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DATES AND RATES: Temporal Resolution in the Deep Time Stratigraphic Record*
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The level of achievable stratigraphic resolution determines the nature of the many ecological, evolutionary, and geological questions for which a reasonable answer may be expected. Advances in correlation techniques and in high-resolution radiometric dating and their integration with the fossil record through quantitative biostratigraphy and potentially orbital cyclicity now allows many questions about rates of geological, geochemical, and evolutionary processes to be extended into deep time.
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... High-precision geochronology is essential to investigate and test hypotheses about the global correlation of events, the driving mechanisms for change in the Earth system, and rates of geological, biological, geophysical, and geochemical processes (Erwin, 2006). Biostratigraphy (biozones) provides rough age controls for most Paleozoic geological events, but the low temporal resolution (million-year scale) and strong bio-provincialism obstruct global correlation. ...
... After about 1.9 Ga, the first eukaryotes seem to have made their appearance, but remained highly conservative throughout much of the Proterozoic [159,160]. The time span that stretches from the late Neoproterozoic through to the mid-Cambrian (~800-501 Ma) witnessed increases in the diversity of acritarchs and other protistan morphotypes in fossil assemblages [160,161], heralding the evolution of architecturally complex bauplans and metazoans [162][163][164][165][166][167][168][169][170][171][172]. There are two major steps in the oxygenation of the Earth's surface that broadly correlate with the most important biological upgrades; first, from prokaryotes to eukaryotes around the GOE, and then from single-celled to complex, multicellular organisms in the Neoproterozoic. ...
Banded iron-formations (BIFs) are marine chemical sedimentary rocks composed of siliceous and ferric materials, usually with typical thin layers or sheet structures. BIFs not only record a wealth of information about the state and evolution of the lithosphere, atmosphere, hydrosphere, and biosphere but also host the majority of the economic iron resources in the world. Here, we summarize the types, mineralogical, and geochemical characteristics of BIFs; analyze their formation conditions, their oxidative mechanism, and the absence causes of BIFs; and elucidate the associations between BIFs and major atmospheric oxidation events (Paleoproterozoic great oxidation event (2.4~2.1 Ga) and Neoproterozoic oxidation event (0.8~0.55 Ga)). BIFs are intimately associated with enhanced submarine magmatic–hydrothermal activities. Finally, it is concluded that the deposition and demise of BIFs are closely related to major geological events, and these major geological events interact with each other, jointly constraining the evolution of the atmospheric and marine environment and of geo-biological and geodynamic processes.
... The Neoproterozoic to Early Cambrian geological history documents the changes of global-scale glaciation and deglaciation, eustatic sealevel rise and fall, swinging oxygenation, biological evolution, tectonic upheaval, and continental configuration (Freiburg et al., 2020;Myrow et al., 2018;George and Ray, 2017;Malone et al., 2017;Yonkee et al., 2014;Fritz et al., 2013;Sen et al., 2013;Grantham et al., 2013;Singh and Singh, 2010;Gaucher et al., 2009;Meert and Lieberman, 2008;Pisarevsky et al., 2008;Erwin, 2006;Baker, 2006;Meert and Tamrat, 2004;Berner et al., 2003). The Salt Range is a key area to investigate the Late Neoproterozoic to Early Cambrian paleoclimatic and geological evolutions on Indian plate. ...
This study describes the sedimentological aspects of the Lower Cambrian Khewra Sandstone, along with its lith-ostratigraphic correlation of globally distributed coeval red sandstones to decipher the imprints of Pan-African Orogeny. Despite the economic significance of Khewra Sandstone, the understanding of its environment of depo-sition, provenance and lower contact with the suite of igneous body namely Khewrite is poor. The Khewra Sandstone is an allostratigraphic unit bounded by unconformities. The upward coarsening sequence with abundant sedimentary structures and varying sedimentological properties of the topmost bed suggest that the Khewra Sandstone is tempestites deposited under fluvio-deltaic depositional environment. This sandstone is dominated by subarkoses, feldspathic litharenites and sublitharenites which were derived from the craton interior to recycled orogen provenance during the Pan-African orogeny under humid to semi-humid paleoclimatic conditions. The plutonic to metamorphic characteristics of framework grains suggest that the Bundlekhand Craton, Delhi Fold Belt and Aravalli Orogen rocks were the primary provenances. The lower and middle parts of the Khewra Sandstone are significantly affected by diagenesis while the diagenetic action in upper part is negligible and it acts as a potential hydrocarbon reservoir rock. The lithostratigraphic correlation suggests a worldwide series of rifting events before the deposition of Khewra Sandstone and the presence of Khewrite at lower contact marks a similar rifting event on the Indian plate.
... Specimen choice, including the evidence used to establish stratigraphic age and phylogenetic placement, is very important given the role of calibration in molecular dating. Few fossils have been recovered from rocks that have been directly dated so that usually age must be established through a chain of evidence linking the litho-, bio-, and chronostratigraphic records (Reisz and Müller 2004;Erwin 2006;Benton et al. 2009). Positioning fossils in the tree of life is challenging for several key reasons already noted-the overall number of morphological characters is low, specimens are typically very incomplete, and phenotypic traits are prone to homoplasy (Lee and Palci 2015;O'Reilly et al. 2015). ...
The molecular clock in combination with evidence from the geological record can be applied to infer the timing and dynamics of evolutionary events. This has enormous potential to shed light on the complex and often evasive evolution of parasites. Here, we provide an overview of molecular clock methodology and recent advances that increase the potential for the study of host-parasite coevolutionary dynamics, with a focus on Bayesian approaches to divergence time estimation. We highlight the challenges in applying these methods to the study of parasites, including the nature of parasite genomes, the incompleteness of the rock and fossil records, and the complexity of host-parasite interactions. Developments in models of molecular evolution and approaches to deriving temporal constraints from geological evidence will help overcome some of these issues. However, we also describe a case study in which the timescale of host-parasite coevolution cannot easily be inferred using existing methods—that of the alpha-proteobacteria Wolbachia. We conclude by providing a prospective on future methodological developments and data collection that will facilitate the understanding of the role of parasitism in deep time.
High-precision U-Pb zircon ages on SE Newfoundland tuffs now bracket the Avalonian Lower–Middle Cambrian boundary. Upper Lower Cambrian Brigus Formation tuffs yield depositional ages of 507.91 ± 0.07 Ma ( Callavia broeggeri Zone) and 507.67 ± 0.08 Ma and 507.21 ± 0.13 Ma ( Morocconus-Condylopyge eli Assemblage interval). Lower Middle Cambrian Chamberlain’s Brook Formation tuffs have depositional ages of 506.34 ± 0.21 Ma ( Kiskinella cristata Zone) and 506.25 ± 0.07 Ma ( Eccaparadoxides bennetti Zone). The composite unconformity separating the Brigus and Chamberlain’s Brook formations is constrained between these ages. An Avalonian Lower–Middle Cambrian boundary between 507.2 ± 0.1 and 506.3 ± 0.2 Ma is consistent with maximum depositional age constraints from southwest Laurentia, which indicate an age for the base of the Miaolingian Series, as locally interpreted, of ≤ 506.6 ± 0.3 Ma. The Miaolingian Series’ base is interpreted as correlative within ≤ 0.3 ± 0.3 Ma between Cambrian palaeocontinents, although its exact synchrony is questionable due to taxonomic problems with a possible Oryctocephalus indicus -plexus, invariable dysoxic lithofacies control of O. indicus and diachronous occurrence of O. indicus in temporally distinct δ ¹³ C chemozones in South China and SW Laurentia. The lowest occurrence of O. indicus assemblages is linked to onlap (epeirogenic or eustatic) of dysoxic facies. A united Avalonia is shown by late Early Cambrian volcanics in SW New Brunswick; Cape Breton Island; SE Newfoundland; and the Wrekin area, England. The new U-Pb ages revise Avalonian geological evolution as they show rapid epeirogenic changes through depositional sequences 4a–6.
Mass extinctions’ have been a hot topic for several decades. What triggers a mass extinction? How does a mass extinction impact the evolution of life? How does our ecosystem recover after a mass extinction? These questions attracted the interest of both scientists and the public alike. NSR spoke to two renowned researchers in the field of mass extinctions: Prof. Douglas H. Erwin from the National Museum of Natural History of the USA, and Prof. Shuzhong Shen from Nanjing University, China. Prof. Erwin has been interested in the end-Permian mass extinction since graduate school. He has worked on a variety of problems, from Permian gastropod systematics to the origin of animals. Currently his work focuses on the nature of evolutionary novelty and innovation. Prof. Shen's research career is centered upon the end-Permian mass extinction, Permian stratigraphy and global correlations, with taxonomic expertise on brachiopods and conodonts. The International Commission on Stratigraphy recognizes his outstanding singular contribution to stratigraphy and awarded him the ICS Stratigraphy Medal in 2019.
The advent of greatly improved radiometric dating techniques with lower uncertainties, the development of new dating and correlation techniques, including vastly expanded quantitative biostratigraphic methods, and the possibility of reliable extension of orbital cyclostratigraphy into the Paleozoic all promise a great improvement in the ability of geologists to construct high-resolution temporal frameworks far deeper into the past. Such techniques have already allowed the generation of a high-resolution temporal framework for the Ediacaran-Cambrian radiation of metazoa, helped greatly narrow the duration of the great Permo-Triassic mass extinction and eliminated several hypothesized causes, and narrowed the duration of the oceanic anoxic event at the Cenomanian-Turonian (Late Cretaceous boundary). Temporal resolution of 100 kyr (0.02%) or even better into the early Paleozoic now seems likely, opening a host of new questions for reliable investigation. Further exploiting the possibilities of these techniques will require paleontologists to improve methods to integrate these disparate techniques, improve our understanding of the analysis of evolutionary rates, and confront the challenges of settings where geochronologic resolution may be greater than paleontologic resolution.
Perhaps no term in the geological lexicon excites more passions than uniformitarianism, whose motto is “the present is the key to the past.” The term is controversial in part because it contains several meanings, which have been implicated in creating a situation of “semantic chaos” in the geological literature. Yet I argue that debates about uniformitarianism do not arise from a simple chaos of meanings. Instead, they arise from legitimate disagreements about substantive questions. This paper examines these questions and relates them to several “forms of understanding” pursued by researchers in geohistory.
Rock outcrops of the sedimentary-stratigraphic record often reveal bedding planes that can be considered to be true substrates: preserved surfaces that demonstrably existed at the sediment–water or sediment–air interface at the time of deposition. These surfaces have high value as repositories of palaeoenvironmental information, revealing fossilized snapshots of microscale topography from deep time. Some true substrates are notable for their sedimentary, palaeontological and ichnological signatures that provide windows into key intervals of Earth history, but countless others occur routinely throughout the sedimentary–stratigraphic record. They frequently reveal patterns that are strikingly familiar from modern sedimentary environments, such as ripple marks, animal trackways, raindrop impressions or mudcracks: all phenomena that are apparently ephemeral in modern settings, and which form on recognizably human timescales. This paper sets out to explain why these short-term, transient, small-scale features are counter-intuitively abundant within a 3.8 billion year-long sedimentary-stratigraphic record that is known to be inherently time-incomplete. True substrates are fundamentally related to a state of stasis in ancient sedimentation systems, and distinguishable from other types of bedding surfaces that formed from a dominance of states of deposition or erosion. Stasis is shown to play a key role in both their formation and preservation, rendering them faithful and valuable archives of palaeoenvironmental and temporal information. Further, the intersection between the time–length scale of their formative processes and outcrop expressions can be used to explain why they are so frequently encountered in outcrop investigations. Explaining true substrates as inevitable and unexceptional by-products of the accrual of the sedimentary–stratigraphic record should shift perspectives on what can be understood about Earth history from field studies of the sedimentary–stratigraphic record. They should be recognized as providing high-definition information about the mundane day to day operation of ancient environments, and critically assuage the argument that the incomplete sedimentary–stratigraphic record is unrepresentative of the geological past.
It is now possible to routinely determine the age of 200-600-m.y.old volcanic rocks interlayered with fossil-bearing deposits to uncertainties of less than 1 m.y. with uranium-lead zircon geochronology. This level of precision, coupled with the recognition that volcanic ash beds are much more common in fossiliferous rocks that previosuly realized, opens new opportunitites for the study of evolutionary rates in deep time. It is now possible to constrain rates of evolutionary radiations, mass extinctions, and other evolutionary events as well as evaluate potentially diachronous biostratigraphic boundaires. For example, a combination of detailed biostratigraphic and chemostratigraphic data with new U-Pb zircon dates for the late Neoproterozoic and Early Cambrian has demonstrated that the soft-bodied Ediacaran fossils immediately underlie the Cambrian, that the base of the Cambrian is much younger than previously recognized, and that the Cambrian explosion lasted 10 m.y. or less. Other recent studies have shown the Middle and Late Cambrian each lasted only about 10 m.y. suggesting that the duration often included trilobite zones was similar to those of Jurassic ammonites. Recent data from the Late Perman and ealiest Triassic of South China now constrain the duration of the most profound mass extintion in the history of life to less than 1 m.y. Collaboration between paleontologists and geochronologists offers the prospect of accurately assessing the rates of evolutionary processes, from speciation to evolutionary radiations and mass extinctions, throughout the Phanerozoic.
This volume delves into a spectrum of theoretical as well as applied aspects of high-resolution stratigraphic approaches in paleontology. It explores how increasingly detailed knowledge of the fossil record can enhance our understanding of the evolution of life on Earth and also allows geoscientists to address a broad range of important evolutionary and environmental questions in this arena.
A 'zipped' version of the program CONOP9 2007 along with read-me files, sample files, and other documentation are available via a web site (see below). An earlier version of CONOP9 was initially supplied with 'High-Resolution Approaches in Stratigraphic Paleontology' (PJ Harries, editor) and described in Chapter 13 of that volume. This is an updated version of the program, and the documentation supplied with this version supersedes the information supplied in that chapter.
To view the CONOP9 Programs, click on the link CONOP9 Programs on the right side of this page under Related links.
Advances in taphonomy and stratigraphy over the past two decades have dramatically improved our understanding of the causes, effects, and remedies of incompleteness in the fossil record for the study of evolution. Taphonomic research has focused on quantifying probabilities of preservation across taxonomic groups, the temporal and spatial resolution of fossil deposits, and secular changes in preservation over the course of the Phanerozoic. Stratigraphic research has elucidated systematic trends in the formation of sedimentary gaps and permanent stratigraphic records, the quantitative consequences of environmental change and variable rock accumulation rates over short and long timescales, and has benefited from greatly improved methods of correlation and absolute age determination. We provide examples of how these advances are transforming paleontologic investigations of the tempo and mode of morphologic change, phylogenetic analysis, and the environmental and temporal analysis of macroevolutionary patterns.
Patterns of temporal variation of six characters in a Miocene stickleback (Gasterosteus doryssus) are presented. We argue that most observed temporal variation represents intrapopulation evolutionary change. Gradual variation is predominant, and in one case is nearly linear, but very rapid evolutionary bursts are also seen. The most rapid stratigraphic change appears to represent a local extinction, followed by recolonization by a differentiated population, but another episode of rapid change probably represents evolution in situ by means of standard neo-Darwinian mechanisms, without involvement of 'macromutations' or true saltation. from Authors
The equations for calculating classical confidence intervals on the end points of stratigraphic ranges are based on the restrictive assumption of randomly distributed fossil finds. A method is presented for calculating confidence intervals on the end-points of stratigraphic ranges that partially relaxes this assumption: the method will work for any continuous distribution of gap sizes, not just those generated by random processes. The fossil record of the Neogene Caribbean bryozoan Metrarabdotos is analyzed with the new approach. -from Author
A successor to A Geologic Time Scale 1989 (Cambridge, 1990), this volume introduces the theory and methodology behind the construction of the new time scale, before presenting the scale itself in extensive detail. An international team of over forty stratigraphic experts develops the most up-to-date international stratigraphic framework for the Precambrian and Phanerozoic eras. A large wallchart (not available for eBook) summarizing the time scale at the back of the book completes this invaluable reference for researchers and students.