(U-Th)/He Dating of Uplift-Induced Cooling in a Complex Terrestrial Impact Structure: The Manicouagan Example.

Biren, M. B., van Soest, M. C., Wartho, J.-A. and Spray, J. G. (2014) (U-Th)/He Dating of Uplift-Induced Cooling in a Complex Terrestrial Impact Structure: The Manicouagan Example. Chemical Geology, 377 . pp. 56-71. DOI 10.1016/j.chemgeo.2014.03.013.

[img] Text
Biren.pdf - Published Version
Restricted to Registered users only

Download (2661Kb) | Contact

Supplementary data:

Abstract

Highlights

• The central uplift of the Manicouagan impact structure has been dated by (U–Th)/He
• A (U–Th)/He central age (207.1 ± 6.4 Ma, 2 standard error, n = 40) has been determined
• This age reflects the rapid uplift, cooling and closure of He in ~ 1 Gyr-old titanites
• This correlates with the previously determined U–Pb impact-melt age of 214 ± 1 Ma
• Our new approach enables dating complex impact structures that lack impact melt rocks

Abstract

Forty titanite grain fragments from 9 central uplift samples of metamorphosed anorthosite from the Manicouagan impact structure were dated by the (U–Th)/He technique. A (U–Th)/He central age of 207.1 ± 6.4 Ma (2 standard error (SE), n = 40) has been determined. With 4 outlier ages removed the central age is refined to 208.9 ± 5.1 Ma (2 SE). Both of these ages are within error of the previously determined U–Pb zircon age of 214 ± 1 Ma (2σ) derived from the impact melt. Manicouagan's central uplift formed due to rapid elevation from ~ 7–10 km depth as part of the modification stage of the impact process, which has facilitated the dating of its emplacement due to resulting rapid exhumation and cooling and closure of the (U–Th)/He system in titanite. Correlation with the previous U–Pb zircon 214 ± 1 Ma impact melt crystallization age indicates that the (U–Th)/He titanite dating technique offers a new approach to dating complex impact structures in the absence of viable melt sheets, or other melt products. The youngest ca. 195 Ma (U–Th)/He dates preserved in some titanite fragments are synchronous with Early Jurassic, rift-induced lithospheric thinning and associated igneous activity that defines the Central Atlantic Magmatic Province (CAMP). The (U–Th)/He titanite data from Manicouagan indicate that the influence of this regional event may extend west of the previously proposed limit of CAMP activity.

Document Type: Article
Keywords: Helium diffusion, Thermochronology, Radiation damage, Shock metamorphism, Central uplift, Central Atlantic Magmatic Province
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.chemgeo.2014.03.013
ISSN: 0009-2541
Related URLs:
Date Deposited: 16 Nov 2015 13:26
Last Modified: 16 Nov 2015 13:26
URI: http://oceanrep.geomar.de/id/eprint/30229

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...