Broken River Province Research Articles

Growth and provenance of a Paleozoic subduction complex in the Broken River Province, Mossman Orogen: evidence from detrital zircon ages

A Paleozoic subduction complex dominates the Mossman Orogen developed at the northern extremity of the Tasmanides, eastern Australia. Its southern part, displayed in the Broken River Province, is characterised by dismembered ocean-plate stratigraphy in which turbidite-dominated packages and widespread tectonic mélange development are characteristic. The Broken River complex is characterised by formations with quartzose sandstone alternating with those largely formed of sandstone of more labile character. The two compositional groups are considered to reflect separate, age-significant sedimentary regimes, but their ages have hitherto been poorly constrained. With the use of 1082 concordant detrital zircon ages from 13 samples we provide age control for the complex and track its sedimentary provenance. Of quartzose units, the Tribute Hills Arenite and Pelican Range Formation are late Cambrian–Early Ordovician, and the Wairuna Formation is Middle to Late Ordovician, in age. The more labile units (Greenvale, Perry Creek and Kangaroo Hills formations) are collectively of late Silurian–mid-Devonian age. Development of the complex spanned some 130 Myr. Continent-derived sediment involved in accretion of much the complex, from mid-Ordovician to mid-Devonian, was largely sourced from a nearby magmatic arc of late Cambrian–Devonian age, now represented by granitoid plutons of the Macrossan and Pama igneous associations. An older far-field Pacific-Gondwana sediment source is characteristic of early-phase (late Cambrian–Early Ordovician) accretion, in common with sedimentary units of this age generally developed in the Tasmanides. We consider the complex to have grown largely by underplating that positioned younger components beneath those that are older, with out-of-sequence thrust interleaving of these components occurring late in the accretionary history. A Late Devonian contractional folding and cleavage development (Tabberabberan orogenesis) is uniformly expressed across the entire complex and reflects an abrupt change in plate engagement with imposition of a compressional stress regime.

Trilobites of the suborder Illaenina from the Silurian of north Queensland, Australia

AbstractThe trilobite fauna of the middle Silurian (Telychian to possibly earliest Sheinwoodian) Tomcat Creek limestone in the Broken River Province of north Queensland is dominated by the suborder Illaenina, including illaenimorphs (Illaeninae and Bumastinae) and members of the Scutelluidae. Scutelluidae are most diverse, with eight genera, of whichDolabrapex,Iotoryx,Perizostra, andQuintoniaare new.Perizostrais the first scutelluid with a cephalon that may be described as of phacomorph appearance. Illaenimorphs are represented by three genera, includingOpsypharus, which is regarded as a senior synonym ofParacybantyxbut distinct fromFailleanawith which it has been placed in synonymy by some authors. Thirteen species are new:Cybantyx?ergodes,Opsypharus pandanensis,Australoscutellum talenti,Dolabrapex acomus,Illaenoscutellum psephos,Iotoryx clarksoni,Japonoscutellum mawsonae,J. drakton,J. fractum,Kosovopeltis avita,Perizostra campbelli,Quintonia arata, andQ. pavo. A species ofStenopariais placed in open nomenclature. The species ofAustraloscutellum,Illaenoscutellum, and possiblyKosovopeltisare the oldest known representatives of those genera. These genera andJaponoscutellumare also common in faunas from limestones of Wenlock to Ludlow age in central western New South Wales, reflecting the similarity in lithofacies. The monotypic Late Ordovician genusCraigheadia, which has been regarded as a scutelluid, belongs to the Lichidae and is probably a junior synonym ofLeiolichas.

Wenlock and Ludlow (Silurian) rugose corals from the type section of the Jack Formation, Broken River Provence, northeast Queensland

The Jack Formation forms part of the Silurian Graveyard Creek Group within the Graveyard Creek Subprovince in northeast Queensland. The formation comprises alternating intervals of carbonate and siliciclastic rocks deposited in a shallow-marine setting. It is very fossiliferous at a number of levels, and contains numerous species of conodonts, rugose and tabulate corals, stromatoporoids, trilobites, brachiopods, crinoids, low-spired gastropods, molluscs, other invertebrates, microvertebrates, and algae. Conodont data indicate that the succession is Wenlock to Ludlow in age at the type section along the Broken River in the Jack Hills Gorge area. Fourteen rugose coral species and one subspecies, referable to eleven genera, are described from the type section of the Jack Formation. New taxa described are Aphyllum pachystele sp. nov., Pycnostylus polyphyllodus sp. nov., Multicarinophyllum vepreculatum sp. nov., Dokophyllum hillae sp. nov., Vesicospina julli gen. et sp. nov. and Ptychophyllum variatum sp. nov. The rugose coral fauna shows a high degree of endemism with only four species recorded outside the Broken River Province. Within eastern Australia, it is comparable with a Gorstian to early Ludfordian fauna of the Yass district, New South Wales (3 species in common), and 1–2 species are also shared with coral faunas from other Silurian localities in New South Wales, Victoria and Tasmania. At the species level, there is very little in common with overseas faunas.

Wenlock and Ludlow (Silurian) rugose corals from the type section of the Jack Formation, Broken River Provence, northeast Queensland

The Jack Formation forms part of the Silurian Graveyard Creek Group within the Graveyard Creek Subprovince in northeast Queensland. The formation comprises alternating intervals of carbonate and siliciclastic rocks deposited in a shallow-marine setting. It is very fossiliferous at a number of levels, and contains numerous species of conodonts, rugose and tabulate corals, stromatoporoids, trilobites, brachiopods, crinoids, low-spired gastropods, molluscs, other invertebrates, microvertebrates, and algae. Conodont data indicate that the succession is Wenlock to Ludlow in age at the type section along the Broken River in the Jack Hills Gorge area. Fourteen rugose coral species and one subspecies, referable to eleven genera, are described from the type section of the Jack Formation. New taxa described are Aphyllum pachystele sp. nov., Pycnostylus polyphyllodus sp. nov., Multicarinophyllum vepreculatum sp. nov., Dokophyllum hillae sp. nov., Vesicospina julli gen. et sp. nov. and Ptychophyllum variatum sp. nov. The rugose coral fauna shows a high degree of endemism with only four species recorded outside the Broken River Province. Within eastern Australia, it is comparable with a Gorstian to early Ludfordian fauna of the Yass district, New South Wales (3 species in common), and 1–2 species are also shared with coral faunas from other Silurian localities in New South Wales, Victoria and Tasmania. At the species level, there is very little in common with overseas faunas.

Heliolitine tabulate corals from Late Ordovician and possibly early Silurian allochthonous limestones in the Broken River Province, Queensland, Australia

Dixon, O.A. & Jell, J.S., iFirst article. Heliolitine tabulate corals from Late Ordovician and possibly early Silurian allochthonous limestones in the Broken River Province, Queensland, Australia. Alcheringa, 1–30. ISSN 0311-5518. Coral faunas of Late Ordovician (Ashgill) and possibly early Silurian age are present in allochthonous limestone blocks incorporated in debris flow deposits in the Broken River Province of north Queensland. The limestones occur in the Carriers Well Formation and Crooked Creek Conglomerate, which now lie within structurally deformed fault slices, and are evidence of the existence of a former carbonate platform of this age situated to the west. The fauna from the Carriers Well Formation includes 15 taxa belonging to the heliolitine coral families Heliolitidae, Pseudoplasmoporidae, Plasmoporidae, Plasmoporellidae and Sibiriolitidae. New taxa present are Wairunalites greeni gen. et sp. nov. and Plasmoporella marginata sp. nov. The fauna includes other species belonging to Heliolites, Plasmoporella and Sibiriolites in common with Late Ordovician faunas of New South Wales, central Asia and northern China. A limestone block in the Crooked Creek Conglomerate contains a few non-diagnostic heliolitine corals, together with rugosan, favositine and halysitine corals similar to those in the blocks of the Carriers Well Formation, but it also contains several alveolitine tabulates suggesting a possible early Silurian age.

Collisional accretion of a Late Ordovician oceanic island arc, northern Tasman Orogenic Zone, Australia

A distinctive Late Ordovician volcano-sedimentary terrane, embracing the Carriers Well Formation and Everetts Creek Volcanics and dismembered slivers now structurally intercalated in the adjoining Wairuna Formation, is located within the Broken River Province of the northern Tasmanides. It abuts a basement of mafic–ultramafic rocks (Gray Creek Complex) and overlying Early Ordovician deep marine sedimentary and volcanic strata (Judea Formation) which host tonalitic plutons. The terrane lies at the western, inboard-margin of the Camel Creek Subprovince, a broad tract of multiply deformed mid-Paleozoic turbidites with minor basalt and chert variously interpreted as the infill of a backarc basin or an accretionary wedge. U–Pb dates from detrital zircon indicate a maximum Late Silurian age for siliciclastic rocks from the previously undated Wairuna Formation. Geochemistry of volcanic rocks from the volcano-sedimentary terrane show them to be largely of mafic to intermediate compositions of calc-alkaline affinity, comparable with broadly coeval Macquarie Arc volcanic suites of the southern Tasmanides. Trace-element systematics identify a subduction relationship for the volcanic suite and V/Ti employed as a discrimination tool identifies the terrane as representing an oceanic island arc, consistent with its sedimentary facies which include volcaniclastic mass flow deposits, limestone, and radiolarian chert. Continent-derived sandstone in the sedimentary assemblage, confirmed by the ages of detrital zircon from a sandstone sample from the Carriers Well Formation, indicates that the oceanic island arc developed proximal to the Late Ordovician continental margin of East Gondwana. Its nature and location bear on the tectonic setting of the entire Camel Creek Subprovince, for which interpretation as an Early Silurian–Early Devonian accretionary wedge is favoured. Collision of the island arc with the continental margin, and associated deformation of part the intervening oceanic crustal tract, now represented by the Gray Creek Complex and its sedimentary cover (Judea Formation) registers the initiation of subduction accretion in late Early Silurian (Llandoverian) time. It marks early-stage orogenesis in the Broken River Province, accurately timed by stratigraphic relationships in the basinal succession developed in the Graveyard Creek Subprovince immediately to the west of the arc assemblage. Tectonism was regionally developed in north Queensland at this time, coeval with the Benambran Orogeny of the Lachlan Orogen in which the Macquarie Arc was likewise accreted to the East Gondwana margin. Benambran orogenesis marks a general phase of shortening, and removal by subduction, of oceanic crust and inversion of continent-derived overlying sedimentary cover along the East Gondwana margin.

Arborescent lignophytes in the Tournaisian vegetation of Queensland (Australia): Palaeoecological and palaeogeographical significance

A middle Tournaisian flora comprising several taxa of arborescent lignophytes is documented for the first time in Australia. It challenges earlier hypotheses considering that the early Mississippian vegetation of Australia was impoverished and dominated by small to medium sized arborescent lycopsids until the Serpukhovian when climatic conditions became favorable to the thriving of the famous lignophyte-dominated “ Rhacopteris flora” recorded in Australia but also South America. The present account is based on anatomically preserved fragments of trunks and branches from two localities of Queensland, in the Broken River Province and the Burdekin Basin. Three taxa are recognized, Dameria hueberi gen. et sp. nov., the putative progymnosperm species Protopitys buchiana Goeppert 1850, and a taxon of uncertain affinities characterized by a Pitus type of wood but which differs from the latter genus by anatomical traits relative to its primary body. The possible occurrence of subtle growth rings in some of the woods from the Burdekin Basin and the conifer like traits of the Dameria wood are interpreted as ecological clues suggesting that these trees may have inhabited drier settings than the wetland habitats generally inferred for the lycopsids. This difference in habitats is suggested to explain the rarity of arborescent lignophytes compared to lycopsids in the Australian record of plants of early Mississippian age. The three taxa reported in this paper represent the earliest record of arborescent lignophytes in Australia after the global events that affected the vegetation at the Devonian–Carboniferous boundary and the extinction of Archaeopteris. They show that the successional pattern of arborescent lignophytes around the Devonian–Carboniferous boundary is comparable to that observed in Western Europe with the evidence of a diversification occurring as early as the middle Tournaisian. The palaeogeographic and stratigraphic distribution of Protopitys and Dameria indicates the occurrence of extensive floral exchanges between southern Laurussia and north-eastern Gondwana in the Late Devonian to Mississippian.

Time-space evaluation of the tectono-metallogenic evolution of the northern Tasman Fold Belt System, northeast Queensland, Australia

The Tasman Fold Belt System in eastern Australia provides a record of the Palaeozoic geological history and growth of the Australian continent along the proto-Pacific margin of Gondwana inboard of an extensive and long-lived subduction system. The Hodgkinson and Broken River provinces represent prominent geological elements of this system and together form the northern Tasman Fold Belt System. Integration of newly-obtained data with a time-space evaluation of the geological evolution of the Hodgkinson and Broken River provinces, as well as other terranes in the northern Tasman Fold Belt System, allows for the development of a geodynamic model for the Palaeozoic evolution of the northern Tasman Fold Belt System. Our model indicates that three cycles of extension ? contraction occurred during the Palaeozoic evolution of the northern Tasman Fold Belt System. Episodes of extension were controlled by roll-back of the subduction system along the Australian margin, whereas episodes of contraction resulted from accretion following the arrival of positively buoyant segments (i.e., micro-continental blocks / oceanic plateaux) at the subducting trench. Our composite interpretative model on the geodynamic evolution of the northern Tasman Fold Belt System integrates the timing of the development of mineral deposits throughout this part of the system and provides a significant advancement in the understanding of Palaeozoic geodynamics along the margin of Gondwana in northeast Australia.

The Palaeozoic tectono-metallogenic evolution of the northern Tasman Fold Belt System, Australia: Interplay of subduction rollback and accretion

The Tasman Fold Belt System in eastern Australia provides a record of the Palaeozoic geological history and growth of the Australian continent along the proto-Pacific margin of Gondwana inboard of an extensive and long-lived subduction system. The Hodgkinson and Broken River provinces represent prominent geological elements of this system and together form the northern Tasman Fold Belt System. Geochronological age dating of the timing of gold formation in the Amanda Bel Goldfield in the Broken River Province and the Hodgkinson Goldfield in the Hodgkinson Province provides constraints on the occurrence of a deformation and mineralisation episode in the Late Devonian–Early Carboniferous. Integration of these newly-obtained data with petrogenetic constraints and a time–space evaluation of the geological evolution of the Hodgkinson and Broken River provinces, as well as other terranes in the northern Tasman Fold Belt System, allows for the development of a geodynamic model for the Palaeozoic evolution of the northern Tasman Fold Belt System. Our model indicates that three cycles of extension–contraction occurred during the Palaeozoic evolution of the northern Tasman Fold Belt System. Episodes of extension were controlled by rollback of the subduction system along the proto-Pacific margin of Gondwana, whereas episodes of contraction resulted from accretion following the arrival of positively buoyant segments (i.e., micro-continental blocks/oceanic plateaus) at the subducting trench. Our composite interpretative model on the geodynamic evolution of the northern Tasman Fold Belt System integrates the timing of the development of mineral deposits throughout this part of the system and provides a significant advancement in the understanding of Palaeozoic geodynamics along the margin of Gondwana in northeast Australia and allows comparison with the southern part of the Tasman Fold Belt System.

Genesis of orogenic-gold deposits in the Broken River Province, northeast Queensland

We report results of metallogenic, structural, petrological, and fluid-inclusion studies that characterise the nature of gold mineralisation in the Amanda Bel Goldfield, the most significant gold producer in the Palaeozoic Broken River Province of northeastern Queensland, Australia. Gold–antimony–arsenic and gold–arsenic deposits in the Amanda Bel Goldfield occur along distinctive northeastern trends, suggesting a strong structural control for their development during several phases of deformation in the Devonian to Carboniferous. Field evidence, as well as petrographic, scanning electron microscope and fluid-inclusion analysis of mineralised samples, indicate the presence of two main stages of gold genesis. These are distinguished by the coarse grained versus invisible nature of gold particles and their association with particular sulfide phases. A third stage of gold deposition is attributed to introduction of antimony±gold-rich ore fluids. Fluid-inclusion studies record minimum trapping temperatures between 140 and 380°C, and salinities of up to 6.5 wt% NaCl equivalent for the two main gold-forming stages. Our analyses further indicate that mineralising solutions for the earlier of the two main gold-forming stages were slightly more saline, and that the ore-hosting veins formed at higher temperatures. The style of gold mineralisation in the Amanda Bel Goldfield is compatible with orogenic gold deposits that form primarily during compressional and transpressional deformation along convergent plate margins in accretionary and collisional orogens. The increased understanding gained from our studies on the origin and nature of the deposits aids predictive mineral discovery elsewhere in the Broken River Province, and also in analogous terranes throughout the Tasman Fold Belt System of eastern Australia.

Age constraints on deformation of the eastern Hodgkinson Province, north Queensland: New perspectives on the evolution of the northern Tasman Orogenic Zone

Granitic plutons of the Wangetti and Mt Formartine Supersuites intrude the Hodgkinson Formation of the Macalister Range district of the eastern Hodgkinson Province, north Queensland, Australia. Field and microstructural analyses of country‐rock fabrics and those of the granites show four deformational events (D1–D4) for the district, in common with other sectors of the Hodgkinson Province. Structural relationships show that plutons of the two supersuites were emplaced at different times. The Wangetti Granite lacks fabric development, but the deflection of country‐rock cleavage trends around it and the microscale crenulation of S2 on the rims of D4 porphyroblasts within its aureole indicate syn‐D4 emplacement, consistent with the Early Permian crystallisation age attributed to this pluton from isotopic evidence. Plutons of the Mt Formartine Supersuite show the effects of multiple (D2–D4) deformation. An emplacement age of 357 ± 6 Ma (latest Devonian) was obtained for this granite by SHRIMP U–Pb analyses of zircon. This identifies an early episode of plutonism for the Hodgkinson Province, most granites from which are of Permian age. The new date constrains the age of D2 for the Macalister Range district and the age of the protolith of the Hodgkinson Formation as pre‐Carboniferous. It matches the age previously determined for one of several small, related granitic stocks in the southeastern Camel Creek Subprovince of the Broken River Province. Structural relationships for granites of this age suggest that their emplacement was broadly associated with the first episode of regional‐scale orogenesis and the development of penetrative fabrics in the Hodgkinson — Broken River Fold Belt.

Evolution of Devonian alluvial systems in an oblique-slip mobile zone—an example from the Broken River Province, northeastern Australia

The lower 1500 m of the Late Devonian Bulgeri Formation was deposited in a tectonically active foreland basin in response to a major Late Devonian orogeny in the Broken River Province, northeastern Australia. The basin was bounded to the east by an uplifted belt of Palaeozoic sedimentary and volcanic rocks that was deformed east of an active thrust zone (Gray Creek Fault). To the south, the basin was bounded by igneous and metamorphic basement rocks, uplifted along a major oblique-slip fault zone (Clarke River Fault). Facies analysis and mapping of alluvial stratigraphy has resulted in the recognition of compositionally distinct, coalescing, axial and transverse alluvial drainage systems.The axial drainage system flowed to the northeast, approximately parallel to the Gray Creek Fault and away from the Clarke River Fault. The system drained the cratonic basement to the south and west, and accumulated mainly feldspathic and quartzose sediments. A lower, fine-grained succession, and an upper coarse-grained succession are recognised. The lower succession (‘Rockfields’ alluvial system) was deposited in broad, sandy, low-sinuosity channels and semi-permanent floodplain lakes. These rivers drained ultimately northward into a retreating coastal plain and shallow sea that lay over the Georgetown Province. The upper succession (‘Bulgeri’ alluvial system) was deposited in gravelly and sandy braided rivers emanating from south of the Clarke River Fault. The transverse distributary system (‘Stopem Blockem’ alluvial system), accumulated mainly lithic, coarse-grained sediments deposited in gravelly braided rivers sourced from the uplifted orogenic belt to the east. These rivers flowed towards the northwest before coalescing with the axial drainage system where they changed to a northerly orientation. Uplifted fault blocks of Devonian limestone within the basin locally contributed limestone gravel to these rivers. Between the coalescing axial and transverse river systems lay extensive floodplains, which received a slow, but compositionally mixed supply of mainly fine-grained sediments. Long periods of weathering resulted in the development of reddened palaeosols, with well developed calcrete horizons. The palaeogeography and fluvial style of the lower Bulgeri Formation is compared to the Gulf of Carpentaria in northeastern Australia.Analysis of the architecture of these alluvial systems has led to recognition of at least three, subsidence-driven, tectonic cyclothems and this is supported by simple quantitative modelling. The lower part of each cycle begins with a thin conglomeratic succession above an unconformity, and is overlain by thick, relatively fine-grained, syn-tectonic alluvial facies deposited during maximum subsidence. The upper part of each cycle is marked by increasingly coarse-grained, post-tectonic alluvial facies. These were deposited by gravel progradation following cessation of uplift or thrusting in the source areas and concomitant slowing of subsidence rates.

The eastern part of the Tasman Orogenic Zone

The eastern part of the Tasman Orogenic Zone (or Fold Belt System) comprises the Hodgkinson—Broken River Orogen (or Fold Belt) in the north and the New England Orogen (or Fold Belt) in the centre and south. The two orogens are separated by the northern part of the Thomson Orogen. The Hodgkinson—Broken River Orogen contains Ordovician to Early Carboniferous sequences of volcaniclastic flysch with subordinate shelf carbonate facies sediments. Two provinces are recognized, the Hodgkinson Province in the north and the Broken River Province in the south. Unlike the New England Orogen where no Precambrian is known, rocks of the Hodgkinson—Broken River Orogen were deposited immediately east of and in part on, Precambrian crust. The evolution of the New England Orogen spans the time range Silurian to Triassic. The orogen is orientated at an acute angle to the mainly older Thomson and Lachlan Orogens to the west, but the relationships between all three orogens are obscured by the Permian—Triassic Bowen and Sydney Basins and younger Mesozoic cover. Three provinces are recognized, the Yarrol Province in the north, the Gympie Province in the east and the New England Province in the south. Both the Yarrol and New England Provinces are divisible into two zones, western and eastern, that are now separated by major Alpine-type ultramafic belts. The western zones developed at least in part on early Palaeozoic continental crust. They comprise Late Silurian to Early Permian volcanic-arc deposits (both island-arc and terrestrial Andean types) and volcaniclastic sediments laid down on unstable continental shelves. The eastern zones probably developed on oceanic crust and comprise pelagic sediments, thick flysch sequences and ophiolite suite rocks of Silurian (or older?) to Early Permian age. The Gympie Province comprises Permian to Early Triassic volcanics and shallow marine and minor paralic sediments which are now separated from the Yarrol Province by a discontinuous serpentinite belt. In morphotectonic terms, a Pacific-type continental margin with a three-part arrangement of calcalkaline volcanic arc in the west, unstable volcaniclastic continental shelf in the centre and continental slope and oceanic basin in the east, appears to have existed in the New England Orogen and probably in the Hodgkinson—Broken River Orogen as well, through much of mid- to late Palaeozoic time. However, the easternmost part of the New England Orogen, the Gympie Province, does not fit this pattern since it lies east of deepwater flysch deposits of the Yarrol Province.

Mafic‐ultramafic complexes of the Greenvale area, North Queensland: Devonian intrusions or precambrian metamorphics?

Abstract In the Greenvale area, mafic‐ultramafic complexes occur along the boundary between the Georgetown and Broken River Provinces, in a zone believed to have been a continental margin in the Precambrian and early Palaeozoic. This margin was the site of repeated metamorphism, deformation, and igneous activity until the Carboniferous; the resulting complication of the geology clearly exemplifies problems in the interpretation of the genesis of ultramafics and ophiolites in highly deformed regions. Following their emplacement, Precambrian layered mafic‐ultramafic complexes were interfolded and metamorphosed with schist and phyllite of the Georgetown Province. The Broken River Province was subsequently the site of lower Palaeozoic igneous activity contemporaneous with the initial deposition of quartz‐rich flysch intercalated with basaltic lavas. In the Gray Creek Complex this phase of igneous activity is represented by gabbro, tonalite, and trondhjemite, and basaltic and calcalkaline dykes which intruded ...

Lower palaeozoic history of the Southwestern broken river province, North Queensland

The southwestern segment of the Broken River Province, here termed the Graveyard Creek Sub‐province, possesses a distinctive history of sedimentation, igneous activity, and structural development. ...