Researchers examined several K-T boundary cores at Deep Sea Drilling Project (DSDP) core reposito... more Researchers examined several K-T boundary cores at Deep Sea Drilling Project (DSDP) core repositories to document biostratigraphic ranges of inoceramid shell fragments and prisms. As in land-based sections, prisms in the deep sea cores disappear well before the K-T boundary. Ammonites show a very different extinction pattern than do the inoceramids. A minimum of seven ammonite species have been collected from the last meter of Cretaceous strata in the Bay of Biscay basin. In three of the sections there is no marked drop in either species numbers or abundance prior to the K-T boundary Cretaceous strata; at the Zumaya section, however, both species richness and abundance drop in the last 20 m of the Cretaceous, with only a single ammonite specimen recovered to date from the uppermost 12 m of Cretaceous strata in this section. Researchers conclude that inoceramid bivalves and ammonites showed two different times and patterns of extinction, at least in the Bay of Biscay region. The inoceramids disappeared gradually during the Early Maestrichtian, and survived only into the earliest Late Maestrichtian. Ammonites, on the other hand, maintained relatively high species richness throughout the Maestrichtian, and then disappeared suddenly, either coincident with, or immediately before the microfossil extinction event marking the very end of the Cretaceous.
Helium concentration and isotopic composition were measured in a suite of samples across the Perm... more Helium concentration and isotopic composition were measured in a suite of samples across the Permian-Triassic boundary at Opal Creek, Canada, to determine whether high extraterrestrial helium concentrations are associated with a possible extinctioninducing impact event at this time. No extraterrestrial 3 He was detected, implying that neither fullerene-hosted nor IDP-hosted He is present at or near the boundary. This observation is consistent with similar studies of some Permian-Triassic sections, but contrasts sharply with reports of both fullerene-and IDP-hosted extraterrestrial 3 He at other sections. Step-heat experiments indicate rapid diffusion of extraterrestrial helium from sediments heated to temperatures above~70 8C. Given the likelihood of burial and associated heating in Permian-Triassic age rocks, the initially unexpected absence of IDP-hosted 3 He likely indicates thermally induced diffusive loss. Indeed one of the key sections (Graphite Peak, Antarctica) from which extraterrestrial 3 He has been reported at and near the Permian-Triassic boundary has been sufficiently heated that the reported preservation of extraterrestrial helium, in both IDPs and fullerenes, is inexplicable. Recent contamination provides a plausible explanation for extraterrestrial 3 He in these samples. While no extraterrestrial 3 He was detected at Opal Creek, there is a sharp increase in nucleogenic 3 He very close to or at the Permian-Triassic boundary. This presumably arises from the major lithologic change at this time, from cherts in the Permian to shales and siltstones in the Triassic. Increased nucleogenic 3 He is associated with increases in both lithium and organic carbon content into the Triassic. Either the production rate or the retention of this 3 He is higher in the shales and siltstones than in the cherts. Care must be taken to eliminate such artifacts before interpreting changes in 3 He concentration in terms of fluctuations in the delivery of 3 He from space.
We have sampled for stable isotopes from paleontologically constrained stratigraphic sections in ... more We have sampled for stable isotopes from paleontologically constrained stratigraphic sections in the southern and central Karoo basin of South Africa, which contains the most abundantly fossiliferous succession of late Permian to middle Triassic terrestrial vertebrates yet described. Over a narrow stratigraphic interval at the end of the Permian in this region, we have found a light carbon isotope anomaly (Ccarb) and succession of negative anomalies (Corg) coincident with, and right after an enhanced pulse of extinction among terrestrial vertebrates. While it is clear that a short interval of intense environmental change occurred over our sampled interval, there is no evidence of impact debris or characteristic boundary sedimentology equivalent to that observed in similar terrestrial facies at numerous Cretaceous/Paleogene boundaries. Our isotopic and paleontological data also show marked dissimilarity to similar data from terrestrial K/P sites. The Permian/Triassic succession in South Africa is thus inconsistent with the K/P model of single-impact mass extinction, and to date shows no evidence of impact of any size.
While the end-Permian extinction in the marine realm is well known from the Tethys Ocean, it rema... more While the end-Permian extinction in the marine realm is well known from the Tethys Ocean, it remains little studied in the vast Panthalassic Ocean. Opal Creek, Alberta, Canada is a biostratigraphically continuous Permian-Triassic Boundary (PTB) section that is interpreted to have been deposited in a deep outer shelf setting along the Panthalassic western margin of Pangaea. Significant organic carbon and nitrogen isotope excursions precede the extinction of the dominant Late Permian benthic organisms (siliceous sponges). Geochemical comparison with underlying Guadalupian age rocks and analysis of the conodont fauna suggest that the latest Permian at Opal Creek records the shutdown of a productive cold-water upwelling ecosystem with a mid-water column oxygen minimum followed by the transition to a warm and less vigorously circulating system with a bottom-water oxygen minimum. The transition from a low-diversity, cold-water conodont fauna in the Middle Permian to a more diverse latest Permian fauna containing equatorial species coincides with a transition from elevated δ 15 N values characteristic of coastal zones with denitrification in a mid-water oxygen minimum to more normal marine values. A spike in the δ 13 C of organic carbon following a latest Permian marine transgression along western Pangaea is here attributed to transient increased productivity in the photic zone preceding the main extinction, likely related to the synergistic effects of warming, increased nutrient runoff, and residual upwelling. This is followed by an equilibration to lower δ 13 C org values characteristic of a lower productivity regime in the Early Triassic.
... Abstract/FREE Full Text. ↵ Lucas, S., 1998, Global Triassic tetrapod biostratigraphy and bioc... more ... Abstract/FREE Full Text. ↵ Lucas, S., 1998, Global Triassic tetrapod biostratigraphy and biochronology ... CrossRef. ↵ Visscher, H., Brinhuis, H., Dilcher, D., Elsik, W., Eshet, Y., Looy, C ... CrossRef. ↵ Ward, P., Montgomery, DR, and Smith, R., 2000, Altered river morphology in South ...
The latest Permian mass extinction (LPME) was triggered by magmatism of the Siberian Traps Large ... more The latest Permian mass extinction (LPME) was triggered by magmatism of the Siberian Traps Large Igneous Province (STLIP), which left an extensive record of sedimentary Hg anomalies at Northern Hemisphere and tropical sites. Here, we present Hg records from terrestrial sites in southern Pangea, nearly antipodal to contemporaneous STLIP activity, providing insights into the global distribution of volcanogenic Hg during this event and its environmental processing. These profiles (two from Karoo Basin, South Africa; two from Sydney Basin, Australia) exhibit significant Hg enrichments within the uppermost Permian extinction interval as well as positive Δ199Hg excursions (to ~0.3‰), providing evidence of long-distance atmospheric transfer of volcanogenic Hg. These results demonstrate the far-reaching effects of the Siberian Traps as well as refine stratigraphic placement of the LPME interval in the Karoo Basin at a temporal resolution of ~105 years based on global isochronism of volcanog...
The 315 m of Rosario Formation exposed at the San Antonio del Mar (SADM) section (Baja California... more The 315 m of Rosario Formation exposed at the San Antonio del Mar (SADM) section (Baja California, Mexico) contains moderately-to-well preserved benthic and planktic foraminifera, calcareous nannofossils, and molluscs. Nannofossils suggest most of the SADM section ...
... Abstract: Multivariate analyses of Upper Cretaceous (Santonian-Campanian) molluscan assemblad... more ... Abstract: Multivariate analyses of Upper Cretaceous (Santonian-Campanian) molluscan assembladges from the ... 1960) discussed a number of faunal associations from the Upper Cretaceous section ... nal assemblage P of KAUFFMAN (1967), which shows high diversity and ...
Introduction: The catastrophe that befell life on Earth at the end of the Permian Period, some 25... more Introduction: The catastrophe that befell life on Earth at the end of the Permian Period, some 252.5 million years ago, represents the most severe disruption of the biosphere since the rise of animals. Over 90% of marine species perished, and while very few taxa escaped unscathed, some groups suffered disproportionate losses. In one particularly striking example, articulate (rhynchonelliform) brachiopods are the most abundant fossils found in Paleozoic rocks and represent the dominant suspension-feeding constituent of the Paleozoic Fauna. They proved to be among the groups most susceptible to the mass extinction; of the 135 genera present in the uppermost Permian stage, 122 (or 90.4%) did not survive into the Triassic [1]. By contrast, their ecological counterparts, bivalve molluscs, suffered more moderate losses (26 of 58 genera, 44.8%) and found themselves in an Early Triassic world nearly devoid of competition. This point in time thus marks the transition to the Modern Evolutiona...
Key Point Errors in stratigraphic age assignment of Cretaceous detrital zircon samples result in ... more Key Point Errors in stratigraphic age assignment of Cretaceous detrital zircon samples result in incorrect understanding of ages of geologic units
The ammonite speciesPuzosia(Mesopuzosia)densicostataMatsumoto,Kitchinites(Neopuzosia)japonicusSpa... more The ammonite speciesPuzosia(Mesopuzosia)densicostataMatsumoto,Kitchinites(Neopuzosia)japonicusSpath,Anapachydiscuscf.A. nelchinensisJones,Menuitescf.M. menu(Forbes),Submortoniceras chicoense(Trask), andBaculitescf.B. bouleiCollignon are described from Santonian–Campanian strata of western Canada and northwestern United States. Stratigraphic occurrences and ranges of the species are summarized and those taxa important for correlation with other areas in the north Pacific region are noted.
Ammonoids were dominant elements of marine Cretaceous faunas. Their fossils are important biostra... more Ammonoids were dominant elements of marine Cretaceous faunas. Their fossils are important biostratigraphic indicators, in some cases with worldwide distribution. Their paleobiogeographic distributions were influenced by changing continental positions, currents, sea level change, and perhaps by their mode of life as reflected in the evolution of many diverse lineages of heteromorphic, possibly rather vertically migrating than horizontally swimming taxa through the Cretaceous. Here, we review the current paleobiogeographic understanding of Late Cretaceous ammonoid distribution in an effort to complement and add to previous work in this field. Four principal paleobiogeographic areas can be distinguished in the Cretaceous: The Boreal Realm, the Tethyan Realm, the Pacific Realm, and the Austral Realm. A Tethyan Superrealm is repeatedly recognized throughout the Late Cretaceous, although represented by varying taxa. Migration between the realms and provinces appears to be linked to changes of migration routes, triggered by sea level changes. At the end of the Cretaceous, provincialism disappears, preceding the extinction of the Ammonoids.
A CRITICAL aspect of the debate over the origin of the chemical, biological and climatological pe... more A CRITICAL aspect of the debate over the origin of the chemical, biological and climatological perturbations that characterize the Cretaceous/Tertiary boundary (K/T boundary) is the timescale and detailed pattern of the extinctions and geochemical ...
Thirteen Maastrichtian-aged stratigraphic sections from a variety of sites spanning the ancient T... more Thirteen Maastrichtian-aged stratigraphic sections from a variety of sites spanning the ancient Tethys ocean in Western and Eastern Europe and Northern Africa have been measured in this study. The similarity in lithologies between even geographically separated localities allows refined lithostratigraphic correlation; individual members first defined from Bay of Biscay sections can now be recognized through all sections. The sections are
Researchers examined several K-T boundary cores at Deep Sea Drilling Project (DSDP) core reposito... more Researchers examined several K-T boundary cores at Deep Sea Drilling Project (DSDP) core repositories to document biostratigraphic ranges of inoceramid shell fragments and prisms. As in land-based sections, prisms in the deep sea cores disappear well before the K-T boundary. Ammonites show a very different extinction pattern than do the inoceramids. A minimum of seven ammonite species have been collected from the last meter of Cretaceous strata in the Bay of Biscay basin. In three of the sections there is no marked drop in either species numbers or abundance prior to the K-T boundary Cretaceous strata; at the Zumaya section, however, both species richness and abundance drop in the last 20 m of the Cretaceous, with only a single ammonite specimen recovered to date from the uppermost 12 m of Cretaceous strata in this section. Researchers conclude that inoceramid bivalves and ammonites showed two different times and patterns of extinction, at least in the Bay of Biscay region. The inoceramids disappeared gradually during the Early Maestrichtian, and survived only into the earliest Late Maestrichtian. Ammonites, on the other hand, maintained relatively high species richness throughout the Maestrichtian, and then disappeared suddenly, either coincident with, or immediately before the microfossil extinction event marking the very end of the Cretaceous.
Helium concentration and isotopic composition were measured in a suite of samples across the Perm... more Helium concentration and isotopic composition were measured in a suite of samples across the Permian-Triassic boundary at Opal Creek, Canada, to determine whether high extraterrestrial helium concentrations are associated with a possible extinctioninducing impact event at this time. No extraterrestrial 3 He was detected, implying that neither fullerene-hosted nor IDP-hosted He is present at or near the boundary. This observation is consistent with similar studies of some Permian-Triassic sections, but contrasts sharply with reports of both fullerene-and IDP-hosted extraterrestrial 3 He at other sections. Step-heat experiments indicate rapid diffusion of extraterrestrial helium from sediments heated to temperatures above~70 8C. Given the likelihood of burial and associated heating in Permian-Triassic age rocks, the initially unexpected absence of IDP-hosted 3 He likely indicates thermally induced diffusive loss. Indeed one of the key sections (Graphite Peak, Antarctica) from which extraterrestrial 3 He has been reported at and near the Permian-Triassic boundary has been sufficiently heated that the reported preservation of extraterrestrial helium, in both IDPs and fullerenes, is inexplicable. Recent contamination provides a plausible explanation for extraterrestrial 3 He in these samples. While no extraterrestrial 3 He was detected at Opal Creek, there is a sharp increase in nucleogenic 3 He very close to or at the Permian-Triassic boundary. This presumably arises from the major lithologic change at this time, from cherts in the Permian to shales and siltstones in the Triassic. Increased nucleogenic 3 He is associated with increases in both lithium and organic carbon content into the Triassic. Either the production rate or the retention of this 3 He is higher in the shales and siltstones than in the cherts. Care must be taken to eliminate such artifacts before interpreting changes in 3 He concentration in terms of fluctuations in the delivery of 3 He from space.
We have sampled for stable isotopes from paleontologically constrained stratigraphic sections in ... more We have sampled for stable isotopes from paleontologically constrained stratigraphic sections in the southern and central Karoo basin of South Africa, which contains the most abundantly fossiliferous succession of late Permian to middle Triassic terrestrial vertebrates yet described. Over a narrow stratigraphic interval at the end of the Permian in this region, we have found a light carbon isotope anomaly (Ccarb) and succession of negative anomalies (Corg) coincident with, and right after an enhanced pulse of extinction among terrestrial vertebrates. While it is clear that a short interval of intense environmental change occurred over our sampled interval, there is no evidence of impact debris or characteristic boundary sedimentology equivalent to that observed in similar terrestrial facies at numerous Cretaceous/Paleogene boundaries. Our isotopic and paleontological data also show marked dissimilarity to similar data from terrestrial K/P sites. The Permian/Triassic succession in South Africa is thus inconsistent with the K/P model of single-impact mass extinction, and to date shows no evidence of impact of any size.
While the end-Permian extinction in the marine realm is well known from the Tethys Ocean, it rema... more While the end-Permian extinction in the marine realm is well known from the Tethys Ocean, it remains little studied in the vast Panthalassic Ocean. Opal Creek, Alberta, Canada is a biostratigraphically continuous Permian-Triassic Boundary (PTB) section that is interpreted to have been deposited in a deep outer shelf setting along the Panthalassic western margin of Pangaea. Significant organic carbon and nitrogen isotope excursions precede the extinction of the dominant Late Permian benthic organisms (siliceous sponges). Geochemical comparison with underlying Guadalupian age rocks and analysis of the conodont fauna suggest that the latest Permian at Opal Creek records the shutdown of a productive cold-water upwelling ecosystem with a mid-water column oxygen minimum followed by the transition to a warm and less vigorously circulating system with a bottom-water oxygen minimum. The transition from a low-diversity, cold-water conodont fauna in the Middle Permian to a more diverse latest Permian fauna containing equatorial species coincides with a transition from elevated δ 15 N values characteristic of coastal zones with denitrification in a mid-water oxygen minimum to more normal marine values. A spike in the δ 13 C of organic carbon following a latest Permian marine transgression along western Pangaea is here attributed to transient increased productivity in the photic zone preceding the main extinction, likely related to the synergistic effects of warming, increased nutrient runoff, and residual upwelling. This is followed by an equilibration to lower δ 13 C org values characteristic of a lower productivity regime in the Early Triassic.
... Abstract/FREE Full Text. ↵ Lucas, S., 1998, Global Triassic tetrapod biostratigraphy and bioc... more ... Abstract/FREE Full Text. ↵ Lucas, S., 1998, Global Triassic tetrapod biostratigraphy and biochronology ... CrossRef. ↵ Visscher, H., Brinhuis, H., Dilcher, D., Elsik, W., Eshet, Y., Looy, C ... CrossRef. ↵ Ward, P., Montgomery, DR, and Smith, R., 2000, Altered river morphology in South ...
The latest Permian mass extinction (LPME) was triggered by magmatism of the Siberian Traps Large ... more The latest Permian mass extinction (LPME) was triggered by magmatism of the Siberian Traps Large Igneous Province (STLIP), which left an extensive record of sedimentary Hg anomalies at Northern Hemisphere and tropical sites. Here, we present Hg records from terrestrial sites in southern Pangea, nearly antipodal to contemporaneous STLIP activity, providing insights into the global distribution of volcanogenic Hg during this event and its environmental processing. These profiles (two from Karoo Basin, South Africa; two from Sydney Basin, Australia) exhibit significant Hg enrichments within the uppermost Permian extinction interval as well as positive Δ199Hg excursions (to ~0.3‰), providing evidence of long-distance atmospheric transfer of volcanogenic Hg. These results demonstrate the far-reaching effects of the Siberian Traps as well as refine stratigraphic placement of the LPME interval in the Karoo Basin at a temporal resolution of ~105 years based on global isochronism of volcanog...
The 315 m of Rosario Formation exposed at the San Antonio del Mar (SADM) section (Baja California... more The 315 m of Rosario Formation exposed at the San Antonio del Mar (SADM) section (Baja California, Mexico) contains moderately-to-well preserved benthic and planktic foraminifera, calcareous nannofossils, and molluscs. Nannofossils suggest most of the SADM section ...
... Abstract: Multivariate analyses of Upper Cretaceous (Santonian-Campanian) molluscan assemblad... more ... Abstract: Multivariate analyses of Upper Cretaceous (Santonian-Campanian) molluscan assembladges from the ... 1960) discussed a number of faunal associations from the Upper Cretaceous section ... nal assemblage P of KAUFFMAN (1967), which shows high diversity and ...
Introduction: The catastrophe that befell life on Earth at the end of the Permian Period, some 25... more Introduction: The catastrophe that befell life on Earth at the end of the Permian Period, some 252.5 million years ago, represents the most severe disruption of the biosphere since the rise of animals. Over 90% of marine species perished, and while very few taxa escaped unscathed, some groups suffered disproportionate losses. In one particularly striking example, articulate (rhynchonelliform) brachiopods are the most abundant fossils found in Paleozoic rocks and represent the dominant suspension-feeding constituent of the Paleozoic Fauna. They proved to be among the groups most susceptible to the mass extinction; of the 135 genera present in the uppermost Permian stage, 122 (or 90.4%) did not survive into the Triassic [1]. By contrast, their ecological counterparts, bivalve molluscs, suffered more moderate losses (26 of 58 genera, 44.8%) and found themselves in an Early Triassic world nearly devoid of competition. This point in time thus marks the transition to the Modern Evolutiona...
Key Point Errors in stratigraphic age assignment of Cretaceous detrital zircon samples result in ... more Key Point Errors in stratigraphic age assignment of Cretaceous detrital zircon samples result in incorrect understanding of ages of geologic units
The ammonite speciesPuzosia(Mesopuzosia)densicostataMatsumoto,Kitchinites(Neopuzosia)japonicusSpa... more The ammonite speciesPuzosia(Mesopuzosia)densicostataMatsumoto,Kitchinites(Neopuzosia)japonicusSpath,Anapachydiscuscf.A. nelchinensisJones,Menuitescf.M. menu(Forbes),Submortoniceras chicoense(Trask), andBaculitescf.B. bouleiCollignon are described from Santonian–Campanian strata of western Canada and northwestern United States. Stratigraphic occurrences and ranges of the species are summarized and those taxa important for correlation with other areas in the north Pacific region are noted.
Ammonoids were dominant elements of marine Cretaceous faunas. Their fossils are important biostra... more Ammonoids were dominant elements of marine Cretaceous faunas. Their fossils are important biostratigraphic indicators, in some cases with worldwide distribution. Their paleobiogeographic distributions were influenced by changing continental positions, currents, sea level change, and perhaps by their mode of life as reflected in the evolution of many diverse lineages of heteromorphic, possibly rather vertically migrating than horizontally swimming taxa through the Cretaceous. Here, we review the current paleobiogeographic understanding of Late Cretaceous ammonoid distribution in an effort to complement and add to previous work in this field. Four principal paleobiogeographic areas can be distinguished in the Cretaceous: The Boreal Realm, the Tethyan Realm, the Pacific Realm, and the Austral Realm. A Tethyan Superrealm is repeatedly recognized throughout the Late Cretaceous, although represented by varying taxa. Migration between the realms and provinces appears to be linked to changes of migration routes, triggered by sea level changes. At the end of the Cretaceous, provincialism disappears, preceding the extinction of the Ammonoids.
A CRITICAL aspect of the debate over the origin of the chemical, biological and climatological pe... more A CRITICAL aspect of the debate over the origin of the chemical, biological and climatological perturbations that characterize the Cretaceous/Tertiary boundary (K/T boundary) is the timescale and detailed pattern of the extinctions and geochemical ...
Thirteen Maastrichtian-aged stratigraphic sections from a variety of sites spanning the ancient T... more Thirteen Maastrichtian-aged stratigraphic sections from a variety of sites spanning the ancient Tethys ocean in Western and Eastern Europe and Northern Africa have been measured in this study. The similarity in lithologies between even geographically separated localities allows refined lithostratigraphic correlation; individual members first defined from Bay of Biscay sections can now be recognized through all sections. The sections are
Uploads
Papers by peter ward