Large ripples are described from the Mesoproterozoic Hilfordy Formation in the Kimberley region,northwestern Australia.Both ripple index(RI)and ripple symmetry index(RSI)suggest the Kimberley ripples were likely gener...Large ripples are described from the Mesoproterozoic Hilfordy Formation in the Kimberley region,northwestern Australia.Both ripple index(RI)and ripple symmetry index(RSI)suggest the Kimberley ripples were likely generated by storm waves.Their wave height is up to 1523 cm and wave length is up to 7090 cm.These features,incorporated with other morphological characteristics such as symmetry,steepness,ripple spacing,and compositions,agree well with the megaripples previously reported from the intertidal-nearshore settings of modern seas and the geological past.The Mesoproterozoic ripples were likely generated by the storm-induced flows.Literature survey of the global record of megaripples reveals that such structures have occurred through the geological past from the Archean to present day.They were particularly common in the Neoproterozoic and had the largest ripple length and ripple height among the modern and geological records.This is probably because extreme storms prevailed at that time.Their frequent occurrence in present day beach is probably due to the prevalence of extreme storms caused by the monsoon or tsunami/earthquake influenced climatic regimes.展开更多
The history of the Kimberley region in the far north of Western Australia began in the Paleoproterozoic with rifting along the North Australian Craton margin at 1910–1880 Ma,followed by plate collision as part of a s...The history of the Kimberley region in the far north of Western Australia began in the Paleoproterozoic with rifting along the North Australian Craton margin at 1910–1880 Ma,followed by plate collision as part of a series of 1870–1790 Ma events that formed the Diamantina Craton within the supercontinent Nuna.Collision involved the accretion of an intra-oceanic arc to a continent that included the Kimberley Craton before final collision and suturing with the North Australian Craton.The c.1835 Ma Speewah Basin formed as a retro-arc foreland basin to the W.The post-orogenic,c.1800 Ma shallow-marine to fluvial Kimberley Basin and its equivalents had a provenance to the N and extended across both the Lamboo and Hooper provinces.Subsequent late Paleoproterozoic and Mesoproterozoic basins formed broadly similar depositional settings during break-up and reassembly into the supercontinent Rodinia.The intracratonic Yampi Orogeny generated large-scale folding and thrusting and sinistral strike-slip faulting between 1400–1000 Ma.The Neoproterozoic Centralian Superbasin formed as a broad intracratonic sag basin throughout central Australia between c.830 Ma and the earliest Cambrian,including a series of basins across the Kimberley.Glacigene rocks are present with the most widespread being equivalent to the c.610 Ma Elatina(“Marinoan”)glaciation.Folding,thrusting and strike-slip faulting during the c.560 Ma King Leopold Orogeny caused a widespread unconformity at the base of the Ord and Bonaparte basins marked by the c.508 Ma Kalkarindji Continental Flood Basalt Province.In the Early Ordovician,thermal subsidence initiated the Canning Basin.Paleozoic sedimentary rocks,including Devonian reef complexes,were deposited on the Lennard Shelf and in the Fitzroy Trough.In the Halls Creek Orogen,Devonian sedimentary rocks were deposited in subbasins of the Ord Basin during the c.450–300 Ma Alice Springs Orogeny.A widespread glacigene succession followed in the Canning Basin,but by the early Triassic deposition was restricted and the remainder of the Mesozoic succession forms a veneer over much of the basin.展开更多
基金supported by a joint scholarship from China Scholarship Council and the University of Western AustraliaFinancial grant for this research was provided by an Australian Research Council Discovery Grant(DP07752298 to ZQC)
文摘Large ripples are described from the Mesoproterozoic Hilfordy Formation in the Kimberley region,northwestern Australia.Both ripple index(RI)and ripple symmetry index(RSI)suggest the Kimberley ripples were likely generated by storm waves.Their wave height is up to 1523 cm and wave length is up to 7090 cm.These features,incorporated with other morphological characteristics such as symmetry,steepness,ripple spacing,and compositions,agree well with the megaripples previously reported from the intertidal-nearshore settings of modern seas and the geological past.The Mesoproterozoic ripples were likely generated by the storm-induced flows.Literature survey of the global record of megaripples reveals that such structures have occurred through the geological past from the Archean to present day.They were particularly common in the Neoproterozoic and had the largest ripple length and ripple height among the modern and geological records.This is probably because extreme storms prevailed at that time.Their frequent occurrence in present day beach is probably due to the prevalence of extreme storms caused by the monsoon or tsunami/earthquake influenced climatic regimes.
文摘The history of the Kimberley region in the far north of Western Australia began in the Paleoproterozoic with rifting along the North Australian Craton margin at 1910–1880 Ma,followed by plate collision as part of a series of 1870–1790 Ma events that formed the Diamantina Craton within the supercontinent Nuna.Collision involved the accretion of an intra-oceanic arc to a continent that included the Kimberley Craton before final collision and suturing with the North Australian Craton.The c.1835 Ma Speewah Basin formed as a retro-arc foreland basin to the W.The post-orogenic,c.1800 Ma shallow-marine to fluvial Kimberley Basin and its equivalents had a provenance to the N and extended across both the Lamboo and Hooper provinces.Subsequent late Paleoproterozoic and Mesoproterozoic basins formed broadly similar depositional settings during break-up and reassembly into the supercontinent Rodinia.The intracratonic Yampi Orogeny generated large-scale folding and thrusting and sinistral strike-slip faulting between 1400–1000 Ma.The Neoproterozoic Centralian Superbasin formed as a broad intracratonic sag basin throughout central Australia between c.830 Ma and the earliest Cambrian,including a series of basins across the Kimberley.Glacigene rocks are present with the most widespread being equivalent to the c.610 Ma Elatina(“Marinoan”)glaciation.Folding,thrusting and strike-slip faulting during the c.560 Ma King Leopold Orogeny caused a widespread unconformity at the base of the Ord and Bonaparte basins marked by the c.508 Ma Kalkarindji Continental Flood Basalt Province.In the Early Ordovician,thermal subsidence initiated the Canning Basin.Paleozoic sedimentary rocks,including Devonian reef complexes,were deposited on the Lennard Shelf and in the Fitzroy Trough.In the Halls Creek Orogen,Devonian sedimentary rocks were deposited in subbasins of the Ord Basin during the c.450–300 Ma Alice Springs Orogeny.A widespread glacigene succession followed in the Canning Basin,but by the early Triassic deposition was restricted and the remainder of the Mesozoic succession forms a veneer over much of the basin.
