paléoplacer

CONT: [...] les principales provinces aurifères se présentent comme suit : bassins à remplissage détritique, paléoplacers ou placers, sur socle à or disséminé (type Rand) [...]
CONT: Les diamants se rencontrent dans [...] des sédiments non consolidés ou lithifiés (placers ou paléoplacers) [...]
OBS: On a empiriquement établi deux classes de placers sur la base de l'âge et de leur état de consolidation : les paléoplacers, s'ils apparaissent au sein d'anciennes successions de roches silicoclastiques à grain grossier, et les placers récents, s'ils font partie de successions de sédiments clastiques non consolidés du Pliocène à l'Holocène.

CONT: Paleoplacers, like placers, may be formed wherever vigorous water or air currents have sorted heavy and light, large and small, mineral and rock clasts resulting in the formation of lenses or layers containing heavy minerals ... and greater abundance than elsewhere in a clastic sedimentary formation. The term is generally applied only to those heavy mineral accumulations that are notably enriched in particular commodities - e.g. gold paleoplacers - and implies a provenance containing special primary sources of these commodities in addition to sources of the more common heavy minerals.
CONT: Diamonds ... are found in unconsolidated and consolidated sediments (placers and paleoplacers) ...
OBS: Depending on the age and the state of their consolidation, the deposits are empirically classified as paleoplacers if they formed in ancient coarse siliciclastic rocks, or as modern placers if they are a part of Pliocene to Recent unconsolidated clastic sediments.