- abstract:
We present the first finding of the high-pressure mineral coesite in lawsonite-bearing eclogite xenoliths from the Colorado Plateau, United States. The presence of coesite in these xenoliths supports the hypothesis that the eclogite formed in a low-temperature–high-pressure environment such as envisaged inside subducted oceanic lithosphere. Ion-microprobe U-Pb dating of micrometer-scale zircons in the eclogites yields ages ranging from 81 Ma to 33 Ma, the two extremes in age likely indicating the age of crystallization during subduction-related metamorphism and the age of recrystallization by the host magmatic event, respectively. These observations conclusively demonstrate that certain eclogite xenoliths from the Colorado Plateau originated as fragments of the subducted Farallon plate, which had been residing in the upper mantle since the Late Cretaceous. This is the first conclusive evidence that any eclogite xenoliths can be directly linked to a known subducted plate.
- doi: 10.1130/0091-7613(2003)031<0589:FOTSFP>2.0.CO;2
- modified at 8 h ago
@article{20200421154037-588998,
author = "Usui, Tomohiro and Nakamura, Eizo and Kobayashi, Katsura and Maruyama, Shigenori and Helmstaedt, Herwart",
title = "Fate of the subducted Farallon plate inferred from eclogite xenoliths in the Colorado Plateau",
journal = "Geology",
year = "2003",
number = "7",
volume = "31",
pages = "589–592",
doi = "10.1130/0091-7613(2003)031<0589:FOTSFP>2.0.CO;2",
}| caption | ID | rowname | stone | ||
|---|---|---|---|---|---|
| Table DR3a. Mineral compositions of lawsonite and zoisite in eclogite samples pub | 20200422121841-299065 | major-Lw-Zo (Usui et al.) | 4 | ||
| Table DR1. Mineral compositions of garnet in eclogite samples pub | 20200422115701-043327 | major (Usui et al., 2006) | 6 | ||
| Table DR3b. Mineral compositions of other constituent minerals in eclogite samples pub | 20200422123230-430665 | major (Usui et al., 2006) | 3 | ||
| Table DR2. Mineral compositions of clinopyroxene in eclogite samples pub | 20200422120816-470766 | major (Usui et al., 2006) | 5 | ||