Revised Chronostratigraphic Framework of the Metamorphic Strata in the Jiangnan Orogenic Belt,South China and its Tectonic Implications

In a re-study of regional geology by the China Geological Survey （CGS）, the key problem is in the stratigraphical division and correlation. According to the new isotopic dating of the Mesoand Neoproterozoic in China, there have been great changes in the strata correlation and tectonic explanation. The authors obtained four zircon sensitive high resolution ion micro-probe （SHRIMP） U- Pb datings from the bentonite of the Lengjiaxi Group （822±10 Ma, 823±12 Ma and 834±11 Ma） and Banxi Group （802.6±7.6 Ma） in north Hunan Province, which is considered to be the middle part of the Jiangnan Orogenic Belt. On the basis of the zircon dating mentioned above, the end of the Wuling orogen is first limited in the period from 822 Ma to 802 Ma in one continued outcrop （Lucheng section） in Linxiang city, Hunan Province. Combining a series of new zircon U-Pb datings in the Yangtze and Cathaysia blocks, several Neoproterozoic volcanic events and distribution of the metamorphic rocks in the Jiangnan Orogenic Belt have been distinguished. In the context of the global geodynamics, it is useful to set up a practical and high precision chronological framework and basic and unified late Precambrian section in South China.

Qingbaikouan and Crygenian in South China:Constraints by SHRIMP Zircon U-Pb dating

The Qingbaikouan System is the lowest unit of the Neoproterozoic Erathem in Chinese stratigraphic succession,and it now provides a precise geochronological framework and geological time scale for mapping and stratal correlation in China.However,a sensitive high-resolution ion microprobe （SHRIMP） U-Pb zircon age date （1368±12 Ma） obtained from a bentonite in the Qingbaikouan Xiamaling Formation indicates that it belongs to the Mesoproterozoic Erathem instead.This change is a milestone in understanding the Precambrian Stratigraphic Time Scale in China,and it has had great influence on Precambrian correlations in Asia.Otherwise,a large amount of geochronological work has been done in the ＂Jiangnan Orogen Belt＂ of South China,and new isotopic data have redefined the traditional recognition of metamorphosed Mesoproterozoic strata from the Sibao orogeny to the Neoproterozoic Erathem.Based on SHRIMP zircon U-Pb age data,the authors regard the Sibao orogeny （equal to the Wuling orogeny） as a movement at ca 820 Ma,meaning that the Sibao orogeny was not equivalent to the Grenvillian orogeny.Finally,we report here the first SHRIMP U-Pb age of the boundary between the top of the Qingbaikouan Gongdong Formation （786.8±5.6 Ma） and the bottom of the Chang＇an （diamictite） Formation （778.4±5.2 Ma）,which is the age of the lowest diamictite of the Nanhuan System in China.

Asymptotic Property of Approximation to x~αsgnx by Newman Type Operators

The approximation of ｜x｜ by rational functions is a classical rationalproblem. This paper deals with the rational approximation of the function xasgnx, which equals ｜x｜ if α=1. We construct a Newman type operator rn（x） and show max｜x｜≤1{｜x^αsgnx-rn（x）｜}-Cn-α/2e-√2nα where C is a constant depending on α.

Great Paleozoic-Mesozoic Biotic Turnings and Paleontological Education in China: A Tribute to the Achievements of Professor Zunyi Yang

Professor Zunyi Yang is a pioneer paleontologist who established the earliest Paleontological education and research in China, and has contributed his lifetime to promotion of Chinese paleontological education and researches as well as the studies on the Permian-Triassic （P-Tr） mass extinction and its possible causes. Yang has studied six fossil clades and trace fossils, together with his colleagues, he has established 6 new species of cephalopods, 1 new genus and 15 new species of gastropods, 8 new genera and 31 new species of bivalves, 17 new genera and 66 new species of brachiopods, 1 new genus and 4 new species of ophiuroids, 2 new genera and 7 new species of triopsids （Crustacea）, and 3 new ichnogenera and 7 new ichnospeeies of trace fossils. Yang led the 2nd IGCP working on the P-Tr mass extinction in the world. His group＇s excellent works on basic stratigraphy and paleontology enable the GSSP of P-~r boundary （PTB） to be ratified in China. Yang＇s earlier works on three-episode extinction pattern and volcanism-causing extinction hypothesis are also highlighted here to show how their first-hand data and initiative hypothesis have influenced the current and ongoing debates on the P-Tr crisis and possible causation. Yang school＇s extinction pattern is reviewed here, and their 2nd phase of extinction is marked by a dramatic loss in biodiversity, pointing to a widely accepted mass extinction. The 3rd extinction is characterized by ecological collapse of ecosystem structures and disappearance of the PTB microbialite ecosystem, while the 1st extinction （also prelude extinction） is indicated by the collapses of deep-water and reef ecosystems. Updated studies show that the volcanic ashes near the PTB originated from silicic, subduction-related igneous activity with little or no basaltic input. This subduction zone activity is related to closure of the Paleo-Tethys Ocean, and the intensity and frequency of the volcanic activity appear to increase near the P-Tr extinction interval. Hg anomalies （Hg/TOC ratios and Hg isotopes） were also detected from the P-Tr extinction interval, and they are interpreted as the results of enhanced volcanic-generated atmospheric mercury, which was injected by the violate eruption of the Siberian traps. Thus, the peak felsic volcanism is coeval with violate eruption of Siberian traps, and the coupled relationship between both types of volcanisms and biotic extinction suggests a causal relationship.

Asymptotic Property of Approximation to x~αsgn x by Newman Type Operators

Approximation to the function ｜x｜ plays an important role in approximation theory. This paper studies the approximation to the function xαsgn x, which equals ｜x｜ if α = 1. We construct a Newman Type Operator rn（x） and prove max ｜x｜≤1｜xαsgn x-rn（x）｜～Cn1/4e-π1/2（1/2）αn.

Synthesis of Hirtellanine B, an Isoflavonoid with Potent Antiproliferative Effects in Cancer Cells

我们报导了 hirtellanine B 的第一全部的合成，用为关键反应的氧化联合，它导致了高收益。对 Jurkat 房间， Raji 房间和 K562 房间的 hirtellanine B 的 antiproliferative 活动也被调查。hirtellanine B 能在人的 lymphoid/leukemia 肿瘤房间导致 G2/M 拘捕和 apoptosis，这被发现。