- Timing constraints on thermal episodes derived from AFTA data
in individual samples from Keep River-1 and shallow onshore boreholes.
- Two major thermal episodes are recognised: 200-155 Ma (Early
to Middle Jurassic) and 50-20 Ma (Paleocene-Miocene).
- Reconstructed thermal history of units preserved in Keep-River-1
based on thermal history interpretation of AFTA and VR.
- Two paleo-thermal episodes have been recognised:
- Cooling beginning between 200 and 155 Ma (Early to Middle
Jurassic) attributed to decline in basal heat flow combined
with uplift and erosion.
- Cooling beginning between 50 and 20 Ma (Eocene-Miocene) attributed
solely to uplift and erosion.
Timing limits derived from AFTA samples in this well are shown
as the grey shading.
- Variation of maturity with time for Keep River-1 derived from
the reconstructed thermal history illustrated in the figure above,
with the grey columns representing the two major thermal episodes
revealed by AFTA.
- The figure shows cessation of active source rock maturation
throughout the drilled section at 200 Ma (200-155 Ma allowed by
AFTA) due to cooling as a response to decline in basal heat flow
and minor (1000 m) uplift and erosion. Note that the Tertiary
thermal episode has no effect on the source rock maturation history
anywhere in the section.