Minerais Pesados Provenientes Do Leito Do Rio Amazonas

Landim, Paulo Milton Barbosa; Bósio, Nivaldo J.; Wu, Fu; Castro, Paulo R. M.

doi:10.1590/1809-43921983131051

Cited by 8 publications

(12 citation statements)

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“…However, the hydraulic-barrier effect hinders sediment transportation into the lake in the area where the Tapajós River flows into the Amazon River (Nascimento et al 1976). The Amazon River is also unlikely to be the sole source for the lake sediments, as the heavy minerals in this part of the Amazonas have a very different composition (Landim et al 1983;Nascimento Jr. et al 2015).…”

Section: Discussionmentioning

confidence: 99%

Provenance of heavy and clay minerals in bottom sediments of Green Lake, an Amazonian fluvial lake in Brazil

et al. 2020

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ABSTRACT Studies on provenance of minerals in Amazonian rivers focus mostly on suspended sediments, while processes that control bottom-sediment production and distribution are still little known. We determined the provenance of the bottom sediments of Green Lake, a micro-basin draining into the Tapajós River, in the eastern Brazilian Amazon. We used X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and, cathodoluminescence techniques to analyze clay, light and heavy minerals of 22 samples. The lake is L-shaped, with 5.5 m maximum depth, and predominance of mud over sand in the center. Quartz and feldspar were dominant in the light fraction, while zircon, tourmaline, kyanite, rutile, and staurolite were dominant in the heavy fraction. The clay fraction was dominated by kaolinite, with morphology and degree of crystallinity indicative of a detrital origin related to weathering. The Alter do Chão Formation (ACF) is suggested as the main source of sand sediments and heavy minerals, due to their mineralogical and percentage similarity. The provenance of kaolinite was mainly the ACF, with a minor contribution of the Amazon and Tapajós rivers. The primary origin of the heavy minerals in the ACF indicates the basement of the Amazonas Basin as source rock and this formation as a source of sediments for Green Lake through weathering and erosion processes under current tropical conditions. The presence of Aulacoseira granulata and Aulacoseira ambigua indicates the importance of current erosive processes on sediment production.

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Section: Discussionmentioning

confidence: 99%

Provenance of heavy and clay minerals in bottom sediments of Green Lake, an Amazonian fluvial lake in Brazil

et al. 2020

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“…Studies of heavy minerals in recent sediments are commonly conducted to understand fluvial dynamics (Landim et al, 1983;Pan et al, 2016;Yang et al, 2009) although it is traditionally used in provenance (Mendes et al, 2015;Moral Cardona et al, 2005;Morton andHallsworth, 1994, 1999), coastal dynamic (Nascimento Jr. et al, 2017;Sousa et al, 2017) and stratigraphic analyses (Góes et al, 2007;Knox et al, 2007;Svendsen and Hartley, 2002).…”

Section: Introductionmentioning

confidence: 99%

Distribution and provenance of heavy minerals from recent sediments of Green Lake, North Brazil, revisited

Ribeiro

Santos²,

Junior³

et al. 2022

GeA

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Geostatistical and multivariate statistical analyses were applied to heavy mineral data from an Amazonian fluvial-lake system near the Tapajós River mouth to investigate the spatial distribution and source-area of sediments. Twenty-one points were investigated, and the physical characteristics of the Green Lake deepest point were determined. Sand accumulates in the lake margins and mud quantity increases towards the lake center. Heavy mineral assemblage is composed of zircon, tourmaline, kyanite, rutile, staurolite, anatase, sillimanite, garnet, and spinel. Tourmaline, staurolite, and spinel are more abundant in the southeast area of the lake, while kyanite is dominant in the north area and zircon is in the whole lake except in its southeast area. Zircon - tourmaline and zircon - staurolite pairs are negatively correlated (r= -0.947 and -0.775, respectively), while tourmaline - staurolite and sillimanite - anatase pairs have a positive correlation (r= 0.628 and 0.675, respectively) which indicate different source rock types. Geostatistical analysis grouped the heavy minerals in three grups: Group 1 (tourmaline – staurolite – spinel - kyanite) and Group 2 (garnet – rutile – sillimanite - anatase) related to metamorphic source rocks ranging from medium to high grade, and Group 3 (zircon) related to acid igneous source rocks. The heavy mineral assemblage of Green Lake is analogous to the assemblage of the Alter do Chão Formation, indicating that this formation is the source of sediments of Green Lake.

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“…However, the sum of these two sources in the Blue Amazon resulting in an immense volume of trace metals, which partly is carried by the current flow associated with suspended sediments, towards the mouth of the Amazon River following the sedimentation process. The natural composition of the Amazonian soil is considered enriched in trace metals as explained by researchers in 90th decade [1][2][3][4]. The balance between the erosion, transport and sedimentation processes interferes with the volume of suspended solids and, consequently, the concentration of trace metals in the fluvial-marine environment.…”

Section: Introductionmentioning

confidence: 99%

Trace-elements Behavior in the Sedimentary Transport Regime of the Blue Amazon, Brazil

Siqueira

Aprile

Darwich

et al. 2018

IJECC

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Trace elements or trace metals are of great interest in environmental studies due to their toxic and cumulative properties in the biological and sedimentary compartments. The discharge area of the Amazon River mouth receives an immense volume of suspended material with adsorbed trace elements, which mostly ends up depositing in the shelf area influenced by the fluvial-marine currents and physical-chemical properties of the water and sediment. This research aims to quantify and to discuss the routes of trace elements (Cr, Pb, Ni, Zn and Hg), associated with sedimentary transport and deposition in the Amazon Continental Shelf (ACS). The results showed a sediment distribution by zone, with a non-continuous range of erosive processes and areas of deposition for mud and sand sediments. The trace elements contents in the sediments are strongly influenced by the pH, salinity, organic compounds, clay minerals and CaCO3content. Fluvial-marine currents were important drive forces for deposition and accumulation of fine sediments in the shelf, especially the North Brazilian Coastal Current (NBCC). Statistical analysis and hypothesis testing confirmed the trend of sediment accumulation by zone, influenced by the physical-chemical parameters.

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Minerais Pesados Provenientes Do Leito Do Rio Amazonas

Cited by 8 publications

References 0 publications

Provenance of heavy and clay minerals in bottom sediments of Green Lake, an Amazonian fluvial lake in Brazil

Provenance of heavy and clay minerals in bottom sediments of Green Lake, an Amazonian fluvial lake in Brazil

Distribution and provenance of heavy minerals from recent sediments of Green Lake, North Brazil, revisited

Trace-elements Behavior in the Sedimentary Transport Regime of the Blue Amazon, Brazil

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