Kenneth G. MacLeod

Kenneth G. MacLeod
University of Missouri | Mizzou · Department of Geological Sciences

PhD

About

217
Publications
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6,136
Citations
Citations since 2016
73 Research Items
3287 Citations
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500

Publications

Publications (217)
Article
Full-text available
The latest Cenomanian to Santonian sedimentary record recovered at IODP Expedition 369 Site U1513 in the Mentelle Basin (SE Indian Ocean, paleolatitude 60°S at 85 Ma) is studied to interpret the paleoceanographic evolution in the Southern Hemisphere. The planktonic foraminiferal assemblage changes, the depth ecology preferences of different species...
Article
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International Ocean Discovery Program (IODP) Expedition 369 recovered a stratigraphically complete, Santonian-aged, pelagic sedimentary sequence at Site U1513 on the Naturaliste Plateau (33°47.6084′S, 112°29.1338′E) at ~2800 m water depth. The site was located at ~60°S paleolatitude in Cretaceous times. A total of 59 samples studied from Holes 1513...
Article
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Oceanic anoxic event 1d (OAE 1d) has been well studied at northern low latitudes (i.e., in Tethys and the North Atlantic); however, the paleoenvironmental response to this event at high latitudes has not been documented and the triggering mechanism remains unknown. Here, we address both of these shortcomings by presenting the first detailed sedimen...
Article
Species distributions of well-preserved and diverse assemblages of planktonic foraminifera and calcareous nannofossils spanning the last 10 m.y. of the Cretaceous (middle Campanian through Maastrichtian) are analyzed from samples taken across a 1400 m depth transect at Blake Nose in the western subtropical North Atlantic (Ocean Drilling Program Sit...
Article
Full-text available
The latest Cenomanian to Santonian sedimentary record recovered at IODP Expedition 369 Site U1513 in the Mentelle Basin (SE Indian Ocean, paleolatitude 60°S at 85 Ma) is studied to interpret the paleoceanographic evolution in the Southern Hemisphere. The planktonic foraminiferal assemblage changes, the depth ecology preferences of different species...
Article
Full-text available
Here we report on the oxygen isotope compositions of four proposed apatite reference materials (chlorapatite MGMH#133648 and fluorapatite specimens MGMH#128441A, MZ-TH, and ES-MM). The samples were initially screened for 18O/16O homogeneity using secondary ion mass spectrometry (SIMS) followed by δ18O determinations in six gas source isotope ratio...
Article
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The Kuroshio Current Extension (KCE) is the major western boundary current of the North Pacific Subtropical Gyre. To better understand how the KCE behaved under elevated CO2 conditions and how it came into its modern configuration, we use stable isotopic analyses from mixed‐layer planktic foraminifera from three Ocean Drilling Program sites that li...
Article
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Planktonic foraminiferal population dynamics and benthic foraminiferal and radiolaria distributions combined with δ¹³C and δ¹⁸O measurements of both bulk carbonate and foraminifera provide clues concerning the paleoceanographic changes across the Cenomanian-Turonian boundary interval and the Oceanic Anoxic Event 2 (OAE 2) at southern high latitudes...
Article
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Austral planktonic foraminiferal assemblages from immediately above the Cretaceous/Paleogene (K/Pg) boundary at Ocean Drilling Program Hole 690C (Maud Rise, Weddell Sea) and International Ocean Drilling Program Hole U1514C (southeast Indian Ocean) show a much different record of post-extinction recovery than anywhere outside the circum-Antarctic re...
Article
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The Upper Cretaceous sedimentary sequence at International Ocean Discovery Program Site U1512 in the Ceduna Sub-basin of the Great Australian Bight represents a continuous, > 690 m thick interval of black silty clay and claystone spanning the lower Turonian through Lower Campanian (~10 million years). Sediments were deposited in an elongate, ~E-W o...
Article
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Understanding of the role of ocean circulation on climate during the Late Cretaceous is contingent on the ability to reconstruct its modes and evolution. Geochemical proxies used to infer modes of past circulation provide conflicting interpretations for the reorganization of the ocean circulation through the Late Cretaceous. Here, we present climat...
Article
The Naturaliste Plateau is a submarine continental ribbon rifted from the southwest Australian margin during the Early Cretaceous breakup of East Gondwana. It occupied a key position near the juncture of Greater India and the boundary between Australia and Antarctica. However, details of the Early Cretaceous evolution of the plateau are not well kn...
Data
Supplementary data 1. Mineral data of Unit V at Site U1513, analyzed by whole-rock XRD. Supplementary data 2. Numerical analysis of Unit V at Site U1513. A) Porosity data of the Cretaceous succession. B) Cretaceous compaction trend. C) Magnetostratigraphic age-depth model. D) Sedimentation profile. E) Subsidence curve. Supplementary data 3. Alter...
Article
The biogeographic distribution of planktonic foraminifera from southern mid-to high latitudes region are discussed to identify links between species distribution patterns and the changes in Late Cretaceous climate. We present relative abundance data for planktonic foraminifera spanning from the hot greenhouse climate of the Turonian to the cooler g...
Conference Paper
Full-text available
Minerals of the apatite group, especially hydroxylapatite Ca5(PO4)3OH, are valuable archives for reconstructing environmental conditions occurring throughout the Earth's history (e.g., Joachimski et al. 2009). Apatite oxygen isotope compositions have proved useful in studies of conodonts as well as fish and mammalian teeth and bones. Secondary ion...
Article
Geochemical data suggest that ocean circulation patterns changed over a period of longterm cooling during the last 10 m.y. of the Cretaceous (late Campanian–Maastrichtian). Proposed changes include enhanced deep-water formation in the South Atlantic and/or Indian sectors of the Southern Ocean, initiation or enhanced deep-water formation in the Nort...
Preprint
Full-text available
Understanding of the role of ocean circulation on climate during the Late Cretaceous is contingent on the ability to reconstruct its modes and evolution. Geochemical proxies used to infer modes of past circulation provide conflicting interpretations for the reorganization of the ocean circulation through the Late Cretaceous. Here, we present climat...
Article
Full-text available
The geologic time scale for the Cenozoic Era has been notably improved over the last decades by virtue of integrated stratigraphy, combining high-resolution astrochronologies, biostratigraphy and magnetostratigraphy with high-precision radioisotopic dates. However, the middle Eocene remains a weak link. The so-called "Eocene time scale gap" reflect...
Presentation
Events during the Ordovician Period include both the largest and longest period of sustained biodiversification—the Great Ordovician Biodiversification Event (GOBE)—and the second largest mass extinction of the Phanerozoic. Global changes in climate have been invoked as one of the primary forcing mechanisms of both events. Considerable data have be...
Article
Ammonites are iconic members of Jurassic and Cretaceous marine communities, but many questions remain about their ecology. Because it contains a diverse assemblage of well-preserved macro- and microfossils, the upper Maastrichtian Owl Creek Formation exposed in Tippah County, Mississippi, is an excellent site at which to compare carbonate isotopic...
Article
Stable isotopic analyses of bulk carbonates recovered from Ontong Java Plateau during Ocean Drilling Program (ODP) Leg 192 (Holes 1183A and 1186A) show an ~0.5‰ increase in δ 18 O values from the upper Campanian/lower Maastrichtian to the upper Maastrichtian. This shift is consistent with widespread evidence for cooling at this time. Similar shifts...
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Article
Exceptionally well-preserved palynomorphs were recovered from a Turonian section cored in Tanzania. Here we provide an in-depth evaluation of the terrestrial palynomorph assemblages recovered, discuss their environmental affinity, and provide taxonomic descriptions for seventeen angiosperm species. Forms present include various species of Liliacidi...
Article
Global cooling and the establishment of a moderate climate in the Middle Ordovician has been invoked as the primary driver of the tenfold increase in marine biodiversity that characterized the Great Ordovician Biodiversification Event (GOBE). Arguments suggesting that climate change played a significant role in biodiversification purport that the E...
Article
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A compilation of foraminiferal stable isotope measurements from southern high latitude (SHL) deep-sea sites provides a novel perspective important for understanding Earth's paleotemperature and paleoceanographic changes across the rise and fall of the Cretaceous Hot Greenhouse climate and the subsequent Paleogene climatic optimum. Both new and prev...
Article
Warming after the big one The Chicxulub impact 65 million years ago, which caused the mass extinction at the Cretaceous-Paleogene boundary, also initiated a long period of strong global warming. Using data from phosphatic microfossils, including fish teeth, scales, and bone, MacLeod et al. estimated global average temperature. Immediately after the...
Article
Full-text available
The tectonic and paleoceanographic setting of the Great Australian Bight (GAB) and the Mentelle Basin (MB; adjacent to Naturaliste Plateau) offered an outstanding opportunity to investigate Cretaceous and Cenozoic climate change and ocean dynamics during the last phase of breakup among remnant Gondwana continents. Sediment recovered from sites in b...
Article
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Global cooling during the late Campanian–Maastrichtian (78 – 66 Ma) has been linked to changes in ocean circulation. In the North Atlantic, both Northern Component (NCW) and Southern Component (SCW) Waters have been proposed as primary deep water sources in the Late Cretaceous. Neodymium (Nd) isotope records alone do not distinguish between these t...
Conference Paper
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Regions of intermediate/deep water formation and water-mass mixing in the North Atlantic are poorly defined for the Late Cretaceous, a time of gateway evolution and cooler conditions following the Mid Cretaceous greenhouse. Improved proxy data combined with modeling efforts are required to effectively evaluate the relationship between CO2, paleogeo...
Article
The GICE (Guttenberg Carbon Isotope Excursion) is a positive δ13C excursion and a prominent feature of the Late Ordovician chemostratigraphic record. The GICE has been identified on different paleocontinents, and its cause is still unresolved. One explanation suggests that the GICE is the carbon isotopic expression of changes that occurred during t...
Article
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Postel Nunatak in the Patuxent Range has been previously mapped as Nelson Limestone but there was no biostratigraphic support for that interpretation until now. We confirm that limestone exposures at Postel Nunatak are at least partly correlated with the Nelson Limestone of the Neptune Range, 160 km north-east, and are not correlative with the lowe...
Article
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Latest Sandbian to early Katian sequences across Laurentia's epicontinental sea exhibit a transition from lithologies characterized as ‘warm-water’ carbonates to those characterized as ‘cool-water'carbonates. This shift occurs across the regionally recognized M4/M5 sequence stratigraphic boundary and has been attributed to climatic cooling and glac...
Article
Biotic perturbations and changes in ocean circulation during the Maastrichtian stage of the latest Cretaceous raise questions about whether the biosphere was preconditioned for the end-Cretaceous mass extinction of calcareous plankton. A brief acme of inoceramid clams at ~ 71 Ma on Shatsky Rise in the tropical North Pacific was followed by their ex...
Article
Sediment cores from southeastern Tanza-nia contain exceptionally well-preserved cal-careous and organic-walled microfossils in numerous samples spanning from the Aptian to the Miocene. The unusually high quality of preservation is commonly attributed to shallow burial and high clay content of the host sediments. However, such attributes apply to ma...
Article
Marine mudstone sediments recovered from multiple boreholes drilled in southeast Tanzania yield some of the best preserved Turonian microfossils in the world, and these specimens provide a valuable new perspective on planktonic foraminiferal and calcareous nannofossil evolution, taxonomy, biostratigraphy, and biodiversity. High sedimentation rates...
Article
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The Permian-Triassic (P-T) mass extinction is the largest extinction event of the Phanerozoic and has been causally related to eruption of the Siberian Traps (Siberia, Russia) through climatic and ecological effects of volcanically forced greenhouse gas emissions. Given anthropogenic changes to the atmosphere, documenting details of links between g...
Article
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A 101 m thick stratigraphically complete late Coniacian–early Santonian (ca 89 to 83 Ma) sedimentary sequence drilled in Tanzania (Tanzania Drilling Project Site 39) allows, for the first time, examination of the planktonic foraminiferal biostratigraphy and evolution, the depositional history, and geochemical patterns of the subtropical–tropical In...
Article
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The carbon and oxygen isotope compositions of calcium carbonate shells are widely accepted and applied proxies for tracking changes in paleoenvironmental conditions such as temperature, salinity and productivity. In order to accurately interpret isotopic measurements, diagenetic alteration must first be assessed. The occurrence of aragonitic shells...
Article
Oxygen isotopic measurements of conodont elements can provide important paleoclimatic, paleoecological, and paleoenvironmental information. However, preparation techniques are often cited as a potential, albeit poorly constrained, source of error. Prior to isotopic measurements, conodont elements are typically liberated from a calcium carbonate mat...
Article
The ~35-m.y.-long Late Cretaceous greenhouse climate has been the subject of a number of studies, with emphasis on the Cenomanian–Turonian and late Cam-panian–Maastrichtian intervals. By contrast , far less information is available for the Turonian–early Campanian interval, even though it encompasses the transition out of the extreme warmth of the...
Article
The Cretaceous deep-sea record of the Santonian–Campanian transition is commonly interrupted by an extensive unconformity (representing
Article
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Significance Because ammonites are one of the most diverse, abundant, and well-preserved clades in the history of life, they are a mainstay in macroevolutionary and biodiversity studies; however, their ecologies are poorly understood, and it is unknown whether taxa lived near the sea surface or seafloor. This uncertainty undermines their use in pal...
Article
The search into Earth's mid-Cretaceous greenhouse conditions has recently been stimulated by the Tanzania Drilling Project (TDP) which has recovered exceptionally well-preserved biogenic carbonates from subsurface pre-Neogene marine sediments in the eastern margin of central Africa. Published Tanzanian oxygen isotope records measured on exquisitely...
Article
The Guttenberg Isotope Carbon Excursion (GICE), a positive carbon isotope excursion that occurs near the base of the Katian Stage, is thought to be a global event possibly related to Late Ordovician cooling. Documenting how much regional and global variability exists in carbon isotopic trends prior to and during the GICE is a critical aspect in und...
Conference Paper
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The argument that temperature change and biological change during the Ordovician are correlated and, perhaps, causally related has been advanced by measurements of δ18Ophos values on conodont apatite, a phase more resistant to diagenetic alteration than carbonates. However, the available conodont δ18Ophos records are discontinuous and are biased to...
Article
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Oxygen isotopic ratios of conodont apatite can be a robust proxy for sea surface temperatures and provide important constraints on global climate. The oxygen isotopic composition of seawater is a function of local, regional, and global processes. To determine the relative importance of regional and local influences (and therefore make global infere...
Article
In this paper we critically examine the biostratigraphy and systematics of late Albian–Coniacian biserial planktic foraminifera using measurements and qualitative observations from SEM and X-radiograph images of exquisitely preserved specimens from hemipelagic sediments of southeast Tanzania, augmented by analogous observations of selected Ocean Dr...