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Petroleum Geological Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
The concept of continental drifting is extended to explain the formation of today’s seven continents. The seven continents of the earth were formed by their relative drifting from each other in the ocean. Earlier all seven continents were joined together into one supercontinent called Pangaea. Super Pangaea was formed about 350 million years ago and the Pangaea was broken and split into several parts about 200 million years ago, due to underground tectonic activities. The parts of super Pangaea drifted slowly across the earth’s surface and ultimately attained their present geographical positions. The drifting of continents is a continuous geological process. Every continent is drifting in one direction or the other. The rate of drifting varies from continent to continent. The drifting rate may vary from un-noticeable to 1 mm to 100 mm per year.
The Earth Through Time
Published in Aurèle Parriaux, Geology, 2018
At the beginning of the Proterozoic (2500–1950 Ma), the process of magmatic segregation (Chap. 6) continued in the Earth’s crust. The continents were composed of light rocks enriched in silicon (granitic crust). The later Proterozoic saw the beginning of plate tectonics as we know it: long distance movements of a small number of thick, almost undeformed lithospheric plates. The ocean began to open (rifting); the first continental plates began to move due to deep convection currents. Their collisions led to the formation of the first mountains and the formation of the vast supercontinent Rodinia, which will break up at the end of the Precambrian.
The Earth in Time
Published in Aurèle Parriaux, Geology, 2018
At the beginning of the Proterozoic (2500–1950 Ma), the process of magmatic segregation (Chapt. 6) continued in the Earth’s crust. The continents were composed of light rocks enriched in silicon (granitic crust). The later Proterozoic saw the beginning of plate tectonics as we know it: long distance movements of a small number of thick, almost undeformed lithospheric plates. The ocean began to open (rifting); the first continental plates began to move due to deep convection currents. Their collisions led to the formation of the first mountains and the formation of the vast supercontinent Rodinia, which will break up at the end of the Precambrian.
The geochemistry and petrogenesis of Carnley Volcano, Auckland Islands, SW Pacific
Published in New Zealand Journal of Geology and Geophysics, 2018
John A. Gamble, Chris J. Adams, Paul A. Morris, Richard J. Wysoczanski, Monica Handler, Christian Timm
A major thermal event ∼ 180 Ma resulted from or led to the mantle instability that generated the massive continental flood basalt provinces of the Parana-Karroo-Ferrar, now preserved in Brazil, southern Africa, Antarctica, south eastern Australia and New Zealand and may have been a precursor to breakup of the Gondwana supercontinent and opening of the Tasman Sea and Southern Ocean, between 84 and 79 Ma (Gaina et al. 1998; Cande and Stock 2004; van der Meer et al. 2017). Prior to these events and possibly since early Phanerozoic or late Proterozoic times, the continental lithosphere of the palaeo-Pacific margin had been subjected to subduction and subsequently to the possible effects of an impinging mantle plume. While mantle lithosphere, in its pristine form, is refractory and depleted in nature having been produced by partial melting processes that yielded basalt, this ‘lithospheric lid’ may have been exposed periodically to transitory melts and fluids that differentiate, mingle, degass and dewater, and variably infiltrate and enrich the lithospheric mantle. This is most certainly the case for the SW Pacific subduction-related margins of Gondwana and evidence of this process is recorded in mantle xenoliths from southern Zealandia (Scott et al. 2013; Scott 2014; Scott et al. 2014; McCoy-West et al. 2015, 2016; Scott, Liu et al. 2016; Scott, Brenna et al. 2016; Dalton et al. 2017), Antarctica (Gamble and Kyle 1987; Gamble et al. 1988; Handler et al. 2003; Martin et al. 2014, 2015) and SE Australia (O’Reilly and Griffin 1988; Yaxley et al. 1991; McBride et al. 1996).
Genetic and ore-forming ages of the Fe–P–(Ti) oxide deposits associated with mafic–ultramafic–carbonatite complexes in the Kuluketage block, NW China
Published in Australian Journal of Earth Sciences, 2019
W. Chen, X. B. Lü, X. F. Cao, Q. Yuan, X. D. Wang
The absence of ca 850–750 North China Craton has been used to argue that they are not close to South China Craton or Australia in the Rodinia supercontinent (Li et al., 2008). Although the early Permian mafic–ultramafic rocks around the TC were thought to be part of a LIP event (Liu et al., 2015, 2016), no Neoproterozoic LIP events have been indentified in the TC. During this period (850–760 Ma), magmatism in the TC is related to plate subduction. Mafic–ultramafic rocks related to subduction are common in China, for example the newly discovered giant Xiarihamu Ni deposit in the Eastern Kunlun Orogenic belt (Liu et al., 2018) but magmatism in Australia is related mantle plumes (Ernst, Wingate, Buchan, & Li, 2008; Zhao, Li, Liu, & Wang, 2018).
Precise U–Pb baddeleyite dating of the Derim Derim Dolerite, McArthur Basin, Northern Territory: old and new SHRIMP and ID-TIMS constraints
Published in Australian Journal of Earth Sciences, 2021
S. Bodorkos, J. L. Crowley, J. C. Claoué-Long, J. R. Anderson, C. W. Magee
This date is significantly older than a baddeleyite U–Pb ID-TIMS date of ca 1313 Ma recently reported from dolerite in the Beetaloo Sub-basin (Collins et al., 2018; Yang et al.,in press), some 200 km south of the Derim Derim Dolerite type locality, which indicates that magmatism attributed to the Derim Derim Dolerite spanned at least 10–15 Ma. The possibility of episodic emplacement of phonolites and intraplate mafic rocks as far afield as the Nimbuwah Domain of the eastern Pine Creek Orogen (Hollis & Glass, 2012; Whelan et al., 2016), and the Tomkinson Province (Melville, 2010), has hitherto been obscured by the relatively low precision of the available isotopic dates. Hollis and Glass (2012) documented a range of Ti/Y values in mafic rocks of the Nimbuwah Domain, which they interpreted to reflect different depths of partial melting, and it is possible that such variations can be attributed to temporally distinct pulses of magmatism. Zhang et al. (2017) documented a strikingly similar range of baddeleyite 207Pb/206Pb dates (ca 1330 Ma to ca 1305 Ma, with peak activity at ca 1323 Ma) from the Yanliao rift zone of the North China Craton and demonstrated strong geochemical similarities between the Yanliao and Derim Derim-Galiwinku mafic rocks. Even in the absence of supporting paleomagnetic data, these relationships suggest that the North Australian Craton and North China Craton were near-contiguous in the Mesoproterozoic (Zhang et al., 2017), and defined the epicontinental ‘McArthur-Yanliao Gulf’ within the supercontinent Nuna/Columbia (Collins et al., 2019).