Geochemistry of late Mesozoic adakites from the Sulu belt, eastern China: magma genesis and implications for crustal recycling beneath continental collisional orogens

2005 ◽  
Vol 143 (1) ◽  
pp. 1-13 ◽  
Author(s):  
FENG GUO ◽  
WEIMING FAN ◽  
CHAOWEN LI
Keyword(s):  
Trace Element ◽  
Continental Crust ◽  
Eastern China ◽  
Lower Continental Crust ◽  
Nd Isotope ◽  
Late Mesozoic ◽  
Crustal Recycling ◽  
The North ◽  
Mantle Peridotites ◽  
Collisional Orogens

Both low-Al and high-Al adakitic andesites erupted at ∼ 114 Ma in the Sulu collisional belt, eastern China, provide evidence for recycling of continental crust into the mantle more than 100 million years after the Triassic (∼ 240 Ma) collision between the North China and Yangtze blocks. These rocks display similar normalized trace element patterns, with enrichments in large ion lithophile elements (LILE), light rare earth elements (LREE) and depletions in Nb, Ta and Ti, and have highly radiogenic Sr and non-radiogenic Nd isotopic compositions (high-Al: 87Sr/86Sr(i)=0.70645–0.70715 and εNd(t)=−20.1 to −19.1; low-Al: 87Sr/86Sr(i)=0.70593–0.70598 and εNd(t)=−17.1 to −15.8). The high-Al (Al2O3 > 15 %) adakitic andesites are compositionally comparable with experimental slab melts, whereas the low-Al series (Al2O3 ∼ 13 %) have higher MgO, Cr and Ni, and higher Sr/Y ratios, and are compositionally comparable with slab melts hybridized by mantle peridotites. Combined major- and trace-element and Sr–Nd isotope data indicate that the two types of adakitic andesites have been derived from a LILE- and LREE-enriched eclogitic lower continental crust; in the case of the high-Al adakitic andesites, the melts underwent insignificant mantle contamination, whereas the low-Al magmas reacted with peridotites. Generation of the two types of late Mesozoic adakitic andesites favours a model of lithospheric delamination, leading to asthenospheric upwelling and extensive melting of lower continental crust, including a delaminated block, in the Sulu belt.

Recycling lower continental crust in the North China craton

Nature ◽  
2004 ◽  
Vol 432 (7019) ◽  
pp. 892-897 ◽  
Author(s):  
Shan Gao ◽  
Roberta L. Rudnick ◽  
Hong-Ling Yuan ◽  
Xiao-Ming Liu ◽  
Yong-Sheng Liu ◽  
...  
Keyword(s):  
Continental Crust ◽  
North China Craton ◽  
North China ◽  
Lower Continental Crust ◽  
The North

Zoned olivine xenocrysts in a late Mesozoic gabbro from the southern Taihang Mountains: implications for old lithospheric mantle beneath the central North China Craton

2009 ◽  
Vol 147 (2) ◽  
pp. 161-170 ◽  
Author(s):  
JI-FENG YING ◽  
HONG-FU ZHANG ◽  
YAN-JIE TANG
Keyword(s):  
North China Craton ◽  
Lithospheric Mantle ◽  
Large Scale ◽  
North China ◽  
Eastern China ◽  
Late Mesozoic ◽  
Mantle Peridotites

AbstractZoned olivine grains are abundant in the late Mesozoic Shatuo gabbro (southern Taihang Mountains, central North China Craton). Olivine cores are rich in MgO and NiO, rims are rich in FeO and MnO, and both cores and rims have very low CaO contents. The cores invariably have a high Mg no. (92–94), similar to olivine xenocrysts from Palaeozoic kimberlites in eastern China. The compositional features of these olivines imply that they are xenocrysts rather than phenocrysts, namely, disaggregates of mantle peridotites at the time of intrusion. The compositional similarity of olivine cores to xenocrysts from Palaeozoic kimberlites suggests that the lithospheric mantle beneath the central North China Craton is ancient and refractory in nature, and quite different from eastern China, where the mantle is mainly composed of newly accreted materials resulting from large-scale lithospheric removal and replacement. The contrasting features of the lithospheric mantle beneath the eastern and central North China Craton imply that the large-scale lithospheric removal in Phanerozoic times was mainly confined to the eastern North China Craton.

The kinematics of the Tan-Lu Fault zone during the Mesozoic-Palaeocene and its relations with the North China – South China block collision (Anhui Province, China)

2007 ◽  
Vol 178 (5) ◽  
pp. 353-365 ◽  
Author(s):  
Pierre Vergely ◽  
Ming Jin Hou ◽  
Young Ming Wang ◽  
Jacques-Louis Mercier
Keyword(s):  
Continental Crust ◽  
Fault Zone ◽  
South China ◽  
North China ◽  
Sedimentary Cover ◽  
Eastern China ◽  
Strike Slip ◽  
Late Triassic ◽  
South China Block ◽  
The North

Abstract The Tan-Lu Fault zone (TLFZ), often considered as a major sinistral strike-slip fault, extends in a NE to NNE direction for more than 2,000 km in eastern China. A structural analysis of the southern segment of the TLFZ (STLFZ) and surrounding areas enables us to propose the following evolution of this area during the Mesozoic-Palaeocene. The mid-Triassic NNW-SSE and late Triassic SSW-NNE to SSE-NNW strikes of the stretching lineations in the Zhangbaling massif favour ductile shears in a Zhangbaling metamorphic formation located along a ~NNE-SSW orientated “Tan-Lu margin”; this margin connected two margin segments situated north of the Dabie and Sulu belts. During the Mid-Late Triassic, the continental crust of the South China block (SCB) has been obliquely subducted along this margin below the North China block (NCB). We confirm that the SCB continental crust has been sliced and thrust toward the SSE and propose that the ductile thrusts have merged into the decollements of the sedimentary cover of the platform, forming the thrust-and-fold belt which has acted as a sinistral compressional transfer zone between the Dabie and Sulu collision belts. Thrusting and folding, under a N to NNE compression, affecting Jurassic deposits north and south of the Dabie Shan, indicate that the SCB/NCB collision has continued during the Jurassic. We show that a strike-slip tectonic regime occurred at that time, east of the STLFZ, which initiated as a sinistral continental transform fault between the Dabie and Sulu collisional belts. Dikes and strike-slip faults confirm that a ~NW-SE stretching was active during the basal early Cretaceous (~135–130 Ma), in and around metamorphic domes intruded by plutons. We show that strike-slip faulting, under a NW-SE compression-NE-SW tension, has been active subsequently, until the Aptian-? Early Albian (110/105 Ma), possibly until the Cenomanian (~95 Ma); at that time, the TLFZ has acted as a sinistral continental trans-current fault zone in eastern Asia. Subsequently, normal faulting, under a WNW-ESE extension, indicates that the TLFZ has been a normal fault zone during the Campanian-Palaeocene (~83–55 Ma), possibly until the Early Ypresian (~50 Ma). Sinistral offsets, in the order of several 100 of kilometres, on both sides of the TLFZ have been proposed; the present study does not support such large offset magnitudes.

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