Two research methods, geomicrobiology and carbonate sedimentology, were adopted to study the microbial carbonates in the beachrocks, Shuiweiling, Luhuitou, Sanya City, Hainan Island. The results indicate that microbia...Two research methods, geomicrobiology and carbonate sedimentology, were adopted to study the microbial carbonates in the beachrocks, Shuiweiling, Luhuitou, Sanya City, Hainan Island. The results indicate that microbial carbonates occur in Shuiweiling beachrocks and cements related to microbial activitives are common. Microbial carbonates were mainly developed on the surfaces of coral skeletons and within the coral (fragments and shivers) skeletal cavities,and rarely grew in interspaces formed by coral and other biological detritus. The growth morphologies of microbial carbonates are various, including stromatolitic lamination, thin crusts, dome-like, and microbialites. Microbial carbonates commonly trap fine-sized bioclasts, contain tubular filaments, and show laminated growth striation. Microbial carbonates within the coral skeletal cavities are generally stromatolitic cone-shaped, with a random growth direction along the bearing of trend of cavities, showing distinct growth laminae and recognizable growth phases. It is a special growth pattern of crypt microbial carbonates. Microbial cements occur mainly in shape of needle cement, calcified filaments, microborings, and calcified framboidal spheres. The needle cement is the most common type. These microbial cements indicate that microbial activities and microbial carbonates played an important role in beachrock formation in which carbonates were dominant components and the climate of tropical ocean monsoon was influential. Such microbial carbonates and microbial cementation have not been reported here from beachrocks along the northern shorelines of the South China Sea. The results support a clear microbial origin for certain carbonate cements in beachrocks, confirm that microbial carbonates are a significant contributor to carbonate sedimentation, and widen the knowledge of beachrocks from a new field.展开更多
Six species, belonging to five genera, of large animal remains are firstly described andreported in this paper. They were found in the late Holocene high beachrock of 25--m ele-vation on Longhu Hill of Houshijing, Pin...Six species, belonging to five genera, of large animal remains are firstly described andreported in this paper. They were found in the late Holocene high beachrock of 25--m ele-vation on Longhu Hill of Houshijing, Pinghai Village, Putian County, Fujian Province. Theseanimal remains are found mostly between intertidal and subtidal zones in the tropical areafrom the Miocene to the recent. The research results have confirmed that the coastal sedi-ments belong to the beachrock, which is formed in the tropical coastal areas. This paperproposes that the study of large animal remains in the beachrock can provide a scientificbase for the understanding of the sedimentographic environment of the beachrock, andvaluable information for the study on paleoclimate and paleo-shoreline evolution.展开更多
热带—亚热带潮间带沉积物中丰富的菌—藻类微生物及其复杂的生命活动对颗粒的早期胶结过程起重要作用。本文通过16S r RNA高通量基因测序方法分析西沙群岛石屿、全富岛及海南龙湾珊瑚礁滨岸带海滩岩表生微生物群落结构,确定主导海滩岩...热带—亚热带潮间带沉积物中丰富的菌—藻类微生物及其复杂的生命活动对颗粒的早期胶结过程起重要作用。本文通过16S r RNA高通量基因测序方法分析西沙群岛石屿、全富岛及海南龙湾珊瑚礁滨岸带海滩岩表生微生物群落结构,确定主导海滩岩快速胶结的共性菌株/微生物功能群。表层生长草皮海藻的全富岛海滩岩原核生物多样性最高。龙湾潮间带上部暴露时间较长的海滩岩比潮间带下部海滩岩原核生物多样性高。相对固结的石屿海滩岩原核生物多样性最低。4个取样点具有较为相似的细菌门类组成,物种丰度由大到小依次为变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteriota)、蓝细菌门(Cyanobacteria)、绿弯菌门(Chloroflexi)、芽单胞菌门(Gemmatimonadota)和脱硫杆菌门(Desulfobacterota)。不同点位的海滩岩形成环境中蓝细菌主要种类大体相同,其中眉藻(Calothrixsp.)是主导海滩岩早期胶结的共性钙化菌株,通过分泌胞外聚合物成为碳酸盐矿物沉淀的“热点”。群落中检出的反硝化细菌和硫酸盐还原菌表明海滩岩内部氧化还原梯度较大,表面下极浅处即存在缺氧微环境。微生物群落内强烈的光合作用、硫酸盐还原作用和反硝化作用不断提高微环境pH值,有利碳酸盐矿物在粒间孔内的成核和生长并加速颗粒胶结。展开更多
浙江沿海全新世海滩岩是正处于中亚热带的海滩岩,迄今已发现有13处,主要出露于两侧为基岩岬角的小海湾潮间带中部的沙滩上,^(14)C年龄主要为2705 a±160 a BP～6485 a±210 a BP。通过多学科手段的综合研究,初步探讨了其基本特...浙江沿海全新世海滩岩是正处于中亚热带的海滩岩,迄今已发现有13处,主要出露于两侧为基岩岬角的小海湾潮间带中部的沙滩上,^(14)C年龄主要为2705 a±160 a BP～6485 a±210 a BP。通过多学科手段的综合研究,初步探讨了其基本特征及古地理意义。研究结果表明,受海水作用影响产生的颗粒(如生活于潮间带-潮下带的贝类壳体及其碎片、近岸底栖的有孔虫和介形虫等生物碎屑、花岗岩岩屑等)、颗粒支撑结构及文石针胶结物是其最重要特征。在其形成过程中,适宜的地貌如处于有砂砾滩的小海湾中,充足的经海蚀搬运来的陆源岩屑、石英、长石,大量的海洋生物碎屑作为物源,合适的颗粒粒径,适中的水动力,基本稳定或缓慢下降的海面及较高的气温等,都是有利的条件。在海滩岩形成时期,浙江中、北部地区沿岸线基本稳定,或略微缓慢向海推进。东海沿岸流不是如今这种低温水团,其水温应比现今高5～6℃,最少应高2℃,而其低盐度性质则古今基本一致。同时,热带扩展到浙江中、北部地区,或者当时的气候分带性不如现今这么明显。展开更多
浙江全新世海滩岩是目前公认的中国最北的海滩岩,对它的研究在古气候、古环境、古海面变化等方面都具有重要意义。笔者对浙江海滩岩进行了综合研究,揭示其古动物学、岩石学、矿物学、元素地球化学、氧碳稳定同位素和^(14)C测年等特征,...浙江全新世海滩岩是目前公认的中国最北的海滩岩,对它的研究在古气候、古环境、古海面变化等方面都具有重要意义。笔者对浙江海滩岩进行了综合研究,揭示其古动物学、岩石学、矿物学、元素地球化学、氧碳稳定同位素和^(14)C测年等特征,从中提取了古气候、古环境信息。研究表明,浙江海滩岩由8个岩石类型组成,其沉积可分两阶段8期:6.5—2.4 ka BP阶段(细分为6.5 ka BP,6.1—5.8 ka BP,5.5 ka BP,5.2—5.1 ka BP,4.8—4.1 ka BP,3.8 ka BP,3.5—2.4 ka BP 7期)和1.1 ka BP阶段(共8期),其所含动物遗骸具有较强烈的热带色彩,由δ^(18)O计算,中全新世海水温度高于现今3.25—4.25℃。展开更多
基金the Hundred Talents Program of Chinese Academy of Sciences, the National Natural Science Foundation of China (Grant Nos. 40472067 and 40572072)the Foundation of CAS Key Laboratory of Marginal Sea Geology, South China Sea Institute of Oceanology (Grant No. MSGL0601)
文摘Two research methods, geomicrobiology and carbonate sedimentology, were adopted to study the microbial carbonates in the beachrocks, Shuiweiling, Luhuitou, Sanya City, Hainan Island. The results indicate that microbial carbonates occur in Shuiweiling beachrocks and cements related to microbial activitives are common. Microbial carbonates were mainly developed on the surfaces of coral skeletons and within the coral (fragments and shivers) skeletal cavities,and rarely grew in interspaces formed by coral and other biological detritus. The growth morphologies of microbial carbonates are various, including stromatolitic lamination, thin crusts, dome-like, and microbialites. Microbial carbonates commonly trap fine-sized bioclasts, contain tubular filaments, and show laminated growth striation. Microbial carbonates within the coral skeletal cavities are generally stromatolitic cone-shaped, with a random growth direction along the bearing of trend of cavities, showing distinct growth laminae and recognizable growth phases. It is a special growth pattern of crypt microbial carbonates. Microbial cements occur mainly in shape of needle cement, calcified filaments, microborings, and calcified framboidal spheres. The needle cement is the most common type. These microbial cements indicate that microbial activities and microbial carbonates played an important role in beachrock formation in which carbonates were dominant components and the climate of tropical ocean monsoon was influential. Such microbial carbonates and microbial cementation have not been reported here from beachrocks along the northern shorelines of the South China Sea. The results support a clear microbial origin for certain carbonate cements in beachrocks, confirm that microbial carbonates are a significant contributor to carbonate sedimentation, and widen the knowledge of beachrocks from a new field.
基金Project sponsored by the Joint Fund of S.S. Sciences, Approval No. 90020.
文摘Six species, belonging to five genera, of large animal remains are firstly described andreported in this paper. They were found in the late Holocene high beachrock of 25--m ele-vation on Longhu Hill of Houshijing, Pinghai Village, Putian County, Fujian Province. Theseanimal remains are found mostly between intertidal and subtidal zones in the tropical areafrom the Miocene to the recent. The research results have confirmed that the coastal sedi-ments belong to the beachrock, which is formed in the tropical coastal areas. This paperproposes that the study of large animal remains in the beachrock can provide a scientificbase for the understanding of the sedimentographic environment of the beachrock, andvaluable information for the study on paleoclimate and paleo-shoreline evolution.
文摘热带—亚热带潮间带沉积物中丰富的菌—藻类微生物及其复杂的生命活动对颗粒的早期胶结过程起重要作用。本文通过16S r RNA高通量基因测序方法分析西沙群岛石屿、全富岛及海南龙湾珊瑚礁滨岸带海滩岩表生微生物群落结构,确定主导海滩岩快速胶结的共性菌株/微生物功能群。表层生长草皮海藻的全富岛海滩岩原核生物多样性最高。龙湾潮间带上部暴露时间较长的海滩岩比潮间带下部海滩岩原核生物多样性高。相对固结的石屿海滩岩原核生物多样性最低。4个取样点具有较为相似的细菌门类组成,物种丰度由大到小依次为变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteriota)、蓝细菌门(Cyanobacteria)、绿弯菌门(Chloroflexi)、芽单胞菌门(Gemmatimonadota)和脱硫杆菌门(Desulfobacterota)。不同点位的海滩岩形成环境中蓝细菌主要种类大体相同,其中眉藻(Calothrixsp.)是主导海滩岩早期胶结的共性钙化菌株,通过分泌胞外聚合物成为碳酸盐矿物沉淀的“热点”。群落中检出的反硝化细菌和硫酸盐还原菌表明海滩岩内部氧化还原梯度较大,表面下极浅处即存在缺氧微环境。微生物群落内强烈的光合作用、硫酸盐还原作用和反硝化作用不断提高微环境pH值,有利碳酸盐矿物在粒间孔内的成核和生长并加速颗粒胶结。
文摘浙江沿海全新世海滩岩是正处于中亚热带的海滩岩,迄今已发现有13处,主要出露于两侧为基岩岬角的小海湾潮间带中部的沙滩上,^(14)C年龄主要为2705 a±160 a BP～6485 a±210 a BP。通过多学科手段的综合研究,初步探讨了其基本特征及古地理意义。研究结果表明,受海水作用影响产生的颗粒(如生活于潮间带-潮下带的贝类壳体及其碎片、近岸底栖的有孔虫和介形虫等生物碎屑、花岗岩岩屑等)、颗粒支撑结构及文石针胶结物是其最重要特征。在其形成过程中,适宜的地貌如处于有砂砾滩的小海湾中,充足的经海蚀搬运来的陆源岩屑、石英、长石,大量的海洋生物碎屑作为物源,合适的颗粒粒径,适中的水动力,基本稳定或缓慢下降的海面及较高的气温等,都是有利的条件。在海滩岩形成时期,浙江中、北部地区沿岸线基本稳定,或略微缓慢向海推进。东海沿岸流不是如今这种低温水团,其水温应比现今高5～6℃,最少应高2℃,而其低盐度性质则古今基本一致。同时,热带扩展到浙江中、北部地区,或者当时的气候分带性不如现今这么明显。
文摘浙江全新世海滩岩是目前公认的中国最北的海滩岩,对它的研究在古气候、古环境、古海面变化等方面都具有重要意义。笔者对浙江海滩岩进行了综合研究,揭示其古动物学、岩石学、矿物学、元素地球化学、氧碳稳定同位素和^(14)C测年等特征,从中提取了古气候、古环境信息。研究表明,浙江海滩岩由8个岩石类型组成,其沉积可分两阶段8期:6.5—2.4 ka BP阶段(细分为6.5 ka BP,6.1—5.8 ka BP,5.5 ka BP,5.2—5.1 ka BP,4.8—4.1 ka BP,3.8 ka BP,3.5—2.4 ka BP 7期)和1.1 ka BP阶段(共8期),其所含动物遗骸具有较强烈的热带色彩,由δ^(18)O计算,中全新世海水温度高于现今3.25—4.25℃。
