The times they are a-changin': Australian biozones, petroleum basins, and the international geologic time scale (GTS) 2012

The international Geologic Time Scale (GTS) continually evolves due to refinements in age dating and the addition of more defined stages. The GTS 2012 has replaced GTS 2004 as the global standard timescale, resulting in changes to the age and duration of most chronological stages. These revisions have implications for interpreted ages and durations of sedimentary rocks in Australian basins, with ramifications for petroleum systems modelling. Accurate stratigraphic ages are required to reliably model the burial history of a basin, hence kerogen maturation and hydrocarbon expulsion and migration. When the resolution of the time scale is increased, models that utilise updated ages will better reflect the true basin history. The international GTS is largely built around northern hemisphere datasets. At APPEA 2009, Laurie et al. announced a program to tie Australian biozones to GTS 2004. Now, with the implementation of GTS 2012, these ties are being updated and refined, requiring a comprehensive review of the correlations between Australian and International biozonation schemes. The use of Geoscience Australia’s Timescales Database and a customised ‘Australian Datapack’ for the visualisation software package TimeScale Creator has greatly facilitated the transition from GTS 2004 to GTS 2012, as anticipated in the design of the program in 2009. Geoscience Australia’s basin biozonation and stratigraphy charts (e.g. Northern Carnarvon and Browse basins) are being reproduced to reflect the GTS 2012 and modified stratigraphic ages. Additionally, new charts are being added to the series, including a set of onshore basin charts, such as the Georgina and Canning basins.

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Geologic Time

10.1093/oso/9780197502464.003.0005 ◽

2021 ◽

pp. 69-81

Author(s):

Elisabeth Ervin-Blankenheim

Keyword(s):

Time Scale ◽

Age Dating ◽

Marie Curie ◽

Ernest Rutherford ◽

Relative Age ◽

Geologic Time ◽

The Earth ◽

Geologic Time Scale ◽

Geologic Maps ◽

History Of

Geologists first unraveled the geologic time scale by relative age-dating, discussed in the last chapter. Once geologists sorted out the order of rock units, subsequent advances in methodologies, detailed in this chapter, by chronometric and numerical means based on radioisotopes, other atomic measures, and quantitative techniques, were employed to measure time. Many minerals and rocks have “clocks” within them that can be used to pin down the actual age of the particular geologic sample or the age of boundaries between formal units of the geologic time scale. This chapter explains how geologists decipher those clocks and determine the ages of rocks by numerical age-dating. The history of radioisotopes is tracked, starting with Ernest Rutherford and Pierre and Marie Curie. The modern geologic time scale is depicted and expanded upon, along with why it is essential for geologic maps and how the time scale can help with people-sized problems and challenges faced on the Earth.

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Sequencing Time

The Paleontological Society Papers ◽

10.1017/s108933260000320x ◽

1996 ◽

Vol 2 ◽

pp. 127-136

Author(s):

Judy Scotchmoor

Keyword(s):

Time Scale ◽

Geologic Time ◽

The Earth ◽

Geologic Time Scale ◽

History Of

Telling the history of the earth requires placing events in sequence so that reference can be given to the relative and/or numerical time at which each event occurred. This helps to make sense out of the enormous expanse of time that has elapsed since the origin of the earth. This activity will help students to understand the methods used by geologists in creating the Geologic Time Scale.

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The Geological Time Scale

The Paleontological Society Papers ◽

10.1017/s1089332600001376 ◽

2006 ◽

Vol 12 ◽

pp. 107-123 ◽

Cited By ~ 1

Author(s):

Felix M. Gradstein

Keyword(s):

Time Scale ◽

Best Practice ◽

Age Dating ◽

Geological Time ◽

Geological Time Scale ◽

Geologic Time ◽

Global Correlation ◽

Geologic Time Scale ◽

Orbital Tuning ◽

Stage Boundaries

This lecture reviews Geologic Time Scale 2004 (Gradstein, Ogg et al., 2004; Cambridge University Press), constructed and detailed by 40 geoscience specialists, and indicates how it will be further refined. Since Geologic Time Scale 1989 by Harland et al., many developments have taken place: (1) Stratigraphic standardization through the work of the International Commission on Stratigraphy (ICS) has greatly refined the international chronostratigraphic scale. In some cases, traditional European-based stages have been replaced with new subdivisions that allow global correlation. (2) New or enhanced methods of extracting high-precision age assignments with realistic uncertainties from the rock record. These have led to improved age assignments of key geologic stage boundaries and other global correlation horizons. (3) Orbital tuning has greatly refined the Neogene, and improved parts of Paleogene and Mesozoic. (4) Statistical techniques of compiling integrated global stratigraphic scales within geologic periods.Anticipated advances to the Geologic Time Scale during the next 8 years include: a geologically realistic Precambrian scale, formal definition of all Phanerozoic stage boundaries, orbital tuning of polarity chrons and biostratigraphic events for entire Cenozoic and Cretaceous, a detailed database of high-resolution radiometric ages that includes “best practice” procedures, full error analysis, monitor ages and conversions, resolving age dating controversies (e.g., zircon statistics and possible reworking) across Devonian/Carboniferous, Permian/Triassic, and Anisian/Ladinian boundaries, improved and standardized dating of several ‘neglected’ intervals (e.g., Upper Jurassic – Lower Cretaceous, and Carboniferous through Triassic, and detailed integrated stratigraphy for Upper Paleozoic through Lower Mesozoic.The geochronological science community and ICS are focusing on these issues. A modified version of the time scale to accompany the standardization (boundary definitions and stratotypes) of all stages is planned for 2008 (to be presented at the 33th International Geologic Congress in Oslo), with a totally revised version of GTS available in 2012.

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