| 词条 | Morton Gneiss |
| 释义 |
The Morton Gneiss is an Archean-age migmatitic gneiss found in the Minnesota River Valley of southwestern Minnesota. Zircon crystals from the gneiss have been dated to 3524 ± 9 Ma. Zircons from the Montevideo Gneiss from Chippewa County have an age of 3485 ± 10 Ma.[1] Its type locality is in Morton, Minnesota where it is also known as "Rainbow Gneiss", and is quarried as a facing stone for buildings.[2] The Morton Gneiss is the oldest rock unit in the United States.[3] References1. ^M.E. Bickford, J.L. Wooden and R.L. Bauer, 2006 SHRIMP study of zircons from Early Archean rocks in the Minnesota River Valley: Implications for the tectonic history of the Superior Province, GSA Bulletin, v. 118 no. 1-2 p. 94-108 2. ^Minnesota Geological Survey 3. ^Emporia State University External links
2 : Geology of Minnesota|Gneiss |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。