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A systematic appraisal of the Neoproterozoic stratigraphy of the Amadeus Basin – building a framework for assessing resource potential

C Edgoose1, V Normington1

N Donnellan1, N Kositcin2

1 NTGS, 2 Geoscience Australia

Neoproterozoic stratigraphy of the Amadeus Basin Project aims and scope

• systematically characterise stratigraphy and define depositional history • address issues of correlation • develop a better understanding of basin architecture and tectonic framework through integration with other datasets • provide the basis for mineral and petroleum prospectivity assessment of stratigraphic intervals • provide useful datasets to assist with mineral and petroleum exploration.

Presenter

Presentation Notes

NTGS has discussed the intention of commencing a major program in the Amadeus Basin at recent AGES conferences. My presentation this afternoon is to report that in late 2013 the Amadeus basin project commenced after a successful recruitment of new geoscience staff. The projects initial focus will be on taking a systematic approach to building a comprehensive dataset to characterise the stratigraphy and depositional history of the basin……

Neoproterozoic stratigraphy of the Amadeus Basin

Ngalia Basin

Arunta Region

Georgina Basin

Musgrave Province

Eromanga Basin

Irindina Province

• large (~170,000 km2) Neoproterozoic-Devonian intracratonic sedimentary basin (the Arunta Region is ~200,000 km2)

• internationally important for its preserved record of Earth history over that period

• basement comprised of both Musgrave Province (south) and Arunta Region (north)

• affected by major intracratonic orogenic events at 580-530 Ma and 450- 300 Ma

• Up to 14 km of sediments are preserved along the northern margin • large, underexplored terrane – a significant portion has had no

modern exploration

Presenter

Presentation Notes

To set the scene a little for those who are unfamiliar with the basin -

Neoproterozoic stratigraphy of the Amadeus Basin Basin development

• Initiated as part of the Neoproterozoic intracratonic Centralian Superbasin, related to the break up of the Rodinia supercontinent

• Mechanism of basin formation is the subject of debate – rifting? plume related? • Centralian Superbasin dismantled by 580-530 Ma Petermann Orogeny, related to

assembly of Gondwana • Present day architecture strongly controlled by the effects of the two major

intracratonic orogenic events at 580-530 Ma and 450-300 Ma

Presenter

Presentation Notes

What do we know about the development of the basin?

Neoproterozoic stratigraphy of the Amadeus Basin Stratigraphic characterisation

• Mapping of key sections and localities • Lithological, depositional environment, facies variations • Petrography • Geochemistry • Stable isotope analyses on carbonates • Biostratigraphy on undescribed units • Geochronology – U/Pb and Hf on zircon - provenance • Rock property data

Interpreted Neoproterozoic geology of the Amadeus Basin

2014 2015 -

Presenter

Presentation Notes

What are the key datatsets that we will be focused on collecting for this project? For many units the type sections are poorly described and or located, and many have never been completely formalised. In particular, significant revision of the Bitter Springs Formation is warranted. Each unit will have an updated lithollogical description, depositional environment assessment, and recording of any facies variations. Quantitative data in relation to geochemistry, stable isotpoes and geochronology will be acquired. Initially, the project will focus on the Neoproterozoic stratigraphy,of the basin beginning in the NE of the basin where it is best exposed and described, and indicated in red on the slide. From 2015 onwards, the project will move into the lesser known Neoproterozoic stratigraphy of the central and southern parts of the basin, based around a 100K mapping program, shown in blue

Neoproterozoic stratigraphy of the Amadeus Basin Why the Neoproterozoic?

Cu occurrences

• Extensive surface and near surface across basin • Depositional history and basin architecture less well known • Significant issues with correlation/age of units • Prospective for base metals, particularly Cu • Largely unexplored

Presenter

Presentation Notes

Why are we starting this project with a focus on the Neoproterozoic? As you can see from the diagram, the Neoproterozoic is extensive in the surface and near surface across the basin. The basin architecture and the depositional history of this time period is less well known, largely a result of the significant transformation of the basin architecture as the result of the 580 – 530 ma Petermann Orogeny. Correlation of units – recent excellent work by Peter Haines and heidi Allen of the geological Survey of WA in the WA portion of the basin has raised several questions about our understanding of the relative ages and therefore correlation of units in the Neoproterozoic, and this work has highlighted that a significantr revision of this stratigraphy in the NT is warranted, as demonstrated in the following slides. The Neoproterozoic of the Amadeus Basin is perceived to contain some of the most prospective stratigraphy of the basin fill, with known Au, and multiple base metal (dominantly Cu) occurrences. Most of the succession has had no modern exploration.

Neoproterozoic stratigraphy of the Amadeus Basin Prospective for conventional and unconventional hydrocarbons – 3 systems, 1 established

From Munson 2014

Magee 1 – oil shows in Gillen Member of BSF, sub-commercial gas flow with 6% He in Heavitree Q

Magee 1

Dingo .

Presenter

Presentation Notes

The Neoproterozoic stratigraphy is also prospective for both conventional and unconventional hydrocarbons. In the recent review by Munson 2014, three petroleum sysytems are recognised, with the oldest one in the Heavitree quartzite and Gillen Member of the Bitter Springs formation, being considered established. This is largely on the basis of the Magee 1 well, shown on the figure, which intersected oil shows in shales of the Gillen member, and a sub-commercial gas flow from the underlying 10M of Heavitree Quartzite, which also contained 6% helium. Interest in the Neoproterozoic succession is current, with Santos drilling the Mt Kitty well through the Neoproterozoic succession in the southern part of the basin. A contract has recently been signed for the supply of gas from the Dingo where the source rock is most likely the Pertatataka Fm, into Alice Springs. This is the first pre-0rdovician commercial gas project in Australia.

Neoproterozoic stratigraphy of the Amadeus Basin Correlation issues

Musgrave Province

Heavitree Quartzite/ Bitter Springs

Inindia/Winnall

Arumbera/Mt Currie Petermann Orogeny 580-540 Ma

Areyonga/Aralka/Olympic/Pioneer/Pertatataka/Julie

Presenter

Presentation Notes

This slide illustrates an example of some of the major correlation issues in the Neoproterozoic succession of the central and southern Amadeus Basin. Historically in the NT the post Heavitree Quartzite/Bitter Springs and pre-Petermann Orogeny succession has been identified in two informal units – the Inindia beds, and the Winnall beds. THE WA stratigraphy has several equivalent units. Post-Petermann Orogeny deposition belongs to the Arumbera ss in the north, and the Mt Currie conglomerate in the south. This image shows the current distribution of the NT succession, with reference to the Petermann Orogeny . The Petermann Orogeny was a significant intracratonic orogenic event focused in the Musgrave Province to the south, and resulted in significant exhumation along deep crustal tapping structures. Given the proximity to the locus of the Petermann orogeny, the lack of post-Petermann orogeny sediments across most of the southern and central parts of the basin has always been enigmatic.




Inindia

Arumbera/Winnall/Mt Currie Petermann Orogeny 580-540 Ma

Winnall beds

Mt Currie Conglomerate

AYERS ROCK 250K

Musgrave Province

Presenter

Presentation Notes

Recent work in the WA portion of the basin by GSWA, as mentioned earlier, has resulted in a significant revision of the Neoproterozoic succession in that region. Lithological comparisons between post-Petermann orogeny units in WA, with the Winnall beds in the NT shows strong similarities in these successions, and indicates that they are likely to be correlatives. This revision significantly alters our understanding of the Neoproterozoic history of the basin, in particular that the Winnall beds were deposited in response to the Petermann Orogeny rather than prior to it, and therefore would correlate with the Arumbera Sandstone of the northern basin. The entire post Heavitree/Bitter Springs succession in the central and southern part of the basin now resides in a single unit – the Inindia beds. As mentioned earlier, the Mt Currie conglomerate represented the only deposition in the southern part of the basin resulting from uplift during the Petermann orogeny. The Mt Currie conglomerate sits on folded and dipping Winnall beds with an angular unconformity, CLICK as shown on this excerpt from the Ayers Rock 250K map, and also includes clasts of Winnall beds near its base. This unconformity was formerly interpreted to represent the PO.


Woodroffe Thrust

Musgrave Province



Inindia

Arumbera/Winnall Petermann Orogeny 580-540 Ma

Mt Currie

Presenter

Presentation Notes

Based on the work of Haines and Allen, the deposition of the Mt Currie conglomerate is now interpreted to be related to a late phase of the Petermann Orogeny, possibly significant uplift on the Woodroffe Thrust. The unconformity between the Winnall beds and the Mt Currie conglomerate reflects different phases of activity during the Petermann Orogeny. During earlier cycles of orogenesis the Winnall beds were deposited, buried, folded and exhumed, prior to deposition of the Mt Currie conglomerate in a late phase. This illustrates well how provenance studies on sedimentary successions in basins can also provide useful detail of the complex interplay of discrete events within a long lived orogen, and the subsequent uplift history in adjacent basement and source areas.

Neoproterozoic stratigraphy of the Amadeus Basin From Haines 2013

Arunta signature

Musgrave signature

Julie Fm Pertatataka Fm Olympic/Pioneer

Fm Aralka Fm Areyonga Fm

Heavitree Q/Bitter Springs Fm

Inindia

Northeast South-central Arumbera Mt Currie

Petermann Orogeny Winnall

Previous




Inindia

Northeast South-central

Arumbera Winnall Mt Currie

Revised

Arunta

Musgrave

Arunta

Musgrave

580-530 Ma Petermann Orogeny

Presenter

Presentation Notes

This histogram of detrital zircon spectra from the NT, reproduced from Haines 2013, provides some quantitative support for the revised stratigraphy. As you can see, the Winnall beds spectra in red correlates quite well with that of the Arumbera sandstone and other clearly post Petermann orogeny units, eg Mt Currie Conglomerate, in blue, and is quite different to that of the Pertatataka formation in green, with which it was previously considered to be an equivalent. The Pertatataka Fm has a dominant source area in the Arunta, whereas the Post-Petermann orogeny stratigraphy, not surprisingly, show the Musgrave province as the dominant source area.

Neoproterozoic stratigraphy of the Amadeus Basin Biostratigraphy

• Important for stratigraphic correlation – intra-basin to international

• Significant studies on stromatolites and acritarchs • Some still need to be described – eg distinctive “clast-

supported” stromatolite in Ringwood Member of Aralka Formation

Undescribed ‘clast-supported’ stromatolite, Ringwood Member, Aralka Formation

Julie Fm

Pertatataka Fm

Olympic/Pioneer Fm

Aralka Fm

Areyonga Fm


Kulparia alicia, Acaciella Australica assemblage, Loves Creek Member, Bitter Springs Formation

Heavitree Quartzite

Presenter

Presentation Notes

Biostratigraphy is an important tool for Neoproterozoic stratigraphy, despite the lack of hard bodied fossils. Stromatolites and acritarchs are particularly important and useful for this work. There have been several important studies on the biostratigraphy of the Neoproterozoic succession, and several key stromatolite assemblages have been first described from the Amadeus Basin. These have been applied to intra-basin, national and international correlation of units. However, there are still forms that are yet to be described and assessed as to whether they can be useful as a diagnostic tool. The example shown here is an informally named ‘clast-supported’ stromatolite from the Ringwood Member of the Aralka Formation. This stromatolite has been recognised in the NE, north central,s outhern and far western parts of the basin and consequently is an important marker horizon.

Neoproterozoic stratigraphy of the Amadeus Basin Biostratigraphy

Stratigraphic correlation - Stromatolite Tungussia julia found in Julie Fm in the Amadeus Basin, and in the Elkera Fm of the Georgina Basin and the basal Bonney Sst of the Adelaide Fold Belt

1 3

2

Basal Bonney Sst

Elkera Formation

JulieFormation

Adapted from Haines, 2013

1 2

3

Julie Fm

Pertatataka Fm

Olympic/Pioneer Fm

Aralka Fm

Areyonga Fm


Presenter

Presentation Notes

This slide gives an example of inter-basin correlation via biostratigraphy. The stromatolite Tungussia Julia is a form first identified and named from the Julie Formation in the Amadeus Basin. It has also been described from lithologically similar units in the Adelaide Fold Belt and in the Georgina Basin, indicating these units are correlatives.

Neoproterozoic stratigraphy of the Amadeus Basin Stable isotopes

Carbon – δ13C (carbonate and organic) Oxygen – δ18O Sulphur – δ34S Strontium – 87Sr/86Sr

• Composition of sea water • Palaeoenvironments • Age estimate via correlation

From Walter et al 2000

Adelaide FB

Officer

Amadeus Georgina

Presenter

Presentation Notes

Stable isotope studies on carbonate rocks provide information related to sea water composition and palaeoenvironments, and most importantly may allow age estimates via correlation with other units where other methods provide age control, for example radiometric ages of underlying or overlying units. This is particularly important where biostratigraphic ages are difficult due to the lack of diagnostic fossil material. Once again using the Julie Formation as an example , this diagram shows how, in addiotn to the bistratigraphic markers on the previous slide, the Julie Fm can also be correlated with the same units in the Adelaide Fold Belt and the Georgina Basins , and also the Officer basin by the distinctive large positive excursion in Carbon isotope values.

Pertatataka Fm

Neoproterozoic stratigraphy of the Amadeus Basin Geochronology

Olympic Fm ?

? ?

Aralka Fm Musgrave Arunta U-Pb detrital zircon spectra for

Neoproterozoic succession in NE Amadeus Basin

Julie Fm

Pertatataka Fm

Olympic/Pioneer Fm

Aralka Fm

Areyonga Fm


Provenance/palaeogeographical/ tectonic information

Gillen Member Bitter Springs Fm

Areyonga Fm

Musgrave

Arunta

?

Heavitree Q

Arunta Region

Musgrave Province

Presenter

Presentation Notes

Detrital zircon dating is more about gaining useful information on sediment source areas, palaeogeographic settings, and tectonic activity in adjacent basement terrains than about dating the age of the sediments. This slide shows some recent results from U-Pb detrtiatl zircon dating bt natalie Kositcin of Geoscience Australia, of samples collected late last year from the NE Amadeus Basin. In the heavitree quartzite, gillen member of the Bitter Springs Formation, and the Sturtian glacial Areyonga Formation, we see a strong dominance of detritus from the Aileron province of the Arunta Region to the north, with lesser detritus from the Musgrave province to the south. In the Gillen member and Areyonga Fm there is also a small component of younger material, around 880-900 Ma from a source area currently unknown. In the case of the Gillen Member this could be relatively close to a depositional age, as the uppermost member of the Bitter Springs Formation has an inferred age of around 820 Ma. A shift in dominant source areas can be observed in the overlying units shown on the left – with the Musgrave province becoming increasingly dominant up section, this trend has been noted on limited data by Maidment et al 2007. In the Olympic and overlying Pertatataka fm a younger population also appears, source unidentified at this stage.


• Restricted to NE Amadeus • Major provenance appears to be 1750 Ma granite of the eastern Arunta • Hf data will allow direct comparison

Eastern Arunta Region

Amadeus Basin 1750 Ma granite

Gaylad Sandstone

1744 Ma

1750 Ma 1750 Ma

+

+

+

Geochronology

Arunta

Musgrave

Gaylad Sandstone

Julie Fm

Pertatataka Fm

Olympic/Pioneer Fm Aralka Fm

Areyonga Fm Heavitree Q/Bitter Springs

Fm

Pertatataka Fm

Presenter

Presentation Notes

The Gaylad sandstone is a unit restricted to the NE part of the Basin. Its detrital zircon spectra provides useful information on its depositional setting , and indicates it differs significantly from the environment other units in this area. The histogram shows a very strong peak for detrital zircons at about 1750 Ma, with very little older material and minimal younger material, quite an unusual spectra for a sedimentary rock. The image shows the location of the Gaylad outcrops with reference to the distribution of 1750 Ma granites to the north in the Arunta region, and granites of this age are pretty much restricted to this part of the eastern Arunta region. Obviously significant post-depositional deformation has disturbed the original distribution of these units, however it appears clear that this basement area formed a dominant source for the gaylad sandstone, with very little other detritus being incorporated. CLICK Correlative units with more widespread distribution show a much broader range of source areas, and therefore significantly different depostional environments.


Bitter Springs Formation

Aralka Formation Areyonga Formation

Inindia beds

Winnall beds




Inindia beds

Northeast South-central Mt Conner area

Silicified stromatolites in Bitter Springs Fm

clast-supported stromatolite, Aralka Fm

.

Presenter

Presentation Notes

So, what indications might we have that it will be possible to relate the Neoproterozoic stratigraphy of the NE across the broader basin, the aim of the second part of this project? Some reconnaissance work done in the southern part of the basin around Mt Conner indicates that there is significant scope to be able to redefine the stratigraphy across this region, with reference to the better known Neoproterozoic stratigraphy of the NE part of the basin. This map shows in red the current distribution of Winnall beds and Inindia beds in the area. Reconnaissance work by NTGS and GSWA geologists identified Bitter Springs Formation, Areyonga Formation and Aralka Formation in the area currently mapped as Inindia beds.


BR05DDH01

This drill hole was logged using the stratigraphy of the northeast Amadeus Basin

Source: NTGS Record 2011/002




Inindia beds

Northeast South-central

Source: NTGS Record 2010/015

Pertatataka Fm

Areyonga Fm

Johnnys Creek beds Bitter Springs Fm

Loves Creek Mbr Bitter Springs Fm

Correlation issues

.

Presenter

Presentation Notes

A further indication comes from an assessment of NTGS diamond drillhole BR05DD01. This drillhole,in the west of the basin was logged using the stratigraphy of the NE Basin, and subsequent hyperspectral data from NTGS HHyLogger shown on the right, broadly supports the interpreted stratigraphy of the lithological logging.


. Basalts (spilite) in Bitter Springs Formation

• Upper part of Johnnys Creek beds • Outcrop in NE Basin • Intersected in BMR stratigraphic hole in SW Basin

Heavitree Quartzite

Presenter

Presentation Notes

Basalts , mostly spilites, are relatively poorly and sporadically exposed in the Johnnys Creek beds, the uppermost member of the Bitter Springs Formation in the NE of the basin, and were intersected in a GA stratigraphic hole in the south of the basin. The rocks are clearly extrusive, and previously were interpreted to occur at several levels in the Johnnys Creek beds, the Loves Creek Member, as well as possibly in the Gillen Member.

Neoproterozoic stratigraphy of the Amadeus Basin Bitter Springs Formation basalts

. • More extensive than previously indicated • Strong spatial association with surface Cu occurrences

Presenter

Presentation Notes

Preliminary field work in the NE part of the basin indicates that the basalts may be far more widespread in this area than previously indicated. This image shows previously known basalt occurrences, new occurrences recognised in early work in this project, and an interpretation of the possible extent of basalts from geophysical and geological interpretation. The basalts and immediately overlying stratigraphy are commonly associated with surface Cu occurrences, indicating there is potential for the presence of a widespread Cu mineralising system associated with these rocks. Further work planned for this year will focus on confirming the true extent of basalts in the NE basin

Neoproterozoic stratigraphy of the Amadeus Basin Basalts in Bitter Springs Formation?

Bitter Springs Formation

Inindia/Winnall beds

Cenozoic

Presenter

Presentation Notes

Geophysical data in the central part of the basin, as wellas in the far west in WA, suggests the possibility of shallow subsurface basalts. This example in the central part of the basin shows an area of shallow subsurface linear magnetic highs. These highs generally parallel stratigraphic trends in the region, and are coincident with outcrop of Bitter Springs formation in an area dominated by Cenozoic cover.


• Major program to characterise the stratigraphy of the Amadeus Basin • Initial focus on the Neoproterozoic (pre-Petermann Orogeny succession) • Acquire fundamental datasets for understanding basin history and development • Integrate with other datasets to build a framework on which assessment of mineral and petroleum prospectivity can be based

Presenter

Presentation Notes

Write summary!!!


References Haines PW 2013. The Petermann Orogeny: syntectonic sediment pulse across the Centralian Superbasin and beyond traced by detrital zircon ages and Hf-isotopes. Presentation to GSA, Perth, WA Maidment DW, Williams IS and Hand M, 2007. Testing long-term patterns of basin sedimentation by detrital zircon geochronology, Centralian Superbasin, Australia. Basin Research 19, 335–360. Walter MR, Veevers JJ, Calver CR, Gorjan P, Hill AC 2000. Dating the 840-544 Ma Neoproterozoic interval by isotopes Of strontium, carbon, and sulfur in seawater, and some interpretative models. Precambrian research 100, 371-433

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