| 词条 | Rock Elm Disturbance |
| 释义 |
| name = Rock Elm Disturbance | other_name = | photo = Middle Ordovician craters.jpg | photo_size = 300 | photo_alt = | photo_caption = North American Middle Ordovician impact craters, which may be part of the Ordovician meteor event. Key: 1: Ames crater, 2: Decorah crater, 3: Rock Elm Disturbance, 4: Slate Islands crater | map = United States | map_alt = | map_caption = Location of the crater in the United States | map_size = | location = | label = | label_position = | coordinates = {{coord|44|43|N|92|14|W|region:US-WI_type:landmark_scale:50000|display=inline,title}} | coordinates_ref = | confidence = Confirmed | diameter = {{convert|6|km|mi|abbr=on}} | depth = | rise = | imp_size = | age = 430-455 Ma Middle Ordovician | exposed = - | drilled = - | bolide = Ordovician meteor event? | translation = | language = | pronunciation = | topo = | access = | country = {{USA}} | state = Wisconsin | province = | district = Pierce County | municipality = Rock Elm }} The Rock Elm Disturbance is an impact crater in Wisconsin, United States, roughly {{convert|40|km|mi}} southwest of Menomonie.[1] The disturbance is named for Rock Elm, Wisconsin, a nearby community. DescriptionThe meteorite is estimated to have been {{convert|170|m|abbr=on}} in diameter with a mass of {{convert|9e9|kg|abbr=on}} and impact velocity of {{convert|30|km/s|mph|abbr=on}}. The crater is {{convert|6|km|mi|abbr=on}} in diameter, and fossils found in the rock filling the crater suggest it dates to the Middle Ordovician Period, about 455 to 430 million years ago.[2] It may be one of several Middle Ordovician meteors that fell roughly simultaneously 469 million years ago, part of a proposed Ordovician meteor event that includes the Decorah crater in Iowa, the Slate Islands crater in Lake Superior, and the Ames crater in Oklahoma.[3] CompositionResearchers discovered a rare mineral called reidite at the Rock Elm impact site. Reidite is a dense form of zircon (ZrSiO4) and has been found in three other massive meteorite impacts.[4] References1. ^{{cite Earth Impact DB |name=Rock Elm |linkname=rockelm |accessdate=2017-10-14}} 2. ^{{cite journal | year=2002 | title=Paleontology of the Rock Elm Disturbance | journal=Abstracts with Programs - Geological Society of America | volume=34 | issue=2 | pages=95 | url=http://gsa.confex.com/gsa/2002NC/finalprogram/abstract_32679.htm | author=Peters, Christopher William, Middleton, Michael D., & Cordua, William S.}} 3. ^{{cite news|last=Vastag|first=Brian|title=Crater found in Iowa points to asteroid break-up 470 million years ago|url=https://www.washingtonpost.com/national/health-science/crater-found-in-iowa-points-to-asteroid-break-up-470-million-years-ago/2013/02/18/545131f8-76d5-11e2-aa12-e6cf1d31106b_story.html?wprss=rss_national|accessdate=19 February 2013|newspaper=Washington Post|date=18 February 2013}} 4. ^ {{cite news |last=Oskin |first=Becky |url=http://www.livescience.com/48584-reidite-discovered-rock-elm-wisconsin.html |title=Rare Mineral Discovered in Ancient Meteorite Impact Crater |work=Live Science |date=November 3, 2014 |accessdate=2015-02-17 }} External links
4 : Impact craters of the United States|Ordovician impact craters|Landforms of Pierce County, Wisconsin|Landforms of Wisconsin |
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