The Experts below are selected from a list of 330 Experts worldwide ranked by ideXlab platform
Jean Besse - One of the best experts on this subject based on the ideXlab platform.
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A new Late Cretaceous to Present APWP for Asia and its implications for paleomagnetic shallow inclinations in Central Asia and Cenozoic Eurasian plate deformation
Geophysical Journal International, 2013Co-Authors: Jean-pascal Cogné, Jean Besse, Ying Chen, Fatim HankardAbstract:Based on a compilation of 533 Cretaceous to present-day palaeomagnetic poles obtained from both sedimentary and igneous rocks, we present a new analysis of the so-called 'Asian inclination anomaly' and demonstrated the anomaly to be twofold: a 2nd-order anomaly, characterized by high palaeolatitudes in Indochina and low palaeolatitudes over Tibet and Central Asia, is superimposed on a 1st-order anomaly, characterized by Cenozoic low palaeolatitudes found all over northeastern Asian stable blocks. The analysis herein convincingly shows that the Europe Apparent Polar Wandering Path (APWP) can no longer be used to interpret palaeomagnetic data East of the Urals, including interpretation of Asian Tertiary deformation related to the India-Asia Collision. We, thus, construct a new APWP for East Asia, based on palaeopoles from blocks assumed to be stable. This new APWP is consistent with and reinforces previous analyses of Asian tectonics, such as the age (∼55 Ma) and locus (∼5-10°N) of the Indo-Asian collision, the lateral extrusion of SE Asian continental blocks and the intracontinental shortening in Central Asia. Possible origins of the 1st-order palaeolatitude anomaly are: (1) a geomagnetic origin, due to long-lasting non-diPolar contribution to the magnetic field and (2) a tectonic hypothesis, in which a newly defined East Asia Plate was located ∼10° farther south than expected from the current Europe APWP. Based on a set of six new reconstructions from 90 Ma to present, we show that our tectonic model reconciles geophysical, geological and tectonic observations throughout Eurasia, from Siberia to Europe, including kinematics in the Arctic Ocean, up to northwestern Arctic Alaska. Beyond possible occurrences of non-diPolar field contribution and/or local inclination flattening in the sedimentary data, our model leads us to conclude that Cenozoic tectonics is the dominant contributor to the observed 1st-order ∼10° low palaeolatitude anomaly over Asia during the Tertiary.
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a new global paleocene eocene apparent Polar Wandering path loop by stacking magnetostratigraphies correlations with high latitude climatic data
Earth and Planetary Science Letters, 2007Co-Authors: Mariegabrielle Moreau, Jean Besse, Frederic Fluteau, Marianne GrefflefftzAbstract:A new apparent Polar wander path (APWP) from the beginning of the Paleocene (65 Ma) to the middle of the mid-Eocene (42 Ma) is shown to be correlated with Polar climatic data of the same time period. Rather than applying the classical method based on analysis of site-based poles, we “stacked” the APWPs obtained from magnetostratigraphies. Magnetostratigraphies have the advantage of displaying an unbroken record of local APWPs through time and, for a magnetozone (defined as the a combination of normal and reversed Polarity intervals), the instantaneous poles are synchronous. Seven magnetostratigraphies located on 4 different plates covered sufficient time to be used in the analysis. An average APWP was then determined with respect to age at the magnetozone level for the African plate, which was arbitrarily chosen as a reference frame; virtual geomagnetic poles were transferred onto the African plate using ocean kinematic Euler rotations. The calculated APWP is characterized by a loop with two main changes of direction at magnetozones 26–25 (61.5–56.5 Ma) and 24–22 (56.5–48.6 Ma) distinct at a 95% level of probability, and indistinct poles related to magnetozones 29–27 (65.5–61.5 Ma) and 21–19 (48.6–40.6 Ma). We also show that the implied rapid shift of the lithosphere with respect to the geographic pole, possibly an episode of true Polar wander, was coeval with the time evolution of vertebrate occurrence on Ellesmere Island (Canadian Arctic) and with the tree ring growth rate in Western Antarctica.
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apparent Polar Wandering paths for north america europe africa laurussia and west gondwana since the upper carboniferous
1995Co-Authors: Jean Besse, Herve Theveniaut, Vincent CourtillotAbstract:The accurate determination of apparent Polar Wandering paths (APWPs) of major cratons is one of the important goals pursued by the paleomagnetic community. They are a prerequisite for meaningful paleogeographic reconstructions and determination of the reliability of terrane displacements. A close analysis of available paleomagnetic data shows that the number and distribution, both in time and space, of reliable pole positions for each of the main continents is insufficient to allow the construction of a well-constrained APWP. Therefore, it is natural to turn to data of the same age observed on other continents, hopefully in more reliable or straightforward conditions. Data from various continents can be combined as reliable kinematic models of plate motions are available.
N. Astudillo - One of the best experts on this subject based on the ideXlab platform.
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Paleomagnetism and tectonics of the South Shetland Islands and the northern Antarctic Peninsula
Earth and Planetary Science Letters, 2011Co-Authors: F. Poblete, César Arriagada, Pierrick Roperch, N. AstudilloAbstract:New paleomagnetic data presented here from 61 sites in Paleozoic, Mesozoic and Cenozoic igneous and sedimentary rocks from the Antarctic Peninsula and the South Shetland Islands constrain the relative motion of the Antarctic Peninsula since the mid-Cretaceous and allow the quantification of tectonic rotation between the different blocks recognized within the area. Paleozoic and Jurassic results failed the fold test and suggest an important remagnetization in the area. The similarity between these results and those obtained from Cretaceous intrusives indicates a mid-Cretaceous age for the remagnetization. The paleopoles obtained for the different blocks and for different ages suggest that there is no relative rotation among them. These combined results allow us to obtain a Cretaceous (90 Ma) and Paleocene (60 Ma) paleopole. These paleopoles document a very low apparent Polar Wandering of the Antarctic Peninsula for the last 100 Ma.
Fatim Hankard - One of the best experts on this subject based on the ideXlab platform.
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A new Late Cretaceous to Present APWP for Asia and its implications for paleomagnetic shallow inclinations in Central Asia and Cenozoic Eurasian plate deformation
Geophysical Journal International, 2013Co-Authors: Jean-pascal Cogné, Jean Besse, Ying Chen, Fatim HankardAbstract:Based on a compilation of 533 Cretaceous to present-day palaeomagnetic poles obtained from both sedimentary and igneous rocks, we present a new analysis of the so-called 'Asian inclination anomaly' and demonstrated the anomaly to be twofold: a 2nd-order anomaly, characterized by high palaeolatitudes in Indochina and low palaeolatitudes over Tibet and Central Asia, is superimposed on a 1st-order anomaly, characterized by Cenozoic low palaeolatitudes found all over northeastern Asian stable blocks. The analysis herein convincingly shows that the Europe Apparent Polar Wandering Path (APWP) can no longer be used to interpret palaeomagnetic data East of the Urals, including interpretation of Asian Tertiary deformation related to the India-Asia Collision. We, thus, construct a new APWP for East Asia, based on palaeopoles from blocks assumed to be stable. This new APWP is consistent with and reinforces previous analyses of Asian tectonics, such as the age (∼55 Ma) and locus (∼5-10°N) of the Indo-Asian collision, the lateral extrusion of SE Asian continental blocks and the intracontinental shortening in Central Asia. Possible origins of the 1st-order palaeolatitude anomaly are: (1) a geomagnetic origin, due to long-lasting non-diPolar contribution to the magnetic field and (2) a tectonic hypothesis, in which a newly defined East Asia Plate was located ∼10° farther south than expected from the current Europe APWP. Based on a set of six new reconstructions from 90 Ma to present, we show that our tectonic model reconciles geophysical, geological and tectonic observations throughout Eurasia, from Siberia to Europe, including kinematics in the Arctic Ocean, up to northwestern Arctic Alaska. Beyond possible occurrences of non-diPolar field contribution and/or local inclination flattening in the sedimentary data, our model leads us to conclude that Cenozoic tectonics is the dominant contributor to the observed 1st-order ∼10° low palaeolatitude anomaly over Asia during the Tertiary.
F. Poblete - One of the best experts on this subject based on the ideXlab platform.
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Paleomagnetism and tectonics of the South Shetland Islands and the northern Antarctic Peninsula
Earth and Planetary Science Letters, 2011Co-Authors: F. Poblete, César Arriagada, Pierrick Roperch, N. AstudilloAbstract:New paleomagnetic data presented here from 61 sites in Paleozoic, Mesozoic and Cenozoic igneous and sedimentary rocks from the Antarctic Peninsula and the South Shetland Islands constrain the relative motion of the Antarctic Peninsula since the mid-Cretaceous and allow the quantification of tectonic rotation between the different blocks recognized within the area. Paleozoic and Jurassic results failed the fold test and suggest an important remagnetization in the area. The similarity between these results and those obtained from Cretaceous intrusives indicates a mid-Cretaceous age for the remagnetization. The paleopoles obtained for the different blocks and for different ages suggest that there is no relative rotation among them. These combined results allow us to obtain a Cretaceous (90 Ma) and Paleocene (60 Ma) paleopole. These paleopoles document a very low apparent Polar Wandering of the Antarctic Peninsula for the last 100 Ma.
Marianne Grefflefftz - One of the best experts on this subject based on the ideXlab platform.
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a new global paleocene eocene apparent Polar Wandering path loop by stacking magnetostratigraphies correlations with high latitude climatic data
Earth and Planetary Science Letters, 2007Co-Authors: Mariegabrielle Moreau, Jean Besse, Frederic Fluteau, Marianne GrefflefftzAbstract:A new apparent Polar wander path (APWP) from the beginning of the Paleocene (65 Ma) to the middle of the mid-Eocene (42 Ma) is shown to be correlated with Polar climatic data of the same time period. Rather than applying the classical method based on analysis of site-based poles, we “stacked” the APWPs obtained from magnetostratigraphies. Magnetostratigraphies have the advantage of displaying an unbroken record of local APWPs through time and, for a magnetozone (defined as the a combination of normal and reversed Polarity intervals), the instantaneous poles are synchronous. Seven magnetostratigraphies located on 4 different plates covered sufficient time to be used in the analysis. An average APWP was then determined with respect to age at the magnetozone level for the African plate, which was arbitrarily chosen as a reference frame; virtual geomagnetic poles were transferred onto the African plate using ocean kinematic Euler rotations. The calculated APWP is characterized by a loop with two main changes of direction at magnetozones 26–25 (61.5–56.5 Ma) and 24–22 (56.5–48.6 Ma) distinct at a 95% level of probability, and indistinct poles related to magnetozones 29–27 (65.5–61.5 Ma) and 21–19 (48.6–40.6 Ma). We also show that the implied rapid shift of the lithosphere with respect to the geographic pole, possibly an episode of true Polar wander, was coeval with the time evolution of vertebrate occurrence on Ellesmere Island (Canadian Arctic) and with the tree ring growth rate in Western Antarctica.