云南会泽石炭纪珊瑚

CARBONIFEROUS CORALS IN HUIZE,YUNNAN

一、前言 1977年,云南会泽县铅锌矿勘探队在云南会泽县铅锌矿区的石炭纪地层剖面(A-A′和B-B′)采得一批珊瑚化石标本,有四射珊瑚和床板珊瑚共9属12种和1未定种,包括1新属和9新种,产化石层位为下石炭统上司段、上石炭统威宁组上部和马平组底部,珊瑚化石较为丰富的是在上司段。下石炭统在结山组和上石炭统威宁组中、下部是含铅锌矿的层位。据有关资料证实。

The Carboniferous corals described in this paper were collected some years ago by the Lead-Zinc Prospecting Team of Huize from Sections A—A'and B—B'(Text-fig.1)in Huize County(26°—27°north latitude and 103°—104° east longitude),Yunnan. These two sections can be'simply recognized in descending order as follows:Upper Carboniferous Maping Formation Upper Part Thick-bedded argillaceous limestone(1—3m),changing to pure biolithite(2—20m)in some places.13—30m Middle and Lower Parts Purple limestone gravels cemented by mud and purple shale.18—35m Bottom Pure limestone,yielding Axolithophyllum sp 5—8m Weining Formation Upper Part Grey limestone networked with dolomite veins,yielding Amygdalophylloides kionophylloides sp.nov.,A.aepitabulatus sp.nov.and A.stenotabulatus sp.nov.14—19m Lower Part Greyish white,yellowish coarse-grained dolomite,representing an important pay rock horizon.47—77m Lower Carboniferous Shangssu Member Dark grey limestone,yielding abundant fossils such as Corwenia magna Wu et Zhao,Arachnolasma leptaxia sp.nov.,A.multitabulata sp.nov., Axophylloides huizensis gen.et sp.nov.,A.varium(Fan),Durhamina yunnanensis sp.nov.,Syringopora honanensis Lin,Kueichowpora distans sp.nov.and Chaetetes huizensis sp.nov.,with greyish yellow sandstone at the base(0.5—20m).34—36m Zaijieshan Formation Grey limestone,intercalated with dolomite,changing to coarse-grained mineralized dolomite in some places.33—39m This paper describes 9 genera and 12 species in total(including 1 new genus,9 new species and 1 indeterminate species).They can be divided into 3 groups:(1)solitary corals,such as Arachnolasma,Axophylloides,Amygdalophylloides and Axolithophyllum,accounting for 44.4% of the total genera;(2) fasciculate corals,such as Corwenia,Durhamina,Syringopora and Kueichowpora,accounting for 44.4% of the total genera;(3)massive coral,represented by Chaetetes,accounting for 11.2% of the total genera. The solitary corals are all developed with axial structures,but there are differences in their internal composition.In transverse section,it seems that the axial structures of Arachnolasma and Axophylloides are similar to those of Dibunophyllum.In fact,Dibunophyllum is developed with a high-level complete axial column composed of a median plate,septal lamellae and axial tabellae.This column structure zone is located at the central part of the coral,bearing a clear dividing line with the tabularium.But Arachnolasma and Axophylloides are only developed with a median plate(also called columella)and a few of septal lamellae.In these genera,the tabulae or tabellae usually ascended towards,especially near the median plate,and so in the transverse section,there appeared transverse lines or concentric traces between the septal lamellae.The terms for those structures is proposed as follows.In Arachnolasma,they should be called tabellae or cystotabellae for their tabularium is composed of cystose plates.In order to avoid confusion with the axial tabellae of the complete axial column,here the tabellae near the median plate are called the inner tabellae(or inner cystotabellae)and the others near the dissepimentarium the outer tabellae(or outer cystotabellae).In fact,both the inner and outer tabellae are transitional(Pl.I,fig.5d;pl.Ⅲ,fig.1b),generally,with the inner tabellae small and round and the outer ones long and flat.Axophylloides gen.nov.is also developed with an incomplete axial column.Its tabularium is composed of complete or alternate tabulae,ascending towards the median plate(or columella),and appearing stronger near the median plate but weaker near the dissepimentarium(Pl.Ⅱ,figs.1d,2b). Axolithophyllum and Amygdalophylloides have swollen solid columella in younger stage,but they show extreme variability in adult stage(Pl.Ⅳ,fig.2b;pl.Ⅱ,fig.4a;pl.Ⅲ,figs.2,3).Those axial structures can be called the complex columella, which is different from the simplex columella of Lophopyllidium. Among the fasciculate corals,the axial structures of the rugose Corwenia and Durhamina are the same as those of Arachnolasma and Axophylloides respectively. The recent corals from Huize,Yunnan obviously belong to two groups.In the first group,since both Rugosa and Tabulata occur,and the rugose corals all have tabulae or tabellae ascending towards the median plate,this group can be roughly correlated with the Yuanophyllum zone of the Zhimenqiao Formation of Hunan,the Zhongchanggou Member of Sichuan,and the Shangssu Member of Guizhou.In the second group,there are only two genera and 4 species of Rugosa,but it can be easily made out that this group had entered into the Late Carboniferous facies. According to the structural morphology of these corals,they are regarded as then living in a warm neritic environment,but of some mud and low turbulence. Description of new genus and species Amygdalophylloides kionophylloides sp.nov(Pl.Ⅲ,fig.2;text-figs.2,3) Diagnosis: Solitary coral measuring about 12mm in diameter in mature stage.Major septa 21 in number,mainly diffusotrabecular in fine skeletal structure(Text-fig.2),extending for about 2/3 of the corallum diameter;minor septa about half as long as major ones.Septa sometimes discontinuous at periphery in dissepimentarium.Axial structure composed of median plate,a few of septal lamellae,and inner tabellae,irregularly thickened,with its inner holes full of stereoplasm(Text-fig.3). Dissepimentarium composed of 2 rows of normal dissepiments mixed with a few of irregularly inflated ones.Tabularium composed of clinotabulae in the peripheries with flat or concave tabulae in the central part. Remarks: The new species is similar to A.uzurense(Yamagiwa et Ota)in the corallum diameter,number of septa and fine skeletal structure,but in the latter,the skeletal structures are obviously thickened and the axial structure oval and compact.It is similar to A.sp.described by Rodriguez(1984)in the corallum diameter and axial structure,but in the latter,the septa are more in number and the dissepimentarium is more regular. Locality and Horizon: Section B—B＇,Lead-Zine Mineral Area,Huize,Yunnan;Upper Carboniferous Weining Formation. Amygdalophylloides aepitabulatus sp. nov.(Pl.Ⅳ,fig.2) Diagnosis: Solitary coral measuring about 7.5 mm in diameter in mature stage.Major septa 21 in number,diffusotrabecular in fine skeletal structure,extending for about 2/3 of the corallum diameter;cardinal septum long,extending into the axial structure;counter septum short;minor septa also short,about 1/5 to 1/3 as long as major ones.Axial structure composed of median plate continuous with cardinal septa,with 5 septal lamellae and a few of inner tabellae.Dissepimentarium composed of I row of normal dissepiments.Tabulae steeply declined inwards. Calicular pit deep.Septa in late mature stage withdrawn,with only median plate in the central part. Locality and Horizon:Idem. Amygdalophylloides stenotabulatus sp,nov.(Pl.Ⅱ,fig.4;text-figs.4,5) Diagnosis:Solitary coral measuring about 8mm×6.5mm in transverse section.Septa of two orders,thickened.Major septa 25 in number,fibro-normal and in transition from trabecular to diffusotrabecular in fine skeletal structure(Text-fig 4),extending for about 2/3 of the corallum diameter;minor ones very short,submerged in marginal stereozone.Axial structure solid-oval,composed of cloud-like stereoplasm.Dissepiments discontinuous,in 1 to 2 rows.Tabularium narrow,with tabulae flat and widely arranged(Text-fig.5). Remarks: The new species is similar to A.crassicolumellatus D.et K.,1948 in the swollen oval axial structure and marginal stereozone,but the latter has a thicker marginal stereozone,less septa and inwards declined tabulae. Locality and Horizon:Idem. Arachnolasma multitabulata sp.nov.(Pl.Ⅰ,fig.5) Diagnosis: Solitary coral with corallum conico-cylindrical,large,measuring 15mm in diameter in mature stage.Major septa 35 in number,thickened in the middle and thinner at the ends which either or not revolve around,and extend into the axial structure;cardinal septum thinner than others;minor ones very short;mainly diffusotrabecular in fine skeletal structure.Axial structure in the transverse section dibunophylloid,but with obviously thickened median plate,a spindlelike columella.Dissepimentarium wide,but becoming narrower near cardinal fossula,with many dissepiments herringbone in arrangement.Tabularium composed of tabellae or cystotabellae ascending towards the columella,which are roughly divided into two parts:outer tabellae long,vesicular,widely arranged;inner tabellae small,vesicular,closely arranged. Remarks: The new species is similar to A.irregulare Yu,1933 in columella and number of septa,but the latter has more developed minor septa and widely arranged tabellae. Locality and Horizon: Section A-A＇,Lead-Zinc Mineral Area,Huize,Yunnan;Shangssu Member of Lower Carboniferous. Arachnolasma leptaxia sp.nov.(Pl.Ⅲ,fig.1;text-fig.7) Diagnosis: Solitary coral with corallum conico-cylindrical,20—30mm in diameter.Major septa long,40—46 in number;minor ones short;diffusotrabecular to fibro-normal in fine skeletal structure.Axial structure composed of a long, slightly thickened median plate,two segments of septal lamellae and long,straight and cosely arranged concentric traces of upturned inner tabellae(text-fig.7). Dissepimentarium wide,but narrower near cardinal fossula,with dissepiments herringbone or concentric in arrangement.Tabularium composed of tabellae or cystotabellae ascending towards the median plate and roughly divided into two parts:outer part very wide,with outer tabellae long,vesicular,widely arranged,and inner part very narrow,with inner tabellae small,vesicular,closely and steeply arranged. Remarks: The new species is similar to A. sinense(Yabe et Hayasaka)in the corallum diameter,with many septa,but in the former,the axial structure is narrow and closely arranged,with a median plate not obviously thickened,and its tabularium can be roughly divided into the inner zone, which is very narrow with tabellae arranged closely and steeply,and the outer zones,which are very wide with longer tabellae arranged widely and gently.A.Karatawica(Bikova)is similar to the new species in the large corallum diameter,numerous septa,wide dissepimentarium,few septal lamellae,long and straight concentric traces of inner tabellae in axial structure,but in the former,the septa are obviously thickened in the tabularium,especially in cardinal quadrant,but thinner and meandering in dissepimentarium,the minor septa are poorly developed and the median plate is obviously thickened. Locality and Horizon:Section B—B',Lead-Zine Mineral Area,Huize,Yunnan;Shangssu Member of Lower Carboniferous. Genus Axophylloides gen.nov. Type species:Axophylloides huizensis gen.et sp.nov. Diagnosis:Solitary coral with septa arranged in two orders.Axial structure composed of median plate(or lath-like columella),septal lamellae and upturned tabulae,web-like in transverse section.Lonsdaleoid dissepiments developed.Tabulae complete or incomplete,ascending towards the median plate,wide and gentle in wide peripheries,but close and steep in the middle. Remarks:The new genus is very similar to Axophyllum in the transverse section,but the latter has a continuous complete axial column zone longitudinally,and tabulae on both sides of the complete axial column zone flat or concave. Hill(1981)assigned Axophyllum to Axophyllidae,in which the coral axial tabellae zone is developed and the tabulae are horizontal or concave.In the new genus,the tabulae are outwards and the tabularium is wider.Obviously, it belongs to Durhaminidae.It is easy to distinguish Axophylloides from Durhamina,because the latter is fasciculate,with axial structure very simple and median plate discontinuous. Distribution:Late stage of Early Carboniferous;Southwest China. Axophylloides huizensis gen.et sp.nov.(Pl.Ⅱ,fig.1;taxt-fig.8) Diagnosis:Solitary coral with corallum conico-cylindrical,attaining 26mm in diameter.Major septa long,27—28 in number;minor ones developed;simple to multi-trabecular in fine skeletal structure (Text-fig,8).Septa discontinuous in dissepimentarium.Axial structure nearly isolated,medium in size,composed of not long median plate(or lath-like columella),septal lamellae and concentric traces of upturned tabulae and tabellae.Lonsdaleoid dissepimentarium wide.Tabulae complete or incomplete,ascending towards median plate,and steeply arranged with more tabellae near median plate. Remarks:The new species may be distinguished from A.varium(Fan)by the fewer septa with a large diameter,closely arranged axial structure,short and thick median plate,fewer septal lamellae,and very closely arranged tabulae. Locality and Horizon:Section A—A',Lead-Zinc Mineral Area,Huize,Yunnan;Shangssu Member of Lower Carboniferous. Durhamina yunnanensis sp.nov.(Pl.Ⅱ,fig.3) Diagnosis:Fasciculate coral with thick outer walls.Corallite diameter 18—21mm.Major septa thickened,33 in number,extending for about 2/3 of the corallite diameter,with part of them discontinuous in dissepimentarium;minor septa developed.Inner walls developed along inner row of dissepiments.Axial structure composed of a median plate,a few septal lamellae,and concentric traces of upturned tabulae arranged irregularly or regularly.Lonsdaleoid dissepiments developed mainly in outer dissepimentarium,while small and concentric dissempiments developed in inner dissepimentarium.Tabularium wide,with tabulae complete,ascending towards median plate,and spaced 0.7—1mm apart. Remarks:The new species is similar to D.cordillerensis(Easton)in the features of dissepimentarium and tabularium,but the latter has a smaller corallite diameter,less septa, more irregularly developed axial structure and irregular;discontinuous median plate. Locality and Horizon:Section B—B',Lead-Zinc Mineral Area,Huizer,Yunnan;Shangssu Member of Lower Carboniferous. Kueichowpora distans sp.nov.(P1.Ⅳ,fig.3) Diagnosis: Fasiculate coral composed of small cylindrical corallites ramose in arrangement,with very large spaces between corallites.Corallite diameter 2.5—3mm.Outer walls 0.4—0.6mm thick.Tabulae cystose,sparsely arranged in one row.Aulos well developed;aulo walls thick.Connecting tube structure not seen. Remarks:The new species is characterized by the larger corallite diameter,the larger space between corallites which are ramose in arrangement and the thickened aulo walls,and therefore can be easily distinguished from other species of this genus. Locality and Horizon:Section A—A',Lead-Zinc Mineral Area,Huize,Yunnan;Shangssu Member of Lower Carboniferous. Chaetetes huizensis sp.nov.(Pl.Ⅳ,fig.1) Diagnosis:Massive coral with corallites of 0.5—0.8mm intermixed with some of them less than 0.4mm in diameter,irregularly polygonal,more generally quadrilateral to hexagonal.Outer walls thick,0.05—0.15mm in thickness.Tabulae complete and flat,zonated in arrangement,spaced 0.2—0.4mm apart in dense zone,but with very few of them between dense zones.Spines very poorly developed. Locality and Horizon:Section B—B',Lead-Zinc Mineral Area,Huize,Yunnan;Shangssu Member of Lower Carboniferous.