1.1.3.2 Stratigraphy and rock type


1.1.3.2.1 Bowen Basin

There are almost 50 stratigraphic units recognised in the Bowen Basin (Australian Stratigraphic Units Database, 2013). The spatial distribution and stratigraphic relationships of these rock units vary within the basin, particularly between the main depositional centres such as the Taroom and Denison troughs. The most important coal-bearing stratigraphic units in the Bowen Basin that occur in the Maranoa-Balonne-Condamine subregion are summarised in this section, and are visually represented in Figure 19.

Arbroath beds

Early Permian deposition within a half-graben structure formed this unit, which consists of shale and siltstone with some sandstone, conglomerate and coal (Green et al., 1997). A correlative of the more widely distributed Reids Dome beds, this unit is known only from the Roma Shelf region.

Muggleton Formation

The Muggleton Formation occurs in the Roma region and is considered the lowermost formation of Permian age in the vicinity (Green et al., 1997). It is a shale, siltstone and sandstone unit with minor coal and tuff layers (Green et al., 1997). The Lorelle Sandstone Member, a sub-unit of the Muggleton Formation, is composed largely of sandstone with minor shale, siltstone, coal and tuff (Green et al., 1997).


For a description of this image please contact bioregionalassessments@bom.gov.au

Figure 19 Stratigraphic column of the Maranoa-Balonne-Condamine subregion

The stratigraphic units listed here are those that could not be definitively excluded from the subregion based on the current literature. Source data: derived from data presented in McKellar (1998), Wells and O’Brien (1994), Totterdell et al. (2009), Doig and Stanmore (2012) and Cook and Draper (2013) This figure has been optimised for printing on A3 paper (297 mm x 420 mm)


Tinowon Formation

An Early Permian fluvio-deltaic and brackish marine unit consisting of shale, siltstone, sandstone and coal (Green et al., 1997). Significant amounts of coal from the Tinowon Formation occur on the Roma Shelf (Green et al., 1997). The Wallabella Coal Measures, part of the Tinowon Formation, is a swamp coal deposit that occurs in relatively thick and continuous sections (Green et al., 1997), and is interbedded with shale, siltstone, tuff and minor sandstone (Green et al., 1997).

Flat Top Formation

The Flat Top Formation formed in a delta fan to shallow marine setting and is composed of siltstone, sandstone, mudstone, conglomerate, coal and tuff (Draper, 2013).

Banana Formation

The Banana Formation is an assemblage of mudstone, shale, siltstone and sandstone with minor coal formed during the Late Permian in brackish to marine settings (Green et al., 1997).

Burunga Formation

The Burunga Formation is a Late Permian sandstone, shale, siltstone, tuff and clay unit with significant lithological variations from region to region (Green et al., 1997). In the central and southern Bowen Basin this unit appears in three distinct layers, with the upper and lower layers being coal measures and the middle layer a marine mudstone (Green et al., 1997). A sub-unit within the Burunga Formation is the Scotia Coal Member, which contains sandstone, shale, siltstone, coal and tuff (Green et al., 1997).

Black Alley Shale

A shale-rich unit with beds of tuff, coal and sandstone formed in brackish marine conditions during a Late Permian transgression, followed by a change to freshwater lake sedimentation (Mollan et al., 1969; Green et al., 1997; Hoffmann et al., 1997). This unit also contains the Winnathoola Coal Measures, a thin bed of coal and sandstone formed in a deltaic setting along the Roma Shelf (Green et al., 1997).

Bandanna Formation

Formed as infill sediments within a large lake or inland sea by deltaic input, the Bandanna Formation is composed of sandstone, mudstone, siltstone and rare coal (Green et al., 1997; Draper, 2013). It is part of the Blackwater Group and is one of the main geological units mined for coal in the Bowen Basin.

Baralaba Coal Measures

A marine and fluvial unit deposited during the Permian containing sandstone, siltstone, mudstone, coal and tuff (Green et al., 1997). The basal sub-unit of the Baralaba Coal Measures, the Kaloola Member, consists of siltstone, sandstone, tuff and conglomerate (Green et al., 1997).

1.1.3.2.2 Surat Basin

There are close to 70 stratigraphic units recognised across the entire Surat Basin, most of which belong to one of five main stratigraphic groups (Australian Stratigraphic Units Database, 2013). The spatial distribution and stratigraphic relationships of these units vary within the basin, particularly between the main depositional centre and the other structural elements of the basin. Summaries of the most important coal-bearing stratigraphic units in the Maranoa-Balonne-Condamine subregion (Figure 19) of the Surat Basin are given in this section. The major aquifers are discussed in Section 1.1.4 .

Evergreen Formation

The Evergreen Formation consists of siltstone, shale, sandstone and coal that formed in a fluvial depositional setting on a coastal plain, with possible deltaic influence (Exon, 1976; Cook and Draper, 2013). The formation contains two sub-units, the Boxvale Sandstone Member and the Westgrove Ironstone Member (Exon, 1976; Cook and Draper, 2013). The Boxvale Sandstone Member, consisting of sandstone, siltstone and coal, was deposited during a brief marine transgression (Exon, 1976).

Walloon Coal Measures

The Walloon Coal Measures are the most significant coal resource in the Surat Basin, and the only unit mined for coal in the basin. A compositionally varied formation that consists of thinly bedded claystone, shale, siltstone, sandstone (lithic and sublithic to feldspathic arenite), coal seams and minor limestone (Exon, 1976). A muddy pebble conglomerate also occurs in several locations (Exon, 1976). The depositional environment is interpreted as fluvial and swampy plains (Exon, 1976). The Walloon Coal Measures can be subdivided into four sub-units: the Durabilla Formation, Taroom Coal Measures, Tangalooma Sandstone and the Juandah Coal Measures (Exon, 1976; Swarbrick, 1973). The Taroom Coal Measures are a mixed sequence of sandstone, siltstone and mudstone, with abundant coal and carbonaceous mudstone interbeds (Scott et al., 2004). A mixed assemblage of sandstone, siltstone, mudstone, claystone, tuff and thin coal to carbonaceous mud seams form the Tangalooma Sandstone (Rohead-O’Brien, 2011). The sandstone is commonly heavily cemented or in-filled with clay (Rohead-O’Brien, 2011). The Juandah Coal Measures are similar in composition and coal volume to the Taroom Coal Measures (Scott et al., 2004).

Westbourne Formation

A Late Jurassic formation of interbedded mudstone, siltstone, sandstone and some coal (Exon, 1976).

Orallo Formation

The Orallo Formation is composed of thin beds of siltstone and mudstone with some sandstone and minor conglomerate and coal deposited by fluvial channels in the Early Cretaceous to Late Jurassic (Exon, 1976).

Griman Creek Formation

A sandstone-dominated unit grading in places to siltstone and mudstone. Minor conglomerate and coal bands occur throughout and are more common in the upper section (Exon, 1976). The lower part of the Griman Creek Formation (Wallangulla Sandstone Member) is interpreted to have formed in a marine environment whereas the upper section (Coocoran Claystone Member) is interpreted as non-marine (Exon, 1976).

1.1.3.2.3 Clarence-Moreton Basin

There are close to 40 stratigraphic units in the Clarence-Moreton Basin, most of which belong to one of two main sub-groups (Australian Stratigraphic Units Database, 2013). The spatial distribution and stratigraphic relationships of these units vary across the basin. There are several different interpretations for the base of the Clarence-Moreton Basin, the two most common being the base of the Woogaroo Subgroup (the Aberdare Conglomerate) or the base of the Nymboida Coal Measures (Wells and O’Brien, 1994; Doig and Stanmore, 2012). For this product, the base of the Nymboida Coal Measures will be considered to be the base of the Clarence-Moreton Basin. Summaries of the most important coal-bearing units (Figure 19) in the Clarence-Moreton Basin are given in this section.

Nymboida Coal Measures

The Nymboida Coal Measures formed during the Middle Triassic in lake and marsh depositional environments (Stewart and Adler, 1995; Cadman et al., 1998). This unit is composed of interbedded sandstone, shale, siltstone, claystone, conglomerate, felsic tuff, basalt and coal, forming a unit up to 1000 metres in thickness to the east, thinning to the west (Stewart and Adler, 1995; Cadman et al., 1998). There are also some rhyolitic tuff deposits (Packham and Day, 2008). The Cloughers Creek Formation and Basin Creek Formation are the coal-bearing sub-units of the Nymboida Coal Measures. The Cloughers Creek Formation is a shale-rich formation, carbonaceous in places, that outcrops as lenses in creek beds sporadically throughout the basin (McElroy, 2008). In some places this unit may also contain conglomerate, breccia, siltstone, sandstone and coal (McElroy, 2008). The Basin Creek Formation is a thick unit of sandstone, shale, conglomerate and some coal (McElroy, 2008). The rocks are generally finely laminated, forming a unit up to 1000 metres in thickness (Stewart and Adler, 1995; McElroy, 2008).

Ipswich Coal Measures

During the Late Triassic the Ipswich Coal Measures of Queensland were deposited across the basin after a period of uplift and erosion, but are not located to the west of the West Ipswich Fault (Korsch et al., 1989; Cadman et al., 1998; Chern, 2004). Composition is a varying mix of interbedded sandstone, siltstone, claystone, conglomerate and coal, as well as some volcanic rocks (Stewart and Adler, 1995; Cadman et al., 1998). In Queensland the Ipswich Coal Measures can reach a thickness of one kilometre (Stewart and Adler, 1995). The Ipswich Coal Measures have two equivalent units in the Maranoa-Balonne-Condamine subregion in NSW: the Red Cliff Coal Measures and the Evans Head Coal Measures (Stewart and Adler, 1995). The Red Cliff Coal Measures are a conglomerate, sandstone, shale, breccia, siltstone, mudstone and coal unit deposited during the Triassic, reaching up to 600 m in thickness (McElroy, 2008; Doig and Stanmore, 2012). The Red Cliff Coal Measures correlate with the Ipswich and Evans Head Coal Measures (Doig and Stanmore, 2012). The group, up to 300 m thick, is composed of sandstone, shale, conglomerate and mudstone with minor coal forming parting of very fine bands make up the Evans Head Coal Measures (McElroy, 2008; Doig and Stanmore, 2012). This sequence correlates to the Ipswich and Red Cliff Coal Measures (Stewart and Adler, 1995; McElroy, 2008).

Woogaroo Subgroup

The Woogaroo Subgroup formed during the Late Triassic and is divided into four separate units, which combine for a maximum thickness of 1200 m: the Aberdare Conglomerate, Laytons Range Conglomerate, Raceview Formation and Ripley Road Sandstone (Wells and O’Brien, 1994; Australian Stratigraphic Units Database, 2013). Both the Raceview Formation and the Ripley Road Sandstone contain coal and fall within the Maranoa-Balonne-Condamine subregion. The Raceview Formation is composed of sandstone, siltstone and shale, with some limited coal deposited in a fluvial, lacustrine and swamp environment (Wells and O’Brien, 1994). In the Maranoa-Balonne-Condamine subregion the Raceview Formation is located in the deeper depositional sites (Wells and O’Brien, 1994). The Ripley Road Sandstone is a sandstone-rich unit with conglomerate, minor mudstone and coal, deposited as channel fill and point bar deposits (Wells and O’Brien, 1994; Ingram and Robinson, 1996). It has a maximum thickness of 150 m (Wells and O’Brien, 1994; Ingram and Robinson, 1996).

Gatton Sandstone

The Gatton Sandstone is a stacked channel sand unit from the Early Jurassic composed of thick beds of sandstone, with carbonate material and clay; some pebble beds are also noted (Wells and O’Brien, 1994; Ingram and Robinson, 1996; Cadman et al., 1998). It stands alone as a formation of the Marburg Subgroup, but is also composed of two sub-units that are found in the lower sections of the Gatton Sandstone, which contain no coal seams: the Koreelah Conglomerate Member, a conglomerate and sandstone unit, and the Calamia Member of thin mudstones and siltstones (Wells and O’Brien, 1994; Ingram and Robinson, 1996; Cadman et al., 1998).

Koukandowie Formation

An Early Jurassic Marburg Subgroup formation consisting of interbedded sandstones, siltstone, claystone and minor coal (Willis, 1994). Reaching a maximum thickness of 500 m, the Koukandowie Formation can be further divided into three sub-units: the Heifer Creek Sandstone, the Ma Ma Creek Member and the Towallum Basalt (Wells and O’Brien, 1994). The Ma Ma Creek Member is dominantly shale with siltstone interbedding and some sandstone deposited during a lacustrine incursion over a fluvial system; some minor fossilised wood and conglomerate bands have also been observed (Wells and O’Brien, 1994). The Hiefer Creek Sandstone Member is asandstone to conglomeritic sandstone deposited as fluvial bedload and point bar facies (Powell et al., 1993; Ingram and Robinson, 1996).

Walloon Coal Measures

Middle Jurassic lakes and rivers deposited the Walloon Coal Measures in the Clarence-Moreton Basin, which is slightly different from the fluvial and swampy plains depositional environment of the Surat Basin Walloon Coal Measures in Section 1.1.3.2.2 (Cadman et al., 1998; McElroy, 2008). The unit is compositionally similar to strata in the Surat Basin, containing calcareous sandstone, siltstone, mudstone, claystone and discontinuous coal; volcanic ash falls are also common (Cadman et al., 1998; McElroy, 2008). Also similar to the Surat Basin sequence, it is divided into several distinct sub-units (Wells and O’Brien, 1994). The Taroom Coal Measures are a compositionally mixed sequence of sandstone, siltstone and mudstone, with abundant coal and carbonaceous mudstone beds (Scott et al., 2004). The Tangalooma Sandstone is an interbedded mix of sandstone, siltstone, mudstone, claystone, tuff and thin coal to carbonaceous mud seams (Rohead-O’Brien, 2011). The Juandah Coal Measures are unit similar in composition and coal volume to the Taroom Coal Measures of the same subgroup (Scott et al., 2004).

Kangaroo Creek Sandstone

A massive sandstone member with layers of siltstone and carbonaceous mudstone, it formed in fluvial channel environments (Doig and Stanmore, 2012). It is observed as a coarse to very coarse grained, highly friable sandstone (P Baker (Department of the Environment), 2014, pers. comm.). Currently the Kangaroo Sandstone Member stands as a separate unit above the Walloon Coal Measures, although there is a current review of the stratigraphic nomenclature and this unit may soon form part of a newly proposed unit, the Orara Formation (Wells and O’Brien, 1994; Doig and Stanmore, 2012; Australian Stratigraphic Unit Database, 2013).

Grafton Formation

A Late Jurassic to Early Cretaceous unit composed of sandstone, siltstone, mudstone and minor coal from a dominantly fluvial environment (Wells and O’Brien, 1994).

Last updated:
5 January 2018
Thumbnail of the Maranoa-Baloone-Condamine subregion

Product Finalisation date

2014