Tectonic Characteristics And Evolution Analysis Of Waters In The East Of Australia

Waters in the east of Australia lies in eastern margin of the Australia Plate,encompassed by the Pacific plate in the east and north.Basement beneath this region is composed by remnants of Paleozoic-Mesozoic Folded Belt and Orogenic Belt in the eastern margin of the Australia Plate.The region was a component of the Tethyan tectonic domain as the same as the oil-rich Middle East Area,with great prospective resource potential,which is one of forward positions in global petroleum exploration.However,basic geology and marine geology study of waters in the east of Australia is poor and petroleum exploration degree is low.What's worse is that we know much less of this region,which seriously restrict autonomous exploration feasibility to our country in the region.In this paper,we identified fractures,divided the first and second structure units,briefly analysed petroleum resource condition in the study area.On that basis,we reconstructed formation and evolution process of waters in the east of Australia since the Late Cretaceous according to global crustal age data since 90 Ma.From what has been discussed above,the following results were as follows:(1)Fractures in the waters of Australia extend along two main trends,NE-SW and NW-SE.Among which NE-SW fractures are parallel to the Cretaceous-early Cainozoic Tasman Basin spreading direction,and NW-SE fractures are roughly perpendicular to the convergence direction between the Australian and Pacific Plates in the late Cainozoic.The NE-SW fractures have played a particularly important role in formation of the present-day regional structure within the study area and segmented the Lord Howe Rise into a southern province,which includes the Monowai Basin and Ridge,and the Moore Basin;a central province,which includes the southern Dampier Ridge,Lord Howe Basin and Gower Basin;and a northern province,which includes the central and northern segments of the Dampier Ridge,Middleton Basin,Capel Basin and Faust Basin.(2)The evolution process of waters in the east of Australia can be divided into four stages:(1)Late Mesozoic intra-continental rift phase(90Ma—83Ma);(2)Expansion phase of the Tasman Sea(83Ma—61Ma);(3)Stop expansion phase of north of the Tasman Sea(61Ma—52Ma);Transformation of Southern Sub(4)-basin(52Ma—0Ma).(3)The most prospective areas in the study region are the central rift province of Lord Howe Rise(Gower Basin),the eastern flank of Lord Howe Rise(Fairway Basin),and New Caledonia Basin,where the sediment thickness reaches 3.5 s TWT(4km).Less prospective basins include those of the central rift province(Faust Basin)and western rift province(Capel,Middleton,Moore and Monowai Basins)where sediment thickness is relatively thin.