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1.
Linella avis, an early to middle Neoproterozoic (Tonian to Cryogenian) stromatolite, occurs in the Eliot Range Dolomite, part of the Ruby Plains Group in the Wolfe Basin, east Kimberley. Previously, this dolomite was assigned to the Mesoproterozoic Bungle Bungle Dolomite in the Osmond Basin, which contains a different suite of stromatolites. Linella avis, which also occurs in the Neoproterozoic Bitter Springs Formation of the Amadeus Basin, central Australia, appears to be restricted to rocks aged around 850 to 800 Ma. The presence of L. avis indicates that the Ruby Plains Group is a probable correlative of the Heavitree Quartzite and Bitter Springs Formation, and is probably much younger than the Bungle Bungle Dolomite. If the correlation suggested here is correct, the Wolfe Basin, together with the Amadeus and Ngalia Basins, formed part of the Centralian Superbasin.  相似文献   

2.
Detailed mapping and C and O stable isotopic data from sedimentary carbonate in units both above and below the paleo-erosion surface on the Bitter Springs Formation (BSF) in the northeastern Amadeus Basin, Australia, have clarified the stratigraphy of the area. Isotopic data indicate that the top of the Loves Creek Member of the Bitter Springs Formation is preserved near Corroboree Rock, and is overlain by fenestrate-carbonate-clast breccia, and dolomitic quartz sandstone and chert-pebble conglomerate of the Pioneer Sandstone. The isotopic data, as well as lithologic data, indicate the presence of a 1–2 m-thick cap carbonate preserved between Corroboree Rock and areas 10 km to the northeast. In many places the cap carbonate layer is mostly a syn-sedimentary dolomite-clast breccia, consistent with deposition and disturbance in shallow water. C and O isotopic data also indicate that thin-bedded sandstone and dolomite above the Bitter Springs Formation at Ellery Creek, and a newly discovered massive chert-bearing dolomite at Ross River could both belong to the glaciogenic Olympic Formation. Detailed mapping also provides a more detailed context for the famous black chert microfossil locality in the Bitter Springs Formation at Ross River.  相似文献   

3.
The c. 570–530 Ma intraplate Petermann Orogeny of central Australia involved high temperature and pressure metamorphism, deformation, and uplift of the Mesoproterozoic Musgrave region and associated components of the Neoproterozoic Centralian Superbasin. Orogenesis was accompanied by deposition of a syn-tectonic siliciclastic sedimentary package (Supersequence 4) in adjacent depocentres such as the Amadeus Basin. Here we investigate the provenance of Supersequence 4 within the western Amadeus Basin using U–Pb age and Hf isotope data for detrital zircons. The data from eight samples are dominated by Mesoproterozoic zircons (peak at c. 1.18 Ga) matched by age and Hf isotopes to the Musgrave region. Smaller Palaeoproterozoic components match best with the Arunta region north of the Amadeus Basin. The latter zircons are likely reworked from older Amadeus Basin sediments uplifted and eroded during the Petermann Orogeny. The combined detrital zircon age signature from Supersequence 4 in the western Amadeus Basin is strongly similar to previously published data from successions of similar age in the eastern Amadeus Basin and from two metasedimentary units in the Charters Towers Province of Queensland; a K–S test indicates that these datasets are statistically identical at > 95% confidence. This suggests a sediment pathway from the Petermann Orogen to the palaeo-Pacific margin of East Gondwana via the Amadeus Basin. From existing data, a similar pathway can be inferred from the Officer Basin to the Adelaide Rift Complex on the southern side of the Petermann Orogen, although these zircon age spectra show differences in pre- and post-Mesoproterozoic components compared to the Amadeus Basin. Differences in detrital zircon age spectra and lithology between confirmed Supersequence 4 and previously inferred components of Supersequence 4 at Uluṟu (Mutitjulu Arkose) and Kata Tjuṯa (Mount Currie Conglomerate) on the southern Amadeus Basin margin raise questions about the stratigraphic position of these latter units.  相似文献   

4.
《Precambrian Research》2004,128(3-4):475-496
The Proterozoic igneous, deformation and metamorphic histories of the Palaeoproterozoic Rudall Complex in the northwestern Paterson Orogen can be linked to those of the Arunta Inlier in central Australia, and in part with the Capricorn Orogen in central Western Australia. The similarities in deformation and metamorphic histories for these widely separated regions indicate a Palaeoproterozoic continent–continent collisional event between the Palaeoproterozoic West Australian and North Australian cratons between c. 1830 and 1765 Ma. In the Paterson Orogen this Palaeoproterozoic collisional event resulted in the Yapungku Orogeny, which included thrust stacking of clastic sedimentary and volcanic rocks, deposition of the protoliths for the c. 1790 Ma siliciclastic paragneiss succession contemporaneous with granitic intrusion, and metamorphism up to granulite facies. During this 65-million-year period, the Arunta Inlier and Capricorn Orogen were deformed, metamorphosed at medium to high grades and intruded by granitoids during the Strangways Orogeny in the Arunta Inlier and the Capricorn Orogeny in the Capricorn Orogen.The Neoproterozoic Tarcunyah, Throssell and Lamil groups are clastic sedimentary sequences that were deposited after 1070 Ma in the northwestern Paterson Orogen, and deformed by the Miles Orogeny before 678 Ma. The Miles Orogeny produced a northwesterly trending fold and fault system of tight to isoclinal upright and overturned folds and thrust faults. The orogeny may have been coincident with the c. 750–720 Ma Areyonga tectonic movement affecting the Arunta Inlier and the lower Neoproterozoic part of the Amadeus Basin in central Australia. At c. 550 Ma the Paterson Orogeny, which is most likely equivalent to the Petermann Orogeny in the Musgrave Complex of central Australia, deformed the northwestern Paterson Orogen and was preceded by local intrusion of granites.The similarities of styles and timing of deformation in the northwestern Paterson Orogen, Arunta Inlier and Capricorn Orogen indicate that these three regions were probably linked during most of the Proterozoic.  相似文献   

5.
A major, linear, west-trending deformed zone (The Redbank Zone), 350 km long and up to 20 km wide, can be identified in the Arunta Block immediately north of the Amadeus Basin. The marked linearity of this zone and of the coincident gravity anomaly probably result from thrust-fault movement during the Carboniferous Alice Springs Orogeny. However, in the Ormiston area, there is evidence that the zone originated prior to 1070 m.y. and acted as a major crustal feature controlling the later orogenic event.The Alice Springs Orogeny affected the overlying Proterozoic and Lower Palaeozoic cover rocks as well as the Arunta Block basement. During the orogeny, steep north-dipping thrusts within the Redbank Zone were reactivated causing uplift to the north. These faults penetrated the Heavitree Quartzite—the basal unit of the cover sequence—to drive wedges of basement, with attached veneers of Heavitree Quartzite, for up to 20 km southward within the overlying Bitter Springs Formation. The nappes did not reach the surface or penetrate formations above the Bitter Springs. Accompanying nappe emplacement the Basin to the south rapidly deepened to receive a thick wedge of synorogenic molasse sediments.Gravity, sedimentary and structural features combine to suggest that the Alice Springs orogeny movements reached their maximum on the central part of the northern margin of the Amadeus Basin, in the Ormiston area.  相似文献   

6.
Parts of the Late Proterozoic to Cambrian sequence along the northeastern margin of the Amadeus Basin were deposited under the influence of salt movement within the underlying Bitter Springs Formation. Later folding during the Devonian Alice Springs Orogeny and subsequent erosion has exposed salt‐influenced structures to provide a rare opportunity to observe the effects of diapiric growth on local facies and structure. Such effects are commonly only seen in seismic section. Salt withdrawal led to normal faulting and syn‐sedimentary thickening of adjacent units. The Undoolya Sequence, a previously undescribed 710 m section, was deposited within a salt‐withdrawal basin adjacent to a proposed diapiric structure. Periods of salt mobilization are recorded by syn‐depositional thickening and localized unconformities within units flanking the diapiric structure. This structure is representative of the influence salt movement had on deposition in the northeastern Amadeus Basin during the Late Proterozoic.  相似文献   

7.
The Amadeus Basin displays subtle magnetic anomalies that trace strata for considerable distance, highlighting complex folding patterns. Magnetic modelling techniques can be utilised on these stratiform anomalies to extrapolate the near-surface structure of the basin. However, because of the mathematical trade-off between the dip and magnetisation of bodies, the dips of the bodies cannot be known unless the magnetisation is also known. Normally it would be optimal to measure the magnetisation, but this is not always possible or feasible. In this study, we investigate the relationships between dip and magnetisation using an approach that would generally be considered a little backward, i.e. constraining magnetisation direction using geological data. Three study areas were chosen to investigate a number of stratigraphic horizons, the Waterhouse Range, Glen Helen and Ross River areas. Modelling results suggest that some layers primarily retain induced magnetisation, remanence is dominant in others, but both are present in most. Remanence is mainly associated with relatively oxidised units that contain only hematite (e.g. Arumbera Sandstone), and we have demonstrated that these magnetisations predate folding of the Ross River Syncline. In some cases, the anomalies represent redox zonation within units, e.g. the Pertatataka Formation near Glen Helen, where discrete magnetic layers correspond to thin grey (reduced, magnetite-rich) horizons interbedded with more prevalent red (oxidised, hematite-rich) horizons. We also found that where magnetised units are relatively thin and occur near the surface, their magnetic response is sharp, and in aeromagnetic data such adjacent anomalies commonly overlap to form a single anomaly, thus misrepresenting the magnetic field, and mis-mapping the actual magnetic horizons. While the magnetic properties of the causative bodies are variable, we have demonstrated that a better understanding of the magnetic properties of these magnetised horizons can be used to provide insights into the structure and tectonic history of the Amadeus Basin.  相似文献   

8.
The basal unit of the Amadeus Basin sequence is the Heavitree Quartzite, and this formation usually forms a single east‐west ridge along the northern side of the MacDonnell Ranges. However, at Alice Springs there are two such ridges. Basement rocks crop out on the northern side of each ridge, and dolomite and shale of the Bitter Springs Formation crop out on their southern sides. The northern outcrop of dolomite and shale is tightly folded, and is separated from the southern outcrop of basement by a major fault. The bedding of the sediments, the axial plane of the fold, and the fault all dip south at about 45°. Inverted facings on parasitic folds indicate that the northern outcrop of quartzite and dolomite plus shale is an antiform in inverted rocks. Hence the southern outcrop of basement and quartzite is synformal, and is interpreted as the frontal part of a fold nappe. The nappe started as a recumbent anticline whose middle limb of quartzite sheared out as the anticline travelled several kilometres southwards relative to the dolomite and shale below, which formed a tight recumbent syncline. Later monoclinal uplift of the northern half of the area tilted the nappe into its present south‐dipping attitude, thus converting the recumbent anticline into a synform and the recumbent syncline into an antiform.  相似文献   

9.
Great Victoria Desert: Development and sand provenance   总被引：1，自引：0，他引：1  
Sands of the Great Victoria Desert, south‐central Australia, can be divided into three main groups on the basis of their physical and chemical characteristics (colour, grainsize parameters, mineralogy of heavy‐mineral suites, quartz oxygen isotopic composition, zircon U–Pb ages). The groups occupy the western, central and eastern Great Victoria Desert respectively, boundaries between them corresponding approximately to changes in the underlying rocks associated with the Yilgarn Craton to Officer Basin to Arckaringa Basin. Several lines of evidence suggest derivation of the sands mainly from local bedrock with very little subsequent aeolian transport. Ultimate protosources for the sands, each in order of importance, are: western Great Victoria Desert—Yilgarn Craton, Albany‐Fraser Orogen, Musgrave Complex; central Great Victoria Desert—Musgrave Complex; eastern Great Victoria Desert—Gawler and Curnamona Blocks, Adelaide Geosyncline, Musgrave Complex. Sediment from the Adelaide Geosyncline includes in addition an ‘exotic’ component from Palaeozoic sedimentary rocks probably derived mainly from Antarctica. Sediment transport of several hundred kilometres from these protosources to the sedimentary basins was dominantly by fluvial, not aeolian, means. Post‐Tertiary aeolian transport or reworking has been minimal, serving only to shape sand eroded from underlying sedimentary rocks or residual products of local basement weathering into the current dunes.  相似文献   

10.
The Palaeozoic Alice Springs Orogeny was a major intraplate tectonic event in central and northern Australia. The sedimentological, structural and isotopic effects of the Alice Springs Orogeny have been well documented in the northern Amadeus Basin and adjacent exhumed Arunta Inlier, although the full regional extent of the event, as well as lateral variations in timing and intensity are less well known. Because of the lack of regional isotopic data, we take a sedimentological approach towards constraining these parameters, compiling the location and age constraints of inferred synorogenic sedimentation across a number of central and northern Australian basins. Such deposits are recorded from the Amadeus, Ngalia, Georgina, Wiso, eastern Officer and, possibly, Warburton Basins. Deposits are commonly located adjacent to areas of significant basement uplift related to north‐south shortening. In addition, similar aged orogenic deposits occur in association with strike‐slip tectonism in the Ord and southern Bonaparte Basins of northwest Australia. From a combination of sedimentological and isotopic evidence it appears that localised convergent deformation started in the Late Ordovician in the eastern Arunta Inlier and adjacent Amadeus Basin. Synorogenic style sedimentation becomes synchronously widespread in the late Early Devonian and in most areas the record terminates abruptly close to the end of the Devonian. A notable exception is the Ngalia Basin in which such sedimentation continued until the mid‐Carboniferous. In the Ord and Bonaparte Basins there is evidence of two discrete pulses of transcurrent activity in the Late Devonian and Carboniferous. The sedimentological story contrasts with the isotopic record from the southern Arunta Inlier, which has generally been interpreted in terms of continuous convergent orogenic activity spanning most of the Devonian and Carboniferous, with a suggestion that rates of deformation increased in the mid‐Carboniferous. Either Carboniferous sediments have been stripped off by subsequent erosion, or sedimentation outpaced accommodation space and detritus was transported elsewhere.  相似文献   

11.
During the Alice Springs Orogeny, deformation at Ormiston Gorge, central Australia, occurred under lower- to middle-greenschist facies conditions. Dolomites of the Bitter Springs Formation and quartzites. metagreywackes, and metapelites of the Heavitree Quartzite contain abundant early-, syn-, and post-tectonic veins. However, though vein densities locally approach 15%, the distribution of veins and the oxygen isotope geochemistry of wallrocks and veins suggest that fluid movement was on a local scale. The Heavitree Quartzite contains quartz veins that, even along the main thrust plane, have similar δ18O values (13.5–16.9%o) to those of their wallrocks (13.6–16.9%o), with Δ18O(vein-wallrock) values of -0.6 to 0.4%o. In contrast, the Bitter Springs Formation contains predominantly dolomite veins that have δ18O values of 23.4 to 27.7%o. These differences are observed even at the boundary between the Heavitree and Bitter Springs rocks, implying that significant fluid exchange between these rocks has not occurred, or that fluid flow was channelled through areas outside those sampled for this study. By contrast with the Heavitree Quartzite, δ18O values of wallrocks in individual samples of the Bitter Springs Formation are significantly higher (23.3–29.1%o) than those of the veins, with δ18O(vein-wallrock) values up to -4%o (average of -2.1%o). These systematic differences in δ18O values most likely result from oxygen isotope fractionation caused by fluid immiscibility or disequilibrium dissolution. Smaller differences in δ13C values between some dolomite veins and wallrocks [δ13C(vein-wallrock) up to -1.9%o, average of -0.5%o] are also explained by these processes. This study indicates that large volumes of veins may be produced by repeated fracturing and fluid migration within particular rock units, without involving large volumes of externally derived fluids.  相似文献   

12.
A major west‐trending lineament marked by a wide belt of highly deformed rocks (the Redbank Zone), lies in the Arunta Complex, north of the Amadeus Basin. Along its southern margin the Zone has been progressively affected by, and is hence older than, migmatization and granite intrusion. The migmatization event yields a Rb‐Sr isochron age of 1076 ± 50 m.y. Within the migmatite complex, relicts of a pre‐migmatite metasedimentary sequence around the Chewings Range yield a Rb‐Sr isochron age of 1620 ± 70 m.y. The migmatites are unconformably overlain by the basal unit of the Amadeus Basin sequence, the Heavitree Quartzite. The 1076 ± 50 m.y. date thus provides a maximum age for the start of sedimentation along the northern margin of the Basin. The existence of a major zone of weakness in the basement probably exerted a strong control on basement and cover deformation during the Palaeozoic Alice Springs Orogeny.  相似文献   

13.
The Glikson structure is an aeromagnetic and structural anomaly located in the Little Sandy Desert of Western Australia (23°59'S, 121°34′E). Shatter cones and planar microstructures in quartz grains are present in a highly deformed central region, suggesting an impact origin. Circumferential shortening folds and chaotically disposed bedding define a 19 km-diameter area of deformation. Glikson is located in the northwestern Officer Basin in otherwise nearly flat-lying sandstone, siltstone and conglomerate of the Neoproterozoic Mundadjini Formation, intruded by dolerite sills. The structure would not have been detected if not for its strong ring-shaped aeromagnetic anomaly, which has a 10 km inner diameter and a 14 km outer diameter. We interpret the circular magnetic signature as the product of truncation and folding of mafic sills into a ring syncline. The sills most likely correlate with dolerites that intrude the Boondawari Formation ～25 km to the north, for which we report a SHRIMP U?–?Pb baddeleyite and zircon age of 508?±?5 Ma, providing a precise older limit for the impact event that formed the Glikson structure.  相似文献   

14.
The Southern Arunta block within the Alice Springs region is dissected by an E-W-trending network of high-angle reverse faults. Microstructural evidence indicates that there is a change from dominantly ductile to brittle faulting southwards across the block towards the Amadeus Basin, and this suggests that the faults in the north were progressively uplifted by the more southern faults. The generation of ultramylonite has been particularly extensive in the Alice Springs region. TEM and SEM observations have allowed an appraisal of the deformation mechanisms at ultrafine grainsizes and suggest complex interactions between dislocation processes, diffusion and grain-boundary sliding.  相似文献   

15.
Stromatolite biostromes and bioherms in the lower two units of the Late Proterozoic Loves Creek Member of the Bitter Springs Formation represent shallowing upward and deepening upward sequences. In the central unit stromatolite form is governed by relative position in an asymmetric shallowing upward sequence. Ooid and/or peloid-intraclast grainstones and small, irregular bulbous and columnar stromatolites characterize the basal, transgressive portion of cycles. Domal, columnar and stratiform stromatolites comprise the bulk of the cycle. These forms accreted in a gradually shallowing epeiric sea. Domal stromatolites predominate in the deeper parts of cycles. Here synoptic relief gradually increases upwards. Columnar and stratiform stromatolites predominate in the shallower parts of cycles, where synoptic relief rapidly diminishes upwards. In thin-bedded dolo-mudstones at the tops of cycles the co-occurrence of desiccation cracks, tepee structures, scalloped dissolution surfaces, gypsum moulds and anhydrite nodule pseudomorphs provides evidence for subaerial exposure. In contrast, stromatolites in a unit at the base of the Loves Creek Member accreted during a gradual rise in sealevel. Stratiform, columnar and domal stromatolitic building blocks of the shallowing upward cycle are present in this deepening sequence, but only the lower half of the shallowing upward cycle is represented. Synoptic relief of the stromatolitic laminae gradually increases upward throughout the basal stromatolitic unit. Recognition of a deepening upward stromatolite sequence at the base of the Loves Creek Member, and a disconformity surface between this sequence and the underlying Gillen Member, permits palaeoenvironmental re-interpretation of the Loves Creek Member as a single ‘large scale’ sea-level cycle.  相似文献   

16.
More than forty calcrete and gypcrete samples from bore holes in the Curtin Springs area of the Amadeus Basin, Central Australia, have been dated by means of the 14C and ESR techniques. The results indicate that the application of multiple dating techniques to samples from calcrete and gypcrete deposits enables age limits to be expanded and the number of datable material types to be increased with respect to Quaternary studies. The ability of the 14C and ESR techniques to determine the approximate age of calcrete and gypcrete deposits has been demonstrated.  相似文献   

17.
Rb‐Sr and K‐Ar measurements have been made on five glauconite samples from the near basal Treuer Member of the Vaughan Springs Quartzite of the Ngalia Basin, Northern Territory, Australia. Comparison of results between and within the two groups of data demonstrates that variable losses of radiogenic strontium and argon have occurred, but allows a minimum age of 1280 m.y. to be calculated for the member. Sedimentation began in the Ngalia Basin shortly before the time of deposition of this member.

Regional correlations suggest that this minimum age applies to the adjacent Amadeus Basin as well.

Measurements were also made on glauconite from a single sample of the Lower Palaeozoic Djagamara Formation which is in the same sequence. It yields a mid‐Ordovician K‐Ar age which generally agrees with the broad range of post‐Lower Cambrian to pre‐Carboniferous age determined from fossil evidence in bounding formations. A low Rb/Sr ratio prevented calculation of a Rb‐Sr age, but the combination of K‐Ar age and Rb‐Sr measurements allowed an accurate initial 87Sr/86Sr ratio of .739 to be determined. This is much greater than ocean water values, and it appears that such information on young samples and/or those of low Rb/Sr ratio could help define the source material for glauconite formation.  相似文献   

18.
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19.
Abstract

Silicified fossil macrofloras of the Willalinchina Sandstone, at Stuart Creek in the Billa Kalina Basin of northern South Australia, are most likely early Miocene–early Pliocene with preference for the younger age, based on reinterpretation of published evidence including basin stratigraphy, paleogeography, isotopic and other dating. The macrofloras include Eucalyptus and occur in fluvial channel sandstones. The Willalinchina Sandstone is equated with the Danae Conglomerate Member of the Mirikata Formation, interpreted as older than the Watchie Sandstone, Millers Creek Dolomite Member and Billa Kalina Clay Member, and here regarded as of upper Neogene age. The Billa Kalina Basin lies between Lake Eyre, Torrens and Eucla basins, and has affinities with all three. The Kingoonya Paleochannel, peripheral to the Eucla Basin, joins the southern margin of the Billa Kalina Basin across the Stuart Range Divide, and contains the Garford Formation of mid-Miocene to Pliocene age (palynological dating), here partly equated with the Mirikata Formation. Interpretations of paleolake Billa Kalina and associated paleochannel environments are made, based on a new assessment of stratigraphic and paleogeographic relationships.
  1. KEY POINTS

  2. The Billa Kalina Basin sediments in northern South Australia are equated with the later Neogene ‘upper’ Garford Formation of the Kingoonya Paleochannel, which flowed into the Eucla Basin, and depositional processes are clarified.

  3. A variety of consistent age data from adjacent basins and the Kingoonya Paleochannel indicate the Stuart Creek ‘silcrete floras’, associated with the Willalinchina Sandstone channel deposits, are Neogene, probably early Pliocene, but the possibility remains that they may be incised into the Watchie Sandstone and therefore late Pliocene.

  4. The Billa Kalina Basin was linked to the Kingoonya Paleochannel through much of its history, with flow disrupted by the Stuart Range Divide, local tectonics, and regional tilting.

  相似文献   

20.
A Rb‐Sr age of 897 ± 9 m.y. is obtained for dolerite from the Stuart Dyke Swarm in the southern part of the Arunta Block, Northern Territory. The dyke swarm presents an older age limit for the unconformably overlying Heavitree Quartzite, basal formation of the Amadeus Basin sequence. This limit is consistent with all isotopic data with the exception of previously determined glauconite ages from the Vaughan Springs Quartzite, a correlative of the Heavitree Quartzite in the Ngalia Basin.  相似文献   

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