Thermal history analysis by integrated modelling of apatite fission track and vitrinite reflectance data: application to an inverted basin (Buller Coalfield, New Zealand)

The Emperor and Golden Beach Subgroups are becoming the focus of Gippsland Basin exploration, yet little is known about their composition and distribution. Regional modelling of over 400 apatite fission track analyses in the hinterland constrains the timing, magnitude and distribution of uplift and denudation and hence sediment supply to the basin. The study yielded regional maps through time of palaeotemperature, overburden, denudation rate and palaeotopography, with increasing assumptions and hence uncertainty.Regionally the >60,000 km3 of Strzelecki Group comprises ~90% volcanoclastic detritus and coal with only ~10% basement-derived sediment, but the northern margin of the basin, near Lakes Entrance, is likely to have a higher basement-derived portion resulting in better reservoirs. The basement-derived sediments are probably largely granitic as the Devonian granites were exposed during the Permo-Triassic Hunter-Bowen Orogeny. Regional mid-Cretaceous uplift resulted in increased denudation of basement, but inversion of the basin margins resulted in denudation of the onshore Strzelecki Group sediments. Emperor and Golden Beach Subgroup sediments deposited in the subsiding Central Graben were at least 50% basement-derived, again with higher quality reservoirs predicted near the Lakes Entrance area and poorer reservoirs near to Wilson’s Promontory. The Latrobe Group siliciclastics were at least 80% derived from basement with a substantial portion from northern Tasmania and the Furneaux Islands around 60-50 Ma.

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Apatite fission-track age correction and thermal history analysis from projected track length distributions

Chemical Geology ◽

10.1016/0009-2541(93)90298-w ◽

1993 ◽

Vol 103 (1-4) ◽

pp. 157-169

Author(s):

M. Grivet ◽

M. Rebetez ◽

N. Ben Ghouma ◽

A. Chambaudet ◽

R. Jonckheere ◽

...

Keyword(s):

Thermal History ◽

Fission Track ◽

Track Length ◽

Apatite Fission Track ◽

History Analysis ◽

Age Correction

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The Scotian Basin offshore Nova Scotia: thermal history and provenance of sandstones from apatite fission track and 40Ar/39Ar data

Canadian Journal of Earth Sciences ◽

10.1139/e92-077 ◽

1992 ◽

Vol 29 (5) ◽

pp. 909-924 ◽

Cited By ~ 11

Author(s):

A. M. Grist ◽

P. H. Reynolds ◽

M. Zentilli ◽

C. Beaumont

Keyword(s):

Nova Scotia ◽

Thermal History ◽

Fission Track ◽

Vitrinite Reflectance ◽

Source Rocks ◽

Apatite Fission Track ◽

Eastern Canada ◽

Grenville Province ◽

Thermal Indicators ◽

Fission Track Ages

Apatite fission track and 40Ar/39Ar age spectrum data from sandstone drill-core minerals taken from depths of 2–5 km in nine wells from the Scotian Basin are presented and interpreted in terms of the thermal history of the basin and the provenance of its sediments. The focus of the study is a comparison of the data from these thermochronometers with each other and with previously published vitrinite reflectance and aromatization–isomerization (A–I) reactions in biomarker compounds from the same or nearby wells.Apatite fission track ages are generally in agreement with expectations in that they trend to zero at a depth of ~4 km (corrected bottom-hole temperature ~120 °C). Shallower (lower present temperature) samples are partially annealed; the degree of partial annealing correlates closely with the degree of A–I reactions. Both thermal indicators are activated over the temperature range 60–120 °C.Samples from two wells, Mic Mac J-77 and Erie D-26, are anomalous. They are more annealed than present formation temperatures would predict, an anomaly that is also indicated by the A–I data. These samples are interpreted as having experienced higher than present temperatures subsequent to deposition, possibly resulting from the passage of hot fluids related to localized volcanism or the sudden venting of an overpressured reservoir.K-feldspars record minor (< 20%) argon loss as a result of burial heating in the basin only at the greatest depths of the sampled range (> 4.3 km). This result is in agreement with the thermal models of the Scotian Basin and extrapolation of the A–I and fission track data to greater depths. The inferred argon loss implies an activation energy of 40 ± 4 kcal/mol for the smallest diffusion domains.The argon age spectra for samples that have not lost argon during residence in the basin provide evidence on the provenance of the sediments. K-feldspars from the Early Cretaceous Missisauga Formation have spectra that are similar to those obtained from K-feldspars from the Grenville Province of the Canadian Shield, whereas muscovites from the same formation give Cambrian to Carboniferous argon ages (mean 387 Ma), an indication of contributions from other source rocks. Corresponding data from the Jurassic Mohican Formation are similar to those reported for plutons from the southern Nova Scotia mainland (ca. 250–350 Ma argon ages). By implication, the Mohican Formation, which is the earliest postrift deposit, was derived from local sources inferred to be adjacent flank uplifts, whereas the Missisauga Formation was derived in part either directly or indirectly from the Grenvillian-aged interior of eastern Canada.

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