Composition and accretion rate of fossil micrometeorites recovered in Middle Triassic deep-sea deposits

Abstract

Research Article| June 01, 2011 Composition and accretion rate of fossil micrometeorites recovered in Middle Triassic deep-sea deposits Tetsuji Onoue; Tetsuji Onoue 1Department of Earth and Environmental Sciences, Kagoshima University, Kagoshima 890-0065, Japan Search for other works by this author on: GSW Google Scholar Tomoki Nakamura; Tomoki Nakamura 2Department of Earth and Planetary Material Sciences, Tohoku University, Miyagi 980-8578, Japan Search for other works by this author on: GSW Google Scholar Takeshi Haranosono; Takeshi Haranosono 1Department of Earth and Environmental Sciences, Kagoshima University, Kagoshima 890-0065, Japan Search for other works by this author on: GSW Google Scholar Chika Yasuda Chika Yasuda 3INPEX Corporation, Akasaka, Tokyo 107-6332, Japan Search for other works by this author on: GSW Google Scholar Geology (2011) 39 (6): 567–570. https://doi.org/10.1130/G31866.1 Article history received: 28 Oct 2010 rev-recd: 03 Feb 2011 accepted: 09 Feb 2011 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Tetsuji Onoue, Tomoki Nakamura, Takeshi Haranosono, Chika Yasuda; Composition and accretion rate of fossil micrometeorites recovered in Middle Triassic deep-sea deposits. Geology 2011;; 39 (6): 567–570. doi: https://doi.org/10.1130/G31866.1 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 Micrometeorites, which are submillimeter-sized extraterrestrial particles that survive atmospheric entry, originate from dust-producing objects such as comets and asteroids. Although ancient micrometeorites found in sedimentary rocks are of key interest as a historical record of meteoroid populations in the solar system, they are rare and prone to severe chemical weathering. Here we report the recovery of well-preserved micrometeorites, older than 240 Ma, in radiolarian chert from Japan. The collection of micrometeorites comprised 258 cosmic spherules, which are particles that totally melted during atmospheric entry, and 2 coarse-grained unmelted micrometeorites. These micrometeorites are much older than any previous micrometeorite collection in the sedimentary record. Using this collection, we calculated the accretion rate of iron-type cosmic spherules to the Earth during the Anisian Stage of the Middle Triassic. The estimated accretion rate for Anisian iron-type spherules smaller than 125 μm is 25 ± 8 t yr−1. Analysis of the accretion rate for cosmic spherules also reveals high accretion rates of small spherules (∼8–36 μm) for a 0.74 m.y. period in the late Anisian. However, the possible link between an enhancement in the accretion rate of small cosmic spherules in the late Anisian and variations in the flux of extraterrestrial matter to the Earth requires further scrutiny. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.