Loading...
Please wait, while we are loading the content...
Similar Documents
Late eocene impact events recorded in deep-sea sediments
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Glass, B. P. |
| Copyright Year | 1988 |
| Description | Raup and Sepkoski proposed that mass extinctions have occurred every 26 Myr during the last 250 Myr. In order to explain this 26 Myr periodicity, it was proposed that the mass extinctions were caused by periodic increases in cometary impacts. One method to test this hypothesis is to determine if there were periodic increases in impact events (based on crater ages) that correlate with mass extinctions. A way to test the hypothesis that mass extinctions were caused by periodic increases in impact cratering is to look for evidence of impact events in deep-sea deposits. This method allows direct observation of the temporal relationship between impact events and extinctions as recorded in the sedimentary record. There is evidence in the deep-sea record for two (possibly three) impact events in the late Eocene. The younger event, represented by the North American microtektite layer, is not associated with an Ir anomaly. The older event, defined by the cpx spherule layer, is associated with an Ir anomaly. However, neither of the two impact events recorded in late Eocene deposits appears to be associated with an unusual number of extinctions. Thus there is little evidence in the deep-sea record for an impact-related mass extinction in the late Eocene. |
| File Size | 171439 |
| Page Count | 2 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19890011951 |
| Archival Resource Key | ark:/13960/t4xh4h46v |
| Language | English |
| Publisher Date | 1988-01-01 |
| Access Restriction | Open |
| Subject Keyword | Oceanography Comets Meteorite Collisions Geochronology Deposits Populations Cometary Collisions Extinction Meteorite Craters Ocean Bottom Periodic Variations Sediments Spherules Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
