Braided River Sand, Rio Pitai, Santa Cruz, Bolivia
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Rio Pitai | Macro |
Location | Rio Pitai, Santa Cruz, Bolivia |
Depositional facies | Broad, shallow and sandy riverbed |
Provenance | The Rio Pitai drains the Subandean Ranges and erodes thick palaeozoic and mesozoic continental sedimentary rocks as well as thick eolian sediments |
Composition | Quartz |
Texture | Medium to fine grained, well sorted, subrounded |
Petrographic thin section:
Description | Moderately sorted, moderately to well rounded quartz sand. Typical for provenance from a fold belt of clastic sedimentary rocks |
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Bright field | Dark field |
Sample number | Heubeck0026 |
Collector | Christoph Heubeck, Institut für Geologische Wissenschaften, FU Berlin |
Date of sampling | 2003 |
Comments:
The meandering and braided Rio Pitai in the Bolivian lowland of the Amazonas Basin erodes the Subandean Miocene-Recent fold-and -thrust belt. This belt exposes thick continental successions of Carboniferous to Cretaceous eolian sandstones. The supermature source, the high mechanical resistance, and weathering of river sands under a tropical climate all contribute to the maturity. These sands are most likely multiply recycled.