Extraterrestrial in£uences on mantle plume activity Dallas H. Abbott a; Ã , Ann E. Isley b a Lamont^Doherty Earth Observatory of Columbia University, Palisades, NY 10964 USA b State University of New York at Oswego, Oswego, NY 13126 USA Received 12 September 2001; accepted 14 October 2002 Abstract We use time series analysis to compare the impact histories of the Earth and Moon with the record of mantle plume activity. We use events with errors in their ages of 9 150 Ma. The terrestrial and lunar impact records, when smoothed at a 45-Ma interval, correlate at a 97% confidence level. This high confidence level suggests that we have an adequate sampling of most of the major impact events on the Earth. We then test the idea that existing mantle plumes may be strengthened by impacts. When smoothed at a 45-Ma interval, strong plumes correlate with the terrestrial impact record at better than a 99% confidence level. No time lag is discernible between the data sets, which is expected given their present error level. When the time series are smoothed at a 30-Ma interval, there are 10 major peaks in impact activity. Nine out of ten of these peaks have a counterpart in either or both of the strong mantle plume or the mantle plume time series. As a result, the strong mantle plume and the impact time series correlate at the 97% confidence level. The mantle plume and the impact time series correlate at the 90% confidence level. Finally, the Deccan plume showed greatly increased activity immediately after the Chixculub impact. The results of our analysis suggest that large meteorite and cometary impacts may well increase the amount of volcanism from already active mantle plumes. ß 2002 Elsevier Science B.V. All rights reserved. Keywords: mantle plumes; impact craters; igneous rocks; impacts; komatiites; lunar impacts; time series analysis; mass extinction 1. Introduction Modern versions of catastrophism propose that catastrophic events signi¢cantly in£uence major Earth processes [1,2]. A key question is whether or not these catastrophes are extraterrestrially or internally driven. Speci¢cally, have meteorite and cometary impacts caused repeated mass extinc- tions of life on Earth [3,4] or were mass extinc- tions caused by major episodes of mantle plume volcanism [5,6] ? In this paper, we propose a syn- thesis of these apparently contrary hypotheses: that large meteorite and cometary impacts signi¢- cantly increase the strength of existing mantle plumes [7], thereby producing their observed cor- relations with mass extinction events. 0012-821X / 02 / $ ^ see front matter ß 2002 Elsevier Science B.V. All rights reserved. PII:S0012-821X(02)01013-0 * Corresponding author. E-mail addresses: dallas@ldeo.columbia.edu (D.H. Abbott), isley@oswego.edu (A.E. Isley). Earth and Planetary Science Letters 205 (2002) 53^62 www.elsevier.com/locate/epsl