evolution of China included three megastages inthe Precambrian, marked respectively by the agg-regation of continental nuclei 2.8 Ga, the lateral growth and consolidation of proto-platfo
Trang 1evolution of China included three megastages in
the Precambrian, marked respectively by the
agg-regation of continental nuclei (2.8 Ga), the lateral
growth and consolidation of proto-platforms
throu-gh the Luliangian Orogeny (1.8 Ga), and the
cratoni-zation and coalescence of platforms into the
Cathaysiana Supercontient through the Jinningian
Orogeny (830 Ma) Until the Jinningian, the crustal
evolution of China seems to have been dominated
by continental growth, consolidation, and
conver-gence to form a part of the Neoproterozoic Rodinia
In Mongolia, only the last megastage, ending at
830 Ma, marked by the formation of the main
massifs, is recognized
After the Jinningian, China and Mongolia entered a
megastage characterized by a tectonic pattern
consist-ing of discrete continents and ocean basins, until their
reassembly at the close of the Indosinian Orogeny
(210 Ma) The Cathaysiana Supercontinent began to
dissociate in the Cambrian, and ocean basins were
formed between Sino-Korea and Qaidam, which was
entirely closed through the Caledonian Orogeny, with
marked collision zones The wide Caledonide
be-tween Yangtze and Cathaysia was, however, folded
and uplifted without clear collision To the north of
Tarim and Sino-Korea, the narrow Caledonides
represent continent-arc accretion In Mongolia, the
northern Mongolian massifs were successively
ac-creted to the Siberia Platform, and the Mongolian
massifs, the Salairides and Caledonides, together
formed the northern Mongolian palaeocontinent,
with the Gobi-Altai Caledonian Belt as its southern
margin Two main branches of Late Palaeozoic
oceans, the Zaysan-South Mongolia-Hingan in the
north, and the Ural-Tianshan in the south, were
con-sumed mainly after the Early Carboniferous, and
are represented respectively by the main Hercynian
sutures (Figure 1) The Late Carboniferous to Early
Triassic marine basins in southern Mongolia and
Inner Mongolia of China probably formed an
ocean with scattered islands that were filled up
with-out appreciable collision Furthermore, the Late
Hercynides-Indosinides within northern Mongolia
were actually intracontinental residual seas
To the south of the Kunlun-Qinling central
oro-genic belt of China, an open sea had persisted since
Early Palaeozoic, and the wide Indosinides are
marked by the main Indosinian (Muztagh-Maqen)
convergent zone in the north and the Jinshajiang
zone in the south The main collision zones usually
coincide with older collision zones; in other words,
they are polyphased or superimposed collision zones
It was at the close of the Indosinian Stage that the
Laurasia Supercontinent took its final shape as the
northern half of the Permian-Triassic Pangaea
The post-Indosinian megastage of China and Mongolia witnessed an entirely new tectonic regime
in East Asia, due to the appearance of the Circum-Pacific domain as a result of Pangaea disintegration and the opening of the Atlantic The subduction of the western Pacific beneath East Asia in the Jurassic caused a continent marginal magmatism along east-ern China, including the Hingan belt and easteast-ern Mongolia This new pattern brought about an apparent change of contrast between northern and southern China to that between eastern and western China In eastern China, and to a certain extent in eastern Mongolia, there occurred a combination of continental margin type and intracontinental type of volcanism, which was followed by the Late Cret-aceous to Cenozoic tensional regime of rifted basins and consequent crustal and lithospheric thinning In western China, the tectonic process in the Qinghai-Tibet Plateau consisted of the northward accretion of the Gondwanan massifs to Eurasia, characterized by the northward subduction of the Himalaya beneath Gangise in the south, the distributed crustal thicken-ing and shortenthicken-ing in the middle, and the southward indentation from Tarim and Mongol-Siberia in the northern part The contrast between the compres-sional versus extencompres-sional, and between the crustal and lithospheric thickening versus thinning regimes between western China and eastern China are evi-dent These features may have reflected and induced the deeper process of an eastward flow of the as-thenosphere from under western China, which might have, in turn, caused mantle upwelling and crustal and lithospheric thinning in eastern China
See Also
Asia: Central; South-East Gondwanaland and Gon-dwana Indian Subcontinent Japan Pangaea Russia
Further Reading
Badarch G, Cunningham WD, and Windley BF (2002)
A new terrane subdivision for Monglia: implications for the Phanerozoic crustal growth of Central Asia Journal
of Asian Earth Sciences 21: 87 110
Deng JF, Zhao Hailing, Mo Xuanxue, Wu Zongxu, and Luo Zhaohua (1996) Continental roots plume tectonics
of China: key to the continental dynamics Beijing: Geological Publishing House (In Chinese with English abstract.)
Dewey JF, Shackelton RM, Chang C, and Sun W (1994) The tectonic evolution of the Tibetan Plateau Philosoph ical Transactions of the Royal Society of London, Ser A 327: 379 413
He Guoqi, Li Maosong, Liu Dequan, Tang Yanling, and Zhou Ruhong (1988) Palaeozoic Crustal Evolution and
CHINA AND MONGOLIA 357