|
Part I: Concepts and Methods |
School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ
Department of Geological Sciences, University College London, Gower Street, London, WC1E 6BT
This paper attempts to demonstrate that the multi-disciplinary philosophy behind palynofacies investigations is of great value to the meaningful interpretation of the origins and palaeoenvironment of marine petroleum source rocks (MPSRs).
The key control on the formation of MPSRs is identified as bottom water oxygenation (correlated with the location of the Eh interface and the intensity of macrobenthic activity). Particular emphasis is placed on the necessity for greater accuracy in the terminology used to describe levels of oxygenation. Aerobic environments are characterized by organically lean sediments (0–3.0% TOC) with Type III kerogen assemblages composed of relatively refractory land plant debris or highly degraded, marine-derived, amorphous organic matter (AOM). Their organic richness is largely dependent on sediment accumulation rate and proximity to sources of terrestrial organic matter supply. They produce mainly gas at maturation. Dysaerobic to anoxic environments are characterized by MPSR facies with high TOC values and Type II kerogen assemblages dominated by relatively lipid-rich AOM. These represent the classic ‘black shale’ source rocks and are the main source of petroleum in marine basins.
Except where they are redeposited, dinocysts are characteristically absent or rare in marine ‘black shales’. They are mainly produced in unstable, seasonally mixed water masses and may consequently be regarded as indices of hydrographic stability. Prasinophycean phycomas, which differ from dinocysts in their function, are often the dominant, or most conspicuous, marine palynomorphs of pelagic sediments and stably stratified ‘black shale’ basins.
This article has been cited by other articles:
 |
|
 |
|
  C. E. Barker, M. Pawlewicz, and E. A. Cobabe Deposition of sedimentary organic matter in black shale facies indicated by the geochemistry and petrography of high-resolution samples, Blake Nose, western North Atlantic Geological Society, London, Special Publications, 2001; 183: 49 - 72. [Abstract] [PDF]
|
|
|
|
 |
|
 J. W. Murray, J. W. Murray, and S. S. Bowser MORTALITY, PROTOPLASM DECAY RATE, AND RELIABILITY OF STAINING TECHNIQUES TO RECOGNIZE 'LIVING' FORAMINIFERA: A REVIEW Journal of Foraminiferal Research, 2000; 30: 66 - 70. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. T. Higgs, I. A. J. MacCarthy, and M. M. O'Brien A mid-Frasnian marine incursion into the southern part of the Munster Basin: evidence from the Foilcoagh Bay Beds, Sherkin Formation, SW County Cork, Ireland Geological Society, London, Special Publications, 2000; 180: 319 - 332. [Abstract] [PDF]
|
|
|
|
|
|
A. El Albani, W. Kuhnt, F. Luderer, J. P. Herbin, and M. Caron Palaeoenvironmental evolution of the Late Cretaceous sequence in the Tarfaya Basin (southwest of Morocco) Geological Society, London, Special Publications, 1999; 153: 223 - 240. [Abstract] [PDF]
|
|
|
|
|
|
T. Wagner and T. Pletsch Tectono-sedimentary controls on Cretaceous black shale deposition along the opening Equatorial Atlantic Gateway (ODP Leg 159) Geological Society, London, Special Publications, 1999; 153: 241 - 265. [Abstract] [PDF]
|
|
|
|
|
|
Y. Nathan Humic substances in phosphorites: occurrence, characterization and significance Geological Society, London, Special Publications, 1990; 52: 49 - 58. [Abstract] [PDF]
|
|
