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| 1 | Crustal deformation and dynamics of Early Cretaceous in the North China Craton显示文摘The Early Cretaceous represents a peak period of the North China Craton(NCC)destruction.A comprehensive analysis of crustal deformation during this period can reveal processes and dynamics of the destruction.The peak destruction of the NCC was associated with intense extension whose representative deformation products are metamorphic core complexes(MCCs),extensional domes and rifted basins.These MCCs occurred along both northern and southern margins of the NCC,and resulted from synchronous extension and magmatism,showing difference from the typical orogen-type MCCs in many aspects.The MCCs of the Early Cretaceous were replaced by extensional domes under relatively weak extension and uplift.In contrast to a major depression-type basin of the Early Cretaceous in the western NCC,rifted basins of the same age in the eastern NCC appeared as medium-to small-scale ones extensively.In the eastern NCC,the rifted basins north of the Bohai Bay are characterized by a feature similar to an active rift whereas those south of the Bohai present similarity to a passive rift.Various sorts of extensional structures developed during the peak destruction indicate a stable stress state of NE-SE extension over the entire central to eastern NCC,consistent with the plate margin-driven stress field.Spatial distribution of the extensional structures presents an 1800 km wide back-arc extension region in the central to eastern NCC,consistent with the Paleo-Pacific slab rollback model following flat subduction.Temporal-spatial variation of initial extension and volcanic activity during the peak period also supports the rollback model right after the flat oceanic slab.The crustal deformation evolution demonstrates that the peak destruction of the NCC took place after the B-episode compression of the Yanshan Movement of the earliest Early Cretaceous and terminated with onset of the C-episode compression of the earliest Late Cretaceous. | Guang ZHU Yuanchao LU Nan SU Xiaodong WU Hao YIN Shuai ZHANG Chenglong XIE Manlan NIU | 2021 | Science China Earth Sciences2021，64，9： | 1 |
| 2 | Syn-collisional transform faulting of the Tan-Lu Fault Zone, East China显示文摘 | Zhu Guang Liu Guosheng Niu Manlan | 2009 | In- ternational Journal of Earth Sciences2009，98，： | 1 |
| 3 | Syn-collision- al transform faulting of the Tan-Lu fault zone, East China 显示文摘 | Zhu Guang Liu Guosheng Niu Manlan | 2009 | Int J Earth Sci (Geol Rundsch)2009，98，1： | 1 |
| 4 | Neoproterozoic Crustal Reworking and Growth in the Zhangbaling Uplift, Tan-Lu Fault Zone: Evidence from the Feidong Complex and Zhangbaling Group显示文摘Intensive mid-Neoproterozoic magmatism is the salient feature of the Yangtze Block,preserving abundant information about crustal reworking and growth.Zircon U-Pb-Lu-Hf isotope analysis was performed on material from the Feidong Complex(FDC)and Zhangbaling Group(ZBLG)of the Zhangbaling Uplift,in order to determine the age and magmatic source of the Neoproterozoic igneous rocks as well as the detrital provenance for the sedimentary rocks,to further provide important data for understanding the mid-Neoproterozoic crustal evolution of the Northeast Yangtze Block.The amphibolite and gneissic granites in the Feidong Complex(FDC)gave similar protolith ages of 782-776 Ma.The synmagmatic zircons exhibited variable negativeεHf(t)values of-26.9 to-8.3.Early(ca.2.4 Ga)to late Paleoproterozoic(ca.2.0-1.9 Ga)inherited zircons were found in the gneissic monzogranite,with negativeεHf(t)values of-11.2 to-7.2,indicating strong reworking of the ancient crustal materials of the Northeast Yangtze Block.Whereas the amphibolites represent minor crustal growth through emplacement of continental rifting-related mafic magmas.The quartz-keratophyres in the Xileng Formation of the ZBLG in contrast systematically yield young protolith crystallization ages of 754-727 Ma with highεHf(t)values of-2.0 to+5.6,indicating their derivation from the reworking of juvenile crustal materials.The detrital zircons from the metasiltstone in the Beijiangjun Formation yield variable^(206)Pb/^(238)U ages(871-644 Ma)with a peak age at 741±11 Ma andεHf(t)values of-4.3 to+5.3,which is consistent with those of the Xileng Formation,but distinct from the FDC,indicating that the provenance of the metasiltstone is primarily the underlying Xileng Formation.The mid-Neoproterozoic igneous and sedimentary rocks of the Zhangbaling Uplift were products from continental rifting zones along the northern margin of the Yangtze Block,situated in different positions from the Susong Complex and the Haizhou Group.The transition from ancient to juvenile crustal sources for felsic magmatic rocks is attributed to gradually increased crustal extension during continental rifting. | NIU Manlan CAI Qianru WU Qi YUAN Xiaoyu SUN Yi LI Xiucai LI Chen ZHU Guang LI Zhensheng ZHANG Shuai | 2020 | Acta Geologica Sinica(English Edition)2020，94，6： | 1 |
| 5 | An Early Paleozoic Ultramafic Complex in the North Wulan Metamorphic Complex,North Qaidam:Contraints on the Nature of the Alaskan-type Continental Arc Root显示文摘Orogenic peridotite is an important component of orogenic belts and retains crucial information on mantle magmatic activity,slab subduction,and melt or fluid metasomatism.To determine the source of the mantle-derived parental magma of the peridotite and to investigate the metasomatism that it experienced,we undertook an integrated study of the petrography,whole-rock major-and trace-element compositions,in situ zircon U-Pb geochronology,and mineral majorand trace-element compositions of an early Paleozoic ultramafic complex in the North Wulan area of North Qaidam.The Halihatu ultramafic-mafic complex is composed of dunite,pyroxene peridotite,and gabbro,which are characteristic of Alaskan-type complexes.The dunite yields a weighted mean^(206)Pb/^(238)U age of 479±5 Ma(MSWD=0.7),which reflects the age of the metasomatism rather than the crystallization age of the ultramafic magma.The peridotites have high Mg^(#)(89.8-91.8)and Cr contents(2419-5190 ppm),low Al_(2)O_(3)(0.20-1.68 wt%)and Ni(289-1012 ppm)contents,and high olivine Fo contents(87-91),suggesting a large degree(~15%-22%)of partial melting of lithospheric ultramafic rocks followed by variable degrees of fractional crystallization of olivine and pyroxene.This is consistent with estimates of 15%-22.3%partial melting calculated using the Cr#of spinel crystals and with the low Yb(0.04-0.33 ppm)and Y(0.72-1.29 ppm)contents of clinopyroxene crystals.Whole-rock trace-element patterns show enrichment in large ion lithophile elements and depletion in high field strength elements,along with high Al_(2)O_(3)(2.10-6.47 wt%)and low TiO_(2)(0.01-0.21 wt%)contents of clinopyroxene crystals,suggesting an arc magma cumulate trend.These features,along with the high olivine Fo contents(87-91 ppm),imply that the Halihatu peridotite is an Alaskan-type crustal cumulates derived from Mgrich hydrous basaltic melts.The high estimated f O_(2)(FMQ+1.97 to FMQ+3.81)further supports the idea that they formed in an arc setting.The Ni/Co and Ni/Mn ratios and cumulate textures of the olivine,quenched boundaries between mafic and felsic melts,and the occurrence of tremolite and phlogopite reflect interactions between the Halihatu peridotite and injected silicate and carbonatitic melts in the lower crust.Therefore,we propose a new cumulate-infiltration model for the petrogenesis of Alaskan-type ultramafic complexes,which improves our understanding of the nature of Alaskan-type continental arc root. | SHAN Jinming NIU Manlan LI Xiucai LI Chen WANG Lei ZHANG Shuai | 2023 | Acta Geologica Sinica(English Edition)2023，97，5： | 0 |
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