异珊瑚隔壁的排布系列

异珊瑚原始隔壁数目、后生隔壁的增生部位和方式以及隔壁的排布系列的研究，是探讨异珊瑚的起源、演化和分类的基本前提。通过对3隔壁的Triphyllia和4隔壁的Quadratphyllia二属的研究，结合生物体对称的原则，提出异珊瑚原始隔壁为2条，并认为异珊瑚的后生隔壁发育在原始隔壁所分隔的左右两侧部体腔内缘部位，长隔壁呈树枝状拓布或者末端达中心向某一方面扭曲连接形成轴管构造。依据后生隔壁在体腔内的繁生能力、增殖数量、发生部位、排布方式、分化程度、隔壁始端在外壁中的埋植类型和末端在中心部位的连接类型等方面的不同，异珊瑚隔壁增生大致可划分为7个布系列。     

Structure and Stability of Non-Transform Discontinuities on the Mid-Atlantic Ridge between 24° N and 30° N

Observations of the median valley within the 24–30° N area ofthe Mid-Atlantic Ridge (MAR), using the IOSDL high resolutionside-scan sonar instrument TOBI, image four separate areas of themedian valley, containing part or all of nine spreading segments, and fivenon-transform discontinuities between spreading segments (NTDs).These high resolution side scan images were interpreted in parallel withmultibeam bathymetry (Purdy et al., 1990), giving a greater degree ofstructural precision than is possible with the multibeam data alone. Threedistinct types of NTD were identified, corresponding in part to typespreviously identified from the multibeam bathymetric survey of the area.Type 1 NTDs are termed septal offsets, and are marked by a topographic ridgeseparating the two spreading segments. The offset between the spreadingsegments ranges from 9 to 14 km. These can be further subdivided into Type1A in which the septa run parallel to the overall trend of the MAR and Type1B in which the septa lie at a high angle to the bulk ridge trend. Type 1ANTDs are characterised by overlap of the neovolcanic zones of the segmentson each side, and strong offaxis traces, while Type 1B NTDs show no overlapof neovolcanic zones, and weak offaxis traces. Type 2 NTDs arebrittle/ductile extensional shear zones, marked by oblique extensionalfractures, and associated with rotation of tectonic and volcanic structuresaway from the overall trend of the MAR. Type 3 NTDs are associated withoffsets of less than 5 km, and show no sign of any accommodating structure.In this type of NTD, the offset zone is covered with undeformed volcanics.The type of NTD developed at any locality along the ridge axis appears todepend on the amount of segment offset and segment overlap, the overalltrend of the mid-ocean ridge, the width of the zone of discontinuity, themedian valley offset and the longevity of the offset. These factorsinfluence the mechanical properties of the lithosphere across thediscontinuity, and ultimately the tectonic style of the NTD that can besupported. Thus brittle/ductile extensional shear zones are long-livedstructures favoured by large segment offsets, and small or negative segmentoverlaps. Septa can be short or long lived, and are associated with largesegment offsets. Segment overlaps vary from negative (an along axis gap) tozero, for Type 1B septal offsets, or positive to zero for Type 1A septaloffsets. Non-tectonised NTDs are generally short lived structures,characterised by small segment offsets and zero or positive overlaps.     

异珊瑚隔壁的变异及其分类

自发现具有３个隔壁的异珊瑚新类型之后，对异珊瑚各属之间的隔壁变异关系有了清楚的揭示。按照后生隔壁发育的方式，可分为具内沟的异珊瑚，即由３个隔壁的Ｔｒｉｐｈｙｌｌｉａ，５个隔壁的Ｐｅｎｔａｐｈｙｌｌｉａ，直至多隔壁的Ｆｏｓｓａｐｈｙｌｌｉａ系列和不具内沟的异珊瑚系列，即由４个隔壁的Ｑｕａｄｒａｔｉｐｈｙｌｌｉａ，６个隔壁的Ｈｅｘａｐｈｙｌｌｉｕ，直至多隔壁的Ｈｅｔｅｒｏｐｈｙｌｌｉａ。此外，还可出现具有轴管结构的Ｃｒｅｐｉｄｏｐｈｙｌｌｉｄａｅ及具有特殊外壁结构的Ｌｏｎｇｌｉｎｏｐｈｙｌｌｉｉｄａｅ。对已发现的异珊瑚１９个属作了系统的分类，并将异珊瑚置于珊瑚纲内的一个亚纲，同皱纹珊瑚亚纲相并列的分类单位。     

中国的异珊瑚

从６０年代开始，我国学者陆续发表了异珊瑚的研究成果，建立１３个属，描述１６０余种。所发现属种数量已大大超过国外学者所描述范围，并且在异珊瑚分类、骨骼微细构造及隔壁演变规律研究等方面都取得长足的进展。特别是发现具３个隔壁的异珊瑚，对异珊瑚的隔壁发育方式及各属间隔壁变异关系有了较清楚地揭示。在分类方面可将异珊瑚划分为具内沟和不具内沟的两个系列。异珊瑚在我国产出时代为泥盆纪早期至石炭纪晚期。我国的异珊瑚绝大多数产于早石炭世大塘期的海相地层内，常与Ｙｕａｎｏｐｈｙｌｕｍ带的皱纹珊瑚共生，是划分早石炭世地层的重要化石     

新议异珊瑚的隔壁和横板

本文根据近年来我国的异珊瑚资料,将其某些特征归结如下:1.隔壁自个体体壁至中央发育;2.原始隔壁数目可能是五(或四)个;3.后生隔壁数目尚无规律,其趋势是由少增多插入个体各区域内,一般侧区早发育后生隔壁,且数目较其他区域要多;4.隔壁有分级现象,末端也可游离;5.横板发育,有上穹、平坦、下凹三种形态;6.可分为完整横板和不完整横板两种类型;7.横板排列间距不仅因种类而异,同一个体中也有中央与边缘之别。另外,对异珊瑚目中的六个属也有一定演化关系可寻。