This fraction, which is enriched in heavy minerals relative to the sand fraction, is mainly detrital but contains a strong authigenic component. The authigenic silt heavy-mineral fraction is largely a product of the lateritic weathering and dominated by iron oxides and alterites. Grains of bladed rutile and leached ilmenite are common. Spatial variability in silt-fraction mineralogy is considerable. Within the Rio Cibuco system variability is related to compositional differences in rapidly eroding source rocks. On the shelf, silt heavy-mineral abundances are greatest at the river mouths and decrease seaward. Variability in the shelf samples is controlled primarily by source rivers and shelf sorting processes.
|Title||Silt fraction heavy-mineral distributions in a lateritic environment: The rivers and insular shelf of north-central Puerto Rico|
|Authors||L. J. Poppe, J.A. Commeau, G. Luepke|
|Publication Subtype||Journal Article|
|Series Title||Sedimentary Geology|
|Record Source||USGS Publications Warehouse|
|USGS Organization||Woods Hole Coastal and Marine Science Center|