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anch activities
Curtin Geology Student Society (GEOS) Quiz Night
The WA Branch of PESA sponsored
a Quiz Night in mid-August
for Curtin University geology
students to attend.
PESA provided support to encourage
students to be socially active networking
with each other and to participate in
building stronger relationships with
professional organisations, such as PESA,
throughout their geological careers.
GEOS reports that the Quiz Night was a fantastic
affair, commencing with a BBQ at the beg inning
of the night to provide the 50 attendees with
sustenance for the night ahead. The quiz
consisted of 10 rounds with varying topics
from biology to pop culture. Between
the rounds, attendees were challenged
to create the tallest tower out of items
on the table and to find out who
could do the best impersonations.
It was a great night where people
from different year groups got
to socialise and there were even
a few lecturers who joined in
the fun.
Continued from page 22
Osorio, Fig. 1.
From the relevant scientific literature, it is
believed that earthquakes are among the
most critical factors in submarine landslide
generation. A case study employing a numerical
model of a submarine slope stimulated by
earthquake action was then developed to
test this hypothesis. Through this case study,
it was revealed that submarine slope stability
was highly sensitive to changes in excess
pore pressure generation as a result of varying
earthquake magnitude, demonstrating that
earthquakes can indeed be considered a highly
probable cause for the formation of submarine
landslides. Despite these positive results, the
exact physical mechanism responsible for this
process is still open to debate and other material
parameters utilised in the modelled submarine
slope have yet to be calibrated and verified with
other types of submarine soils. It is concluded
that deep-seated submarine landslides are very
likely to be induced by earthquake excitation.
Chemical analysis of source rocks
Emma Flannery, Macquarie University
The chemical analysis of source rocks and oils
provides invaluable information on thermal
maturity, source characteristics, oil-oil or oilsource
correlations and palaeobiology. The use
of chemical analysis in the understanding of
the palaeobiology is particularly important in
Precambrian rocks, due to the relative scarcity
of body fossils. Many applications involving the
analysis of hydrocarbons in petroleum systems
rely upon the assumption that there has been no
contamination of the sample. Due to both age and
typically low total organic carbon content however,
Precambrian basins are susceptible to hydrocarbon
overprinting due to contamination. In my honours
study three cores from the 1.4 billion year old
Velkerri Formation, McArthur Basin, were subjected
to slice experiments and molecular geochemical
analyses using gas chromatography-mass
spectrometry (GC-MS). Internal slices were found
to have consistent hydrocarbon signals, providing
strong evidence that the organic matter in the
inner slices is indigenous (Figure 1). In all three
cores, both the aliphatic and aromatic hydrocarbon
signatures indicate that the outside of the
core had been exposed to contamination
from both the drilling and sawing processes
(Figure 2). This contamination has the potential
to overprint the indigenous hydrocarbon signal
and highlights the importance of the removal
of the outside portion of the drill core prior to
analysis, even in organic rich rocks.
Biomarkers are molecular fossils that allow us
to infer the past presence of life. In my study,
biomarker analysis of Velkerri Formation rock
extracts allowed for the reconstruction of the
palaeobiology at time of deposition. High
bacterial input into the organic matter was
evidenced by hopanes, bicyclic sesquiterpanes
and monomethylalkanes. This is not unusual
as Precambrian source rocks are thought
to result almost entirely from microbial mat
growth. Steranes, or eukaryotic biomarkers,
have previously reported in Velkerri Formation
oils and rock extracts. However, in this study
steranes were found to be absent or below the
limit of detection, indicating a low input from
eukaryotes in the deep marine environment
of the Velkerri Formation. This suggests that
previous studies on the chemical composition
of Velkerri Formation rock extracts, particularly
that use whole rock extraction, may have
analysed non-indigenous steranes.
Flannery, Fig. 1. An example of one of the many
compound groups studied in McManus-1 1216 m:
n-Alkanes normalised to the n-alkane with the
highest concentration in each slice, showing
inconsistent hydrocarbon distributions in both the
outside flat slice and outside curve slice A. Slices B
to F show a consistent hydrocarbon distribution,
attributable to the indigenous hydrocarbon signal.
Flannery, Fig. 2. An example of one of the many
compound groups studied in McManus-1 1216 m:
Concentration of n-alkanes with % error estimate
in McManus-1 slices. The outside flat slice shows
an increase in concentration in n-alkanes
compared to slices A–F.
December 2012 / January 2013 | PESA News Resources | 23