Late Miocene–mid-Pliocene tectonically induced formation of the semi-closed Japan Sea, inferred from seawater Nd isotopes

Abstract

Research Article| September 11, 2018 Late Miocene–mid-Pliocene tectonically induced formation of the semi-closed Japan Sea, inferred from seawater Nd isotopes Yukiko Kozaka; Yukiko Kozaka 1Graduate School of Science and Engineering for Education, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan Search for other works by this author on: GSW Google Scholar Keiji Horikawa; Keiji Horikawa * 2Graduate School of Science and Engineering for Research, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan *E-mail: horikawa@sci.u-toyama.ac.jp Search for other works by this author on: GSW Google Scholar Yoshihiro Asahara; Yoshihiro Asahara 3Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan Search for other works by this author on: GSW Google Scholar Hiroshi Amakawa; Hiroshi Amakawa 4Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15, Natsushima-cho, Yokosuka-shi, Kanagawa 237-0061, Japan Search for other works by this author on: GSW Google Scholar Yusuke Okazaki Yusuke Okazaki 5Department of Earth and Planetary Sciences, Graduate School of Sciences, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan Search for other works by this author on: GSW Google Scholar Author and Article Information Yukiko Kozaka 1Graduate School of Science and Engineering for Education, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan Keiji Horikawa * 2Graduate School of Science and Engineering for Research, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan Yoshihiro Asahara 3Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan Hiroshi Amakawa 4Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15, Natsushima-cho, Yokosuka-shi, Kanagawa 237-0061, Japan Yusuke Okazaki 5Department of Earth and Planetary Sciences, Graduate School of Sciences, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan *E-mail: horikawa@sci.u-toyama.ac.jp Publisher: Geological Society of America Received: 14 Apr 2018 Revision Received: 08 Aug 2018 Accepted: 15 Aug 2018 First Online: 11 Sep 2018 Online Issn: 1943-2682 Print Issn: 0091-7613 © 2018 Geological Society of America Geology (2018) 46 (10): 903–906. https://doi.org/10.1130/G45033.1 Article history Received: 14 Apr 2018 Revision Received: 08 Aug 2018 Accepted: 15 Aug 2018 First Online: 11 Sep 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Yukiko Kozaka, Keiji Horikawa, Yoshihiro Asahara, Hiroshi Amakawa, Yusuke Okazaki; Late Miocene–mid-Pliocene tectonically induced formation of the semi-closed Japan Sea, inferred from seawater Nd isotopes. Geology 2018;; 46 (10): 903–906. doi: https://doi.org/10.1130/G45033.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The Japan Sea in the western North Pacific was connected to the deep Pacific via deep seaways before it became a semi-closed marginal sea. However, the timing of the semi-closure and its cause(s) remain debatable. To further constrain the timing, for the first time we analyzed Nd isotopic compositions of fossil fish teeth and fish debris deposited in the Japan Sea (Integrated Ocean Drilling Program [IODP] Site U1425, ∼2000 m water depth) over the past 10 m.y. Neodymium isotope values (–4.5 to –3.2 εNd) in the Japan Sea prior to 4.5 Ma illustrate that the deep Japan Sea was composed of an admixture of less-radiogenic Lower Circumpolar Deep Water (avg. –4.3 εNd) and more-radiogenic North Pacific Deep Water (avg. –2.2 εNd), potentially with inflow from the Okhotsk Sea. At 4.5 Ma, εNd values fell to –5.5 εNd within a span of 140 k.y., suggesting that the deep-water communication between the Japan Sea and the North Pacific rapidly declined. We argue that active mountain building in the northern Japan arc, initiated by accelerated Pacific plate motion from the late Miocene to mid-Pliocene, caused the shallowing/narrowing of the Japan Sea–Pacific seaways and rapidly made the Japan Sea semi-closed at 4.5 Ma. As a result, the Japan Sea circulation patterns were realigned; a cyclonic circulation was developed and drew less-radiogenic Amur River–influenced Okhotsk Sea water into the Japan Sea. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.