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제 1 장. 퇴적물 및 퇴적암의 일반적인 성질

정대교 (강원대학교 지질학과)

 

Texture(조직)

  • 입도(grain size) : Udden & Wentworth 분류체계 : Φ = -log2d
  • 입도상수 (grain size parameter)

              Median         

              Mean          

              Sorting         

              Skewness      

              Mode : 최빈값

              Moments : n 번째 value(25, 75 or 16, 84)

              

              

                            

          · Skewness(왜도) :     

 

              + (positive) : fine-skewed - fluvial sand (다량의 점토와 silt 함유)

              - (negative) : coarse-skewed - 해안의 sand ( wave 에 의해 세립질 제거)

 

          · Kurtosis(첨도) :       leptokurtic - peaked curves      ┐

                                           platykurtic - flat curves                ┘  Kurtosis ( Folk)

                                         

  • Grain Shape

          - Roundness : 0~6 rho(ρ) scale (Folk, 1955), 0~1 (Wadell : 1933)

          - Sphericity : oblate(disk), equant, bladed, prolate(roller)

                             Ψ = s/S (Wadell : 1933) (s: 같은 부피의 sphere로 환산한 표면적, S: 실제 표면적)

                             CSF = S/(LI)½ (Corey : 1949)

                             (S: short diameter, L: lond diameter, I: intermediate diameter)

 

  • Surface Texture : SEM을 이용한 표면 긁힘 연구 (주로 석영 모래 입자에 적용)

          ① Concoidal fracture - outwash fan

          ② Smooth  rounded - v_shaped percussion - beach

          ③ Frosted, pock-marked & concoidal fracture - desert

  • Fabric : packing  ┌ cubic - least stable
                               ├ rhombic - most stable
                               ├ point - contact
                               └ concave - convex contact, sutured contact, preferred orientation,                                              (imbrication)
                                  grain-supported & matrix- supported
  • Porosity & permeability (moisture content)
    - cubic : 47.6%. - rhombic : 26%
  • Textural maturity

          immature >5% clay, poor sorting, angular grains.

          submature - little or no clay, poor-sorting, angular grains.

          mature - good sorting, angular grain.

          supermature - good sorting, well-rounded.

  • Textural inversion: well-rounded but poorly sorted sediments

           → two environments or sources에서 유래된 퇴적물의 mixing(예: 하천의 본류와 지류의 합류지점,                조간대에서 storm wave 또는 bioturbation에 의한 상하 퇴적층의 교란)

           → 퇴적암 기원의 recycled퇴적물의 경우.

 

  ** Selective transport : 퇴적물의 초기 이동에 영향을 주는 요소

 

   ① pivot angle

       

 

  ② 기타 : size, shape, density(hydraulic equivalence)

              fluid viscosity, turbulence intensity concentration of particles

  

      기타변수 : particle flocculation - clay mineral : - charged

       

                    transport : 두 요소의 상호작용  ┌ fluid drag velocity

                                                               └ bed stress

  제2장. Mineralogy
  제3장. Sedimentary Processes
  제4장. Sedimentary Structures
  제5장. Sedimentary Facies Model (퇴적환경모델)-1
  제5장. Sedimentary Facies Model (퇴적환경모델)-2

  <참고>
  <부록>

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