Zheng Tang

Publications (3)4.79 Total impact

• Source

  Available from: Zhaokai Xu

  Article: Evolution of East Asian monsoon: Clay mineral evidence in the western Philippine Sea over the past 700 kyr

  Zhaokai Xu, Tiegang Li, Shiming Wan, Qingyun Nan, Anchun Li, Fengming Chang, Fuqing Jiang, Zheng Tang
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  ABSTRACT: Clay mineral assemblage of the core MD06-3047 in the western Philippine Sea has been used to trace sediment provenance and transport process and thus to constrain the East Asian monsoon evolution as well as its forcing mechanism over the past 700 kyr. Clay minerals mainly consist of smectite (61%) and illite (23%), with minor chlorite (10%) and kaolinite (6%). Provenance analyses suggest that the smectite originates predominantly from the alteration of nearby Luzon volcanic rocks. Illite is primarily derived from the Asian continent with eolian origin. Illite contents show strong glacial/interglacial cyclicity as constrained by oxygen isotope stratigraphy. Variations of illite contents are ultimately controlled by the East Asian monsoon evolution, characterized by higher illite values during glacials with relatively stronger East Asian winter monsoon but weaker East Asian summer monsoon. During interglacials, enhanced East Asian summer monsoon and rainfall could produce more smectite with poor crystallinity from Luzon to the study core. Spectral analyses of illite content and smectite crystallinity display a strong periodicity at 100 kyr for the East Asian winter monsoon and 100 kyr, 30 kyr, and 23 kyr periodicities for the East Asian summer monsoon, respectively, suggesting the unique forcing processes of the East Asian winter monsoon from high-latitudes (i.e., ice volume) and the East Asian summer monsoon from both high-latitudes and low-latitudes (i.e., tropical Pacific).
  Journal of Asian Earth Sciences 02/2013; 60:188-196. · 2.15 Impact Factor
• Article: Response of the northwestern Pacific upper water δ13C to the last deglacial ventilation of the deep Southern Ocean

  ShuangXi Chen, TieGang Li, Zheng Tang, XiaoHua Qiu, ZhiFang Xiong, QingYun Nan, ZhaoKai Xu, FengMing Chang
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  ABSTRACT: The deglacial δ 13C minimum events that originated from the ventilation of the deep Southern Ocean around Antarctica, have been recorded in a range of marine sediments from the southern to tropical oceans in late Pleistocene. However, the broad δ 13C minimum event was also reported as far as to the northern middle latitudes, in northwestern Pacific marginal sea areas, during the last deglaciation. In the northwestern Pacific, forcing from the northern high latitudes is strongly expressed, while the records of influence from the southern high latitudes are few. The Kuroshio Source Region (KSR) forms a boundary between the northwestern Pacific and the southern, tropical Pacific. So, high-resolution planktonic foraminiferal records in core MD06-3054 from the KSR are well positioned to identify signals from the southern hemisphere in the northwestern Pacific. Planktonic foraminiferal tests from the upper 1030 cm of the core were subject to AMS14C, carbon and oxygen isotopic measurements. A negative excursion was found to occur from about 20.0-6.0 ka BP in δ 13C records of both surface (Globigerinoides ruber) and subsurface (Pulleniatina obliquiloculata) dwellers, but the overall trends of the two curves have reversed since 26.5 ka BP. Moreover, the δ 13C record of G. ruber (the surface dweller) shows a robust link to the record of atmospheric CO2, and its changes precede the records of P. obliquiloculata (the subsurface dweller). According to the hydrologic conditions, the broad δ 13C minimum event recorded in the KSR is also a response to the increasing ventilation of the deep Southern Ocean around Antarctica during the last deglaciation. The inconsistency between the records of the surface and subsurface dwellers was possibly caused by the ways that the low δ 13C signal was transmitted. Subsurface water primarily received the low δ 13C signal from the Antarctic Intermediate Water (AAIW), whereas the surface water was probably mainly impacted by atmospheric CO2 in the KSR. The records from the KSR confirm the deduction that the broad δ 13C minimum event in the Okinawa Trough was due to the impact of tropical Pacific surface water during the last deglaciation, and suggest that signals from the southern high latitudes also can be delivered to the northern middle latitudes. Keywordsplanktonic foraminiferal δ 13C–ventilation of the deep Southern Ocean–northwestern Pacific–last deglaciation– δ 13C minimum event
  Chinese Science Bulletin 05/2012; 56(24):2628-2634. · 1.32 Impact Factor
• Article: Calcareous nannofossil bioevents and microtektite stratigraphy in the Western Philippine Sea during the Quaternary

  HanJie Sun, TieGang Li, RongTao Sun, XinKe Yu, FengMing Chang, Zheng Tang
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  ABSTRACT: Two sediment cores, MD06-3050 and MD06-3047, were analyzed to study the Quaternary calcareous nannofossil and microtektite records. We dated bioevents and the microtektite impact event by calibrating with oxygen isotope stratigraphy. Seven calcareous nannofossil bioevents were identified over the past 2.36 Ma including the last appearance of data for Discoaster brouweri, Calcidiscus macintyrei, large Gephyrocapsa and Pseudoemiliania lacunosa, the first appearance of data for large Gephyrocapsa and Emiliania huxleyi, and the abrupt increase in the abundance of Gephyrocapsa caribbeanica. In addition, we fortunately observed that Australasian microtektites were distributed in core MD06-3050 from 1340 to 1374 cm. KeywordsWestern Philippine Sea–Quaternary Period–calcareous nannofossil biostratigraphy–oxygen isotope stratigraphy–Australasian microtektites
  Chinese Science Bulletin 04/2012; 56(25):2732-2738. · 1.32 Impact Factor