Thermal Ionization Mass Spectrometry (TIMS)-U-Series Ages of Corals from the South China Sea and Holocene High Sea Level

Coral samples collected from the waters off the Leizhou Peninsula, the Hainan Island and the Yongxing Island of the Xisha Islands were analyzed by thermal ionization mass spectrometry (TIMS) and multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for their U-Th systematics. Their uranium contents are mostly lower than 3μg/g, and the δ+{234}U(T) values are within the range of 150±5. X-ray diffraction analysis showed that the corals are all composed of aragonite. This demonstrates that the corals determined have maintained a close system for 7000 years and their skeletons bear much information about the primitive tropical marine environment. The highly precise age sequence of the corals determined has revealed that there occurred three phases of high sea level in the South China Sea waters, which are dated at 6799-6307 a B.P., 4472-4285 a B.P. and 1279-1012 a B.P., respectively. The three phases lasted 492 a, 187 a and 267 a, respectively. These three phases of high sea level are corresponding to the warm environments that had appeared in China during the Megathermal Period and the Medieval Warm Period in the past ten thousand years.

Middle Holocene warm period and sea level high in coastal areas,North China

Relevant geological, geographical, archaeological data were collected to study the characteristics of middle Holocene warm period and sea level high on North China coast. Middle Holocene climate and sea level change on North China coast were correlated to warm marine environment events in about 8–3 ka B.P. The sea level in about 8 ka B.P. was higher than present mean sea level, then fluctuated for 5 000 years and after that it became even in 3 ka B.P. The highest sea level occurred in about 6–5 ka B.P.; the maximum was about 2–3 m and minimum was about 1–2 m.

Case analysis of water exchange between the Bohai and Yellow Seas in response to high winds in winter

Based on the data from a special project titled China's Offshore Marine Integrated Investigation and Evaluation as well as Regional Ocean Modeling Systems(ROMS)diagnostic numerical model,we studied the influence of high wind processes on the circulation and water exchange between the Bohai and Yellow Seas(BYS)in winter.The results show that the vertical structure of the Yellow Sea Warm Current(YSWC)is relatively uniform under condition of high winds,showing obvious barotropic features.However,this flow is not a stable mean flow,showing strong paroxysmal and reciprocating characteristics.A comparison of the changes in sea level suggests that the intensity of the northwards upwind flow is consistent with the abnormal fluctuations in the sea level.It indicates that the upwind flow is closely related to the water exchange between the BYS.The impact of high wind processes on the water exchange between the BYS is enormous.It can make the flux through the Bohai Strait,as well as that through the mouth of each constituent bay(i.e.,Liaodong Bay,Bohai Bay,and Laizhou Bay)far greater than usual,resulting in a significant increase in the water exchange rate.The exchange capacity,which is about 8%of the total volume of the Bohai Sea,can be completed in a few days.Therefore,the water exchange of the Bohai Sea may be completed by only a few occasional high wind processes in winter.

基于MDCFT与水平集的高海情弹载雷达成像检测方法

针对舰船三维摆动和海尖峰制约高海情环境弹载雷达探测性能的问题,面向高海情探测环境提出了一种新的成像检测思路。首先,基于高海情环境分别建立舰船与海杂波回波模型;其次,将改进离散调频傅里叶变换算法(modified discrete chirp Fourier transform, MDCFT)引入回波多普勒成像,消除了高阶项相位导致的散焦现象;在此基础上,利用水平集算法分割目标与背景区域,然后利用聚类算法确定每个目标区域;最后,基于提取的目标特征判决每个区域对应的目标身份。利用仿真数据的实验结果验证了所提算法的有效性。所提方法综合考虑了成像与检测环节性能的提升,为高海情环境下的弹载雷达制导提供了一种可行思路。

古气候和海平面变化对浅水碳酸盐岩高频层序及有利储层的控制——以川中地区龙王庙组为例

【研究目的】阐明古气候和海平面变化对浅水碳酸盐岩高频层序及有利储层的控制机制,对明确储层成因和分布规律具有重要意义。【研究方法】以川中地区龙王庙组为例,在沉积相及层序地层分析的基础上,通过全井段取心的碳氧同位素、主量和微量元素测试,恢复了海平面和古气候变化并开展了综合讨论。【研究结果】龙王庙组主要发育云质潟湖、滩间海、颗粒滩和云坪4种沉积微相,可清晰识别可区域对比的两个四级层序。龙王庙组的δ^(13)C具有两个变化周期,指示两次海平面升降,这与Al_(2)O_(3)、TiO_(2)、B和V元素变化所反映的古水深变化一致。碳和氧同位素估算的古海水Z值和温度,以及Mg、Ca良好的相关性,共同反映干旱炎热气候和亚热带海洋环境;MgO/CaO、MnO_(2)、Fe_(2)O_(3)/MnO_(2)和Al_(2)O_(3)/MgO的规律性变化,指示两个层序早期的气候短暂过渡为温暖潮湿;Sr/Ba值反映沉积晚期海水盐度明显增高。【结论】气候温暖潮湿和海平面快速上升期形成海侵体系域;气候炎热干旱时,颗粒滩和云坪快速沉积构成高位体系域。高位域上部的滩—坪体系是优质储层的物质基础,在海平面下降和干热气候控制下发生的早期溶蚀和白云化作用是储层改善的关键。

Devonian Frasnian-Famennian Transitional Milankovitch Cycles and High-Resolution Stratigraphic Correlation

Four hierarchical cyclothems, superbundlesets, bundlesets, bundles and laminae, have been identified from the Devonian Frasnian-Famennian carbonate strata in Guangxi, South China. Their hierarchical structures, ratio relationships and sequence in conodont zones are continuous and stable and can be traced across different facies zones and sedimentary basins. Our data show that hierarchically organized superbundlesets, bundlesets, bundles and laminae correspond to the long eccentricity, eccentricity, obliquity or precession and sub-Milankovitch cycles respectively. Their periods were 400,000, 100,000, 33,333, 16,667 and 8,000–17,000 a, respectively. The ratios of long eccentricity to eccentricity, eccentricity to obliquity, and eccentricity to precession in the Devonian are 1:4, 1:3 and 1:6 respectively. Using these hierarchical Milankovitch cyclothems, chronostratigraphical division and correlation can be realized at a resolution of 100 ka or 10 ka at the Frasnian-Famennian transition. The time intervals of the Upper rhenana Zone, linguiformis Zone, and the Lower, Middle and Upper triangularis Zone are 0.6, 0.8, 0.3, 0.3 and 0.3 Ma, respectively. Sea-level changes of the Frasnian-Famennian transition were not coherent and synchronous at the resolution of 100 ka or 10 ka in the basin-slope carbonate sequences of Guangxi, South China.

Sleep quality alterations in healthy workers at high altitude in Yushu area

During the period of reconstruction after Yushu Earthquake,a large number of sea-level or low land workers ascended there and worked at altitudes between 3 750 m and 4 878 m which is a hypoxic environment. To investigate the sleep quality at that altitude,we performed two full polysomnographies (PSGs) in 10 volunteers,who were healthy male workers,aged 31±6.6,born and living at sea level,without experience of pre-altitude exposure. The assessment of subjective sleep quality was performed twice in each volunteer. The first investigations were carried out at sea level in Jinan city (p B =760 torr,1 torr=133.322 4 Pa). The second studies were performed at an altitude of 3 750 m (p B =416 torr) in Yushu Jiegu in the same 10 workers after they lived and worked at that altitude for 5 months. At sea level,workers presented a normal sleep structure and a higher oxygenation during sleep. However,as compared to sea-level sleep,at 3 750 m,workers had a shorter total sleep time (TST) (p<0.001),a longer stage 1 non-rapid eye movement (nREM) sleep (p<0.05) and a shorter 3+4 nREM and rapid eye movement (REM) sleep (p<0.05) with a severe sleep hypoxemia (p<0.01). Our data suggested that sea-level workers revealed a disturbed sleep and a bad sleep quality with a significant sleep hypoxemia at altitude of 3 750 m. Strengthening the prevention and treatment are thereby sorely necessary.

海平面上升对黄浦江1000年一遇高潮位影响研究——基于马尔科夫链蒙特卡罗法

为了研究海平面上升对黄浦江1000年一遇高潮位的影响,以吴淞站为代表,采用马尔科夫链蒙特卡洛法预测模拟了500组吴淞站未来30年年最高潮位序列,在序列生成过程中逐年考虑海平面上升的影响,根据生成的序列对其影响进行计算分析。结果显示,采用马尔科夫链蒙特卡洛法预测的多组吴淞站30年后1000年一遇高潮位符合P-Ⅲ分布;海平面上升能显著改变预测1000年一遇高潮位的频率分布,主要为增加较高高潮位出现的概率,降低较低高潮位出现的概率,整体上提升分布的均值。总体上,海平面上升引起吴淞站未来30年6.6 m以上1000年一遇高潮位出现的概率增加14%,1000年一遇高潮位均值抬升约4 cm。

On the Holocene sea-level highstand along the Yangtze Delta and Ningshao Plain,East China

The temporal-spatial distribution of Neolithicsites shows a long period of absence of human settlementsduring the early Holocene on the Yangtze Delta, and the area has not been colonized until 7000 aBP, corresponding to the onset of the Majiabang culture. Besides the regions east to the sandbar of Maqiao Site in Shanghai, foraminifera are not found in Neolithic cultural layers since 7000 aBP, indicating a widespread transgression between 10000 and 7000 aBP.Evidence of radiocarbon-dated cultural relics, foraminifera and pollen records from the Hemudu Site suggests that the Hemudu culture emerged and developed during themid-Holocene Climatic Optimum. Therefore, the hypothesisof a mid-Holocene sea-level highstand along the YangtzeDelta and Ningshao Plain from 7000 to 5000 aBP is an open debate. New evidence from archaeological excavations andbio-stratigraphy suggests that, prior to 7000 aBP, a high sea level occurred along the Ningshao Plain. Subsequently, the sea level was lowered between 7000 and 5000 aBP, and the area suffered from frequent floods from 5000 to 3900 aBP.

全球变暖背景下南海动力海平面变化

由于分辨率不足等原因,当前大部分全球耦合气候模式对南海等海洋区域的模拟能力仍然较低。本文基于超高分辨率(Ultra high-resolution)CESM-UHR耦合模式(大气和海洋水平分辨率分别达到约25 km和约10 km)研究了南海动力海平面对全球变暖的响应。研究发现:(1)CESM-UHR能够较好地模拟出南海冬、夏季节性动力海面高度和表层环流变化;(2)在四倍二氧化碳试验下,冬季南海动力海平面变化呈现出中部低、近岸高的分布特征;夏季则呈现出西北部低、东南部高的分布特征,分别对应冬、夏表层地转流增强趋势;(3)冬、夏动力海平面变化特征与风应力旋度变化具有很好的对应关系;(4)全球变暖下南海海平面变化存在季节循环放大效应,这将增大南海极端水位灾害风险。

The species diversity of fusulinaceans and high-frequency sea-level changes in the Carboniferous-Permian boundary section at Xikou, Zhen'an County,Shaanxi Province, China

The study on the interrelation between sea-level changes and biodiversity with its evolu-tion has great significance for understanding the impact of global changes on organic evolution and exploring the inherent laws of life-environment coevolution in geological history. In this paper, the stratigraphic distribution of fusulinacean fauna in the Carboniferous-Permian boundary section at Xikou, Zhen’an County, Shaanxi Province, is analyzed quantitatively, and the relationship between the species diversity of fusulinaceans and relative sea-level changes is discussed. As a whole, the spe-cies numbers of fusulinacean fauna experience a rapid increase and an obvious decline in Xikou, Zhen’an County, from the Late Carboniferous to the Early Permian. There is a significant increase in species diversity around the Carboniferous-Permian boundary, which is one of the biggest bio-events of the fusulinacean fauna, and represents the radiation of Pseudoschwagerininae subfamily in the studied area. Integrated fusulinacean species diversity into sequence stratigraphic framework, de-tailed study suggests that the species diversity of the fusulinaceans is closely related to its relative stratigraphic location, and is essentially controlled by the sea-level changes, especially by the high-frequency sea-level changes. Generally, the species diversity of fusulinaceans is low, and the number of first and last appearance datum is small in the lower unit of high-frequency depositional cycle formed during the quick rise of the sea level; whereas the species diversity of fusulinaceans is high, and the number of first and last appearance datum is large in the upper unit of high-frequency cycle formed during the slow fall of the sea level. Within the third-order depositional sequence, the species diversity of the fusulinaceans at the first flooding surfaces and the maximum flooding surfaces is low, and it increases upward. The fusulinacean species diversity is low within the transgressive systems track, and it is high within the highstand systems track. The second-order rise and fall in sea level coincide with the bloom and decline of high order taxa of fusulinaceans.

雷州半岛珊瑚礁生物地貌带与全新世多期相对高海平面

通过多次野外调查 ,将灯楼角珊瑚礁分为 8个生物地貌带 :礁前斜坡活珊瑚林带、外礁坪大块滨珊瑚礁岩带、中礁坪块状珊瑚混合带、中礁坪块状珊瑚—角孔珊瑚混合带、内礁坪角孔珊瑚带、沙坪台—海滩、沙堤和洼地 ,它们是海平面和气候环境变化的产物。以珊瑚礁及其生物地貌带作为高海平面的标志 ,根据 13个表层珊瑚礁样品的 TIMS铀系年代和 1个 1 4C年代 ,指出全新世以来至少存在过 5期相对高海平面 (7.2～ 6 .7、约 5 .8、 5 .0～4 .2、 2 .8～ 2 .0、约 1.5 cal.ka BP) ,每一期中还存在低海平面的波动。其中 6 .7～ 7.2 ka BP是整个全新世最高海平面时期 ,在这个时间段已经基本形成了现代珊瑚礁的地貌格局。这个时间段以后形成的珊瑚礁是在 6 .7～ 7.2 ka BP形成的珊瑚礁礁坪的礁塘或礁坑等低洼地中形成的 ,迄今为止 ,没有再出现过高出 6 .7～ 7.2 ka

中-晚全新世高海平面的琼海珊瑚礁记录

采用精确的高程测量和高精度的TIMS铀系定年方法,对海南岛东部琼海青葛附近低潮时出露的原生死珊瑚和外礁坪上的活微环礁进行调查研究。调查结果表明,青葛附近外礁坪上的微环礁存在狭窄的生长上限(±8cm),位于最低低潮面上,是相当精确的海平面标志物。原生死珊瑚顶面与附近现代活微环礁顶面的高差数据和精确可靠的TIMS铀系年龄数据显示,5500～5200aBP(U/Th年龄,相对于2008年)时海平面至少高出现在(100±8)cm,真实的海平面很可能比现在高2.0～2.2m。总体上,5500～3500aBP期间海平面波动变化,波动幅度约为0.6m,且这种波动与气候波动有较好的对应性。4400～3900aBP期间琼海珊瑚礁的发育缺失很可能与此时的气候干冷有关。

南海周边中全新世以来的海平面变化研究进展

综述了近几十年来前人有关中全新世以来南海海平面变化研究的主要成果,着重探讨了研究中出现的争议和热点问题,结果表明,南海中全新世确实存在高海平面,海平面最高有2-3 m,出现在7.0-5.5 kaBP;而此后的海平面变化呈振荡模式,波动降低到目前海平面的位置,且与温度波动有一定的同步性,揭示了它们之间的紧密联系。而由卫星观测结果统计出的最近十几年以来南海海平面的上升速率达3.9 mm/a,略高于同期全球平均值;由验潮站统计出的南海海平面上升率为2.4 mm/a,同样略高于相应的全球平均值。最后还指出了研究过程中存在的主要问题与不足,并初步总结出一些改进措施：①使用高精度的定年技术,减少年龄误差;②在构造相对稳定的海岸段研究古海平面变化;③尽量采用高精度的标志物,如微环礁、管形虫壳等。

海南岛鹿回头珊瑚礁与全新世高海平面

通过实地考察和资料分析,海南岛南部全新世以来以沉降活动为主要特征,鹿回头珊瑚礁能够反映全新世以来的海平面变化,鹿回头岸礁礁坪面上的原生珊瑚礁是全新世高海平面时期的产物.全新世以来南海北部至少存在过4期相对高海平面阶段:7 300～6 000、4 800～4 700、4 300～4 200和3 100～2 900 cal.aBP.其中7 300～6 000 aBP是整个全新世最高海平面时期,也是鹿回头珊瑚礁发育的繁盛期,基本形成了现代珊瑚礁的地貌格局,后来不同时期发育的珊瑚礁是在此时期形成的礁塘或礁坑等低洼地中形成,并在鹿回头半岛两侧向外发展,现代珊瑚礁则发育于全新世珊瑚礁的外礁坪和礁前斜坡带.另外,鹿回头珊瑚礁反映的南海北部全新世高海平面时间与南海其他地区高海平面时间可以衔接或对应,说明南海地区全新世高海平面具有全球背景,至少在南海是一致的,且与气候变暖紧密相联.

海侵事件成煤作用—— 一种新的聚煤模式

晚古生代华北陆表海聚煤盆地海平面具有高频率变化和复合性特点 ,海侵具有突发事件性 ,这一规律对盆地充填沉积、沉积体系演化和煤聚积具有控制作用。提出了“海侵事件成煤观点”,认为海侵事件成煤是大型陆表海盆地所特有的 ,陆表海盆地的海侵过程是非常短暂的 ,表现出海侵具“突发”性质 ,因此海侵沉积具有较好的等时性。煤层与直接覆盖于其上的海相灰岩为一种事件沉积组合 ,泥炭的煤化作用过程完全处于还原环境下。

南海地区全新世高海平面遗迹高程的区域差异问题

本文较全面地列举南海地区6500～5000a(BP)期间的古海平面遗迹,共61个实例,其中正高程的或高程为0m的有45例.这些遗迹的现存高程差异很大,主要是受构造升降运动的影响.按照遗迹高程的分布,可分为5个区域,台湾为高程最大值,巽他群岛居其次,中南半岛和马来半岛居第三位,华南沿海的高程较小,南海海盆为最小值.负高程的实例主要分布在五大三角洲地区.

新疆柯坪大湾沟剖面中-上奥陶统烃源岩高频海平面变化与有机质的关系

通过对柯坪大湾沟剖面中-上奥陶统萨尔干组与印干组页岩的自然伽马测量,建立了此两套页岩的高频海平面变化曲线。同时,对采自于大湾沟剖面的54块泥页岩样品进行了热解与有机碳含量、泥岩X衍射的矿物种类与含量、泥岩密度等分析,将泥页岩样品的分析结果与高频海平面升降变化对比后,认为:①萨尔干组页岩厚13.4 m,属于一个三级层序的海平面升降变化。在萨尔干组页岩的海侵体系域内,发育4次高频海平面升降变化,而在高位体系域内发育3次高频海平面升降变化。印干组页岩厚34 m,也同样属于一个三级层序的海平面升降变化。海侵体系域内发育2次高频海平面升降变化,在高位体系域内则发育6次高频海平面变化。②萨尔干组页岩与印干组页岩均在海平面上升期黏土矿物含量增加,且有机质丰度增高(有机碳含量值增大)。萨尔干组页岩黏土矿物含量高于印干组页岩,碳酸盐矿物低于印干组页岩,其有机质丰度亦高于印干组页岩。③萨尔干组页岩与印干组页岩的黏土矿物成分主要为伊-蒙混层,由于蒙皂石伊利石化是烃源岩催化活性的主要来源,因此富含伊-蒙混合层的这两套烃源岩是最有利的烃源岩。④萨尔干组页岩、印干组页岩均具有海平面上升,有机质丰度增高、泥页岩密度降低和海平面下降,有机质丰度降低、泥岩密度增高的特征。

内陆表海含煤盆地Ⅲ级层序的划分原则及基本构成特点

华北晚古生代煤系主要形成于陆内相对稳定区，古地貌上表现为受限内陆表海盆地，因此，识别层序界面及内部各级单元界面，划分层序及重建沉积体系域，需要总结出适合内陆表海盆地特点的层序划分原则和方法、技术系统。研究表明，识别沉积体系域，鉴定层序界面和各级构成单元界面，进行沉积体系和成因相的配置，划分小层序组和小层序等，这几项工作同步进行，相互映证，是内陆表海盆地层序地层分析的基本原则。

从SX97孔分析深圳沿海近3万年来海平面及气候变迁

在对深圳地区SX97孔进行沉积物岩相分析和磁性测试的基础上,结合Fe元素含量、石英和粘土矿物含量变化,对钻孔进行了高频层序地层分析。结果表明,钻孔可以划分为1个四级层序(准层序)和6个五级层序。每个层序代表了一次海平面的升降旋回。四级层序的海退沉积与末次冰期的后期对应,海平面下降最大时期是末次冰期最盛期(LGM)的反映,时间大约在21kaB.P.左右;海侵沉积对应着气候的回升,发生在约13.8kaB.P.。在四级层序的海退沉积中,包含2个五级层序,实质上反映了两次气候的暖、冷旋回,但从时间上无法与Heinrich事件相对比。在四级层序的海侵过程中,包含4个比较明显的五级层序,也是4次比较明显的气候变化旋回。其中,从五级层序4的海侵开始到五级层序5的海侵结束,时间约从6.5～2.3kaB.P.,是全新世气候最适宜期,之后从2.3～1.7kaB.P.是气候相对变冷时期。这些主要气候事件与我国其他地区的非同时性,反映了东亚季风和印度季风等对深圳地区气候变化的多重控制作用。