Terrane

About: Terrane is a research topic. Over the lifetime, 11025 publications have been published within this topic receiving 442596 citations. The topic is also known as: tectonostratigraphic terrane.

Tectonic evolution of Proterozoic Australia

Abstract: Proterozoic Australia has long been interpreted as a single intact continent in which all tectonic and magmatic activity was intracratonic This paper proposes an alternative hypothesis in which numerous fragments of continental crust were assembled by plate tectonic processes The assembly was completed between 1300 and 1100 Ma when the crustal fragments were combined as an early component of the Rodinian supercontinent Rifting and fragmentation of Archaean continents began in the late Archaean and continued into the Proterozoic Passive margin deposits, such as those of the Hamersley Basin, accumulated on isolated fragments of Archaean crust These numerous fragments were subsequently assembled into three cratons by ∼ 1830 Ma A West Australian Craton was established by collision of the Archaean Pilbara and Yilgarn cratons, which were joined along the Capricorn Orogen Similarly, a South Australian Craton developed by amalgamation of the proto-Gawler and proto-Curnamona cratons along the Kimban Orogen A North Australian Craton appears to have formed by accretion of numerous crustal fragments, including the Kimberley, Pine Creek, Lucas, and Altjawarra cratons, with sutures marked by the King Leopold, Halls Creek, Tennant Creek and proto-Isan orogens The southern margin of the North Australian Craton was the site of repeated terrane accretion and orogenic activity between ∼ 1880 Ma and 1400 Ma This included an orogenic event at ∼ 1880 – 1850 Ma; the Strangways (1780 – 1730 Ma), Argilke (1680 – 1650 Ma), and Chewings (1620 – 1580 Ma) orogenies; and the intracratonic Anmatjira uplift (1500 – 1400 Ma) Intracratonic rifting at ∼ 1750 to 1710 Ma and ∼ 1640 to 1600 Ma produced the McArthur Basin and related minor basins, parts of which were deformed by the Isan Orogeny at ∼ 1600 and ∼ 1530 Ma Rifting along the line of the Capricorn Orogen led to deposition in the overlying intracratonic Bangemall Basin between 1630 and 1300 Ma Along the eastern margin of the South Australian Craton, the 1670 to 1600 Ma Olarian Orogeny marks interaction with now obscured continental crust to the east Tectonic activity between 1300 and 1100 Ma led to the assembly of Proterozoic Australia as an early component of the supercontinent of Rodinia This first involved the amalgamation of the West Australian and North Australian cratons, followed by collision with the South Australian Craton The Centralian Superbasin developed over the junction of the North, South, and West Australian cratons between ∼ 830 and 750 Ma Rifting to the east formed the “Adelaide Geosyncline” at ∼ 830 Ma This was followed by the breakup of Rodinia, with the rifting apart of Laurentia and Gondwanaland along the eastern margin of Proterozoic Australia at ∼ 750 Ma, and the subsequent formation of the Palaeo-Pacific Ocean After the breakup of Rodinia, a series of northeast-southwest compressional events followed by periods of relaxation, reflect the assembly of a new supercontinent Old lines of weakness were reactivated, culminating in the intracratonic King Leopold, Paterson, Petermann Ranges, and Pinjarra orogenies between 620 and 540 Ma Subsequent reactivation continued into the Phanerozoic, with the widespread eruption of continental flood basalts and the formation of intracratonic basins (540 – 530 Ma)

Paleomagnetic record of plate‐margin tectonic processes along the western edge of North America

Abstract: The paleomagnetic record for the western edge of North America shows consistent, systematic discordance. Virtually none of roughly three dozen high-quality paleomagnetic studies of pre-Pliocene rock units located within several hundred kilometers of the continental margin are lying anywhere near their appropriate reference poles (constructed from high-quality paleomagnetic data from the craton). Nor do these discordant paleomagnetic studies show simple random scatter, as might be expected for rock bodies whose postmagnetization histories include reheating, complex tectonic deformation, or chemical change. Instead, their paleomagnetic poles are clearly displaced systematically away from the reference curve into the general area of the Atlantic Ocean. To accomplish this tectonically requires that the magnetized rock body move northward, rotate clockwise, or both, in relation to North America. The consistency of paleomagnetic record argues that most of the western edge of North America has undergone such block movement and therefore is allochthonous, at a scale at least as large as the area of a typical paleomagnetic study. It further argues that northward transport and clockwise rotation have been prime elements in shaping the Cordillera. Differences between paleomagnetic records for separate parts of the Cordillera probably reflect differences in specific platetectonic histories. For instance, although northward transport of allochthonous blocks is important south of Cape Mendocino and north of southern Vancouver Island, in the area between (the Pacific Northwest), only clockwise rotations are found. This is consistent with steady under-thrusting of the Pacific northwest coastline by the Farallon plate for most of the Tertiary, which is in contrast to the steady or intermittent transform activity to the north and south. Batholith belts, including the Peninsular Range batholith of Southern California and the Coast Plutonic Complex of British Columbia, also seem to have been involved in the general northward transport and clockwise rotation, although the possibility of undetected tectonic tilts clouds the record. However, consideration of the thermal behavior of large, tilted plutonic blocks suggests that post-magnetization tilts probably are small. If so, then most western Cordilleran Cretaceous batholiths (not including the Sierra Nevada) also are allochthonous. Northward transport and clockwise rotation could be accomplished by a variety of mechanisms, involving recognized plate tectonic processes. Some of these mechanisms are discussed. However, dextral shear between North America and plates to the west is central to each mechanism. It seems likely that shear also has disrupted and internally modified older accreted terranes, producing internal block rotations. Such older, disrupted allochthonous terranes appear to be drawn out into highly attenuated tectonic laminae plastered on the western edge of the continent.