Neugrund crater

{{short description|Meteorite crater in Estonia}}

{{Infobox terrestrial impact site

| name = Neugrund crater

| other_name =

| photo = GneissBoulderOsmussaar.jpg

| photo_size =

| photo_alt =

| photo_caption = Boulder of gneiss breccia on Osmussaar, Estonia, possibly thrown there by the Neugrund impact

| map = Estonia

| map_alt =

| map_caption = Location of the crater in Estonia

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| location = Baltic Sea

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| coordinates = {{coord|59|20|N|23|40|E|type:landmark_scale:1000000|display=inline,title}}

| coordinates_ref =

| confidence = Confirmed

| diameter = {{convert|8|km|mi|abbr=on}}

| depth =

| rise =

| imp_size =

| age = ~535 Ma
Cambrian

| exposed = No

| drilled = -

| bolide =

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| state = Estonia

| province =

| district = Lääne County

| municipality =

}}

Neugrund is a meteorite crater in Estonia. It is {{convert|8|km|mi|abbr=on}} in diameter and was previously estimated to have been formed in the Ordovician around 470 Ma, with later research revealing a possible Cambrian origin (around 535 Ma). The crater is at the bottom of the sea and is not exposed at the surface. Boulders of gneissic breccia found on the coast of Osmussaar, a nearby island, are believed to have been thrown there by the explosion.{{cite Earth Impact DB |name=Neugrund |accessdate=2017-10-14}} It has been proposed that the Neugrund crater was created during the Ordovician meteor event when a hypothetical large asteroid transferred directly into a resonant orbit with Jupiter, which shifted its orbit to intercept Earth.{{cite journal|last1=Heck|first1=Philipp|last2=Schmitz|first2=Birger|last3=Baur|first3=Heinrich|last4=Halliday|first4=Alex N.| authorlink4 = Alexander Halliday|last5=Wieler|first5=Rainer|title=Fast delivery of meteorites to Earth after a major asteroid collision|journal=Nature|date=15 July 2004|volume=430|pages=323–325|bibcode = 2004Natur.430..323H |doi = 10.1038/nature02736|pmid=15254530|issue=6997|s2cid=4393398}}{{Cite journal |last=Haack |first=Henning |last2=Farinella |first2=Paolo |last3=Scott |first3=Edward R.D. |last4=Keil |first4=Klaus |date=1996 |title=Meteoritic, Asteroidal, and Theoretical Constraints on the 500 Ma Disruption of theLChondrite Parent Body |url=https://linkinghub.elsevier.com/retrieve/pii/S001910359690010X |journal=Icarus |language=en |volume=119 |issue=1 |pages=182–191 |doi=10.1006/icar.1996.0010|url-access=subscription }}Korochantseva et al. [http://www.ingentaconnect.com/content/arizona/maps/2007/00000042/00000001/art00009 "L-chondrite asteroid breakup tied to Ordovician meteorite shower by multiple isochron 40Ar-39Ar dating"] Meteoritics & Planetary Science 42, 1, pp. 3-150, Jan. 2007.{{Dead link|date=January 2017}}

This attractive theory may need to be changed as more recent study puts the age of the impact in the Cambrian.{{Cite journal |last=Suuroja |first=S. |last2=Suuroja |first2=K. |last3=Flodén |first3=T. |date=2013 |title=A comparative analysis of two Early Palaeozoic marine impact structures in Estonia, Baltic Sea: Neugrund and Kärdla |url=https://www.geologinenseura.fi/sites/geologinenseura.fi/files/bulletin_vol85_1_2013_suuroja_ea.pdf |journal=Bulletin of the Geological Society of Finland |volume=85 |issue=1 |pages=83–101 |doi=10.17741/bgsf/85.1.006 |issn=1799-4632}}