Chemical and Isotopic Composition of Lower to Upper Ordovician Sedimentary Rocks (Central Andes/South Bolivia): Implications for Their Source
| Autor: | F. Lucassen, Sven O. Egenhoff |
|---|---|
| Rok vydání: | 2003 |
| Předmět: | |
| Zdroj: | Journal of Geology |
| ISSN: | 1537-5269 0022-1376 |
| DOI: | 10.1086/375280 |
| Popis: | Fifty million years of erosional history of the early Paleozoic orogen in the Central Andes are documented in the 12‐km‐thick Ordovician siliciclastic sedimentary section from south Bolivia. Transport directions in the north‐south‐trending basins allow a distinction between sediment sources from the Proterozoic Brazilian Shield to the east and the early Paleozoic mobile belt to the west. Major and trace element and isotopic (Nd, Sr, Pb) compositions of stratigraphically well‐defined samples of Tremadocian to Arenigian ages have been studied. The element patterns and isotopic composition of the Ordovician sedimentary rocks (eNd450 Ma, −7.5 to −11; 87Sr/86Sr450 Ma, 0.71–0.72; 206Pb/204Pb450 Ma, 17.2–18.8; 207Pb/204Pb450 Ma, 15.60–15.73; 208Pb/204Pb450 Ma, 36.9–39.1; Nd‐depleted mantle model ages [TDM], 1.7–2.2 Ga) are typical of upper crustal felsic rocks, which underwent one or more cycles of erosion and deposition. The compositional range of the Ordovician sedimentary rocks is similar to that of ... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|