Geochemical variability of the Yucatan basement: Constraints from crystalline clasts in Chicxulub impactites

Details Geochemical variability of the Yucatan basement: Constraints from crystalline clasts in Chicxulub impactites Geochemical variability of the Yucatan basement: Constraints from crystalline clasts in Chicxulub impactites

Jul 2003

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003m%26ps...38.1079k&link_type=abstract

Meteoritics &Planetary Science, vol. 38, no. 7, p.1079-1092

Mathematics

Logic

12

Scientific paper

The 65 Ma old Chicxulub impact structure with a diameter of about 180 km is again in the focus of the geosciences because of the recently commenced drilling of the scientific well Yaxcopoil- 1. Chicxulub is buried beneath thick post-impact sediments, yet samples of basement lithologies in the drill cores provide a unique insight into age and composition of the crust beneath Yucatan. This study presents major element, Sr, and Nd isotope data for Chicxulub impact melt lithologies and clasts of basement lithologies in impact breccias from the PEMEX drill cores C-1 and Y-6, as well as data for ejecta material from the K/T boundaries at La Lajilla, Mexico, and Furlo, Italy. The impact melt lithologies have an andesitic composition with significantly varying contents of Al, Ca, and alkali elements. Their present day 87Sr/86Sr ratios cluster at about 0.7085, and 143Nd/144Nd ratios range from 0.5123 to 0.5125. Compared to the melt lithologies that stayed inside the crater, data for ejecta material show larger variations. The 87Sr/86Sr ratios range from 0.7081 for chloritized spherules from La Lajilla to 0.7151 for sanidine spherules from Furlo. The 143Nd/144Nd ratio is 0.5126 for La Lajilla and 0.5120 for the Furlo spherules. In an tCHUR(Nd)-tUR(Sr) diagram, the melt lithologies plot in a field delimited by Cretaceous platform sediments, various felsic lithic clasts and a newly found mafic fragment from a suevite. Granite, gneiss, and amphibolite have been identified among the fragments from crystalline basement gneiss. Their 87Sr/86Sr ratios range from 0.7084 to 0.7141, and their 143Nd/144Nd ratios range from 0.5121 to 0.5126. The TNdDM model ages vary from 0.7 to 1.4 Ga, pointing to different source terranes for these rocks. This leads us to believe that the geological evolution and the lithological composition of the Yucatàn basement is probably more complex than generally assumed, and Gondwanan as well as Laurentian crust may be present in the Yucatàn basement.

Affiliated with

Also associated with

No associations

Rating

Geochemical variability of the Yucatan basement: Constraints from crystalline clasts in Chicxulub impactites does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Geochemical variability of the Yucatan basement: Constraints from crystalline clasts in Chicxulub impactites, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Geochemical variability of the Yucatan basement: Constraints from crystalline clasts in Chicxulub impactites will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1148557