新疆阿勒泰地区早石炭世晚期菊石相四射珊瑚

LATE EARLY CARBONIFEROUS CORALS IN AMMONOID FACIES FROM ALTAY OF NORTHERN XINJIANG

本文描述的四射珊瑚是1979年窦亚伟同志和1981年新疆区调队十分队采自新疆北部阿勒泰地区下石炭统那林卡拉组,共生的化石还有大量菊石、鹦鹉螺及少数腹足类。文中计描述9属、11种和2未定种,其中新种11个。那林卡拉组的珊瑚群性质特殊,缺乏早石炭世大塘期常见的Kueichouphyllum Yu,Carcinophyllum Thomson et Nicholson,Gangamophyllum(Gorsky),Arachnolasma (Grabau),

The present article deals with the Early Carboniferous corals collected in 1979 and 1981 from the Nalingala Formation of the Altay area,northern Xinjiang.Here described are 9 genera,11 new species and 2 indeterminate species,namely,Zaphrentoides crassiseptatus sp.nov.,Amplexus regularis sp.nov.,Paralleynia xinjiangensis sp.nov.,Plerophyllum bilamellatum sp.nov.,P.sp.,Pleramplexus nalingalaensis sp.nov.,P.multiabulatus sp.nov.,P.raritabulatus sp.nov.,Pentaphyllum elegantum sp.nov.,P.sp.,Cryptophyllum xinjiangense sp.nov.,Cyathaxonia altaiensis sp.nov.,and Endamplexus xinjiangensis sp.nov.,They are especially rich in the middle and upper parts of the Nalingala Formation. This coral fauna is characterized by the corals which are all in simple forms,small,cornutedconical and ceratoid with very thickened septa but no dissepiments.The occurrence of the ammonoids Goniatites,Epicanites,Prolecanites and Stenopronotites in the Nalingala Formation also lends support to such a conclusion. Therefore,the palaeoecological conditions of this coral fauna belong to offshore water rather than to warm water of low energy,and are prevailing in the transitional area from foreslope to organic(ecologic)reef. Description of new species Amplexus regularis sp.nov.(Pl.Ⅱ,figs.1,2) Coral simple,small and circular-conic in shape,with corallum 13mm in diameter.Septa nunibering 22,with major septa shorter and straight,about 2mm in length,and minor septa absent.Tabulae complete,flat and rare in arrangement,mainly about 4mm,with both sides hanging obliquely to epitheca of coral or intersected with the next tabulae. Remarks:A.stucknbergi Sochkina,1953 differs from this species in the even tabulae arrangement,the largest intervals between tabulae and both sides of the tabulae hanging obliquely to the epitheca of coral,but not intersected with the next tabulae. Zaphrentoides crassiseptatus sp.nov.(Pl.Ⅰ,fig.1) Coral simple,trochoid in shape,medium-sized,22×24mm in diameter,with septa 28 in number.Major septa thicker,distinct on both sides;cardinal quadrant septa pinnately arranged;counter quadrant septa radially arranged.Cardinal septum longer,with counter septum and two alar septa shorter and thicker.Minor septa absent.Cardinal fossulae distinct,auloporoid-like.Counter fossulae and two alar fossulae also distinct,with no dissepiments.Tabulae complete and rare,slightly convex or concave. Remarks:The present species differs from all species of Zaphrentoides in its thicker septa and longer cardinal septum. Paralleynia xinjiangensis sp nov.(Pl.Ⅰ,figs.4,5;text-fig.2) Coral simple,small and scolecoid in shape, with 17 septa in diameter (8mm) of transverse section.Major septa extending nearly to axis and radially arranged,with the distal end curving to form semicircular axis-tube which is 3×1mm in diameter;minor septa absent.Cardinal quadrant septum shorter,with no dissepiments.Tabulae complete,thin,rare and convex,with both sides hanging obliquely to epitheca of coral in longitudinal section. Remarks:P.permiana Sochkina,1941 differs from this species in the greater number of septa,the more axis-tubes,and the tabulae closed in the axis-tube. Plerophyllum bilamellatum sp.nov.(Pl.Ⅱ,fig.7;text-fig.3) Coral simple,small and scolecoid in shape.Septa numbering 24 in diameter of transverse section.Major septa straight,composed of two calcilamellae thickened in form.Cardinal septum,two alar septa and two counter-lateral septa longer in comparison with major septa.Counter septum shorter.All septa shrunken backwards from axis in mature stage.Minor septa absent.Counter fossulae and two alar fossulae distinct.No dissepiments.Tabulae complete,domed,with both sides hanging obliquely to epitheca of coral,spaced 1—3mm apart. Remarks:P.dzhulfense Schindewolf,1942 differs from this species in the developed minor septa,with two calci-lamellae of septa indistinctly thickened. Pleramplexus nalingalaensis sp.nov.(Pl.Ⅰ,fig.8) Coral simple,medium-sized and scolecoid in shape,with 26 septa in diameter(21mm)of transverse section.Major septa amplexoid,unequal in length,about 1/3—2/3 as long as coral radius,slightly thickened,with no minor septa.Tabulae complete,with a flat dome in central part or oblique to the curved sides of coral,unequally spaced,with 4--5 in 5mm.No dissepiments. Remarks:P.leptoconicus Ilina,1965 differs from this species in the development of minor septa and the rare tabulae. Pleramplexus multitabulatus sp.nov.(Pl.Ⅱ,fig.3) Coral simple,small and ceratoid in shape,with septa numbering 27 in diameter(13mm)of transverse section.Major septa thickened and slightly curved,unequal in length,not reaching to central part of coral,about 1/2—2/3 as long as coral diameter,with shorter ones not reaching 1/2 of coral radius;minor septa absent.Cardinal fossulae indistinct.Tabulae complete,with central part flat or hanging obliquely to epitheca or coral,rare, with 4—5 in 5mm. Remarks:P.leptococicus Ijlina,1965 differs from this new species in the developed minor septa and the less space between tabulae. Pleramplexus raritabulatus sp.nov.(Pl.Ⅰ,fig.3) Coral simple,small and ceratoid in shape,with epitheca thin.Septa numbering 24 in diameter(13×15mm)of transverse section.Major septa slightly thickened and curved,1/2—2/3 as long as coral radius,radial in arrangement.Cardinal septum shorter than major septa,about 2/3 as long as the latter.Alar septa,counter-lateral septa and counter septum as long as major septa;minor septa absent.Cardinal fossulae indistinct,with no dissepiments.Tabulae complete,flat or shallowly concave in central part,with both sides hanging steeply obliquely to epitheca of coral,rare,spaced 3—4mm apart. Remarks:P.leptoconicus Flugel,1971 differs from the new species in the more septa,development of minor septa and distinct marginarium. Pentaphyllum elegantum sp.nov.(Pl.Ⅰ,fig.6) Coral simple,ceratoid in shape,with corallum medium-sized.Epitheca thin. Septa in mature stage numbering 27 in diameter(18×20mm)of transverse section.Major septa straight,pinnate in arrangement in cardinal quadrant,but radial in arrangement in the counter quadrant,slightly thickened,not reaching to central part of coral,about 2/3 as long as coral radius.Cardinal septum and two alar septa longer than major ones,with no minor septa and dissepiments.Cardinal fossulae dominant. Remarks:P.(Tachylasma)gracile Schdworf,1942 differs from this species in the thickened marginal stereozone and the shorter minor septa. Cryptophyllum xinjiangense sp.nov.(Pl.Ⅱ,figs.5,6.,text-fig.5) Coral simple,small and circular-conic in shape.In young stage diameter 6×7mm;major septa 17 in number;all septa thickened,short and clavate,1/2 as long as coral radius,with shorter ones 1.5mm in length.In mature stage,coral with a diameter of 8×9mm;major septa 23,thickened,and all septa shrunken backwards from axis;cardinal septum,alar septa and counter-lateral septa longer than major ones,with no minor septa and dissepiments.Tabulae complete,thickened,flatly domed,with both sides hanging downward obliquely to coral,sparsely spaced,with 3 in 5mm. Remarks:C.ponderosum Schindewolf,1942 differs from the new species in the large corallum with less septa,and the equaul length of the septa. Cyathaxonia altaiensis sp.nov.(Pl.Ⅰ,fig.2;text-fig.6) Coral simple,small and ceratoid in shape,septa numbering 20×2 in diameter(8mm)of transverse section.Marginarium stereozone 1mm.Major septa longer,thickened in distal part,intersected with columella.Minor septa about 1/2 as long as major ones.Columella circular in shape and solid,with a diameter of 2mm.No dissepiment and cardinal fossulae. Remarks:C.stereoseptata Wu et Zeng,1982 differs from the species in the columella elliptical in shape,and the longer minor septa. Endamplexus xinjiangensis sp.nov.(Pl.Ⅱ,fig.4) Coral simple,with septa numbering 24 in diameter(23×27mm)of transverse section in mature stage.Major septa straight,thickened and clavate in shape,with distal part not reaching the central part of coral,about 2/3 as long as the coral radius;minor septa absent.Marginarium developed with indefinite cystosepiments in mature stage.Tabulae complete,flatly domed in shape,with both sides hanging obliquely to epitheca of coral,numbering about 2—4 in 5mm; no dissepiments. Remarks:E.makros Schouppe et Stacul,1959 differs from this new species in the small size,more cystosepiments and incomplete tabulae.