Abstract We have devised a new absolute Late Jurassic‐Cretaceous Pacific plate model using a fixed hot spot approach coupled with paleomagnetic data from Pacific large igneous provinces (LIPs) while simultaneously minimizing plate velocity and net lithosphere rotation (NR). This study was motivated because published Pacific plate models for the 83.5‐ to 150‐Ma time interval are variably flawed, and their use affects modeling of the entire Pacific‐Panthalassic Ocean and interpretation of its margin evolution. These flaws could be corrected, but the revised models would imply unrealistically high plate velocities and NR. We have developed three new Pacific realm models with varying degrees of complexity, but we focus on the one that we consider most realistic. This model reproduces many of the Pacific volcanic paths, modeled paleomagnetic latitudes fit well with direct observations, plate velocities and NR resulting from the model are low, and all reconstructed Pacific LIPs align along the surface‐projected margin of the Pacific large low shear wave velocity province. The emplacement of the Shatsky Rise LIP at ~144 Ma probably caused a major plate boundary reorganization as indicated by a major jump of the Pacific‐Izanagi‐Farallon triple junction and a noteworthy change of the Pacific‐Izanagi seafloor spreading direction at around chron M20 time.
[1] A major disparity is observed between the late Paleozoic-early Mesozoic apparent polar wander paths (APWPs) of Laurussia and Gondwana when the landmasses are re-assembled in a conventional "A-type" Pangea. This discrepancy has endured from the earliest paleomagnetic reconstructions of the supercontinent, and has prompted discussions of non-dipole paleomagnetic fields and alternative paleogeographic models. Here we report on a joint paleomagnetic-geochronologic study of Late Permian and Early to Middle Triassic volcanic and volcaniclastic rocks from Argentina, which demonstrates support for an A-type model, without requiring modification to the geocentric axial dipole hypothesis. New SHRIMP U-Pb and 40Ar-39Ar isotopic dating has reinforced the inferred age of the sequences, which we estimate at ∼264 Ma (Upper Choiyoi Group) and ∼245 Ma (Puesto Viejo Group). Field-stability tests demonstrate that the volcanic rocks are carrying early/primary magnetizations, which yield paleopoles: 73.7°S, 315.6°E, A95: 4.1°, N: 40 (Upper Choiyoi) and 76.7°S, 312.4°E, A95: 7.3°, N: 14 (Puesto Viejo). A comprehensive magnetic fabric analysis is used to evaluate structural restorations and to correct for magnetization anisotropy. The paleomagnetic results derived from volcaniclastic rocks are interpreted to be affected by inclination shallowing, and corrections are discussed. A comparison of these new results with the existing Permian-Triassic paleomagnetic data from Gondwana suggests the presence of widespread bias in the latter. We contend that such bias can explain the observed APWP disparity, at least for Late Permian-Middle Triassic time, and that alternative paleogeographic reconstructions or non-dipole paleomagnetic fields do not need to be invoked to resolve the discrepancy.
1. Global plate models (GPMs) aim to reconstruct the tectonic evolution of the Earth by modelling the motion of the plates and continents through time. These models enable palaeobiologists to study the past distribution of extinct organisms. However, different GPMs exist that vary in their partitioning of the Earth's surface and the modelling of continental motions. Consequently, the preferred use of one GPM will influence palaeogeographic reconstruction of fossil occurrences and any inferred palaeobiological and palaeoclimatic conclusion.2. Here, using five open-access GPMs, we reconstruct the palaeogeographic distribution of cell centroids from a global hexagonal grid and quantify palaeogeographic uncertainty across the entire Phanerozoic (540–0 Ma). We measure uncertainty between reconstructed coordinates using two metrics: (1) palaeolatitudinal standard deviation and (2) mean pairwise geodesic distance. Subsequently, we evaluate the impact of GPM choice on palaeoclimatic reconstructions when using fossil occurrence data. To do so, we use two climatically sensitive entities (coral reefs and crocodylomorphs) to infer the palaeolatitudinal extent of subtropical climatic conditions for the last 240 million years.3. Our results indicate that differences between GPMs increase with the age of reconstruction. Specifically, cell centroids rotated to older intervals show larger differences in palaeolatitude and geographic spread than those rotated to younger intervals. However, high palaeogeographic uncertainty is also observed in younger intervals within tectonically complex regions (i.e. in the vicinity of terrane and plate boundaries). We also show that when using fossil data to infer the distribution of subtropical climatic conditions across the last 240 Ma, estimates vary by 6–7° latitude on average, and up to 24° latitude in extreme cases.4. Our findings confirm that GPM choice is an important consideration when studying past biogeographic patterns and palaeoclimatic trends. We recommend using GPMs that report true palaeolatitudes (i.e. use a palaeomagnetic reference frame) and incorporating palaeogeographic uncertainty into palaeobiological analyses.
This repository provides access to five reconstruction files as well as the code and the static polygons and rotation files used to generate them. This set of palaeogeographic reconstruction files provide palaeocoordinates for three global grids at H3 resolutions 2, 3, and 4, which have an average cell spacing of ~316 km, ~119 km, and ~45 km. Grids were reconstructed at a temporal resolution of one million years throughout the entire Phanerozoic (540–0 Ma). The reconstruction files are stored as comma-separated-value (CSV) files which can be easily read by almost any spreadsheet program (e.g. Microsoft Excel and Google Sheets) or programming language (e.g. Python, Julia, and R). In addition, R Data Serialization (RDS) files—a common format for saving R objects—are also provided as lighter (and compressed) alternatives to the CSV files. The structure of the reconstruction files follows a wide-form data frame structure to ease indexing. Each file consists of three initial index columns relating to the H3 cell index (i.e. the 'H3 address'), present-day longitude of the cell centroid, and the present-day latitude of the cell centroid. The subsequent columns provide the reconstructed longitudinal and latitudinal coordinate pairs for their respective age of reconstruction in ascending order, indicated by a numerical suffix. Each row contains a unique spatial point on the Earth's continental surface reconstructed through time. NA values within the reconstruction files indicate points which are not defined in deeper time (i.e. either the static polygon does not exist at that time, or it is outside the temporal coverage as defined by the rotation file). The following five Global Plate Models are provided (abbreviation, temporal coverage, reference): WR13, 0–550 Ma, (Wright et al., 2013) MA16, 0–410 Ma, (Matthews et al., 2016) TC16, 0–540 Ma, (Torsvik and Cocks, 2016) SC16, 0–1100 Ma, (Scotese, 2016) ME21, 0–1000 Ma, (Merdith et al., 2021) In addition, the H3 grids for resolutions 2, 3, and 4 are provided. For more information, please refer to the article describing the data: Jones, L.A. and Domeier, M.M. 2023. Earth surface evolution: a Phanerozoic gridded dataset of Global Plate Model reconstructions. (TBC). For any additional queries, contact: Mathew M. Domeier (mathewd@uio.no) or Lewis A . Jones (lewisa.jones@outlook.com) If you use these files, please cite: Jones, L.A. and Domeier, M.M. 2023. Earth surface evolution: a Phanerozoic gridded dataset of Global Plate Model reconstructions. Zenodo data repository. DOI:10.5281/zenodo.10069222
The Late Paleozoic-Early Mesozoic apparent polar wander path of Gondwana is largely constructed from relatively old paleomagnetic results, many of which are considered unreliable by modern standards.Paleomagnetic results derived from sedimentary sequences, which are generally poorly dated and prone to inclination shallowing, are especially common.Here we report the results of a joint paleomagneticgeochronologic study of a volcanic complex in central Argentina.U-Pb dating of zircons has yielded a robust age estimate of 263.0 +1.6/-2.0Ma for the complex.Paleomagnetic analysis has revealed a pretilting (primary Permian) magnetization with dual polarities.Rock magnetic experiments have identified pseudosingle domain (titano)magnetite and hematite as the mineralogic carriers of the magnetization.Lightninginduced isothermal remagnetizations are widespread in the low-coercivity magnetic carriers.The resulting paleomagnetic pole is 80.1°S, 349.0°E,A 95 = 3.3°, N = 35, and it improves a Late Permian mean pole calculated from a filtered South American paleomagnetic data set.More broadly, this new, high-quality, igneous-based
<p><span>The connections between the Earth&#8217;s interior and its surface are manifold, and defined by processes of material transfer: from the deep Earth to lithosphere, through the crust and into the interconnected systems of the atmosphere-hydrosphere-biosphere, and back again. One of the most spectacular surface expressions of such a process, with origins extending into the deep mantle, is the emplacement of large igneous provinces (LIPs), which have led to rapid climate changes and mass extinctions, but also to moments of transformation with respect to Earth&#8217;s evolving paleogeography. But equally critical are those process which involve material fluxes going the other way&#8212;as best exemplified by subduction, a key driving force behind plate tectonics, but also a key driver for long-term climate evolution through arc volcanism and degassing of CO<sub><span>2.</span></sub></span></p><p><span>Most </span><span>hotspots, kimberlites, </span><span>LIPs are sourced by plumes that rise from the margins of two large low shear-wave velocity provinces in the lowermost mantle.</span><span> These thermochemical provinces have likely been quasi-stable for hundreds of millions, perhaps billions of years, and </span><span>plume heads rise through the mantle in about 30 Myr or less. LIPs provide a direct link between the deep Earth and the atmosphere but </span><span>environmental consequences depend on both their volumes and the composition of the crustal rocks they are emplaced through. </span><span>LIP activity can alter the plate tectonic setting by creating and modifying plate boundaries and hence changing the paleogeography and its long-term forcing on climate. Extensive blankets of LIP-lava on the Earth&#8217;s surface can also enhance silicate weathering and potentially lead to CO<sub><span>2</span></sub> drawdown (cooling), but we find no clear relationship between LIPs and post-emplacement variation in atmospheric CO<sub><span>2</span></sub> proxies on </span><span>very long (>10 Myrs) time-scales</span><span>. Hotspot and kimberlite volcanoes generally have relatively small climate effects compared with that of LIPs (because of volumetric and flux differences), but the eruption of large kimberlite clusters, notably in the Cretaceous, could be capable of delivering enough CO<sub><span>2</span></sub> to the atmosphere to trigger sudden global warming events.</span></p><p><span>Subduction is a key driving force behind plate tectonics but also a key driver for the long-term climate evolution through arc volcanism and degassing of CO<sub><span>2</span></sub>. Subduction fluxes </span><span>derived from full-plate models</span><span> provide a powerful way of estimating plate tectonic CO<sub><span>2</span></sub> degassing (sourcing). These correlate well with zircon age frequency distributions and zircon age peaks clearly correspond to intervals of high subduction flux associated with greenhouse conditions. Lows in zircon age frequency are more variable with links to both icehouse and greenhouse conditions, and only the Permo-Carboniferous (~330-275 Ma) icehouse is clearly related to the zircon and subduction flux record. </span><span>A key challenge is to develop reliable full-plate models before the Devonian in order to consider the subduction flux </span><span>during the end-Ordovician Hirnantian (~445 Ma) glaciations, but we also expect refinements in subduction fluxes for Mesozoic-Cenozoic times as more advanced ocean-basin models with intra-oceanic subduction are being developed and implemented in full-plate models.</span></p>
Abstract Understanding the first-order dynamical structure and evolution of Earth's mantle is a fundamental goal in solid-earth geophysics. Tomographic observations reveal a lower mantle characterised by higher-than-average shear-wave speeds beneath Asia and encircling the Pacific, consistent with cold slabs beneath regions of ancient subduction, and lower-than-average shear-wave speeds in broad regional areas beneath Africa and the Central Pacific (termed LLSVPs). The LLSVPs are not well understood from a dynamical perspective and their origin and evolution remain enigmatic. Some numerical studies propose that the LLSVP beneath Africa is post-Pangean in origin, formed as a result of return flow in the mantle due to circum-Pangean subduction, countered by an older Pacific LLSVP, suggested to have formed during the break up of Rodinia. This propounds that, prior to the formation of Pangea, the lower mantle was dominated by a degree-1 convection pattern with a major upwelling centred close to the present-day Pacific LLSVP and subduction concentrated mainly in the antipodal hemisphere. In contrast, palaeomagnetic observations which proffer a link between the reconstructed eruption sites of Phanerozoic kimberlites and Large Igneous Provinces with regions on the margins of the present-day LLSVPs suggest that the anomalies may have remained stationary for at least the last 540 Myr and further that the anomalies were largely insensitive to the formation and subsequent break-up of Pangea. Here we investigate the evolution and long-term stability of LLSVP-like structures in Earth's mantle by integrating plate tectonics and numerical models of global thermochemical mantle dynamics. We explore the possibility that either one or both LLSVPs existed prior to the formation of Pangea and improve upon previous studies by using a new, true polar wander-corrected global plate model to impose surface velocity boundary conditions for a time interval that spans the amalgamation and subsequent break-up of the supercontinent. We find that, were only the Pacific LLSVP to exist prior to the formation of Pangea, the African LLSVP would not have been created within the lifetime of the supercontinent. We also find that, were the mantle to be dominated by two antipodal LLSVP-like structures prior to the formation of Pangea, the structures would remain relatively unchanged to the present day and would be insensitive to the formation and break-up of the supercontinent. Our results suggest that both the African and Pacific LLSVPs have remained close to their present-day positions for at least the past 410 Myr.
This repository provides access to five reconstruction files as well as the code and the static polygons and rotation files used to generate them. This set of palaeogeographic reconstruction files provide palaeocoordinates for three global grids at H3 resolutions 2, 3, and 4, which have an average cell spacing of ~316 km, ~119 km, and ~45 km. Grids were reconstructed at a temporal resolution of one million years throughout the entire Phanerozoic (540–0 Ma). The reconstruction files are stored as comma-separated-value (CSV) files which can be easily read by almost any spreadsheet program (e.g. Microsoft Excel and Google Sheets) or programming language (e.g. Python, Julia, and R). In addition, R Data Serialization (RDS) files—a common format for saving R objects—are also provided as lighter (and compressed) alternatives to the CSV files. The structure of the reconstruction files follows a wide-form data frame structure to ease indexing. Each file consists of three initial index columns relating to the H3 cell index (i.e. the 'H3 address'), present-day longitude of the cell centroid, and the present-day latitude of the cell centroid. The subsequent columns provide the reconstructed longitudinal and latitudinal coordinate pairs for their respective age of reconstruction in ascending order, indicated by a numerical suffix. Each row contains a unique spatial point on the Earth's continental surface reconstructed through time. NA values within the reconstruction files indicate points which are not defined in deeper time (i.e. either the static polygon does not exist at that time, or it is outside the temporal coverage as defined by the rotation file). The following five Global Plate Models are provided (abbreviation, temporal coverage, reference): WR13, 0–550 Ma, (Wright et al., 2013) MA16, 0–410 Ma, (Matthews et al., 2016) TC16, 0–540 Ma, (Torsvik and Cocks, 2016) SC16, 0–1100 Ma, (Scotese, 2016) ME21, 0–1000 Ma, (Merdith et al., 2021) In addition, the H3 grids for resolutions 2, 3, and 4 are provided. For more information, please refer to the article describing the data: Jones, L.A. and Domeier, M.M. 2023. Earth surface evolution: a Phanerozoic gridded dataset of Global Plate Model reconstructions. (TBC). For any additional queries, contact: Mathew M. Domeier (mathewd@uio.no) or Lewis A . Jones (lewisa.jones@outlook.com) If you use these files, please cite: Jones, L.A. and Domeier, M.M. 2023. Earth surface evolution: a Phanerozoic gridded dataset of Global Plate Model reconstructions. Zenodo data repository. DOI:10.5281/zenodo.10069222
Abstract The South Qiangtang block of the Qinghai‐Tibet Plateau represents an area critical to understanding the late Paleozoic and early Mesozoic history of the Tethyan realm, but its drift history remains poorly constrained. Here we report a new quantitative paleogeographic constraint for the South Qiangtang block from a paleomagnetic study of Late Triassic volcanic rocks of the Xiaoqiebao Formation. A characteristic remanent magnetization isolated from 25 sites passes both fold‐ and reversal tests, and likely represents a primary magnetization. On the basis of these data, we estimate that the South Qiangtang block occupied a paleolatitude of 30.1 ± 4.6°N at ca. 222 Ma. When combined with existing paleomagnetic constraints, these new results indicate that the South Qiangtang block (and other “Cimmerian” blocks) moved rapidly northward (in true latitude) between the middle Permian and Late Triassic. Our new data further suggest that the southern branch of the Paleo‐Tethys (Longmuco‐Shuanghu Ocean) likely closed by the mid‐Late Triassic.
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