfying as to see complacency disturbed, and to bring a large continental area, like North America, in contact with a wider world. The closing of the ranks, as exemplified by Falcon-Lang et al. (2011), is a very human response to new information from outside brought to bear on a large continental area where the general assumption has been that size guaranteed completeness of record. Of course, not everyone subscribed to this notion. David White’s papers on the Carboniferous of eastern North America show an awareness of certain comparisons with North and Central European successions that imply changes in stratigraphic development attributed to climatic changes, the suddenness of which inspire doubts about the continuity of the stratigraphic record. Darrah (1969, p. 26) mentioned ‘‘a marked floral break’’ in mid-Conemaugh of the Appalachian succession, and Kosanke and Cecil (1996) also observed a floral break. It may be helpful from a historical perspective that the present writer, after a couple of decades involvement with the International Union of Geological Sciences (IUGS) Subcommission on Carboniferous Stratigraphy (as Secretary and Chairman) was engaged for a report (unpublished) analyzing the Carboniferous (Pennsylvanian) stratigraphy of the British, northern French, Belgian, Dutch and West German areas surrounding the southern North Sea. This involved a revision of borehole material in the Netherlands and the examination of borehole samples in West Germany, in close cooperation with H.W.J. van Amerom. A major conclusion was the recognition of a sizeable lowangle unconformity, with physical evidence including secondary reddening, between lower Rotliegend and various different levels of upper Westphalian strata. The size of the unconformity could only be grasped by the recognition that most of Stephanian time was missing. The date of the unpublished report was 1985. This knowledge was available (privately) when P.C. Lyons (U.S. Geological Survey, Reston) organized a joint fieldtrip in the Appalachians in 1995, primarily with the aim to establish the level at which the Westphalian-Stephanian boundary could be recognized in the Appalachian succession. This had been assumed to lie close to the Middle
Interregional correlation of the marine zones of major cyclothems between North America and easte... more Interregional correlation of the marine zones of major cyclothems between North America and eastern Europe does not support assertions that a major stratigraphic gap exists between the traditional regional Desmoinesian and Missourian stages in North America. Such a gap was previously proposed to explain an abrupt change in megafloral assemblages in the northern Appalachian Basin and by extension across all of North America. Conodont-based correlation from the essentially complete low-shelf Midcontinent succession (distal from the highstand shoreline), through the mid-shelf Illinois Basin, to the high shelf of the Appalachian Basin (proximal to highstand shoreline) demonstrates that all major ,400 kyr cyclothem groupings in the Midcontinent are recognizable in the Illinois Basin. In the Appalachian Basin, however, the grouping at the base of the Missourian is represented only by paleosols and localized coal. The immediately preceding grouping was removed very locally by paleovalley incision, as is evident at the 7-11 Mine, Columbiana County, Ohio, from which the original megafloral data were derived. At the few localities where incised paleodrainage exists, there may be a gap of ,1000 kyr, but a gap of no more than ,600 kyr occurs elsewhere in the Appalachian Basin at that level and its magnitude progressively decreases westward into the Illinois (,300 kyr) and Midcontinent (,200 kyr) Basins. Thus, while a gap is present near the Desmoinesian-Missourian boundary in North America, it is typically more than an order of magnitude smaller than that originally proposed and is similar to the gaps inferred at sequence boundaries between cyclothems at many horizons in the Pennsylvanian of North America.
Proceedings of the Tidalites 2012 conference, 2016
Roof facies of widespread, Pennsylvanian Period, economically important coals in the Eastern Inte... more Roof facies of widespread, Pennsylvanian Period, economically important coals in the Eastern Interior Coal Basin (Illinois Basin) commonly exhibit evidence of extensive and cataclysmic tidal sedimentation during rapid marine-flooding events. Upright Trees and smaller plants were covered and entombed by swiftly deposited, thin-bedded and laminated mud and sand. This facies has historically been interpreted as fluvialstyle cross bedding. Detailed examination clearly shows that these facies consist of inclined heterolith stratifications (IHS). Entire forests of upright trunks have been documented in the roof strata of surface and underground coal mines. Detailed sedi mentological analyses of mine-roof facies indicate a pervasive and significant tidal influence. In some cases, daily and semi-monthly tidal periods have been preserved within laminated facies ('tidal rhythmites'). Based upon modern analogues, the tidal facies are indicative of hypertidal conditions. The hyper-dynamic tidal regime resulted in rapid sediment accumulation, particularly along pre-existing drainages within the ancient coastal swamp. Stratigraphic successions indicate a recurring pattern of very rapid change from widespread coal-swamp conditions to tidally-influenced deposi tion. The repetition of these stratigraphic phenomena throughout the Pennsylvanian Period suggests significant external controls on sea-level, probably related to Gondwanan deglaciations and resultant large-scale meltwater pulses. Despite the rapid changes of sea-level rise, the hypertidal depositional dynamics resulted in conditions whereby inundated coastal forests were buried by tidally influenced sedimentation.
The Pennsylvanian-Permian transition has been inferred to be a time of significant glaciation in ... more The Pennsylvanian-Permian transition has been inferred to be a time of significant glaciation in the Southern Hemisphere, the effects of which were manifested throughout the world. In the equatorial regions of Pangea, the response of terrestrial ecosystems was highly variable geographically, reflecting the interactions of polar ice and geographic patterns on atmospheric circulation.In general, however, there was a drying trend throughout most of the western and central equatorial belt.In western Pangea, the climate proved to be considerably more seasonally dry and with much lower mean annual rainfall than in areas in the more central and easterly portions of the supercontinent.Here we describe lower Permian (upper Asselian) fossil plant assemblages from the Community Pit Formation in Prehistoric Trackways National Monument near Las Cruces, south-central New Mexico, U.S.A. The fossils occur in sediments within a 140-m-wide channel that was incised into indurated marine carbonates. The channel filling can be divided into three phases.A basal channel, limestone conglomerate facies contains allochthonous trunks of walchian conifers. A middle channel fill is composed of micritic limestone beds containing a brackish-to-marine fauna with carbon, oxygen and strontium isotopic composition that provide independent support for salinity inferences.The middle limestone also contains a (par)autochthonous adpressed megaflora co-dominated by voltzian conifers and the callipterid Lodevia oxydata.The upper portions of the channel are filled with muddy, gypsiferous limestone that lacks plant fossils.This is the geologically oldest occurrence of voltzian conifers. It also is the westernmost occurrence of L. oxydata, a rare callipterid known only from the Pennsylvanian-Permian transition in Poland, the Appalachian Basin and New Mexico.The presence of in situ fine roots within these channel-fill limestone beds and the taphonomic constraints on the incorporation of aerial plant remains into a lime mudstone indicate 3 that the channel sediments were periodically colonized by plants, which suggests that these species were tolerant of salinity, making these plants one of, if not the earliest unambiguous mangroves.
In the first phase of the program, March 1996-April 2000, we are estimating strong ground motions... more In the first phase of the program, March 1996-April 2000, we are estimating strong ground motions at each critical site. These estimates are obtained by using an integrated geological, seismological, geophysical, and geotechnical approach, bringing together the unique capabilities of the campus and Laboratory personnel. This program is also designed to maximize student participation. Many of the site-specific results are also applicable to risk evaluation of other sites on the respective campuses. In the next phase, the program is planning to extend the integrated studies of strong ground motion effects to other interested UC campuses which are potentially at risk from damaging earthquakes. This report describes the initial seismic source and site characterization studies performed for the UC San Diego campus where a new seismic station has been installed. The Principal Investigator at San Diego is Professor Bernard Minster. The Campus Earthquake Program is funded from several additional sources, which leverage the core support provided by the Office of the President and which are gratefully acknowledged. These sources included the University Relations Program at LLNL, directed by Dr. Claire Max, and the offices of the appropriate Vice-Chancellors on the various campuses. At UC San Diego, the Senior Vice-Chancellor for Academic Affairs was Marjorie Caserio and is now Marsha Chandler, the Vice-Chancellor for Resource Management and Planning is John A. Woods, and the Assistant Vice-Chancellor for Design and Construction is Boone Hellmann.
The morphology, mineralogy, and stratigraphic and lateral distribution of paleosols in Pennsylvan... more The morphology, mineralogy, and stratigraphic and lateral distribution of paleosols in Pennsylvanian (Moscovian-Gzhelian; Atokan-Virgilian) mixed marine and terrestrial coal-bearing strata (i.e., cyclothems) in the Illinois basin (IB) are presented in order to determine the dominant pedogenic processes within a cyclic sedimentary depositional framework. Paleosol morphologies range from weakly developed horizons with evidence of rooting and little to no pedogenic structure, to horizons with well-developed pedogenic slickensides, angular blocky structure, and carbonate nodules and tubules. The majority of paleosols in strata from the basin interior preserve (1) low chroma (gley) colors, (2) identifiable fossil plant organic matter that increases in abundance upward in the profiles toward the interpreted paleo-surface, and (3) calcite, sphaerosiderite, and pyrite cements and nodules. In contrast, paleosols in strata from the northern margin of the basin display high chroma colors and calcite cements and less fossil organic matter, sphaerosiderite, and pyrite cements. These observations indicate that paleosols from the basin interior underwent a multi-phase pedogenic and shallow burial history characterized by an initial better-drained, oxygenated stage under seasonal precipitation, followed by a poorly drained, reducing stage, while paleosols from the northern margin of the basin experienced overall more oxygenated conditions throughout their pedogenic development. X-ray diffraction analysis of the , 2 mm size fraction of paleosol matrix in IB paleosols indicates a mineralogical composition dominated by kaolinite, randomly interstratified (R0) and ordered (R1) illite-smectite (I/S), and subordinate amounts of chlorite. These combined observational and mineralogical datasets indicate that significant changes in paleohydrology were largely responsible for the development of Pennsylvanian soil profiles in the IB.
Peat-swamp vegetation of the late Middle Pennsylvanian differed markedly from that of the Late Pe... more Peat-swamp vegetation of the late Middle Pennsylvanian differed markedly from that of the Late Pennsylvanian. Dominating the former was a variety of arborescent lycopsids, medullosan pteridosperms, and increasing numbers of marattialean tree ferns. In contrast, marattialean tree ferns and medullosan pteridosperms were dominant in the Late Pennsylvanian whereas lycopsids were of lesser importance, although much species turnover occurred in each of these groups. The most severe turnover was among the lycopsids; the Sigillariaceae were the only major lycopsid lineage to survive, thrive, and attain wide distribution throughout Euramerica, represented almost exclusively by Sigillaria brardii Brongniart (possibly a species complex). The nature of the ecological transition that brought the marattialean vegetation to dominance is not well understood, even though the pattern has been documented across Euramerica. In a study of terminal peat-swamp vegetation preserved at the coal-bed to roof-shale transition in three major late Middle Pennsylvanian age coals of the Illinois Basin, USA, we have identified two major plant assemblages. The first, preserved at the coal-to-roof transitional interface, is autochthonous to minimally parautochthonous and appears to have been buried rapidly during the introduction of sediment to the swamp habitat, burying the vegetation close to its site of growth. This vegetation is similar in taxonomic composition to that documented from the peat swamp (based on coal balls), although the quantitative abundances of the dominant species are different from most coal-ball assemblages. In contrast, the second major plant assemblage occurs in tidal channels that traversed actively developing mudflats flanking major estuaries on the lowland landscape. These channels primarily contain the arborescent lycopsid Sigillaria Brongniart with scattered remains of marattialean tree fern and pteridosperm foliage. This second assemblage more closely resembles the peat-swamp flora of the Late Pennsylvanian than that of the Middle Pennsylvanian and may presage this younger flora. The pattern suggests that following the ecological disruption during the Middle-Late Pennsylvanian transition, vegetation formerly dominant in Middle Pennsylvanian clastic-swamp habitats colonized the Late Pennsylvanian peat swamps and surrounding swampy lowlands. This clastic-swamp vegetation thus appears to have harbored lineages (even if not individual species) that survived the turnover and were then able to move into the disrupted landscape from which the formerly dominant forms had been removed.
in southwestern San Miguel County, New Mexico, the upper paleozoic Sangre de Cristo Formation is ... more in southwestern San Miguel County, New Mexico, the upper paleozoic Sangre de Cristo Formation is ~300 m thick. Most of the lower-middle parts of the formation are poorly exposed, but the base of the formation crops out as extrabasinal conglomerate resting with evident disconformity on the Middle pennsylvanian porvenir Formation. the upper 160 m of the Sangre de Cristo Formation are continuously exposed, and are mostly red-bed, non-fissile mudstone, and less common sandstone, conglomerate and calcrete. the contact of yeso Group strata on Sangre de Cristo Formation strata is very similar to the conformable abo-yeso contact to the south. Most of the sandstones of the Sangre de Cristo Formation are subarkose to arkose, and a few sandstones and pebbly sandstones containing abundant reworked carbonate grains are classified as lithic arenites. trace fossils of invertebrates and vertebrates (mostly arthropod and tetrapod walking traces) are locally common in the upper part of the Sangre de ...
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