Paleomagnetic Reconstruction of Post-Paleozoic Tectonic Motions for the Intermontane and Yukon-Tanana Terranes of Baja British Columbia
Abstract
Paleopoles from 42 Mesozoic and Cenozoic rock units in the Intermontane Belt (IMB) and Yukon-Tanana (YT) terranes are deemed to be sufficiently represented paleomagnetically and well dated radiometrically to merit consideration. Unlike previous analyses based on paleoinclination only that have led to estimates up to ∼3500 Km for northward (poleward) displacement of Baja BC relative to the North American craton, the pattern of both paleoinclination and paleodeclination are used to assess the reliability of each paleopole. The analysis indicates that: 1) the YT terrane is autochthonous or parautochthonous; 2) the IMB terranes rotated steadily atop the craton by 16° ±6° between 54 Ma and the present, accomodated by extension in the south and compression in the north; 3) the IMB terranes were rotated a further 35° ±14° and translated northward by 8° ±7° (900 Km) from 102 to 54 Ma, consistent with geological estimates for the northward displacement of interior Baja BC; and, 4) the Cache Creek, Quesnel and probably Stikine terranes were part of Baja BC since Early Jurassic.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2004
- Bibcode:
- 2004AGUSMGP34A..02S
- Keywords:
-
- 1525 Paleomagnetism applied to tectonics (regional;
- global)