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1.
Amjad Ali Pirzada Jamal A. Siddiqui Kate Bromfield Athar Ali Khan Pervaiz Iqbal 《Arabian Journal of Geosciences》2017,10(23):520
Uplifted reefs due to being important palaeoclimate archives and a rich source of information on past physical and geochemical changes globally have become the centre of marine research. The uplifted fossil Quaternary coral communities of Jiwani and Gwadar are perfect places to study the palaeoclimatic and geological changes that have shaped the Balochistan coast. Studies on the palaeodiversity of corals along the Makran coast of Pakistan are lacking. In the present study, the samples collected using line intercept method from four uplifted sites (Balochistan coast: one at Gwadar and three at Jiwani) were analysed. The relative distribution and diversity of scleractinian fossil corals was determined, and the factors responsible for coral decline along Pakistan coast were compared with modern coral distribution and diversity. A total of 48 fossil coral species were recorded in nine families and 22 genera. High coral diversity was recorded in the uplifted landward sites of Jiwani and Gwadar headland. Terraces close to the shore at Jiwani had lower diversity. The corals seem to be Quaternary: most likely Pleistocene to Holocene. The modern fauna lacks many species recorded in the fossil community, thus suggesting a faunal turnover in diversity and redistribution of coral fauna which may be linked with past geological events and increasing anthropogenic pressure. 相似文献
2.
本文描述了贵州边阳地区中三叠统拉丁尼克期的六射珊瑚4属6种，其中1个已知种，1个亲近种，2个新种和2个未定种：Pinacophyllum spizzensis(Tornquist)，P．aff．yunnanense Wu，P．bianyangense sp．nov，Retiophyllia bianyangensis sp．nov．，Procydolites sp．，Margarosmilia sp．，丰富了世界中三叠世六射珊瑚研究的资料。迄今全世界缺乏早三叠世珊瑚，研究中三叠世珊瑚，对探讨中生代开始出现的六射珊瑚的发生和系统演化，古生代四射珊瑚与中生代珊瑚之间存在的关系，都有很重要的意义。 相似文献
3.
辽宁地质历史时期的植物界 总被引：3，自引：0，他引：3
辽宁地区晚古生代以来的陆相地层发育,丰富的植物化石产于自晚古生代至新生代各地质时期的沉积物中.本文概要地整理了辽宁自晚古生代早石炭世晚期以来,已报道的化石属种名单,共200余属,480余种.包括古生代、中生代及新生代3个组成部分.每个部分的名单均按自然分类系统排列.每个种后面附有拉丁学名、产地、层位及时代.对每个断代的某些重要类群或辽宁独具特色的化石并作简要说明. 相似文献
4.
石珊瑚目是中新生代的重要造礁生物。直到中三叠世才大量出现多种石珊瑚化石，距二叠纪末生物大灭绝、古生代皱壁珊瑚和床板珊瑚灭亡14 Ma之久。石珊瑚的起源和早期系统发育，成为生物大灭绝及复苏的一个难题。文章目的是综述多学科研究石珊瑚早期系统发育的进展，以及多家系统分类，展望前景。研究方法有骨骼构造与微细构造及软体的对比，时空分布分析，寻找早期珊瑚化石及分子生物学等。研究结果主要有石珊瑚可能起源于只有软体的海葵类，发现早期石珊瑚化石，以及石珊瑚在300 Ma之前已演化为两支，但还有不少空白和争议。结论是为了查明石珊瑚的早期系统演化和分类，需要加强古生物与今生物学者多学科交叉的综合研究，努力寻找中间环节，填补研究空白。 相似文献
5.
6.
Jon N Weber 《Geochimica et cosmochimica acta》1973,37(9):2173-2190
Two thousand and twenty well-characterized coral specimens from 17 localities have been analyzed for Sr. Seventy-three genera and subgenera, mostly hermatypic scleractinians, are represented. For some genera, specimens living in surface reef environments are compared with those from 18.3 m depths on the same reefs. Growth rates for some species have also been measured at these depths at one of the sampling sites. Skeletal strontium for a given genus decreases with increasing water temperature, a relationship which previously eluded detection. Aragonite deposited by corals living on the reef at a depth of 18.3 m contains more strontium than the skeletal aragonite of the same coral genera from shallow-water, surface environments. Quantitative treatment of the data for Acropora, one of the most abundant and widely distributed of the reef-building corals, suggests that the observed strontium variations may reflect variations in the rate of skeletal calcification, rather than direct dependence upon temperature or water depth. There is evidence for ‘species effects’, apparently unrelated to growth rate differences, in that certain coral genera are consistently enriched or depleted in skeletal strontium content relative to other genera living in the same reef environments under identical ambient conditions. Temperature, salinity, water depth, seawater composition, and/or other such parameters may in part determine the levels of trace element concentration in carbonates deposited by corals and other marine invertebrates, but it would appear that these variables more directly affect physiological processes which in turn control skeletal chemistry. 相似文献
7.
Wang Zhiping 《《地质学报》英文版》1989,63(2):103-114
China is rich in Middle and Carboniferous fossil corals. The coral faunas in different regions have varying characteristics and can be divided into distinct assemblages. The coral fauna in South China is dominated by the order Caninida and contains numerous endemic elements; that in North China has a lot of Middle Carboniferous corals which are monotonous in species, with Late Carboniferous solitary corals being predominant. The coral fauna in Junggar mainly contains large bi-zoned solitary caninids, while that in southern Khingan is similar to that in South China due to the presence of abundant tri-zoned compound corals. In northern Tibet the coral fauna is also similar to that in South China, but in southern Tibet it is of a cold-water type. Therefore, the Middle and Late Carboniferous coral geography of China can be divided into the Tethys, Boreal and Gondwana Realms. 相似文献
8.
青海省同仁县古浪堤中上三叠统古浪堤组孢粉组合及其地层意义 总被引：3，自引：0，他引：3
经过对青海同仁县古浪堤组实测剖面的17块样品做孢粉分析, 在6个层位样品中见有孢粉化石30属41种, 据此在该剖面自下而上划分2个孢粉组合:Dictyophyllidites-Di-saccus组合和Verrucosisporites-Di-saccus组合.上述孢粉组合中的孢粉的优势属为Dictyophyllidites, Cyathidites, Verrucosisporites和Chasmatosporites, Protopicea, Pinuspollenites.其中, Dictyophyllidites频繁出现于欧亚、北美、大洋州的晚三叠世和早侏罗世组合, Aratrisporites在南半球大量发育于中三叠世, Asseretospora在澳大利亚的分布时期是中三叠世-早侏罗世.前人于黄南的阿龙江上游及柴陇沟北, 古浪堤组产卡尼期的菊石Protrachycerassp.及双壳类Eumorphotis (Asoella) cf.illyrica.综合而言, 该地区古浪堤组时代厘定为中-晚三叠世, 古植物群生长于暖温带-亚热带河控三角洲环境. 相似文献
9.
在西藏班戈县保吉乡嘎热扎地发现了一套碎屑岩和灰岩互层的地层,产珊瑚和苔藓虫化石。珊瑚化石共计7属3种及4未定种,分别为Procyclolites zizaensis Deng&Zhang,Chondrocoenia?sp.,Parastraeomorpha?sp.,Pamiroseris?sp.,Astraeomorpha multisepta Melnikova,Volzeia sublaevis(Laube&Volz),Radiophyllia?sp.,时代为中-晚三叠世。该套地层的发现表明,措勤盆地存在中-晚三叠世地层,为该地区的古地理研究提供了地层古生物学证据。 相似文献
10.
Pinxian Wang 《地球科学进展》2019,34(12):1222-1233
The discovery of deep sea coral forests in the spring of 2018 filled a significant gap in the benthos research and even in carbon cycling in the South China Sea. Previously, the researches of deep-sea benthos were restricted to the sediment-covered soft bottom due to the technical limitations, and the rocky hard bottom was believed to be barren of life. Using submersible technique in the mid-1990s, deep-water coral reefs were first discovered in the Atlantic Ocean, which opened a new research direction in marine sciences. Two groups of deep sea corals have been recognized: scleractinian hexacorals and gorgonian octocorals. The aragonite skeleton of the former group build up deep sea coral reefs, while the latter make up deep sea coral forests with high-Mg calcite skeleton in many gorgonian corals. All kinds of carbonate coral skeletons can record environment changes of the deep sea and provide excellent material for high-resolution paleoceanography. Although the development of deep sea coral reefs in the Pacific Ocean is hampered by its extremely shallow aragonite compensation depth, deep sea coral forests are ubiquitous in the ocean. Up to now, most parts of the Pacific have not yet explored in this respect, and deep sea corals remain outside the research scope. The present paper is a literature review and calls for attention to the deep sea forests. It starts with the composition and distribution of deep sea coral reefs and forests, followed by discussions on the significance of deep sea coral forests in marine ecology and in paleoceanographic reconstructions. 相似文献
11.
Saber Al-Rousan Rasheed Al-Shloul Fuad Al-Horani Ahmad Abu-Hilal 《Environmental Earth Sciences》2012,67(7):2003-2013
The concentrations of six heavy metals were studied in five living coral species and their fossil counterparts collected along the Jordanian Coast of the Gulf of Aqaba. The study aimed at investigating the validity of using coral skeletons as bioindicators for environmental pollution by heavy metals in the Gulf of Aqaba, Red Sea. The skeletal samples of the collected corals were acid digested and analyzed for Cd, Cu, Fe, Mn, Pb, and Zn content using flame atomic absorption spectrophotometer. The results obtained have shown that higher concentrations of heavy metals were found in coral skeletons from areas hosting intense developments and human activities. The massive Porites sp. coral tended to accumulate the highest metal concentrations among the other species (except for Mn). This was due to interspecific differences or selectivity of heavy metals between different coral species. It was noteworthy that fossil coral species recorded higher average metal concentrations than their living counterparts; this was attributed to surface contamination due to prolonged burial of the fossil corals in sediment over the years. The study concluded that corals (specially the massive Porites species) are vulnerable to the accumulation of high concentrations of heavy metals in their skeletons and therefore can serve as proxies to monitor environmental pollution. 相似文献
12.
The collection of fossil plants sampled by geologists from VNIGRI at the end of the 20th century from Triassic continental sections drilled by many wells and cropping out in several natural localities and stored at the Museum of Petroleum Geology and Paleontology of the same institute was critically revised. The use of the epidermal method for the study of plant remains with consideration of recent publications dedicated to continental sections of Central Europe made it possible to substantially broaden the taxonomic composition of the Triassic flora and first specify the composition of its pteridosperm representatives. Unlike the Triassic floras of Western Europe, the pteridosperms the Pechora region appeared to be relatively diverse. They number 37 species of 11 genera, which are confined to the upper part of the Triassic sequence: Anguran and Naryan-Mar formations and their analogs. The Middle Triassic, mainly, Ladinian, age of these formations is reliably substantiated both by paleontological (vertebrate and palynological) data and by results of the comparative analysis of the Anguran–Naryan-Mar taphofloras and coeval European type floras dated back to the Anisian–Ladinian by marine faunal remains. The stratigraphic significance of pteridospermous plant remains becomes undoubted for continental sections of the Timan–Pechora basin, while the genera Scytophyllum, Kalantarium, and Kirjamkenia may be considered with respect to their diversity and abundance as representing orthostratigraphic taxa. 相似文献
13.
Morten B. Andersen Claudine H. Stirling Emma-Kate Potter Steve G. Blake Bridget F. Ayling 《Geochimica et cosmochimica acta》2010,74(12):3598-7020
Direct dating of fossil coral reefs using the U-series chronometer provides an important independent test of the Milankovitch orbital forcing theory of climate change. However, well-dated fossil corals pre-dating the last interglacial period (>130 thousand years ago; ka) are scarce due to, (1) a lack of sampling localities, (2) insufficient analytical precision in U-series dating methods, and (3) diagenesis which acts to violate the assumption of closed-system U-series isotopic decay in fossil corals. Here we present 50 new high-precision U-series age determinations for fossil corals from Henderson Island, an emergent coral atoll in the central South Pacific. U-series age determinations associated with the Marine Isotope Stage (MIS) 9 interglacial and MIS 7.5 interstadial periods are reported. The fossil corals show relatively little open-system U-series behaviour in comparison to other localities with fossil coral reefs formed prior to the last glacial cycle, however, open-system U-series behaviour is still evident in most of the dated corals. In particular, percent-level shifts in the [230Th/238U]act composition are observed, leading to conventional U-series ages that are significantly younger or older than the true sample age. This open-system U-series behaviour is not accounted for by any of the open-system U-series models, indicating that new models should be derived. The new U-series ages reported here support and extend earlier findings reported in Stirling et al. (2001), providing evidence of prolific coral reef development on Henderson Island at ∼320 ka, most likely correlated with MIS 9.3, and subsequent reef development at ∼307 ka during MIS 9.1, while relative sea-level was potentially ∼20 m lower than during MIS 9.3. The U-series ages for additional well-preserved fossil corals are suggestive of minor reef development on Henderson Island during MIS 7.5 (245-230 ka) at 240.3 ± 0.8 and 234.7 ± 1.3 ka. All U-series observations are consistent with the Milankovitch theory of climate change, in terms of the timing of onset and termination of the dated interglacial and interstadial periods. The best preserved samples also suggest that the oceanic 234U/238U during MIS 9 and MIS 7.5 was within five permil of the modern open ocean composition. 相似文献
14.
记述了原长翅亚目化石（Protomecoptera Tillyard,1917）在中国陕西铜川中三叠统中的首次发现,填补这个亚目化石在中国的空白.根据脉序特征,确定是2个新属、种：Glytochorista martynovae gen.et sp.,Phyllochorista orientis gen.et sp.nov.,属这个亚目的汤姆蝎蛉科Tomichoristidae O.Martynova,1958,从而将这个科的化石推向最高层位,即从早二叠世推向中三叠世,跨时5000多万年.从这个意义来讲,对研究该科从古生代晚期向中生代早期的演化有一定的重要参考价值.化石采自铜川中三叠世铜川组下段上部灰绿色泥页岩.新属、新种属于陕西昆虫群（系中三叠世陕西动物群或陕西生物群的一个化石门类）铜川昆虫组合的新成员,时代相当于欧洲拉丁尼期（Ladinian stage）. 相似文献
15.
为进一步精确限定黔西南中三叠统坡段组的地质时代,论文选择贵州册亨中三叠统坡段组典型剖面开展了石珊瑚及牙形石生物地层研究,在中三叠统坡段组(中上部)识别出石珊瑚3属3种,它们包括Pentasmilia zaitingnaensis,Pinacophyllum spizzensis,Gillastraea delicate;识别出牙形石Neogondolella constricta带。该带除含有带分子外,还含有Neogondolella bulgarica,Neogondoela navicula,Neogondolella acuta,Neogondolella alpina alpina,Cratognathodus kochi,Ozarkodina tortilis,Prioniodinasp.,Lonchodinasp.等重要牙形石。通过对牙形石特征的分析和国内外同名带的对比,认为坡段组Neogondolella constricta带大体可与贵州省盘县地区羊圈-楚皮凹剖面中三叠统关岭组上段、贵州罗甸关刀(2)剖面关刀岩楔、和云南开远马者哨法郎组的同名化石带对比,进而确定贵州册亨地区坡段组含牙形石Neogondolella constricta带的地层时代为安尼期的Illyrian亚期。 相似文献
16.
The evolution of modern corals and their early history 总被引：2，自引：0，他引：2
Scleractinians are a group of calcified anthozoan corals, many of which populate shallow-water tropical to subtropical reefs. Most of these corals calcify rapidly and their success on reefs is related to a symbiotic association with zooxanthellae. These one-celled algal symbionts live in the endodermal tissues of their coral host and are thought responsible for promoting rapid calcification. The evolutionary significance of this symbiosis and the implications it holds for explaining the success of corals is of paramount importance. Scleractinia stands out as one of the few orders of calcified metazoans that arose in Triassic time, long after a greater proliferation of calcified metazoan orders in the Paleozoic. The origin of this coral group, so important in reefs of today, has remained an unsolved problem in paleontology. The idea that Scleractinia evolved from older Paleozoic rugose corals that somehow survived the Permian mass extinction persists among some schools of thought. Paleozoic scleractiniamorphs also have been presented as possible ancestors. The paleontological record shows the first appearance of fossils currently classified within the order Scleractinia to be in the Middle Triassic. These earliest Scleractinia provide a picture of unexpectedly robust taxonomic diversity and high colony integration. Results from molecular biology support a polyphyletic evolution for living Scleractinia and the molecular clock, calibrated against the fossil record, suggests that two major groups of ancestors could extend back to late Paleozoic time. The idea that Scleractinia were derived from soft-bodied, “anemone-like” ancestors that survived the Permian mass extinction, has become a widely considered hypothesis. The 14-million year Mesozoic coral gap stands as a fundamental obstacle to verification of many of these ideas. However, this obstacle is not a barrier for derivation of scleractinians from anemone-like, soft-bodied ancestors. The hypothesis of the ephemeral, “naked coral”, presents the greatest potential for solution of the enigma of the origin of scleractinians. It states that different groups of soft-bodied, unrelated “anemone-like” anthozoans gave rise to various calcified scleractinian-like corals through aragonitic biomineralization. Although there is evidence for this phenomenon being more universal in the mid-Triassic interval, following a lengthy Early Triassic post-extinction perturbation, it appears to have occurred at least three other times prior to this interval. This idea suggests that, because of ephemeral characteristics, the skeleton does not represent a clade of zoantharian evolution but instead represents a grade of organization. In the fossil record, skeletons may have appeared and disappeared at different times as some clades reverted to soft-bodied existence and these phenomena could account for notable gaps in the taxonomic and fossil record. A fuller understanding and possible solution to the problem of the origin of modern corals may be forthcoming. However, it will require synthesis of diverse kinds of data and an integration of findings from paleobiology, stratigraphy, molecular biology, carbonate geochemistry, biochemistry and invertebrate physiology. 相似文献
17.
Deep-sea corals have been shown to be useful archives of rapid changes in ocean chemistry during the last glacial cycle. Their aragonitic skeleton can be absolutely dated by U-Th data, freeing radiocarbon to be used as a water-mass proxy. For certain species of deep-sea corals, the growth rate allows time resolution that is comparable to ice cores. An additional proxy is needed to exploit this opportunity and turn radiocarbon data into rates of ocean overturning in the past.Neodymium isotopes in seawater can serve as a quasi-conservative water-mass tracer and initial results indicate that deep-sea corals may be reliable archives of seawater Nd isotopes. Here we present a systematic study exploring Nd isotopes as a water-mass proxy in deep-sea coral aragonite. We investigated five different genera of modern deep-sea corals (Caryophyllia, Desmophyllum, Enallopsamia, Flabellum, Lophelia), from global locations covering a large potential range of Nd isotopic compositions. Comparison with ambient seawater measurements yields excellent agreement and suggests that deep-sea corals are reliable archives for seawater Nd isotopes.A parallel study of Nd concentrations in these corals yields distribution coefficients for Nd between seawater and coral aragonite of 1-10, omitting one particular genus (Enallopsamia). The corals and seawater did however not come from exactly the same location, and further investigations are needed to reach robust conclusions on the incorporation of Nd into deep-sea coral aragonite.Lastly, we studied the viability of extracting the Nd isotope signal from fossil deep-sea corals by carrying out stepwise cleaning experiments. Our results show that physical removal of the ferromanganese coating and chemical pre-cleaning have the highest impact on Nd concentrations, but that oxidative/reductive cleaning is also needed to acquire a seawater Nd isotope signal. 相似文献
18.
Generic distinguishing characteristics and stratigraphic ranges of fossil corallines: An update 总被引：1，自引：0，他引：1
P. Kundal 《Journal of the Geological Society of India》2011,78(6):571-586
Corallines or coralline algae are carbonate secreting and strongly calcified red algae of the order Corallinales of division
Rhodophyta. Architecturally, the corallines have two groups, the nongeniculate and geniculate coralline forms. Corallines
are used as a potential tool for paleoecology, paleoenvironments and paleobathymetry. Coralline algae are builder of porous
and permeable carbonate reservoir rocks for hydrocarbon and reefs rich in hydrocarbon. The old approach, ca. prior to 1977,
of taxonomy of fossil coralline genera has been replaced by the modern approach that established during the last decade using
certain distinguishing features such as arrangement of basal filaments, cell fusions, conceptacle perforations and orientation
of filaments around conceptacles of living corallines. The earliest confirmed fossil record of coralline algae is from the
Hauterivian (Early Cretaceous) and from the Hauterivian to the Pleistocene 9 nongeniculate coralline genera, namely Distichoplax, Lithophyllum, Lithoporella, Lithothamnion, Mesophyllum, Neogoniolithon, Phymatolithon, Spongites and Sporolithon and 7 geniculate genera, viz. Amphiroa, Arthrocardia, Calliarthron, Corallina, Jania, Metagoniolithon and Subterraniphyllum having different stratigraphic ranges are unequivocally known as fossils. After 1977, we do not have a comprehensive publication
giving the generic distinguishing characteristics and stratigraphic ranges of both nongeniculate and geniculate corallines.
The present paper gives an update of distinguishing characteristics of fossil coralline algal genera and their stratigraphic
ranges. 相似文献
19.
在西藏措勤断块新建了中三叠统—上三叠统卡尼阶岩石地层单位——嘎热扎地组。在建组剖面上,嘎热扎地组厚约485 m,下部岩性以碎屑岩为主上部岩性为碎屑岩夹灰岩。嘎热扎地组与下伏上二叠统—下三叠统木纠错组、上覆上三叠统诺利阶麦龙岗组均为整合接触关系。该组尚未发现指示地层时代的化石,但前人在其下伏的木纠错组中发现了早三叠世牙形石本次在其上覆的麦龙岗组发现7属8种珊瑚化石:Distichophyllia norica(Frech),Retiophyllia?sp.,Cablonzeria?sp.Elysastraea juliana Turnsek,Volzeiasublaevis (Munster),Distuhophyllia sp.,Guembelastraea?sp.和Benedcastraea baiyuensis Deng&Zhang。根据该组地层整合于两者之间,将其时代暂时限定为中—晚三叠世卡尼期。根据珊瑚化石、地层岩性特征及上下地层关系将研究剖面的地层进行了重新划分。嘎热扎地组的建立填补了措勤断块局限台地相三叠系序列中三叠统—上三叠统卡尼阶岩石地层单位名称的空白。嘎热扎地组建立以后,措勤断块局限台地相三叠系的岩石地层单位序列可以划分为上二叠统—下三叠统木纠错组,中三叠统—上三叠统卡尼阶嘎热扎地组,上三叠统诺利阶麦龙岗组,上三叠统瑞替阶—下侏罗统确哈拉组。这一序列的建立对于在措勤断块进一步识别出碳酸盐岩局限台地相三叠系,修订相关地区的地层认识具有指导作用。 相似文献
20.
贵州关岭地区中——上三叠统海参骨片化石的首次发现 总被引：5，自引：1，他引：5
报道了贵州关岭地区中——上三叠统竹杆坡组发现的海参骨片化石5属6种及2个属种未定的形态类型。分析了海参化石属种的历史分布特征，上述化石指示竹杆坡组为晚三叠世沉积产物。这一发现进一步丰富了关岭生物群的内容，为探讨中国三叠纪海参骨片化石的分类及演化增加了新的资料。 相似文献