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Terminal Ediacaran anoxia in deep-ocean: Trace element evidence from cherts of the Liuchapo Formation, South China

Science China Earth Sciences 2009年第6期52卷 807-822页

作者： chang huajin CHU XueLei FENG LianJun HUANG Jing State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Graduate University of Chinese Academy of Sciences Beijing 100049China

Here we report a detailed trace element study of the cherts from Liuchapo Formation, which is a terminal Ediacaran (551-542 Ma) succession in South China deposited in deep-water basinal setting. The REE of Liuchapo cherts shows similar features as observed for anoxic modern seawater (but not for hydrothermal fluids), characterized by positive La anomaly (LaN/CeN = 0.83–1.91, average 1.37), moderately negative Ce anomaly (0.53–1.1, average 0.73), positive Gd anomaly (average 1.08), positive Y anomaly (average 1.21), and depleted LREE and MREE. In addition, the Liuchapo cherts have low ΣREE (3.36–56.13 ppm, average 20.6 ppm), low Al2O3, Ti, Th and Zr concentrations, and high Y/Ho ratios (up to 43.9). The redox-sensitive trace elements concentrations in the cherts do not correlate with detrital input proxies. All of these features suggest that the redox-sensitive trace elements in the cherts were authigenically concentrated in water column and their concentrations thus are excellent indicators of ancient redox conditions. Very low Th/U ratios, high V/(V+Ni) and Fe?/Al ratios, enrichments of redox-sensitive trace elements (U, V, Mo), and low concentration of Mn in the cherts imply anoxia in the deep seawater. Our data reveal that the terminal Ediacaran ocean was not completely oxidized and the deep ocean was still anoxic, at least in South China. We propose that although the oxidative events existed in the terminal Ediacaran oceans, decomposition of organic matter prolonged anoxia in the deep ocean.

关键词： chert anoxia trace elements redox proxy Ediacaran South China

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Iron speciation in cherts from the Laobao Formation,South China:Implications for anoxic and ferruginous deep-water conditions

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Chinese Science Bulletin 2010年第27期55卷 3189-3196页

作者： chang huajin CHU XueLei FENG LianJun HUANG Jing School of Life and Geography Sciences Qinghai Normal University Xining 810008 China Key Laboratory of Tibetan Plateau Environment and Resources Ministry of Education Xining 810008 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Cherts in the Laobao Formation in the Silikou section,South China were deposited in terminal Ediacaran *** speciations of iron in cherts,such as pyrite Fe(FeP),HCl-extractable Fe(FeH),and total Fe(FeT),and their interrelationships,are proxies for distinguishing oxic,anoxic but ferruginous,and sulfidic conditions,which is an effective method for studying the terminal Ediacaran ocean *** chert samples from the Laobao Formation,pyrite concentrations are generally low(<0.56%),degree of pyritization(DOP)ranges from<0.01 to 0.78 and most are<0.45;(FeP+FeH)/FeT ratios are between 0.27 and 0.84 and most exceed 0.38,and most of FeT/Al ratios range from 0.55 to 5.87(averaging 1.1).Relatively high content of highly reactive Fe and low content of pyrite indicate a scarcity of H2S and Fe-enriched *** features suggested that the deposition setting of Laobao cherts was anoxic and *** Ediacaran deep-water in the South China Basin was most likely anoxic and ferruginous,which played a key role in the emergence and evolution of early multicellular life.

关键词：深水条件硅质岩铁质缺氧中国 o形形态场效应晶体管

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Reliable intracavity reflection for self-injection locking lasers and microcomb generation

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Photonics Research 2024年第5期12卷 I0001-I0010页

作者： BITAO SHEN XUGUANG ZHANG YIMENG WANG ZIHAN TAO HAOWEN SHU huajin chang WENCAN LI YAN ZHOU Zhangfeng Ge RUIXUAN CHEN BOWEN BAI LIN chang XINGJUN WANG State Key Laboratory of Advanced Optical Communications System and Networks School of ElectronicsPeking UniversityBeijing 100871China Peng Cheng Laboratory Shenzhen 518055China Peking University Yangtze Delta Institute of Optoelectronics Nantong 226010China Frontiers Science Center for Nano-optoelectronics Peking UniversityBeijing 100871China

Self-injection locking has emerged as a crucial technique for coherent optical sources,spanning from narrow linewidth lasers to the generation of localized *** technique involves key components,namely a laser diode and a high-quality cavity that induces narrow-band reflection back into the laser ***,in prior studies,the reflection mainly relied on the random intracavity Rayleigh backscattering,rendering it unpredictable and unsuitable for large-scale production and wide-band *** this work,we present a simple approach to achieve reliable intracavity reflection for self-injection locking to address this challenge by introducing a Sagnac loop into the *** method guarantees robust reflection for every resonance within a wide operational band without compromising the quality factor or adding complexity to the fabrication *** a proof of concept,we showcase the robust generation of narrow linewidth lasers and localized microcombs locked to different resonances within a normal-dispersion ***,the existence and generation of localized patterns in a normal-dispersion cavity with broadband forward–backward field coupling is first proved,as far as we know,both in simulation and in *** research offers a transformative approach to self-injection locking and holds great potential for large-scale production.

关键词： intracavity injection locking

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草莓状黄铁矿与古海洋环境恢复

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地球科学进展 2011年第5期26卷 475-481页

作者：常华进储雪蕾青海师范大学生命与地理科学学院青海西宁810008 青藏高原环境与资源教育部重点实验室青海西宁810008 中国科学院地质与地球物理研究所北京100029

草莓状黄铁矿是指由等粒度的亚微米级黄铁矿晶体或微晶体紧密堆积而成,形似草莓的黄铁矿球形集合体。它们在氧化和缺氧海洋环境中形成的机理不同,沉积岩中草莓状黄铁矿的粒径分布特征是恢复古海洋的氧化还原状态行之有效的方法之一。然... 详细信息

草莓状黄铁矿是指由等粒度的亚微米级黄铁矿晶体或微晶体紧密堆积而成,形似草莓的黄铁矿球形集合体。它们在氧化和缺氧海洋环境中形成的机理不同,沉积岩中草莓状黄铁矿的粒径分布特征是恢复古海洋的氧化还原状态行之有效的方法之一。然而,草莓状黄铁矿粒径统计仅能区分出氧化和缺氧硫化的环境,不能进一步区分缺氧程度及状态(如次氧化、缺氧含铁等)。桂北泗里口老堡组硅岩沉积于埃迪卡拉纪末期,它们所记录的草莓状黄铁矿粒径分布特征指示了硫化的深水古环境,这与用氧化还原敏感元素等方法获得的深水是缺氧含铁的结论矛盾。这可能是由于当时盆地水体中硫酸盐含量低,细菌硫酸盐还原生成的H2S少,导致形成了粒径小的黄铁矿。在运用草莓状黄铁矿恢复古海洋环境时,还应与其他地球化学手段,如沉积岩中Fe组分、氧化还原敏感元素、稳定同位素等结合才能获得确切的古海洋氧化还原状态。

关键词：草莓状黄铁矿氧化还原状态古海洋

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A sulfate control on marine mid-depth euxinia on the early Cambrian(ca. 529–521 Ma) Yangtze platform, South China

A sulfate control on marine mid-depth euxinia on the early C...

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中国科学院地质与地球物理研究所2014年度（第14届）学术年会

作者： Lianjun Feng Chao Li Jing Huang huajin chang Xuelei Chu Institute of Geology and Geophysics Chinese Academy of Sciences Key Laboratory for Mineral Resources Chinese Academy of Sciences State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space Science University of Science and Technology of China School of Life and Geography Sciences Qinghai Normal University

Given the high oxygen demands of complex metazoans, a sound understanding of marine redox conditions is essential to reconstruct the factors that lead to the dramatic increases in ecosystem complexity and biological diversity in the early Cambrian. In this study, we report new Fe–Mo–C–S geochemical data from black shale-rich strata of the early Cambrian continental margin Yangjiaping section in the Yangtze platform, South China. Integrated Fe speciation and Mo abundance data from the Yangjiaping section, in combination with previously reported data from Shatan(inner shelf), Songtao(slope) and Longbizui(basinal) sections, suggest mid-depth euxinic waters coexisting with ferruginous deep waters and oxic surface waters. This redox structure is similar to conditions previously suggested for the Ediacaran Yangtze platform and other Proterozoic marine basins, indicating that Proterozoic layered ocean redox structure in some basins persisted into the early Cambrian. Furthermore, the Fe–Mo data demonstrate that the mid-depth euxinia was widespread during a marine transgression but shrank gradually along with widespread shelf oxygenation when the basin evolved into subsequent *** highly reactive iron(FeHR) in deep water with a hydrothermal origin may have had a control on the mid-depth euxinia, given geochemical and geological evidence for basinal hydrothermal *** the other hand, a sulfate limitation on bacterial sulfate reduction(BSR) and sulfide generation was suggested by a weak correlation(R2≤ 0.22) between pyrite iron versus FeHRand total organic carbon(TOC) form anoxic deep-water sections and high TOC(averagely 6%) in the deepest-ferruginous-water Longbizui section. Furthermore, a spatial gradient was observed in sulfur isotopic composition of pyrite(averagely from 0.2‰ to 21.0‰), consistent with a lateral gradient of sulfate in concentration or/and in isotope from shore to distal waters on the transgressive Yangtze platform. We accordingly prop

关键词： Yangtze platform Early Cambrian Mid-depth euxinia Iron speciation Sulfur isotope

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华南老堡组硅质岩中草莓状黄铁矿--埃迪卡拉纪末期深海缺氧的证据

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岩石学报 2009年第4期25卷 1001-1007页

作者：常华进储雪蕾冯连君黄晶中国科学院地质与地球物理研究所北京100029 中国科学院矿产资源研究重点实验室北京100029 中国科学院研究生院北京100049

为恢复埃迪卡拉纪末期深海的氧化还原状态,我们对华南桂北泗里口剖面老堡组(大约550～540Ma)硅质岩中草莓状黄铁矿的粒径和分布进行了测量、统计和研究。老堡组硅质岩样品中普遍存在着草莓状黄铁矿,呈星散状分布,未见自形晶的黄铁矿颗... 详细信息

为恢复埃迪卡拉纪末期深海的氧化还原状态,我们对华南桂北泗里口剖面老堡组(大约550～540Ma)硅质岩中草莓状黄铁矿的粒径和分布进行了测量、统计和研究。老堡组硅质岩样品中普遍存在着草莓状黄铁矿,呈星散状分布,未见自形晶的黄铁矿颗粒和明显后期充填的草莓状黄铁矿集合体。硅质岩中草莓状黄铁矿颗粒的统计表明,它们具有很窄的变化范围,最大粒径小于18μm,大多数样品中草莓状黄铁矿的平均粒径和中间粒径均小于5μm。根据这些硅质岩中原生黄铁矿的粒径和分布,我们判定埃迪卡拉纪末期的深部海水是缺氧的。泗里口剖面老堡组硅质岩中草莓状黄铁矿的平均粒径、中间粒径和最大直径沿剖面向上逐渐增加,这意味着埃迪卡拉纪末期华南的深部海水有逐步被氧化的趋势。

关键词：黄铁矿硅质岩埃迪卡拉纪末期氧化还原状态古海洋

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Submilliwatt, widely tunable coherent microcomb generation with feedback-free operation

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Advanced Photonics 2023年第3期5卷 144-154页

作者： Haowen Shu Lin chang Chenghao Lao Bitao Shen Weiqiang Xie Xuguang Zhang Ming Jin Yuansheng Tao Ruixuan Chen Zihan Tao huajin chang Shaohua Yu Qifan Yang Xingjun Wang John E.Bowers Peking University School of ElectronicsState Key Laboratory of Advanced Optical Communication Systems and NetworksBeijingChina University of California Santa BarbaraDepartment of Electrical and Computer EngineeringSanta BarbaraCaliforniaUnited States Peking University School of PhysicsState Key Laboratory for Artificial Microstructure and Mesoscopic PhysicsBeijingChina Peng Cheng Laboratory ShenzhenChina Peking University Frontiers Science Center for Nano-OptoelectronicsBeijingChina

Microcombs are revolutionizing optoelectronics by providing parallel, mutually coherent wavelengthchannels for time-frequency metrology and information processing. To implement this essential function inintegrated photonic systems, it is desirable to drive microcombs directly with an on-chip laser in a simpleand flexible way. However, two major difficulties have prevented this goal: (1) generating mode-lockedcomb states usually requires a significant amount of pump power and (2) the requirement to align laser andresonator frequency significantly complicates operation and limits the tunability of the comb lines. Here, weaddress these problems by using microresonators on an AlGaAs on-insulator platform to generate dark-pulsemicrocombs. This highly nonlinear platform dramatically relaxes fabrication requirements and leads to arecord-low pump power of <1 mW for coherent comb generation. Dark-pulse microcombs facilitated bythermally controlled avoided mode crossings are accessed by direct distributed feedback laser *** any feedback or control circuitries, the comb shows good coherence and stability. With around150 mW on-chip power, this approach also leads to an unprecedentedly wide tuning range of over one freespectral range (97.5 GHz). Our work provides a route to realize power-efficient, simple, and reconfigurablemicrocombs that can be seamlessly integrated with a wide range of photonic systems.

关键词： dark-pulse microcomb direct pumping scheme widely tunable source

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青海湖流域沙柳河下游沉积物中重金属污染风险评价

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地理科学 2017年第2期37卷 259-265页

作者：常华进曹广超陈克龙孙小舟湖北文理学院管理学院湖北襄阳441053 青海省自然地理与环境过程重点实验室青海西宁810008

对青海湖流域沙柳河下游沉积物中As、Cd、Pb、V、Cr、Mn、Ni、Cu和Zn 9种重金属元素的含量进行了分析测定,采用污染系数、富集系数、地累积指数和潜在生态危害指数评估了其污染程度。结果表明:无论在横向还是纵向上,重金属元素含量均低... 详细信息

对青海湖流域沙柳河下游沉积物中As、Cd、Pb、V、Cr、Mn、Ni、Cu和Zn 9种重金属元素的含量进行了分析测定,采用污染系数、富集系数、地累积指数和潜在生态危害指数评估了其污染程度。结果表明:无论在横向还是纵向上,重金属元素含量均低于青海湖土壤背景值;重金属元素污染系数和富集系数均小于2,且大多数样品的值低于1(高于1者多为Cd、Cu、Ni、Zn,且具高值);地累积指数均为负值(除QB-19中Cd和Cu分别为0.10和0.02);潜在生态风险因子大多低于30,潜在生态危害指数大多低于70。沙柳河下游沉积物尚未出现重金属污染,具有低的生态风险,但该流域重金属的人为排放确实存在(主要是Cd、Cu、Ni、Zn等),而且在近代排放更为显著。

关键词：重金属沉积物沙柳河青海

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集成微腔光梳色散调控技术研究进展(特邀)

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激光与光电子学进展 2024年第19期61卷 1-13页

作者：沈碧涛常华墐舒浩文王兴军北京大学电子学院区域光纤通信网与新型光通信系统国家重点实验室北京100871 北京大学教育部纳光电子前沿科学中心北京100871

集成微腔光梳技术,利用集成微腔内的光学非线性作用可在连续光泵浦下产生周期性光脉冲,其在频域上表现为等间隔的光学频率成分。与传统光梳相比,集成微腔光梳具有小型化、功耗低、重复频率大等优势,其独特的时频特性在推动传统光梳向片... 详细信息

集成微腔光梳技术,利用集成微腔内的光学非线性作用可在连续光泵浦下产生周期性光脉冲,其在频域上表现为等间隔的光学频率成分。与传统光梳相比,集成微腔光梳具有小型化、功耗低、重复频率大等优势,其独特的时频特性在推动传统光梳向片上化演进的同时,也可与波分复用技术结合,推动了片上集成并行化、大容量的信息传输、处理与感知。在微腔光梳的产生过程中,微腔的色散,即不同波长的光在腔内的群速度差异特性,具有决定性作用。面对不同的应用需求,不同的腔体色散设计至关重要。本文首先介绍了色散对光梳状态影响的研究进展,然后介绍了近年来集成微腔色散设计方面取得的进展,最后对当前的技术与问题进行总结,并对未来的发展进行展望。

关键词：集成光学光频梳集成微腔光梳色散

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当代大学生第二外语学习意向调查研究——以湖北文理学院为例

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湖北文理学院学报 2024年第3期45卷 62-66页

作者：赵荣常华进湖北文理学院外国语学院湖北襄阳441053 湖北文理学院教务处湖北襄阳441053

为了解当代大学生第二门外语的学习现状及意向动机,项目组对湖北文理学院在校学生展开线上问卷调查。调查显示,大多数学生仅学习英语一门外语,但为拓宽自己的就业渠道,他们有强烈的意愿选择自己感兴趣的语言作为第二外语在校内进行线下... 详细信息

为了解当代大学生第二门外语的学习现状及意向动机,项目组对湖北文理学院在校学生展开线上问卷调查。调查显示,大多数学生仅学习英语一门外语,但为拓宽自己的就业渠道,他们有强烈的意愿选择自己感兴趣的语言作为第二外语在校内进行线下课堂学习,内容以掌握日常交际用语和语言国家文化为主。目前,因时间精力不足、学习路径不畅等原因未能达成意愿。由此建议学校赋予学生外语学习自主选择权,充分利用现有资源,满足学生第二外语学习的意愿,助力国家建构公共外语多元化格局,促进学生自由全面发展,进而为社会培养“专业+多语种”复合型人才。

关键词：第二外语学习意向外语教学

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