A pavement of faceted pebbles of haematite ore has been discovered in Amazonia. It occurs on the top of a lateritic plateau in Carajás, beside lakes and marshes where the available palynological data indicate dry periods during the Pleniglacial. The pebbles have pyramidal tops and characteristic polished facets. They are interpreted as ventifacts additionally worn by fluvial action. The possible occurrence of ventifacts may represent the erosional manifestation, hitherto unrecognised, of the Ice Age aridity recorded in these Amazonian lacustrine sediments.
KnightJ. and BurninghamH.: ‘Formation of bedrock-cut ventifacts and Late Holocene coastal zone evolution, County Donegal, Ireland', J. Geol., 2001, 109, 647—660.
2.
SharpR. P.: ‘Pleistoeene ventifacts east of the Big Horn Mountains, Wyoming', J. Geol., 1949, 57, 175–195.
3.
WhitneyM. I. and DietrichR. V.: ‘Ventifact sculpture by windblown dust', Geol. Soc. Am. Bull., 1973, 84, 2561–2582.
4.
ReineckH. E. and SinghI. B.: ‘Depositional sedimentary environments'; 1980, Berlin, Springer-Verlag.
5.
ClappertonC.: ‘Quaternary geology and geomorphology of South America'; 1993, Amsterdam, Elsevier.
6.
ColinvauxP. A., de OliveiraP. E. and BushM. B.: ‘Amazonian and neotropical plant communities on glacial time-scales: the failure of the aridity and refuge hypothesis', Quaternary Sci Rev., 2000, 19, 141–169.
7.
HooghiemstraH. and Van der HammenT.: ‘Neogene and Quaternary development of the neotropical rain forest: the forest refugia hypothesis, and a literature overview', Earth ScL Rev., 1998, 44, 147–183.
8.
Van der HammenT. and AbsyM. L.: ‘Amazonia during the last glacial', Palaeogeogr Palaeod Palaeoecol, 1994, 109, 247–261.
9.
CabralA. R., LehmannB., KwitkoR. and Cravo CostaC. H.: ‘The Serra Pelada Au—Pd—Pt deposit, Carajás mineral province, northern Brazil: reconnaissance mineralogy and chemistry of very high grade palladian gold mineralization'Econ. Geol., 2002, 97, 1127–1138.
10.
DardenneM. A. and SchobbenhausC.: ‘Metalogênese do Brasil'; 2001, Brasilia, Editora Universidade de Brasilia.
11.
VillasR. N. and SantosM. D.: ‘Gold deposits of the Carajás mineral province: deposit types and metallogenesis', Mineral. Deposita, 2001, 36, 300–331.
12.
TrendallA. F., BaseiM. A. S., de LaeterJ. R. and NelsonD. R.: ‘SHRIMP zircon U—Pb constrains on the age of the Cara* Formation, Grão Para Group, Amazon Craton', J. South Am. Earth Set, 1998, 11, 265–277.
13.
VasconcelosP. M., RenneP. R., BrimhallG. H. and BeckerT. A.: ‘Direct dating of weathering phenomena by Ar/Ar and K—Ar analysis of supergene K—Mn oxides', Geochim. Cosmochim. Acta, 1994, 58, 1635–1665.
14.
LedruM. P., BertauxJ., SifeddineA. and SuguioK.: ‘Absence of last glacial maximum records in lowland tropical forests', Quaternary Res., 1998, 49, 233–237.
15.
MinterW. E. L.: ‘Detrital gold, uranium, and pyrite concentrations related to sedimentology in the Precambrian Vaal Reef placer, Witwatersrand, South Africa', Econ. Geol., 1976, 71, 157–176.
16.
ColinvauxP. A. and de OliveiraP. E.: ‘Amazon plant diversity and climate through the Cenozoic', Palaeogeogr Palaeod Palaeoecol, 2001, 166, 51–63.
17.
RuddimanW. F.: ‘Tropical Atlantic terrigenous fluxes since 25, 000 yrs B. P.', Mar. Geol., 1997, 136, 189–207.
18.
SarntheinM., TetzlaffG., KoopmannB., WolterK. and PflaumannU.: ‘Glacial and interglacial wind regimes over the eastern subtropical Atlantic and North-West Africa', Nature, 1981, 293, 193–196.
