80 research outputs found
Deconstructing Tectonics: Ten Animated Explorations
The configuration of continents and oceans of our tectonically active planet is ever changing. Using new, high‐resolution paleogeographic base maps, we created a set of animations that examine key elements of plate tectonics. These time‐ and space‐based paleoglobe reconstructions illustrate continental rifting, continental breakup, ocean ridges and fracture zones, hot spot tracks, arc‐backarc systems, continental collision, terrane accretion, opening‐closing of ocean basins, supercontinent formation, plate velocities, and future Earth. Each animation is supported by a narrative that offers a brief topical overview, some observations to guide a user’s exploration, and key references that formulated the main ideas and concepts that became the foundations of modern plate tectonics.Key PointsFundamentals of plate tectonics are explored with paleogeographyShort animations and supporting write‐ups illustrate key processes and properties of tectonicsPresenting plate reconstructions from Cambrian to Today, and a permissible future EarthPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163371/2/ess2650.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163371/1/ess2650_am.pd
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Preliminary plate tectonic reconstruction of the Indian Ocean at Anomaly M10, 34, 28, 13, and 5 times, Part I.
Contact [email protected] for more information.During the winter of 1984 work was begun on the Paleoceano graphic Mapping Project at the Institute for Geophysics, Univer sity of Texas, Austin, Texas. The goal of the Paleoceanographic Mapping Project (POMP) is to produce a set of maps and film animations illustrating the tectonic evolution of the ocean ba sins during the last 200 million years. The basis of these global reconstructions is a new digital data base of linear magnetic anomaly data and sea floor bathymetry. Initial support for the Paleoceanographic Mapping Project was received from British Petroleum, and as a result of their support a set of the Indian Ocean reconstructions were produced using a preliminary version of the POMP database. The six reconstructions described in this report represent the initial test of POMP data gathering procedures and mapping programs.
The maps in this report are based on the published rotation
parameters of Norton and Sclater (1979), Sclater et al. (1981 ), Scotese and Ross (1982), Fisher and Sclater (1983) (see Appendix I)., and represent our current understanding of the plate tectonic evolution of the Indian Ocean. These maps highlight the remaining problem areas, and serve as the starting point from which a revised set of Indian Ocean reconstructions will be produced.Paleoceanograhic Mapping Project Consortium, Institute for Geophysics, The University of Texas at AustinInstitute for Geophysic
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Plate Tectonic Reconstructions of the Larson et al. (1985) Map of the Age of the World Oceans (Paleoceanographic Mapping Project Report No. 05-0985)
During the past 20 years, numerous oceanographic surveys have mapped the age of the ocean floor in great detail (NGOC data bank). Recently, two separate studies have compiled these results and have produced maps illustrating the age of the ocean basins on a global scale (Sclater and Parsons, 1981; Larson et al., 1985). This work has been done with the realization that in order to make accurate plate tectonic reconstructions, an accurate map of the age of the ocean floor is required. This report compares these two compilations and presents a new set of Mesozoic and Cenozoic plate reconstructions based on the magnetic isochrons of Larson et al. ( 1985).UT Institute for Geophysics Paleoceanographic Mapping Project (POMP)Institute for Geophysic
Paleomagnetism of the Upper Silurian and Lower Devonian carbonates of New York State: evidence for secondary magnetizations residing in magnetite
Paleomagnetic directions for the Upper Silurian and Lower Devonian carbonates of the Helderberg escarpment (New York State) differ from expected Late Silurian and Early Devonian directions for cratonic North America. The mean direction (D = 165[deg], I = -10[deg]; paleopole at 50[deg]N 129[deg]E) is similar to Late Carboniferous and Early Permian results. Negative fold tests, and a lack of reversals, suggest that the magnetization is secondary. However, low coercivities, low blocking temperatures, the thermomagnetic curves (TC near 570[deg]C) and the acquisition of isothermal remanent magnetizations all suggest that the remanence is carried by magnetite. If a detrital origin of these magnetites is assumed, the secondary nature of the remanence would argue for thermal resetting as a result of deep burial of the rocks. However, no evidence for such thermal resetting is seen in the alteration of conodonts. More likely perhaps is a chemical or thermochemical origin of the remanence; this would require the magnetites to be authigenic.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23790/1/0000028.pd
Long-term Phanerozoic global mean sea level: Insights from strontium isotope variations and estimates of continental glaciation
Global mean sea level is a key component within the fields of climate and oceanographic modelling in the Anthropocene. Hence, an improved understanding of eustatic sea level in deep time aids in our understanding of Earth's paleoclimate and may help predict future climatological and sea level changes. However, long-term eustatic sea level reconstructions are hampered because of ambiguity in stratigraphic interpretations of the rock record and limitations in plate tectonic modelling. Hence the amplitude and timescales of Phanerozoic eustasy remains poorly constrained. A novel, independent method from stratigraphic or plate modelling methods, based on estimating the effect of plate tectonics (i.e., mid-ocean ridge spreading) from the 87Sr/86Sr record led to a long-term eustatic sea level curve, but did not include glacio-eustatic drivers. Here, we incorporate changes in sea level resulting from variations in seawater volume from continental glaciations at time steps of 1 Myr. Based on a recent compilation of global average paleotemperature derived from δ18O data, paleo-Köppen zones and paleogeographic reconstructions, we estimate ice distribution on land and continental shelf margins. Ice thickness is calibrated with a recent paleoclimate model for the late Cenozoic icehouse, yielding an average ∼1.4 km thickness for land ice, ultimately providing global ice volume estimates. Eustatic sea level variations associated with long-term glaciations (>1 Myr) reach up to ∼90 m, similar to, and is at times dominant in amplitude over plate tectonic-derived eustasy. We superimpose the long-term sea level effects of land ice on the plate tectonically driven sea level record. This results in a Tectono-Glacio-Eustatic (TGE) curvefor which we describe the main long-term (>50 Myr) and residual trends in detail
Amber and the Cretaceous Resinous Interval
Amber is fossilized resin that preserves biological remains in exceptional detail, study of which has revolutionized understanding of past terrestrial organisms and habitats from the Early Cretaceous to the present day. Cretaceous amber outcrops are more abundant in the Northern Hemisphere and during an interval of about 54 million years, from the Barremian to the Campanian. The extensive resin production that generated this remarkable amber record may be attributed to the biology of coniferous resin producers, the growth of resiniferous forests in proximity to transitional sedimentary environments, and the dynamics of climate during the Cretaceous. Here we discuss the set of interrelated abiotic and biotic factors potentially involved in resin production during that time. We name this period of mass resin production by conifers during the late Mesozoic, fundamental as an archive of terrestrial life, the `Cretaceous Resinous Interval (CREI).This work was supported by the Spanish Ministerio de Ciencia, Innovación y Universidades [research agreement CRE CGL2017-84419 AEI/FEDER, UE] and by the Consejería de Industria, Turismo, Innovación, Transporte y Comercio of the Gobierno de Cantabria through the public enterprise EL SOPLAO S.L. [research agreement #20963 with University of Barcelona and research contract Ref. VAPC 20225428 to CN-IGME CSIC, both 2022–2025]; the Conselho Nacional de Pesquisa (Brazil) [research grand PQ 304529/19–2]; National Geographic Global Exploration Fund Northern Europa [research agreement GEFNE 127-14]; Deutsche Forschungsgemeinschaft (DFG) [research agreement SO 894/6-1]; VolkswagenStiftung [research agreement 90946]; the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 program of research and innovation of the European Union under the Marie-Curie [research contract no. 801370, Beatriu de Pinós]; the Secretary of Universities and Research (Government of Catalonia) and the European Social Fund [research contract 2021FI_B2 00003]; this work is a contribution to the grant RYC2021-032907-I, funded by the MCIN/AEI/10.13039/501100011033 and by the European Union «NextGenerationEU»/PRTR; and the National Agency for Research and Development (ANID) Scholarship Program [BECAS CHILE 2020-Folio 72210321].Abstract
Keywords
1. Introduction
2. Definition of the Cretaceous Resinous Interval
3. Conditional factors on resin production and preservation
3.1. Abiotic factors
3.1.1. Atmospheric gas composition, temperature, and wildfires
3.1.2. Volcanism and changes in sea level
3.1.3. Oceanic physicochemical properties and hurricanes
3.1.4. Climatic overview throughout the CREI
3.2. Biotic factors
4. Present limitations and future directions
5. Conclusions
Funding
Author contributions
Declaration of Competing Interest
Acknowledgements
Appendix A. Supplementary data
Data availability
Reference
The Atlantic Jigsaw Puzzle and the geoheritage of Angola
The jigsaw-puzzle fit of South America and Africa is an icon of plate tectonics and continental drift. Fieldwork in Angola since 2002 allows the correlation of onshore outcrops and offshore geophysical and well-core data in the context of rift, sag, salt, and post-salt drift phases of the opening of the central South Atlantic. These outcrops, ranging in age from >130 Ma to <71 Ma, record Early Cretaceous outpouring of the Etendeka–Paraná Large Igneous Province (Bero Volcanic Complex) and rifting, followed by continental carbonate and siliciclastic deposition (Tumbalunda Formation) during the sagging of the nascent central South Atlantic basin. By the Aptian, evaporation of sea water resulted in thick salt deposits (Bambata Formation), terminated by seafloor spreading. The Equatorial Atlantic Gateway began opening by the early Late Cretaceous (100 Ma) and allowed flow of currents between the North and South Atlantic, creating environmental conditions that heralded the introduction of marine reptiles. These dramatic outcrops are a unique element of geoheritage because they arguably comprise the most complete terrestrially exposed geological record of the puzzle-like icon of continental drift
Paleomap Project
This site has information about where the tectonic plates were located in the Pleistocene and throughout geologic time. You can view animations of the plates moving or download models. Educational levels: General public, High school, Informal education
Paleomap Project
The goal of the PALEOMAP Project is to illustrate the plate tectonic development of the ocean basins and continents, as well as the changing distribution of land and sea during the past 1100 million years. In the section on Earth history you can select any time period, read about that period, and see the plate distribution during that period. There is also a section on climate history where you can select a time period, see the climatic distribution of that period, and learn what evidence was used to reconstruct the paleoclimate. A collection of animations shows the plate distribution during different parts of Earth history. The site also has a section where you can print paleomaps that are formatted to be cut out and pasted on a 4 inch Styrofoam sphere to create your own paleoglobes. Educational levels: High school, Informal education, Undergraduate lower division, Undergraduate upper division
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