鄂尔多斯盆地西南缘陕西陇县晚奥陶世背锅山组生物礁

鄂尔多斯盆地西南缘的陕西陇县李家坡晚奥陶世背锅山组生物礁为典型的台地边缘礁,包括层孔虫礁、珊瑚礁、钙藻礁等几种类型,主要为层孔虫礁。经过系统古生物学研究,鉴定出层孔虫有5个属,分别为Ecclimadictyon(蜂巢层孔虫)、Clathrodictyon(网格层孔虫)、Tuvaechis(图瓦层孔虫)、Rosenella(罗森层孔虫)、Labechiella(小拉贝希层孔虫)等;珊瑚有6个属,分别为Tetradium(四分珊瑚),Hemiagetolitella(拟半阿盖特珊瑚),Plasmoporella(似网膜珊瑚),Eofletcheria(始弗莱契珊瑚),Catenipora(镣珊瑚),Reuschia(劳氏珊瑚);钙藻以Vermiporella(蠕孔藻)和Solenopora(管孔藻)为主。礁发育早期以层状层孔虫包卷砂屑、单体珊瑚、管状海绵、块状钙藻等形态为主要特征,礁发育中后期以块状和球状的层孔虫以及大型的床板珊瑚形成格架为主要特征。礁体发育过程中居礁生物都很丰富,有三叶虫、腕足类、介形类、大棘皮类和丛状的蓝细菌等。通过与塔中台地以及扬子台地的晚奥陶世台缘礁对比,发现造礁生物的属种和礁岩类型均有相似之处,说明中国晚奥陶世生物礁的分布具有等时性。     

桂林北郊岩山中泥盆世吉维期珊瑚-层孔虫礁

桂林北郊灵川县岩山大村剖面和乌龟山剖面为中泥盆世吉维期沉积,其沉积构造、生物组成、微相序列反映出生物礁的特点,大量层孔虫为造礁的主要生物,其生长形式为：（１）厚板状;（２）半球状和穹窿状;（３）大型柱状和不规则状;（４）披覆状或薄板状。珊瑚有３层,或作为礁基,或参加造礁,前者为单体珊瑚,后者为复体珊瑚。刺毛虫主要为根茎状,常被层孔虫包统,也是造礁的主要生物。藻类生物很少。横向上可以分出礁核相,礁后相和礁前斜坡相。主要的微相类型有１３种,纵向上可以识别出两个造礁旋回,从礁基－珊瑚、层孔虫礁－礁后外带－礁后内带,两个造礁旋回之上为礁坪所覆。根据礁的规模、礁体与上下沉积物的关系、礁生物组成的变化和古地理位置的讨论推测为一岸礁体系。     

桂林北郊岩山中泥盆世吉维期珊瑚-层孔虫礁

桂林北郊灵川县岩山大村剖面和乌龟山剖面为中泥盆世吉维期沉积，其沉积构造、生物组成、微相序列反映出生物礁的特点，大量层孔虫为造礁的主要生物，其生长形式为：（１）厚板状；（２）半球状和穹窿状；（３）大型柱状和不规则状；（４）披覆状或薄板状。珊瑚有３层，或作为礁基，或参加造礁，前者为单体珊瑚，后者为复体珊瑚。刺毛虫主要为根茎状，常被层孔虫包统，也是造礁的主要生物。藻类生物很少。横向上可以分出礁核相，礁后相和礁前斜坡相。主要的微相类型有１３种，纵向上可以识别出两个造礁旋回，从礁基－珊瑚、层孔虫礁－礁后外带－礁后内带，两个造礁旋回之上为礁坪所覆。根据礁的规模、礁体与上下沉积物的关系、礁生物组成的变化和古地理位置的讨论推测为一岸礁体系。     

云南宁蒗泥盆纪层孔虫的记述

本文首次描述了云南西部泥盆纪层孔虫7属13种。分布于宁蒗泸沽湖的早泥盆世晚期至中泥盆世早期的大槽子组,含层孔虫2属5种,包括1新种Amphipora ninglangensis sp.nov.和1新亚种Paramphipora raritatis variabilis subsp.nov.,其共骨多为枝状类型,反映了比较闭塞的潟湖或半潟湖相的沉积环境。分布于昔腊坪中泥盆世晚期至晚泥盆世早期的层孔虫出现在拉古德组的中上部,多为块状类型的共骨,有的大量聚集可形成生物层或生物礁。该动物群的面貌除接近于苏联萨拉伊尔外,还含有西藏日土、芒康,滇东、黔南及广西中东部的分子。说明上述海域在中、晚泥盆世时期是连通的。     

湖南新邵巨口铺泥盆纪棋梓桥组的层孔虫及其造礁特征

湖南新邵巨口铺泥盆纪生物礁出现在中泥盆统棋梓桥组中上部,根据沉积特征的差异,礁体分上下两部分;下部成层性明显,以厚层生物格架灰岩为主;上部以灰白色块状徽晶一亮晶灰岩为主,灰岩成层性很差,生物也较单调。礁体可划分8种沉积微相,其发展过程有明显阶段性。这些阶段性与礁体群落的发展和演替相联系。它是开阔浅海与台地浅海相变过渡带上的一种层状礁。礁体内有丰富的层孔虫,计16属近40种。该文选择了较为常见、保存较好的10属18种进行了描述和研究。     

塔里木板块塔中区上奥陶统良里塔格组的生物礁类型

塔里木板块塔中Ⅰ号坡折带附近上奥陶统良里塔格组取芯井段中可识别多种生物礁灰岩类型,包括珊瑚骨架/障积岩、海绵骨架/绑结岩、苔藓虫绑结岩、钙藻障积岩、钙质菌藻障积/绑结岩等礁灰岩类,藉此可归纳出珊瑚礁、珊瑚-钙藻礁、层孔虫礁、层孔虫-钙藻礁、珊瑚-层孔虫-钙藻礁、苔藓虫礁丘、钙藻礁丘、灰泥丘和微生物礁等生物建造单元。这些礁体的时空分布模式与古环境分异相关联,纵向上具有灰泥丘向珊瑚-层孔虫-钙藻礁至苔藓虫礁丘和钙藻礁的群落结构更替趋势;空间分布则向台地北缘,即I号坡折带延伸显示由低能带灰泥丘向高能带珊瑚-层孔虫-钙藻礁的相变,而且高能带珊瑚-层孔虫-钙藻主体礁和环其周缘相对低能带的钙藻礁丘、灰泥丘等在一定范围内构成造礁群落结构分异。     

广西隆林德峨泥盆纪层孔虫及其在沉积相划分中的作用

本文描述了广西隆林德峨泥盆纪层孔虫7属lO种。东岗岭组的层孔虫虽以块状,球状为主,但也有一些枝状类型的,而且局部较富集。曾有人认为它们是生物礁,但是通过对层孔虫并结合其它生物组合、沉积特征、海水能量及化学成分等因素的研究,表明它们是水下局部隆起的岩滩,属于盆地相的大滨外滩即浅海带的较深部分局部隆起的孤立的碳酸盐岩滩。而层孔虫则是组成碳酸盐岩滩的主体。     

广西南丹拉要泥盆纪礁组合剖面的古生态特征

广西南丹拉要泥盆纪生物礁发育在台地的边缘,是一个礁、滩、开阔台地沉积互相交替的叠置礁。礁组合中出现5个主要的生物群落。其中以层孔虫、床板珊瑚为主的 Stromatopora-Alveolites群落是最重要的造礁群落。这些群落有规律地分布在礁组合的不同部位。它们在剖面上的垂直分布显示礁组合的发育过程分成3个大的旋回,其中包括9个次一级的成礁旋回。旋回反映了海水深浅的变化。     

湖南涟源雷鸣洞中泥盆世礁组合剖面的生态特征

雷鸣洞礁组合发育在湘中桥头河向斜北翼的中泥盆统棋子桥组中。剖面位于雷鸣洞以北,涟源和宁乡两县交界处的一个采石场内。属于礁核亚相的地层厚81m,地貌上形成约30m高的陡崖。礁组合剖面在古地理位置上处于浅海碳酸盐台地的边缘。主要造礁生物是层孔虫和珊瑚。     

浙赣交界地区上奥陶统三衢山组礁灰岩的分类

本文讨论了礁灰岩的分类历史,特别对Ｔｓｉｅｎ,Ｈ．Ｈ．的礁灰岩分类系统进行了介绍．浙赣交界地区上奥陶统三衢山组生物礁发育良好,通过对其所含造礁生物的形态及功能分析,区分出五大类礁灰岩,即格架岩、障积岩、盖复岩、绑结岩和生物粘结岩,并指出生物礁礁核相主要由以上各种礁灰岩的复合类型所组成．     

Growth forms and palaeoenvironmental interpretation of stromatoporoids in a Middle Devonian reef, southern Morocco (west Sahara)

Growth forms of well-preserved stromatoporoids, including genera Actinostroma, Stachyodes, and Stromatopora, are described for the first time from the Devonian Sabkhat Lafayrina reef complex of southern Morocco (west Sahara), one of the best exposed Middle-Devonian stromatoporoid-dominated fossil reefs. Three facies types representing the well illuminated fore-reef, reef-core and transition to back-reef facies display the distribution and growth of stromatoporoids in a high latitude setting at 40–50° south of the palaeoequator. Stromatoporoids are largely in growth position and reflect the well-preserved reef architecture. Although outcrops are low topography, the reef's prominent profile is indicated by presence of spur and groove form and a clearly defined reef margin. Stromatoporoids are mostly laminar and domical forms, with little evidence of ragged margins, and indicate normal turbulence shallow waters, with low sediment deposition.     

A late Devonian (Frasnian) coral-bafflestone reef at Houshan in Guilin, South China

Summary Givetian to early Carboniferous sediments of South China are characterized by carbonates. Middle and Late Devonian strata are best developed in the Guilin area. Reefs and organic shoals are recorded by various lithofacies types indicating the existence of an extended carbonate platform and a change of the composition of reef communities in time. Starting in the late Devonian, stromatoporoids and corals were replaced by algae that subsequently played an important role together with stromatoporoids, receptaculitids and fasciculate rugose corals in reef communities. In Houshan, 5 km west of Guilin, a coral-bafflestone reef occurs in the Frasnian strata, situated near an offshore algal-stromatoporoid reef. The coral reef was formed in a back-reef area adjacent to the inner platform margin. The coral-bafflestone reef is unique among the late Devonian reefs of South China with regard to the biotic composition. The reef is composed of fasciculate colonies ofSmithiphyllum guilinense n. sp. embedded within in packstones and wackestones. The height of colonies reaches 1 m. The community is low-diverse. The species ofSmithiphyllum occurring in the Frasnian reef complexes of Guilin exhibit a distinct facies control:Smithiphyllum guilinense occurs in or near to margin facies and formed bafflestone, constituting a coral reef whereasSmithiphyllum occidentale Sorauf, 1972 andSmithiphyllum sp.—characterized by small colonies with thin corallites—are restricted to the back-reef and marginal slope facies. The bush-like coral colonies baffled sediments. Algae and stromatoporoids (mainlyStachyodes) are other reef biota. Reef-dwelling organisms are dominated by brachiopods. The reefs are composed from base to top of five lithofacies types: 1) cryptalgal micrite, 2) peloidal packstone, 3) stromatactis limestone, 4) coral-bafflestone, and 5) pseudopeloidal packstone. The reef complex can be subdivided into back-reef subfacies, reef flat and marginal subfacies, and marginal fore-slope subfacies. The Houshan coral-bafflestone reef is not a barrier reef but a coral patch reef located near the inner margin of a carbonate platform.     

Facies models for middle to late devonian Shallow-Marine carbonates,with comparisons to modern reefs: a guide for facies analysis

Summary Shallow marine tropical Devonian carbonates commonly were deposited in two major geologic settings, i.e., shallow shelf with shelf margin reef, and gently sloping ramp that grades into peritidal to supratidal, in places evaporitic facies. The facies types within these two settings can be grouped into a few distinct zones on the basis of water, energy, texture, amount of micrite, porosity, fossil assemblages, and indicaton fossils. These zones have been integrated into a composite facies model for shallow marine, tropical Devonian carbonates. The facies zones are easily recognizable in hand specimen and core, and can be used for fast and accurate facies analysis. Some facies recognizable in hand specimen or core do not easily fit into the integrated model and represent facies of short-lived depositional events, such as hurricanes or slump deposits, or spatially restricted areas, such as channel fills. Such facies have to be interpreted on a case-by-case basis by comparison to the surrounding facies and depositional framework through time. Comparisons with Cenozoic reefs reveal a number of similarities. In particular, large metazoans in both Devonian and Cenozoic reefs display a range of growth forms that is not species-specific. Furthermore, several metazoans display comparable growth forms in equivalent facies zones. For example, dendroid stromatoporoids, such asStachyodes, and branching coral, such asPorites porites, occur in equivalent facies zones.     

Devonian carbonate buildup facies in an intra-oceanic island arc (Tamworth Belt, New South-Wales, Australia)

Summary  Biohermal and biostromal buildups were investigated in late Early and Middle Devonian carbonate complexes of the Tamworth Belt. The buildup types and subtypes were studied in three regions (Yarramanbully, Sulcor and, Wyaralong') to clarify their paleo-environmental position. Two stages of development are recognized: Incipient bioherms and bioherms. Incipient bioherms are carbonate buildups with organisms which commonly form true bioherms. They dominate the sediment with small growth forms but are not prolific enough to build large bio-frameworks. Small nodular and globular stromatoporoids characterize the incipient bioherms and are interpreted as stunted growth forms. In one location (‘Wyaralong’) the coarse stromatoporoid calcarenite represents a fore-reef facies, at Sulcor a shallow subtidal setting with moderate water energy can be deduced. The bioherms can be sub-divided into stromatoporoid-, stromatoporoid-Stachyodes-, and stromatoporoid-rugose coral bioherms. Their variable composition probably reflects growth and deposition in different zones of a reef complex and/or different proximity to areas of denundation indicated by high siliciclastic input. In the Tamworth region true bioherms occur only in the Moore Creek Limestone Member (Middle Devonian), and not in older carbonate successions. Biostromes are sub-divided into (1) incipient biostromes with stromatoporoid-heliolitid biostromes and alveolitid biostromes; (2) aggregate biostromes withAmphipora andStachyodes biostromes; (3) stratified biostromes; (4) mixed aggregate/stratified biostromes. The different types of biostromes are not limited to specific time-intervals, but rather to environmental conditions.

Cavities and cryptic faunas beneath non-reef stromatoporoids

Kershaw, Stephen 1980 10 15: Cavities and cryptic faunas beneath non-reef stromatoporoids. Lethaia , Vol. 13 , pp. 327–338. Oslo. ISSN 0024–1161.
Stromatoporoids from level-bottom shales and argillaceous limestones in the Silurian of Gotland, Sweden, form substrates for a variety of encrusting and boring organisms. Overturned stromatoporoids have encrusters and borers on both upper and lower surfaces, while coenostea preserved in situ have encrusters on both surfaces but borings on upper surfaces only. This suggests that cavities, now infilled, existed below coenostea. The stromatoporoids are isolated and not part of a reef framework where growth alone could have created overhangs and cavities. The scouring activity of currents removing sediment from around and beneath the edges of coenostea, and small current-controlled movements leaving stromatoporoids imperfectly settled on the uneven substrate or partly overlying skeletal debris, are invoked to explain the presence of cavities and hence encrusters on stromatoporoid lower surfaces. Both processes probably operated on many specimens. The lower surfaces of these stromatoporoids also show basal concavities which range from shallow to deep and reflect the topography of the substrate and the success of stromatoporoids growing on positive features from which they could shed sediment easily. Overturned stromatoporoids and coenostea with deep, encrusted, basal concavities, point to violent environmental events, such as storms, more powerful than currents producing scour and small movements of coenostea.     

Early ordovician reefs from Argentina: Stromatoporoid vs stromatolite origin

Summary Late Arenigian biohermal reef mounds and biostromes within the shallow-marine platform facies of the upper San Juan Formation of the Precordillera (Western Argentina) represent a new Early Ordovician reef type. The meter-sized reefs are dominated byZondarella communis n.g. n. sp. The new taxon is characterized by domical, bulbous and laminar morphotypes exhibiting growth layers and thin horizontal and vertical as well as intermingled skeletal elements included within different sets. The fossil maybe compared with stromatolites and stromatoporoids but an interpretation as primitive stromatoporoids is favoured.     

Sedimentary history of Upper Silurian biostromes of Podolia (Ukraine) based on stromatoporoid morphometry

The sedimentary history of stromatoporoid biostromal accumulations reflecting various depositional conditions (autoparabiostromes and parabiostromes) is studied in two isochronous, Late Silurian carbonate sections of the Malynivtsy Formation from Podolia (western Ukraine, Kam'janec' Podil'skyj area). This study focuses on morphometrical analysis of massive stromatoporoids. Various stromatoporoid attributes, such as growth form, volume, surface character etc., are interpreted in terms of growth environments. Attributes of redeposited specimens are also analysed in terms of their susceptibility to exhumation and redeposition, and new criteria are presented in this matter. The exposed facies succession, which can be subdivided into three units: an oncolitic–fenestral complex and the stromatoporoid–coral complexes that underlie and cover it, represents the belt of shoals located at a considerable distance from shore, and its transition to a narrow zone of back-shoal tidal flats. The facies patterns proved to be strongly obscured by an intensive process of onshore redeposition of material during high energy episodes. These events caused exhumation and landward transport of stromatoporoids inhabiting soft-sediment bottoms of outer shelf areas, which were afterwards accumulated in parabiostromes in calm waters on lee side of a zone of shoals. The main process governing the distribution of redeposited stromatoporoids is fractional (weight) segregation. The high energetic events had less effect on stromatoporoid–coral autoparabiostromes that formed the zone of shoals, which were inhabited by stromatoporoids better adapted to permanent wave action, but nonetheless, they caused their partial reworking and depletion from those forms that did not resist redeposition, on one hand, and supplementation by specimens derived from offshore areas, on the other.     

鄂尔多斯盆地南缘上奥陶统生物礁的层孔虫化石

文中系统描述了鄂尔多斯盆地南缘淳化县铁瓦殿、岐山县烂泥沟上奥陶统生物礁中的层孔虫化石,包括2目5属9种,分别为囊层孔虫(Cystistroma)、拉贝希层孔虫(Labechia)、穿孔层孔虫(Forolinia)、网格层孔虫(Clathrod ict yon)和蜂巢层孔虫(Ecclimadictyon).建立拉贝希层孔...     

Establishment and development of patch reefs in the intracratonic Ordovician sequence near Chicoutimi, Quebec

Patch reefs occur near the top of the transgressive sequence of Ordovician Trenton Group limestones in the Chicoutimi area of Quebec, eastern Canada. Despite their small sue, these reefs comprise diverse assemblages dominated by bryozoans, corals, stromatoporoids and receptaculitid algae. Pelmatozoans and gastropods are also conspicuous. The reefs were initiated and grew in a fully marine, open shelf setting. Available substrates varied from loose skeletal lenses to soft, firm or hardened bioturbated wackestones, and the earliest stages of reef growth reflect this heterogeneity. Loose or less firm substrates were colonised by bryozoans and pelmatozoans and/or by receptaculitids, which, together with accessory organisms, stabilised the sediments and provided the basis for further reef development. The resultant firmer, slightly elevated substrates provided sites for attachment of stromatoporoids and colonial corals which spread over earlier reef organisms and sediments and dominated the later stages of reef growth. On hardened areas of sediment, stromatoporoids and corals colonised the surface directly and the early stabilising stage of reef growth is absent. The compositions and developmental stages of these Trenton Group reefs are comparable with those seen in broadly contemporaneous and often larger reefs elsewhere, and are among the earliest in which corals played an important role.     

Biotic structure and morphology of patch reefs from South China (Ningqiang Formation, Telychian, Llandovery, Silurian)

Summary Ningqiang Formation (late Telychian, Llandovery, Silurian), characterized by nearly 3000 m of shales in tercalated with carbonates, is situated between Ningqiang (S. Shaanxi Province) to Guangyuan (N. Sichuan Province) adjacent to the northwest margin of the Yangtze Platform. The high diversity “Xiushan Fauna”, and abundant reef development, illustrate a relatively warm and persistent shallo marine environment in these early Silurian sediments. The sequence shows reef radiation after recovery from the end Ordovician mass extinction envents. Multiple horizons of reef-building occurred within a relatively short geological interval and resulted in more than 30patch reefs up to 200 m in diameter and 1–50 m vertically, composed of abundant fossils. Reef biota include frame-building corals, stromatoporoids, bryozoans, and microbialites, and reef-associated oranisms such as crinoids, brachiopods, trilobites, gastropods, nautiloids and ostracods. Three reefrelated biotic associations are recognised: a) reefs dominated by framework with crinoids and microbia; b) reefs dominated by only crinoids and microbia; and c) crinoiddomainated facies. Seven representative reef examples illustrate different morphologies and growth styles. A high terrigenous debris input and shallow epicontinental ramp, which lacked obvious topographic variation, were major controls which resulted in rather simple reefs; sedimentation was apparently the main constraint on lateral and vertical extension of reefs, and prevented large-scale reef complexes developing.