Title

PRESSURE-TEMPERATURE HISTORY OF PRECAMBRIAN META-SEDIMENTARY ROCKS OF YELLOWSTONE NATIONAL PARK

Presenter Information

Carly Osborne

Presentation Type

Presentation

Abstract

The Archean Rocks of Yellowstone National Park appear to be similar to that of the Precambrian terranes found in neighboring mountain ranges, such as the Beartooths. These Precambrian Archean rocks were sampled last summer from along the Yellowstone River, from Bear Creek near Gardiner, MT to Hellroaring Creek and north of Tower Junction within northern Yellowstone National Park in order to determine if these terranes are from the same depositional environment. The samples collected are representative of shallow regional metamorphism, and are composed primarily of biotite schists containing diagnostic metamorphic assemblages that have been termed the Jardine Metasedimentary Sequence (JMS). The metamorphic grade increases slightly across the study area, which was established based on petrology of the samples. Chlorite-biotite assemblages are more prevalent in biotite schists in the west and transition into garnet-andalusite-chlorite-biotite and garnet-staurolite-biotite in the east. Staurolite occurs in a few of the samples in varying textures. A few of the samples with varying assemblages were analyzed with an electron microprobe obtaining mineral composition data from five samples that were then inputted into the program Thermocalc to calculate average pressures and temperatures (P-T) of metamorphism across the area. Small variations in P-T were observed, ranging from 572-608° C and 4.1-5.8 kbar. The JMS along with adjacent rocks in the Garnet Hill area to the east are of anomalously low metamorphic grade compared to other rocks of the northern Wyoming Province, and the JMS may represent a separate, distinctive unit that is allochthonous within this northern part of YNP.

Category

Physical Sciences

This document is currently not available here.

Share

COinS
 
Apr 15th, 4:40 PM Apr 15th, 5:00 PM

PRESSURE-TEMPERATURE HISTORY OF PRECAMBRIAN META-SEDIMENTARY ROCKS OF YELLOWSTONE NATIONAL PARK

UC 326

The Archean Rocks of Yellowstone National Park appear to be similar to that of the Precambrian terranes found in neighboring mountain ranges, such as the Beartooths. These Precambrian Archean rocks were sampled last summer from along the Yellowstone River, from Bear Creek near Gardiner, MT to Hellroaring Creek and north of Tower Junction within northern Yellowstone National Park in order to determine if these terranes are from the same depositional environment. The samples collected are representative of shallow regional metamorphism, and are composed primarily of biotite schists containing diagnostic metamorphic assemblages that have been termed the Jardine Metasedimentary Sequence (JMS). The metamorphic grade increases slightly across the study area, which was established based on petrology of the samples. Chlorite-biotite assemblages are more prevalent in biotite schists in the west and transition into garnet-andalusite-chlorite-biotite and garnet-staurolite-biotite in the east. Staurolite occurs in a few of the samples in varying textures. A few of the samples with varying assemblages were analyzed with an electron microprobe obtaining mineral composition data from five samples that were then inputted into the program Thermocalc to calculate average pressures and temperatures (P-T) of metamorphism across the area. Small variations in P-T were observed, ranging from 572-608° C and 4.1-5.8 kbar. The JMS along with adjacent rocks in the Garnet Hill area to the east are of anomalously low metamorphic grade compared to other rocks of the northern Wyoming Province, and the JMS may represent a separate, distinctive unit that is allochthonous within this northern part of YNP.