生物活动及DMS.doc

Carbon isotope chemostratigraphy of a Precambrian/Cambrian boundary section in the Three Gorge area, South China: Prominent global-scale isotope excursions just before the Cambrian Explosion This article is not included in your organizations subscription. However, you may be able to access this article under your organizations agreement with Elsevier.Tomoko Ishikawaa, , , Yuichiro Uenob, c, Tsuyoshi Komiyaa, c, Yusuke Sawakia, Jian Hand, Degan Shud, Yong Lie, Shigenori Maruyamaa, c and Naohiro Yoshidac, faDepartment of Earth and Planetary Science, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, JapanbGlobal Edge Institute, Meguro-ku, Tokyo Institute of Technology, Tokyo 152-8551, JapancResearch Center for the Evolving Earth and Planets, Tokyo Institute of Technology, JapandDepartment of Geology and Key Laboratory for Continental Dynamics, Northwest University, Xian 710069, ChinaeSchool of Earth Sciences and Resources Management, Changan University, Xian 710054, ChinafDepartment of Environmental Science and Technology, Tokyo Institute of Technology, Midori-ku Yokohama 152-8551, JapanReceived 13 July 2007; revised 18 October 2007; accepted 23 October 2007. Available online 21 November 2007. AbstractCarbon isotope chemostratigraphy has been used for worldwide correlation of Precambrian/Cambrian (Pc/C) boundary sections, and has elucidated significant change of the carbon cycle during the rapid diversification of skeletal metazoa (i.e. the Cambrian Explosion). Nevertheless, the standard 13C curve of the Early Cambrian has been poorly established mainly due to the lack of a continuous stratigraphic record. Here we report high-resolution 13C chemostratigraphy of a drill core sample across the Pc/C boundary in the Three Gorge area, South China. This section extends from an uppermost Ediacaran dolostone (Dengying Fm.), through a lowermost Early Cambrian muddy limestone (Yanjiahe Fm.) to a middle Early Cambrian calcareous black shale (Shuijingtuo Fm.). As a result, we have identified two positive and two negative isotope excursions within this interval. Near the Pc/C boundary, the 13Ccarb increases moderately from 0 to +2 (positive excursion 1: P1), and then drops dramatically down to 7 (negative excursion 1: N1). Subsequently, the 13Ccarb increases continuously up to about +5 at the upper part of the NemakitDaldynian stage. After this positive excursion, 13Ccarb sharply decreases down to about 9 (N2) just below the basal Tommotian unconformity. These continuous patterns of the 13C shift are irrespective of lithotype, suggesting a primary origin of the record. Moreover, the obtained 13C profile, except for the sharp excursion N2, is comparable to records of other sections within and outside of the Yangtze Platform. Hence, we conclude that the general feature of our 13C profile best represents the global change in seawater chemistry. The minimum 13C of the N1 (7) is slightly lower than carbon input from the mantle, thus implying an enhanced flux of 13C-depleted carbon just across the Pc/C boundary. Hence, the ocean at that time probably became anoxic, which may have affected the survival of sessile or benthic Ediacaran biota. The subsequent 13C rise up to +5 (P2) indicates an increase of primary productivity or an enhanced rate of organic carbon burial, which should have resulted in lowering pCO2 and following global cooling. This scenario accounts for the cause of the global-scale sea-level fall at the base of the Tommotian stage. The subsequent, very short-term, and exceptionally low 13C (9) in N2 could have been associated with the release of methane from gas hydrates due to the sea-level fall. The inferred dramatic environmental changes (i.e., ocean anoxia, increasing productivity, global cooling and subsequent sea-level fall with methane release) appear to coincide with or occur just before the Cambrian Explosion. This may indicate synchronism between the environmental changes and rapid diversification of skeletal metazoa.Keywords: Precambrian/Cambrian boundary; Carbon isotope; Early Cambrian; Cambrian Explosion; South ChinaArticle Outline1. Introduction2. Geological setting3. Method4. Results5. Discussion5.1. Diagenesis 5.2. Characteristics of the 13Ccarb profile 5.2.1. P1 (positive excursion 1)5.2.2. N1 (negative excursion 1)5.2.3. P2 (positive excursion 2)5.2.4. N2 (negative excursion 2)5.2.5. 13C profile above the basal Tommotian unconformity5.3. Correlation of the 13Ccarb profile with other sections 5.3.1. Yangtze Platform5.3.2. Global correlation5.4. Origin of the carbon isotope excursions6. ConclusionAcknowledgementsReferencesFig. 1.(a) Geological map of the Three Gorge area, South China. Box indicates the study area (Fig. 1b). (b) Geological section across Anjiahe region in the Three Gorge area. The black bar line indicates the position of the drilling site in this study.View Within ArticleFig. 2.Lithostratigraphy and carbon and oxygen isotope profile (13Ccarb and 18Ocarb) of the drill core, spanning from the Ediacaran to the Early Cambrian. The biostratigraphy of this section is from Chen (1984) and Qian (1999).View Within ArticleFig. 3.The enlarged 13Ccarb and 18Ocarb profile across the Yanjiahe/Shuijingtuo boundary.View Within ArticleFig. 4.a: an organic-walled acritarch fossil (303111, Table 1), around 79m depth in the Yanjiahe Formation, b: a relatively well preserved, thin, limestone sample with fine-grained carbonate, recording the N2 excursion (303111, Table 1), c: the limestone sample recording the P2 excursion, around 94m depth in the Yanjiahe Formation.View Within ArticleFig. 5.Proposed correlation of the 13Ccarb profiles of the Pc/C boundary sections within the Yangtze Platform. ND; NemakitDaldynian stage; DH, Dahai Member; BYS, Baiyanshao Member; XWTS, Xioawaitoushan Member; ZY, Zhongyicun Menber; A, China Marker A at the first appearance of skeletal fossils; B, China Marker B at the mass appearance of a more diverse assemblage rich in micro-molluscs; C, China Marker C at a major disconformable contact; D, China Marker D at the first appearance of trilobites.View Within ArticleFig. 6.Proposed correlation of the 13Ccarb profiles of representative Pc/C boundary sections in the world. The profiles are arranged by assuming two fixed horizons: (1) the major unconformity at the base of the Tommotian stage and (2) the peak of N1.View Within ArticleFig. 7.A schematic view of the link between inferred environmental changes and early animal evolution. (a) The 13Ccarb profile of the Yangtze Platform against time. (b) The observed isotope excursions and their ecological interpretations. (c) Simplified view of animal evolution across the Pc/C boundary (Knoll and Carroll, 1999 and Budd, 2003). (d) Previous compilation of the Early Cambrian 13C curve from Ripperdan (1994). PTR, Pre-Tommotian 13C Rise; LTM, Late Tommotian 13C Minimum; FA, first archaeocyathids; FT, first trilobites.View Within ArticleTable 1. Results of carbon and oxygen isotope analysisaAnalyzed by GasBench II. See text. View Within ArticleCorresponding author. Gondwana ResearchVolume 14, Issues 1-2, August 2008, Pages 193-208 Snowball Earth to Cambrian Explosion Biogenic emission of dimethylsulfide (DMS) from the North Yellow Sea, China and its contribution to sulfate in aerosol during summer This article is not included in your organizations subscription. However, you may be able to access this article under your organizations agreement with Elsevier.Gui-Peng Yang, a, , Hong-Hai Zhanga, Lu-Ping Sua and Li-Min ZhouaaKey Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, ChinaReceived 13 October 2008; revised 8 January 2009; accepted 10 January 2009. Available online 19 January 2009. AbstractSeawater, atmospheric dimethylsulfide (DMS) and aerosol compounds, potentially linked with DMS oxidation, such as methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO42) were determined in the North Yellow Sea, China during JulyAugust, 2006. The concentrations of seawater and atmospheric DMS ranged from 2.01 to 11.79nmoll1 and from 1.68 to 8.26nmolm3, with average values of 6.20nmoll1 and 5.01nmolm3, respectively. Owing to the appreciable concentration gradient, DMS accumulated in the surface water was transferred into the atmosphere, leading to a net sea-to-air flux of 6.87molm2d1 during summer. In the surface seawater, high DMS values corresponded well with the concurrent increases in chlorophyll a levels and a significant correlation was observed between integrated DMS and chlorophyll a concentrations. In addition, the concentrations of MSA and nss-SO42 measured in the aerosol samples ranged from 0.012 to 0.079gm3 and from 3.82 to 11.72gm3, with average values of 0.039 and 7.40gm3, respectively. Based on the observed MSA, nss-SO42 and their ratio, the relative biogenic sulfur contribution was estimated to range from 1.2% to 11.5%, implying the major contribution of anthropogenic source to sulfur budget in the study area.Keywords: Dimethylsulfide; Methanesulfonic acid; Non-sea-salt sulfate; Sea-to-air flux; North Yellow SeaArticle Outline1. Introduction2. Experimental2.1. Study area 2.2. Sampling stations 2.3. Seawater DMS and chlorophyll a analyses 2.4. Atmospheric DMS and aerosol sample analyses3. Results and discussion3.1. Horizontal distribution of DMS and chlorophyll a in the surface water 3.2. Relationship between seawater DMS and chlorophyll a 3.3. Sea-to-air flux of DMS 3.4. Atmospheric DMS 3.5. Contribution of biogenic SO42 to total nss-SO42 estimated from MSA/nss-SO42 ratios4. ConclusionsAcknowledgementsReferencesFig.1.Cruise track in the North Yellow Sea in summer 2006. Circles (open and solid) indicate surface sampling locations. Solid circles represent stations where atmospheric DMS was also measured. Arrows indicate the trajectory of the ship.View Within ArticleFig.2.Horizontal distribution of chlorophyll a (gl1) and DMS (nmoll1) in the North Yellow Sea in summer.View Within ArticleFig.3.Relationship between DMS and chlorophyll a concentrations in the North Yellow Sea in summer.View Within ArticleFig.4.Distribution of atmospheric DMS concentrations at all stations during the cruise.View Within ArticleTable 1. Description of sampling stations and their chlorophyll a, DMS concentrations as well as sea-to-air fluxes of DMS in summer.View Within ArticleTable 2. Concentrations of MSA, NO3 and SO42 in aerosols and contributions of biogenic SO42 to total nss-SO42.ss-SO42, sea-salt sulfate; nss-SO42, non-sea-salt sulfate; nd, not detected.View Within ArticleCorresponding author. Tel.: +86 532 66782657/66781733; fax: +86 532 66782540. Atmospheric EnvironmentVolume 43, Issue 13, April 2009, Pages 2196-2203 生物活动所产生的放射dimethylsulfide (DMS)从北部黄海、 中国和它的对硫酸盐的贡献在夏天期间的湿剂 这篇文章在您的组织的订阅没有包括。 然而，您可以能根据您的与Elsevier的组织的协议访问这篇文章。Gui彭杨， a， 洪Hai张a， Lu砰地作声Su a和 李分钟周a海洋化学理论aKey实验室和技术、化学教育部，学院和化学工程，中国，青岛266100，中国的海洋大学接受2008年10月13日; 校正2009年1月8日; 接受2009年1月10日。 线上可以得到的2009年1月19日。 摘要海水、大气dimethylsulfide (DMS)和湿剂化合物，潜在地连接与DMS氧化作用，例如methanesulfonic酸(MSA)和非海盐硫酸盐(nssSO42)在北部黄海，在 7月8月期间的中国被确定了2006年。 海水和大气 DMS的集中范围从2.01到11.79 nmol l1和从1.68到8.26 nmol m3，与6.20 nmol l1的平均值和5.01 nmol m3，分别。 由于看得出的浓度差，在水面积累的DMS转移了入大气，导致6.87 mol m2d1净海对空气涨潮在夏天期间。 在表面 海水，高DMS价值很好对应了与在的绿叶素的一致增量水平，并且一种重大交互作用被观察了在联合DMS和的绿叶素之间集中。 另外， MSA和nss的集中SO42在湿剂样品测量了范围从0.012到0.079 g m3和从3.82到11.72 g m3，与0.039和7.40 g m3的平均值，分别。 凭被观察的MSA， nssSO42和他们的比率，相对生物活动所产生的硫磺贡献在学习区域估计从1.2%范围到11.5%，暗示人类来源的大捐献到硫磺预算。主题词： Dimethylsulfide; Methanesulfonic酸; 非海盐硫酸盐; 海对空气涨潮; 北部黄海文章概述1. 介绍2. 实验性2.1. 学习区域 2.2. 取样站 2.3. 海水的DMS和的绿叶素分析 2.4. 大气DMS和湿剂样品分析3. 结果和讨论3.1. DMS和绿叶素在水面的a的水平的发行 3.2. 海水DMS和绿叶素a之间的关系 3.3. DMS海对空气涨潮 3.4. 大气DMS 3.5. 从MSA/nss-SO42比率共计nssSO42估计的生物活动所产生的SO42的贡献4. 结论鸣谢参考 图1.巡航轨道在北部黄海在夏天2006年。 圈子(开放和固体)表明表面采样地点。 坚实圈子代表大气DMS也被测量的驻地。 箭头表明船的弹道。在文章之内的看法图2.绿叶素a (g l1)和DMS (nmol l1)的水平的发行在北部黄海在夏天。在文章之内的看法图3.的DMS和的绿叶素之间的关系集中在北部黄海在夏天。在文章之内的看法图4.大气DMS含量的发行在所有驻地的在巡航期间。在文章之内的看法表1。 取样站和他们的绿叶素a，并且DMS海对空气涨潮的DMS含量的描述在夏天。在文章之内的看法表2。 MSA、在共计nssSO42的生物活动所产生的SO42的湿剂和贡献的NO3和SO42的集中。ssSO42，海盐硫酸盐; nssSO42，非海盐硫酸盐; nd，没检测。在文章之内的看法对应的作者。 Tel. ： +86 532 66782657/66781733; 电传： +86 532 66782540。 大气环境容量43，问题13， 2009年4月寒武纪或寒武纪界限部分在三道峡谷地区，中国南方的碳同位素chemostratigraphy ： 突出全球性称在寒武纪爆炸之前的同位素游览 这篇文章在您的组织的订阅没有包括。 然而，您可以能根据您的与Elsevier的组织的协议访问这篇文章。Tomoko石川a， Yuichiro Ueno b， c， Tsuyoshi Komiya a， c， Yusuke Sawaki a， Jian韩d， Degan Shu d， Yong 李e， Shigenori Maruyama a、c和Naohiro吉田c， f地球的aDepartment和星球科学，东京技术研究所， Meguro-ku，东京152-8551，日本bGlobal边缘学院， Meguro-ku，东京技术研究所，东京152-8551，日本演变的地球和行星，东京技术研究所，日本cResearch中心地质和钥匙实验室，西北大学，西安710069，中国的dDepartment大陆动力学的地球科学和资源管理， Changan大学，西安710054，中国eSchool 环境科学技术，东京技术研究所的fDepartment， Midori-ku横滨15