Geochemical and mineralogical analysis of low-grade metamorphic rocks and their response to shallow landslide occurrence in Central Nepal

被引:0
作者
Silwal, Bishow Raj [1 ]
Gyawali, Babu Ram [2 ]
Yoshida, Kohki [3 ]
机构
[1] Shinshu Univ, Grad Sch Med Sci & Technol, Dept Sci & Technol, 3-1-1 Asahi, Matsumoto, Nagano 3908621, Japan
[2] Pokhara Univ, Lumbini Engn Management & Sci Coll, Butwal, Nepal
[3] Shinshu Univ, Fac Sci, Dept Geol, 3-1-1 Asahi, Matsumoto 3908621, Japan
基金
日本学术振兴会;
关键词
Weathering; Landslide; Clay mineralogy; Lesser Himalaya; Metamorphic rocks; CHEMICAL-WEATHERING INDEXES; PHYSICAL EROSION; PROFILES; CALABRIA; MOUNTAINS; HIMALAYA; TRENDS; RIVERS; MASSES; BASIN;
D O I
10.1186/s40677-024-00301-9
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
BackgroundThe weathering intensity and geochemical properties of a rock contribute to shallow landslide occurrences. This study aims to establish the role of rock weathering in shallow slope instability in low-grade metamorphic rocks of the Lesser Himalaya region of central Nepal. The rocks of the Kuncha Formation, which consist of phyllites, metasandstones, and gritty phyllites are characterized by the formation of shallow landslides. Field characterization of the rock mass within the landslide body, along with petrographic observations, clay mineral analysis, and major bulk geochemistry were adopted to establish a relationship between rock weathering and landslide occurrence.ResultsThe landslides distributed within the Kuncha Formation in the study area are debris-related slides and falls, rock falls, and complex slides. Microscopic petrographic observation of rock from the landslide area revealed well-developed microcracks and intergranular microfractures within the weathered samples, which suggests extensive disintegration and physical alteration. Kinematic analysis of the landslide slope revealed that discontinuities and bedding planes also affected the failure of the slope. The occurrence of neo-formed clay minerals and the conversion of biotite-muscovite to vermiculite, kaolinite, and mixed-layer clays indicate chemical weathering. The CIA ranges between 71 and 80 for the rock samples and between 72 and 84 for the soil samples, signifying moderate to extreme weathering effects. The higher values of PIA and CIW reveal K-feldspar and plagioclase alteration to clay minerals by weathering and alteration. CIA-LOI plots reveal significant relationships corresponding to weathering effects.ConclusionThe transition of rock from a fresh to a moderately weathered state and the development of clay minerals and major discontinuities played a crucial role in shallow landslide occurrence. The weakened physical properties of the rock mass due to weathering coupled with unfavorable joints and fracture conditions have led to instability of the hillslopes in the study area. It was observed that one of the driving factors that drives slopes to erosion and landslides is weathering. The dominant occurrence of landslides in the weathered rock domain within the study area validates the occurrence of landslides and weathering interconnections.
引用
收藏
页数:30
相关论文
共 94 条
  • [31] Major element and REE compositions of Pliocene sediments in southwest Japan: Implications for paleoweathering and paleoclimate
    Hatano, Nozomi
    Yoshida, Kohki
    Mori, Saori
    Sasao, Eiji
    [J]. SEDIMENTARY GEOLOGY, 2020, 408
  • [32] Hoek E., 1997, Rock slope engineering
  • [33] Hutchinson J. N., 1988, Landslides., P3
  • [34] Geotechnical and landslide aspects in weathered granitoid rock masses (Serre Massif, southern Calabria, Italy)
    Ietto, F.
    Perri, F.
    Cella, F.
    [J]. CATENA, 2016, 145 : 301 - 315
  • [35] Weathering characterization for landslides modeling in granitoid rock masses of the Capo Vaticano promontory (Calabria, Italy)
    Ietto, Fabio
    Perri, Francesco
    Cella, Federico
    [J]. LANDSLIDES, 2018, 15 (01) : 43 - 62
  • [36] Irfan TY., 1978, Ann Socit Gologique Belg, V101, P71
  • [37] ISRM (Commission on Standardization of Laboratory and Field), 1977, Int J Rock Mech Min Sci Geomech Abst, V16, P141
  • [38] Morphological and mineralogical characterization of weathering zones in tropical climates: A basis for understanding the weathering process on granitic rocks in southeastern Brazil
    Jaques, Daniel Silva
    Marques, Eduardo Antonio Gomes
    Marcellino, Lazaro Correa
    Leao, Marcio Fernandes
    Carvalho Coelho, Vanessa dos Santos
    [J]. JOURNAL OF SOUTH AMERICAN EARTH SCIENCES, 2021, 108
  • [39] Weathering Controlled Landslide in Deccan Traps: Insight from Mahabaleshwar, Maharashtra
    Joshi, Mayank
    Rajappan, S.
    Rajan, P. Prasobh
    Mathai, J.
    Sankar, G.
    Nandakumar, V.
    Kumar, V. Anil
    [J]. JOURNAL OF THE GEOLOGICAL SOCIETY OF INDIA, 2018, 92 (05) : 555 - 561
  • [40] New climatic classification of Nepal
    Karki, Ramchandra
    Talchabhadel, Rocky
    Aalto, Juha
    Baidya, Saraju Kumar
    [J]. THEORETICAL AND APPLIED CLIMATOLOGY, 2016, 125 (3-4) : 799 - 808