Journal
GEOLOGY
Volume 49, Issue 10, Pages 1187-1192Publisher
GEOLOGICAL SOC AMER, INC
DOI: 10.1130/G49141.1
Keywords
-
Categories
Funding
- U.S. National Science Foundation [EAR-1624538, EAR-028463, EAR-9902955]
Ask authors/readers for more resources
The study in the Rocky Mountain region evaluates the timing of exhumation of basement rocks at five locations, revealing multiple pulses of basement cooling occurring from 1.3 billion to 0.9 billion years ago. These data suggest a tectonic control on basement exhumation and the formation of the Precambrian-Cambrian Great Unconformity.
The Great Unconformity of the Rocky Mountain region (western North America), where Precambrian crystalline basement is nonconformably overlain by Phanerozoic strata, represents the removal of as much as 1.5 b.y. of rock record during 10-km-scale basement exhumation. We evaluate the timing of exhumation of basement rocks at five locations by combining geologic data with multiple thermochronometers. 40Ar/39Ar K-feldspar multi-diffusion domain (MDD) modeling indicates regional multi-stage basement cooling from 275 to 150 degrees C occurred at 1250-1100 Ma and/or 1000-700 Ma. Zircon (U-Th)/He (ZHe) dates from the Rocky Mountains range from 20 to 864 Ma, and independent forward modeling of ZHe data is also most consistent with multi-stage cooling. ZHe inverse models at five locations, combined with K-feldspar MDD and sample-specific geochronologic and/or thermochronologic constraints, document multiple pulses of basement cooling from 250 degrees C to surface temperatures with a major regional basement exhumation event 1300-900 Ma, limited cooling in some samples during the 770-570 Ma breakup of Rodinia and/or the 717-635 Ma snowball Earth, and ca. 300 Ma Ancestral Rocky Mountains cooling. These data argue for a tectonic control on basement exhumation leading up to formation of the Precambrian-Cambrian Great Unconformity and document the formation of composite erosional surfaces developed by faulting and differential uplift.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available