Classification of Kerogen, Perspective on palynofacies in depositional environment and sequence stratigraphic framework

1. Classification of Kerogen,
Perspective on palynofacies in depositional
environment and
sequence stratigraphic framework

2. What is Kerogen:
Kerogen is solid, insoluble organic matter in sedimentary rocks.
The name "kerogen" was introduced by the Scottish organic
chemistAlexander Crum Brown in 1906.
it is the most abundant source of organic compounds on earth,
exceeding the total organic content of living matter 10,000-fold.
It is insoluble in normal organic solvents and it does not have a
specific chemical formula.
Upon heating, kerogen converts in part to liquid and gaseous
hydrocarbons. Petroleum and natural gas form from
kerogen. Kerogen may be classified by its origin: lacustrine
(e.g., algal), marine (e.g., planktonic),
and terrestrial (e.g., pollen and spores).

3. Formation of kerogen:
Kerogen is formed during sedimentary
degradation of living matter. The original organic matter
diagenesis from the
can
comprise lacustrine and marine algae and plankton and terrestrial
higher-order plants. During diagenesis, large biopolymers from,
e.g., proteins, lipids, and carbohydrates in the original organic matter
decompose partially or completely.
material, subsequent sedimentation
When kerogen is contemporaneously deposited with geologic
and
progressive burial or overburden provide elevated pressure and
temperature resulting changes in the burial temperatures and
pressures lead to further changes in kerogen composition.
During the process of thermal maturation, kerogen breaks down in
high-temperature pyrolysis reactions to form lower-molecular-weight
products including bitumen, oil, and gas.

8. Classification of Kerogen:

9. PROPERTIES OF DIFFERENT TYPES OF KEROGEN

13. Perspective on palynofacies in depositional environment
Palynofacies analysis is the study of particulate organic matter assemblages (sensu
Boulter and Riddick 1986) concerned with changes in the relative abundance of
various types of organic debris such as palynomorphs, zooclasts, phytoclasts and
amorphous organic matter (AOM).
The modern palynofacies concept is in many ways equivalent to that of organic
facies, which represents bulk organic geochemistry in the sediments. However,
based on the visual observation of organic particles in the sediment, palynofacies
analysis provides more parameters than bulk geochemical data and allows
interpreting the changes in the sedimentary environment based on high variety of
parameters.
Palynofacies data also provide direct information on the biological sources and
constituents of the particulate organic matter assemblages, therefore palynofacies
analysis is used as an aid in petroleum geology and paleo-environmental and paleo-
oceanographic interpretations.

14. Palynofacies-A= spore-pollen dominating
Palynofacies-B = translucent phytoclasts dominating
Palynofacies-C = opaque phytoclasts dominating
Palynofacies-D = degraded and amorphous organic matter dominating
Lacustrine setting

15. Terrestrial setting

16. TERNARYAPPPALYNOFACIES DIAGRAM OFTYSON (1993) IN MARINE SETTINGS

17. DT/DOM: degraded terrestrial/ Degraded Organic Matter, SP: palynomorphs/spore-pollen, W: wood, NSC: non-
structured charcoal, SC: structured charcoal, CT: cuticle,AOM:Amorphous Organic Matter

20. Combaz (1964) introduced the term palynofacies as “the total complement of
acid resistant particulate organic matter recovered from sediments by
palynological processing techniques”. However, Tyson (1995) provided the most
recent and widely used definition of the palynofacies term as “the total particulate
organic matter assemblage contained in a body of sediment thought to reflect a
specific set of environmental conditions, or to be associated with a characteristic
range of hydrocarbon generating potential”.
The latter definition can be used in paleoenvironment interpretation as well as in
source rock evaluation and will be used here because it links palynofacies types
to sedimentary sequences.
The spatial and stratigraphic variations in the distribution of sedimentary organic
matter reflect changes in the depositional system related to relative sea level
fluctuations. Detecting significant palynofacies patterns within sedimentary series
enables the characterization of Transgressive deposits (TSd) and Highstand
deposits (HSd) and the recognition of maximum flooding zones (mfz) and
sequence boundaries (sb) in terms of sequence biostratigraphy. Resultantly,
palynofacies analysis alongwith some integrated proxies (lithofacies and
geochemical aspects) may be used as a powerful tool for high-resolution
sequence stratigraphy.
Perspective on palynofacies in sequence stratigraphic framework

24. T-lst, T-hst, T-tst and T-mfs corresponding to the Low Stand System Tract (LST), High Stand System Tract
(HST), Transgressive System Tract (TST) and Maximum Flooding Surface (MFS) respectively.

25. 1. Palynofacies showing non-fluorescent AOM (black
arrows marked nf-AOM), 2a. Palynofacies showing
fluorescent organic matter (white arrows marked, f-
AOM and f-SP), non-fluorescent organic matter (black
arrows marked, nf-AOM)), 2b. Palynofacies showing
well-preserved palynomorph under transmitted light
(red arrow marked) 3. Palynofacies showing the
dominance of non-fluorescent organic matter,4.
Palynofacies showing the dominance of non-
fluorescent organic matter (black arrow marked) except
f-SP (white arrow marked), 5. Palynofacies showing
the dominance of non-fluorescent organic matter (black
organic matter) except f-SP (white arrow marked) 6.
Palynofacies showing well-preserved fluorescent
palynomorphs (white arrow marked), 7. Palynofacies is
dominated by the fluorescent organic matter along with
the non-fluorescent structured phytoclasts (red arrow
marked, nf-ST), 8. Palynofacies showing a mixture of
the fluorescent SP and non-fluorescent organic matter
(AOM, CH).