684
a
INTERGRANULAR
POROSITY
POROSITY
PRIMARY DEPOSITIONAL POROSITY
MINERAL
OVERGROWTH
Yt... . . . ~b. ~_1-..1
DUCTlLEGRAIN
DEFORM.
PRESSURE SOLUTION
>
DEPTH
1
POROSITY REDUCTION
SY MECHANICAL
COMPACTION
POROSITY REDUCTION
SY "CHEMICAL CQMPACTION'(PRESSURE
SOLUTION, DISSOLUTION·
REPRECIPITATION)
b
OVERPRESSURE
Chapter 13 Diagenesis
c
POROSITY
INTRAMATRIX
.....-_ ___ ),.. PARTICLE
POROSITY
...------, /1
EARLY CEMENTATIO N
(LiTTLE MECH. COMP.)
LATER CEMENTS
1: REPLACING EARLIEA
CEMENTS
DENUDATION
AND SELECTIVE
d 1
LEACHING
OF CEMENT
: ~_ i
I
I
I
I
I
I
OlL
I
I : . : . : . : . : . :
~
NO FURTHER REDUCTION
SEC~~DARY POROSITY
e CARBONATES
IN PORE SPACE) /
:!: FRACTURING
INTERGRYSTALLINE
MOLDIC AND
SECONDARY
'
~ PARTIALLY FILLE 0
VUGGY POR/,
Y
FRACTURE
Fig. 13.22. Evolution of sandstone porosity with increasing burial depth and time. a Reduction of porosity by mechanical and (iso )chemical compaction predates late (allochernical) cementation. b Same as a
but prograding pore space reduction is hampered or
terminated by overpressure and oil fill. c Early ceneighboring rocks with water-fiHed pores are further
affected by processes changing their porosity.
PRESSURE
SOLUTION
DURING
DEFOR-rv1ATlON
mentation largely prevents mechanical compaction
and pressure solution; secondary porosity by leaching
of cement and unstable grains. d Selective leaching
of cement and unstable grains after uplift and denudation. e Some features of secondary porosity in carbonates. (PartiaHy based on SeHey 1976; Mitra 1988)
a
INTERGRANULAR
POROSITY
POROSITY
PRIMARY DEPOSITIONAL POROSITY
MINERAL
OVERGROWTH
Yt... . . . ~b. ~_1-..1
DUCTlLEGRAIN
DEFORM.
PRESSURE SOLUTION
>
DEPTH
1
POROSITY REDUCTION
SY MECHANICAL
COMPACTION
POROSITY REDUCTION
SY "CHEMICAL CQMPACTION'(PRESSURE
SOLUTION, DISSOLUTION·
REPRECIPITATION)
b
OVERPRESSURE
Chapter 13 Diagenesis
c
POROSITY
INTRAMATRIX
.....-_ ___ ),.. PARTICLE
POROSITY
...------, /1
EARLY CEMENTATIO N
(LiTTLE MECH. COMP.)
LATER CEMENTS
1: REPLACING EARLIEA
CEMENTS
DENUDATION
AND SELECTIVE
d 1
LEACHING
OF CEMENT
: ~_ i
I
I
I
I
I
I
OlL
I
I : . : . : . : . : . :
~
NO FURTHER REDUCTION
SEC~~DARY POROSITY
e CARBONATES
IN PORE SPACE) /
:!: FRACTURING
INTERGRYSTALLINE
MOLDIC AND
SECONDARY
'
~ PARTIALLY FILLE 0
VUGGY POR/,
Y
FRACTURE
Fig. 13.22. Evolution of sandstone porosity with increasing burial depth and time. a Reduction of porosity by mechanical and (iso )chemical compaction predates late (allochernical) cementation. b Same as a
but prograding pore space reduction is hampered or
terminated by overpressure and oil fill. c Early ceneighboring rocks with water-fiHed pores are further
affected by processes changing their porosity.
PRESSURE
SOLUTION
DURING
DEFOR-rv1ATlON
mentation largely prevents mechanical compaction
and pressure solution; secondary porosity by leaching
of cement and unstable grains. d Selective leaching
of cement and unstable grains after uplift and denudation. e Some features of secondary porosity in carbonates. (PartiaHy based on SeHey 1976; Mitra 1988)