|
|
|
|
|
| Yu, Ef; Liang, Ch; Chen, Mt. |
| Anomalously high uranium contents and U-238/Th-232 activity ratios deposited during the oxygen isotope stages 2 to 4 are observed in the MD962085 core from the Benguela Current upwelling area. In conjunction,vith the activity ratio of U-234/U-238, the high uranium contents found in this core cannot be considered as detrital; instead, they must be of authigenic origin. The high biological productivity in the overlying seawater may have induced a high flux of organic matter resulting, directly or indirectly, in a reducing environment, and may have led to the addition of authigenic uranium to the sediments during the last glacial period. The correspondence between the variations in authigenic U content, %TOC, and Th-230(ex)-normalized TOC flux supports this... |
| Tipo: Text |
Palavras-chave: Authigenic uranium; Last glacial stage; Benguela Current upwelling. |
| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00239/35071/34562.pdf |
| |
|
| |
|
|
| LOPES,RENATO P.; DILLENBURG,SERGIO R.; SCHULTZ,CESAR L.. |
| ABSTRACT Loess consists of silt-dominated sediments that cover ~10% of the Earth's surface. In southern South America it occurs in Argentina, Bolivia, Paraguay and Uruguay, and its presence in southern Brazil was never studied in detail. Here is proposed a new lithostratigraphic unit, Cordão Formation, consisting of loess deposits in the southern Brazilian coastal plain. It consists of fine-very fine silt with subordinate sand and clay, found mostly in lowland areas between Pleistocene coastal barriers. These sediments are pale-colored (10YR hue) and forms ~1,5-2,0 meter-thick stable vertical walls. The clay minerals include illite, smectite, interstratified illite/smectite and kaolinite, the coarser fraction is mostly quartz and plagioclase. Caliche and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Chuy Creek; Coastal plain; Last glacial stage; Loess; Pleistocene. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652016000602143 |
| |
|
|
|
