Nd and Sr Isotopes and REE Investigation in Tropical Weathering Profiles of Amazon Region

The exceptional development of lateritic profiles make the Amazon one best places to conduct a refined study on effects long-term tropical climate Earth's surface rocks. Concentrations Nd and Sr isotopes, as well rare earth elements (REE), Sr, other trace were determined in six order shed new light into element behavior processes controlling geochemistry transfer these among different compartments critical zone. Our investigation indicates natural isotope regional pulse transformations Oxisol at top all profiles. ƐNd (t=0) values parent rock, mottled horizon, duricrust are radiogenic similar craton signature. thick has Ɛ Nd(t=0) which much more less variable, whereas it Zr, Th, Y, REE higher concentrations. These issues highlight complex process for system, following possibilities proposed explain this behavior: formation authigenic cerianite and/or kaolinite, penetration low-temperature weathering solutions along zircon fractures, some vegetation uptake. allow keeping is released especially after mineral(s) weathering. system contrary that became relatively rocks content, because nearly was removed K-Rb feldspar mica However, mixture return from plant, biogenic aerosol, rainwater may have helped let become radiogenic. characteristics even but still permitting identify general In contrast, highly fractionated relative rock. Thus, behavior, profiles, does not necessarily reflect only rock geochemistry, also depends multiple surficial typical zone: weathering, pedogenesis, plant root activity, composition change inherited primary minerals signatures.