华宁盘溪金山-大石山泥盆纪珊瑚礁的基本特征     

洪天求  戴清明 《吉林大学学报(地球科学版)》1997,(1)

滇东华宁盘溪火车站以北的金山—大石山地区发育中、晚泥盆世的丘状珊瑚礁。以Ａｌｖｅｏｌｉｔｅｓ和Ｔｈａｍｎｏｐｏｒａ为代表的床板珊瑚为造礁生物。纵剖面上岩相变化的记录清楚地表明，该礁体经历了定殖、繁殖和衰亡三个阶段。海水变浅及其盐化是导致礁体衰亡的直接原因  相似文献   

湖南慈利晚二叠世海绵礁与珊瑚礁的古生态研究   总被引：5，自引：0，他引：5       下载免费PDF全文

王永标  徐桂荣 《地球科学》1997,22(2):135-138

中国南方晚二叠世生物礁分布广泛，但绝大多数属于海绵礁，湖南慈利晚二叠世除发育有海绵礁外，还有至今为止发现的世界上发育最好的古代珊瑚礁，而且海绵礁与珊瑚礁在同一条带上连续分布；因此是研究海绵礁与珊瑚礁古生态关系十分理想的场所，通过对慈利晚二叠世海绵礁及珊瑚礁内部造礁生物群落、沉积相特征，礁化演化序列及成岩作用特征等的分析和对比来研究它们之间的生态关系，发现其中的海绵礁为台地边缘礁，而珊瑚礁则应属于岸  相似文献   

生物礁岩分类方案   总被引：13，自引：4，他引：13  

吴亚生 《地质论评》1997,43(3):281-289

本文系统地提出了一个生物礁岩分类的新方案。生物礁岩首先根据次生组分的有无分为原生礁岩和次生礁岩。次生礁岩根据次生组分来源分为骨源次生礁岩和礁源次生礁岩。次生礁岩的二级分类根据次生组分的含量进行。骨源次生礁岩分为骨屑岩和含骨屑礁（灰）岩、倒骨央和含倒骨礁（灰）岩；礁源次生礁岩分为礁屑岩和含礁屑礁（灰）岩。骨屑岩根据次生组分的粒度分为巨骨砾（屑灰）岩、骨砾（屑灰）岩、细骨砾（屑灰）岩、骨砂（屑灰）岩；  相似文献   

珊瑚礁工程地质研究的内容和方法   总被引：3，自引：0，他引：3  

赵焕庭  汪稔 《工程地质学报》1997,5(1):21-27

珊瑚礁工程地质研究的主要内容为珊瑚礁自然地质条件、珊瑚礁岩土物理力学性质和珊瑚礁混凝土料问题。除了通常的工程地质研究方法外, 着重介绍珊瑚礁工程地质研究的钻探、触探和地球物理勘测方法。  相似文献   

Research on Relationship Between Fluorine in Tap Water and That in Urine of Chinese Residents     

王滨滨  郑宝山  翟城  刘小静  安宁 《中国地球化学学报》2004,23(4):373-379

In this study, the relationship between fluorine in drinking water and that in urine of urban residents in China is assessed. Fluorine concentrations in tap water and those in urine show a good correlation with a linear regression coefficient of 0. 9798, indicating that the fluorine concentrations in big cities under investigation are extremely low, and the main source of fluorine is tap water. The weather effect on the intake amount of fluorine is also discussed. When air temperature is above 15℃, people would intake more fluorine through drinking water with the rise of air temperature. When temperature is below 15℃, no remarkable relationship is observed between air temperature and the intake amount of fluorine. This phenomenon indicates that the main source of fluorine in China is tap water instead of foodstuff.  相似文献   

陕西省区域环境地球化学分区   总被引：2，自引：0，他引：2  

潘爱芳  赫英  马润勇 《地球科学进展》2004,(Z1)

为了利用地壳元素分布特征与动植物微量元素含量间的关系,指导生态环境综合治理,借助已有的基础地球化学资料,进行陕西省地球化学分区,确定各分区的环境背景值、污染起始值、缺乏临界值、过剩值临界值,并将陕西省分为陕北、关中、陕南3个地球化学区,圈定了1个元素贫化区和2个元素富集区。提出应该在元素的缺乏和过剩的异常区内进行生物体内微量元素含量的定期检测。做到对地球化学疾病及时发现及时寻找对策,以保证人类生存环境的安全,提高生存质量。  相似文献   

Taphonomic differentiation of Acropora palmata facies in cores from Campeche Bank Reefs, Gulf of México     

Paul Blanchon  Chris T. Perry† 《Sedimentology》2004,51(1):53-76

A common assumption in the geological analysis of modern reefs is that coral community zonation seen on the surface should also be found in cores from the reef interior. Such assumptions not only underestimate the impact of tropical storms on reef facies development, but have been difficult to test because of restrictions imposed by narrow‐diameter cores and poor recovery. That assumption is tested here using large‐diameter cores recovered from a range of common zones across three Campeche Bank reefs. It is found that cores from the reef‐front, crest, flat and rubble‐cay zones are similar in texture and coral composition, making it impossible to recognize coral assemblages that reflect the surface zonation. Taphonomic signatures imparted by variations in encrustation, bioerosion and cementation, however, produce distinct facies and delineate a clear depth zonation. Cores from the reef‐front zone (2–10 m depth) are characterized by sections of Acropora palmata cobble gravel interspersed with sections of in‐place (but truncated) A. palmata stumps. Upper surfaces of truncated colonies are intensely bioeroded by traces of Entobia isp. and Gastrochaenolites isp. and encrusted by mm‐thick crustose corallines before colony regeneration and, therefore, indicate punctuated growth resulting from a hurricane‐induced cycle of destruction and regeneration. Cores from the reef crest/flat (0–2 m depth) are also characterized by sections of hurricane‐derived A. palmata cobble‐gravels as well as in‐place A. palmata colonies. In contrast to the reef front, however, these cobble gravels are encrusted by cm‐thick crusts of intergrown coralline algae, low‐relief Homotrema and vermetids, bored by traces of Entobia isp. and Trypanites isp. and coated by a dense, peloidal, micrite cement. Cores from the inter‐ to supratidal rubble‐cay zone (+0–5 m) are only composed of A. palmata cobble gravels and, although clasts show evidence of subtidal encrustation and bioerosion, these always represent processes that occurred before deposition on the cay. Instead, these gravels are distinguished on the basis of their limited bioerosion and marine cements, which exhibit fabrics formed in the intertidal zone. These results confirm that hurricanes have a major influence on facies development in Campeche Bank reefs. Instead of reflecting the surface coral zonation, each facies records a distinctive, depth‐related set of taphonomic processes, which reflect colonization, alteration and stabilization following the production of new substrates by hurricanes.  相似文献   

我国农村合作医疗的地区模式     

宋韬 《世界地理研究》2004,13(4):75-78,85

农村合作医疗是我国农村主要的医疗保障形式。但是由于我国各地社会经济发展水平不平衡，中央政府的扶持政策也有所不同，合作医疗出现了多种不同的地区模式。高收入地区、中等收入地区及低收入地区的合作医疗在筹资方式、管理方式和补偿方式上都各有特点。  相似文献   

舟山渔场软体生物中PCBs的残留及潜在生态风险          下载免费PDF全文

潘永强  薛斌  张慎伟  黄子茵 《海洋学研究》2018,36(2):92-98

本文测定了舟山渔场附近6个沿海城市5种软体动物体内多氯联苯的污染水平,并进一步探讨了其潜在来源以及生态风险。结果显示,样品中PCBs的总含量水平为18.0~95.9 ng/g干重,平均含量为51.9 ng/g干重,与世界其他海域相比处于中等污染水平。组分分析表明,五氯联苯和二氯联苯为主要组成。PCBs的健康风险HR值均远低于1,表明日常食用不会对人体健康产生明显危害。  相似文献   

西沙群岛基底火山碎屑岩中单斜辉石的矿物化学特征及其地质意义     

李诗颖  余克服  张瑜  陶士臣  严宏强 《海洋学报》2019,41(7):65-76

本文利用电子探针对南海西沙群岛琛航岛珊瑚礁底部火山碎屑岩中的单斜辉石矿物的化学特征进行了研究。结果表明，该单斜辉石属于富钙透辉石，部分有正环带结构，从核部到边部Ca、Fe、Ti的含量逐渐增加，是岩浆正常结晶顺序的反映，说明该区域的岩浆演化是向着富Ca、Fe、Ti方向发展的。主量元素数据显示，单斜辉石具有低Si高Al的特征(SiO₂=41.40%～48.44%，Al₂O₃=5.54%～10.20%)，且AlⅣ含量较高，说明母岩浆为不饱和碱性岩浆系列；此外，单斜辉石Ca含量偏高，Ca/(Ca+Mg+Fe)值在46.1%～51.4%之间，推测是母岩浆的高Ca含量导致了大量高钙辉石的产出。结合西沙海域的地震和构造资料，推测琛航岛珊瑚礁的基底是玄武质火山碎屑岩组成的平顶状海山，系岩浆穿过断裂发育的岩石圈层在西沙群岛的海底喷发，随后火山碎屑物质经过堆积、固结作用而形成；该火山碎屑岩的原岩为板内碱性玄武岩。  相似文献