Banca de DEFESA: ARTUR HENRIQUE NASCIMENTO DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ARTUR HENRIQUE NASCIMENTO DA SILVA
DATE: 23/02/2022
TIME: 09:00
LOCAL: Defesa remota pelo Google Meet
TITLE:

Mineralogy of Luvissols formed from amphibolite, in the semiarid region of Brazil

KEY WORDS:

Phyllosilicates. Interstratified minerals. Rock alteration. Mineral transformation. Iron oxyhydroxides. Isomorphic substitution.

PAGES: 76
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

Rocks and sediments exposed on the earth's surface are subject to conditions that promote weathering reactions, among the factors that control these reactions, the climate is the main catalyst of the reactions, mainly through precipitation. The rock alteration has clays as one of its main products; clays are particles (< 2 μm) of minerals that play a fundamental role in soil dynamics, they present a wide variety of species that differ according to their formation environment. Arid and semiarid soils generally have clays with complex mineralogy, the mineral species vary from primary minerals inherited from the source material to secondary minerals formed during pedogenesis. The reactions formation and transformation of clay in soils is discussed in different environments, however few studies describe these processes and their resulting mineral phases in semi-arid climates. This work aimed to characterize the mineral phases of clays and identify their main formation processes in two Luvissols formed from the weathering of crystalline rocks (amphibolites) in the semi-arid region under two precipitation conditions (drier and wetter). Different x-ray diffraction techniques XRD were used (Modeling of oriented patterns, analysis of non-oriented patterns in the region of the 060 planes), thermogravimetric analyses, Fourier transform infrared spectroscopy (FTIR), and selective chemical extractions. The results showed the presence of mineral phases formed mainly from the weathering of hornblendes, biotites and feldspars; phyllosilicates are mainly composed of interstratified kaolinite-smectite phases in transformation, having a higher layer proportion of smectites in the drier environment and kaolinites in the wetter environment; both soils presented oxy-hydroxides phases composed of hematite and goethite, with higher Hm/Gt ratios in the wetter environment. The differences between the mineral phases of the two soils explain the variation of physical and morphological characteristics found in the Luvissols of the semiarid region.

BANKING MEMBERS:
Externo à Instituição - FÁBIO SOARES DE OLIVEIRA - UFMG
Externo à Instituição - GABRIEL RAMATIS PUGLIESE ANDRADE - UENF
Presidente - 1538852 - VALDOMIRO SEVERINO DE SOUZA JUNIOR