Mineralogical and geochemical influences on sediment color of Amazon wetlands analyzed by visible spectrophotometry

Abstract

Based on sedimentological and geochemical data, this work relates spectrophotometric measurements with sediment composition and its application in palaeoecological studies of Amazon wetlands. The CIELAB values are directly related to mineralogical and chemical composition, mostly involving quartz, iron oxyhydroxides and sulfides (e.g. pyrite), and total organic carbon. Total organic carbon contents between 0.4-1%, 1-2%, 3-5% and 15-40% were related to L* (lightness) data of 27, 26-15, 7-10 and 7 or less, respectively. The CIELAB values of a deposit in Marabá, Pará, were proportional to variations in quartz and total organic carbon contents, but changes in zones of similar color, mainly in the +a* (red) and +b* (yellow) values of deposits in Calçoene, Amapá and Soure, Pará, indicate a close relationship between total organic carbon content and iron oxyhydroxides and sulfides. Furthermore, the Q7/4 diagram (ratio between the % reflectance value at 700 nm to that at 400 nm, coupled with L*) indicated iron-rich sediments in the bioturbated mud facies of the Amapá deposit, bioturbated mud and bioturbated sand facies of Soure deposit, and cross-laminated sand and massive sand facies of the Marabá core. Also, organicrich sediments were found in the bioturbated mud facies of the Amapá deposit, lenticular heterolithic and bioturbated mud facies of the Soure deposit, and laminated mud and peat facies of the Marabá deposit. At the Marabá site, the data suggest an autochthonous influence with peat formation. The coastal wetland sites at Marajó and Amapá represent the development of a typical tidal flat setting with sulfide and iron oxyhydroxides formation during alternated flooding and drying. KEYWORDS: Sedimentology, Amazon region, Munsell color systems, Mineralogy, chemical composition.Influências mineralógicas e geoquímicas na cor dos sedimentos das zonas úmidas da Amazônia analisada através da espectrofotometria no visível RESUMO Com base em dados sedimentológicos e geoquímicos, este trabalho relaciona medições espectrofotométricas com a composição do sedimento, e sua aplicação em estudos paleoecológicos das áreas alagáveis da Amazônia. Os dados CIELAB estão diretamente relacionados à composição mineralógica e química dos sedimentos, especialmente quartzo, oxihidróxidos e sulfetos de ferro, e carbono orgânico total. Conteúdos de carbono orgânico total entre 0,4-1%, 1-2%, 3-5% e 15-40% foram relacionados a dados de L* (luminosidade) de 27, 26-15, 7-10 e 7 ou menos, respectivamente. Os valores CIELAB de um depósito com turfa em Marabá, Pará, foram proporcionais a variações no conteúdo de quartzo e carbono orgânico total, mas mudanças nas zonas de cores similares, principalmente nos valores de +a* (vermelho) e +b* (amarelo), ao longo de outros depósitos em Calçoene, Amapá e Soure, Pará, indicam uma relação muito próxima entre os conteúdos de carbono orgânico total, oxihidróxidos e sulfetos de ferro. Além disso, o diagrama Q7/4 (razão entre valores percentuais de refletância em 700 nm e 400 nm, juntamente com dados ...

Geochemical Characteristics of Limestone of Wonosari-Punung Formation, Gunungkidul Regency, Yogyakarta, Indonesia

“…The major oxide data in Table 1 show that limestone of Wonosari-Punung Formation contains CaO concentration that ranges from 50.37 -54.84 wt.%, SiO 2 0.61 -3.35 wt.%, Al 2 O 3 0.19 -1.69 wt.%, Fe 2 O 3 0.1 -0.89 wt.%, TiO 2 <0.0003 -0.08 wt.%, and MnO <0.01 -9.186 wt%. Plotting of major oxide variation (x-axis) versus major oxide concentration of the sample on y-axis uses normalization from PAAS (Post-Archean Australian Shale; from Guimaraes et al, 2013). The plotting shows that CaO concentration of white limestone is the highest concentration of all limestone samples (Figure 4).…”

“…Values of normalization for plotting trace element concentration of the limestone samples are from Average Phanerozoic Limestone (Condie et al, 1991), whilst PAAS (Post-Archean Australian Shale) normalization (Guimaraes et al, 2013) is used for plotting major oxide and rare earth element (REE) concentrations of the samples.…”

“…PAAS-normalized REE+Y diagram for limestone samples of Wonosari-Punung Formation. The PAAS normalizing factors are fromGuimaraes et al (2013).…”

Mineralogi Dan Geokimia Batugamping Merah Ponjong, Gunungkidul, Daerah Istimewa Yogyakarta – Indonesia

“…Gambar 7. Plot wt% batugamping Ponjong yang dinormalisasi dengan standar PAAS (Post-Archaean Australian Shale) (Guimaraes, et al, 2013). Terlihat adanya tren pengkayaan SiO2, Al2O3, dan Fe2O3 dari batugamping putih ke batugamping merah dan batugamping abu-abu.…”

Sediment Characteristics of Beachrock: A Baseline Investigation Based on Microbial Induced Carbonate Precipitation at Krakal-Sadranan Beach, Yogyakarta, Indonesia

“…The resulting material was then cooled and dissolved in an acid mixture containing nitric, hydrochloric, and hydrofluoric acids. Beachrock sample consists of 90% carbonate compound, therefore it was sensitive to the acid solution during the chromatography analysis.The normalization values for plotting the trace element concentration of the limestone samples are from the Average Phanerozoic Limestone [19], while Post-Archean Australian Shale (PAAS) normalization [22] was used for plotting major oxide and rare earth element (REE) concentrations in the samples [23,24].…”