Age of the Shirshov submarine ridge basement (Bering Sea) based on the results of investigation of zircons using the U-Pb SHRIMP method

Sukhov, A. N.; Chekhovich, V. D.; Ландер, А. В.; Presnyakov, S. L.; Lepekhina, E. N.

doi:10.1134/s1028334x11070178

Cited by 11 publications

(4 citation statements)

References 4 publications

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“…This young material may represent a fragment of the Aleutian Arc (Scholl, ), or the Bowers Ridge that rifted away in the Neogene, based on the occurrence of the rocks in a NW‐SE‐oriented sector of the ridge, which is parallel to the fracture zones in the Komandorsky Basin to the west of the Shirshov Ridge, and strike‐slip faults in the western part of the Aleutian Arc. Amphiboles within the amphibolites from the oceanic complex were K‐Ar dated as 47 ± 5 Ma and zircons gave a 72 ± 1.4 Ma age (Sukhov et al, ). The amphibolites, metagabbro, and Upper Cretaceous to Paleocene volcanic and sedimentary rocks all underwent intense deformation (Chekhovich et al, ).…”

Section: Reviewmentioning

confidence: 99%

Reconstruction of Subduction and Back‐Arc Spreading in the NW Pacific and Aleutian Basin: Clues to Causes of Cretaceous and Eocene Plate Reorganizations

2019

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The Eocene (~50–45 Ma) major absolute plate motion change of the Pacific plate forming the Hawaii‐Emperor bend is thought to result from inception of Pacific plate subduction along one of its modern western trenches. Subduction is suggested to have started either spontaneously, or result from subduction of the Izanagi‐Pacific mid‐ocean ridge, or from subduction polarity reversal after collision of the Olyutorsky arc that was built on the Pacific plate with NE Asia. Here we provide a detailed plate‐kinematic reconstruction of back‐arc basins and accreted terranes in the northwest Pacific region, from Japan to the Bering Sea, since the Late Cretaceous. We present a new tectonic reconstruction of the intraoceanic Olyutorsky and Kronotsky arcs, which formed above two adjacent, oppositely dipping subduction zones at ~85 Ma within the north Pacific region, during another Pacific‐wide plate reorganization. We use our reconstruction to explain the formation of the submarine Shirshov and Bowers Ridges and show that if marine magnetic anomalies reported from the Aleutian Basin represent magnetic polarity reversals, its crust most likely formed in an ~85‐ to 60‐Ma back‐arc basin behind the Olyutorsky arc. The Olyutorsky arc was then separated from the Pacific plate by a spreading ridge, so that the ~55‐ to 50‐Ma subduction polarity reversal that followed upon Olyutorsky‐NE Asia collision initiated subduction of a plate that was not the Pacific. Hence, this polarity reversal may not be a straightforward driver of the Eocene Pacific plate motion change, whose causes remain enigmatic.

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Section: Reviewmentioning

confidence: 99%

Reconstruction of Subduction and Back‐Arc Spreading in the NW Pacific and Aleutian Basin: Clues to Causes of Cretaceous and Eocene Plate Reorganizations

2019

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“…The geology of the ridge is poorly understood, but avail able data [2] indicate that it consists of Triassic, Creta ceous, and Paleocene radiolarites, Lower-Upper Cre taceous amphibolitic gabbros, and Lower OligocenePleistocene shallow water terrigenous sediments.…”

Section: Resultsmentioning

confidence: 99%

“…The slope angle varies from 1.5°-4° in the north and up to 10° in the south. The ridge is separated from the continental slope (abreast the Cape Olyutorsky) by a transverse fault and cannot be considered as its geological extension [2].…”

Section: Introductionmentioning

confidence: 99%

Late pleistocene sedimentation history of the Shirshov Ridge, Bering Sea

et al. 2013

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Abstract-The analysis of the lithology, grain size distribution, clay minerals, and geochemistry of Upper Pleistocene sediments from the submarine Shirshov Ridge (Bering Sea) showed that the main source area was the Yukon-Tanana terrane of Central Alaska. The sedimentary materials were transported by the Yukon River through Beringia up to the shelf break, where they were entrained by a strong northwestward flowing sea current. The lithological data revealed several pulses of ice rafted debris deposition, roughly synchronous with Heinrich events, and periods of weaker bottom current intensity. Based on the geochemical results, we distinguished intervals of an increase in paleoproductivity and extension of the oxygen minimum zone. The results suggest that there were three stages of deposition driven by glacioeustatic sea level fluctuations and glacial cycles in Alaska.

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“…This young material may represent a fragment of the Aleutian Arc (Scholl, 2007), or the Bowers Ridge that rifted away in the Neogene, based on the occurrence of the rocks in a NW-SE-oriented sector of the ridge, which is parallel to the fracture zones in the Komandorsky Basin to the west of the Shirshov Ridge, and strike-slip faults in the western part of the Aleutian Arc. Amphiboles within the amphibolites from the oceanic complex were K-Ar dated as 47 ± 5 Ma and zircons gave a 72 ± 1.4 Ma age (Sukhov et al, 2011). The amphibolites, metagabbro, and Upper Cretaceous to Paleocene volcanic and sedimentary rocks all underwent intense deformation (Chekhovich et al, 2012).…”

Section: Declination (°)mentioning

confidence: 99%

On pole position

Vaes¹

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Paleomagnetism provides the only quantitative tool to reconstruct the position and motion of tectonic plates and continents in deep geological time. These reconstructions often rely on apparent polar wander paths (APWPs), which describe the past position and motion of plates relative to the Earth’s spin axis. In addition to providing a paleomagnetic reference frame for paleogeography, these paths serve to quantify relative tectonic displacements with other lithospheric blocks. A long-discussed problem is that conventional approaches to computing polar wander do not propagate key sources of uncertainty in the underlying data, such as data scatter or age uncertainty, but proposed solutions remained mostly qualitative. Recently, this problem became more urgent: Rowley (2019, Tectonics) showed that as much as 50% of the data that underlie the currently most widely used global APWP are statistically significantly displaced relative to that APWP. This implies that the resolution at which a geologically meaningful statistical difference between a paleomagnetic dataset and an APWP may be determined, is strongly limited, which undermines the current tectonic and paleogeographic applications of paleomagnetism. This thesis aims to examine the causes of dispersion of paleomagnetic data behind APWPs and to build a global APWP in which key data uncertainties are propagated, such that it may be used to determine geologically meaningful relative displacements. We show that the uncertainty of APWPs computed from paleomagnetic poles, which is the current standard, is mostly determined by the arbitrary choice of how many datapoints are used per pole. This thesis then develops a novel approach in which apparent polar wander paths are computed from site-level paleomagnetic data instead of paleomagnetic poles. In this approach, larger weight is assigned to larger datasets and temporal and spatial uncertainties in the paleomagnetic data are incorporated. We present a global apparent polar wander path for the last 320 Ma using the new statistical approach proposed in this thesis, as well as using a fully updated paleomagnetic database. We find that the first-order geometry of this path is similar to previous models but with smaller uncertainties. Moreover, we show that correcting for temporal bias in the paleomagnetic data allows improved quantification of polar wander rates, and that previously observed peaks in polar wander likely resulted from such bias. We introduce the open-source web application APWP-online.org that provides user-friendly tools to compute apparent polar wander paths using our new methodology as well as the computation of relative paleomagnetic displacements. The website also hosts a community platform for the continuous improvement of the path in the future through the addition of new high-quality paleomagnetic data. Finally, we provide new quantitative estimates of true polar wander during the last 320 Ma by comparing our new global apparent polar wander path with existing mantle reference frames. The computed true polar wander paths suggest that the true polar wander rotations occurred about two roughly orthogonal axes in the equatorial plane. We discuss the geodynamic implications of these findings and highlight future opportunities for the identification and quantification of true polar wander on geological timescales.

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Age of the Shirshov submarine ridge basement (Bering Sea) based on the results of investigation of zircons using the U-Pb SHRIMP method

Cited by 11 publications

References 4 publications

Reconstruction of Subduction and Back‐Arc Spreading in the NW Pacific and Aleutian Basin: Clues to Causes of Cretaceous and Eocene Plate Reorganizations

Reconstruction of Subduction and Back‐Arc Spreading in the NW Pacific and Aleutian Basin: Clues to Causes of Cretaceous and Eocene Plate Reorganizations

Late pleistocene sedimentation history of the Shirshov Ridge, Bering Sea

On pole position

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