Researches on Plants from the Lower Devonian Xujiachong Formation in the Qujing District, Eastern Yunnan

Fossil plants Hedeia sinica Hao et Gensel 1998, Huia gracilis Wang et Hao 2001 and Guangnania cuneata Wang et Hao are described from the Lower Devonian Xujiachong Formation, the Qujing district, eastern Yunnan, China. They contribute to our knowledge of the flora in this district. Based on the occurrence of common plants (Hedeia, Huia, Guangnania and Zosterophyllum australianum) and their horizons, it is proved for the first time that the mid-lower assemblage of the Xujiachong flora is comparable with the Early Devonian ((late) Pragian) Posongchong flora of southeastern Yunnan and the upper Baragwanathia flora of Australia. In view of this fact and the stratigraphic sequence, the mid-lower part of the Xujiachong Formation is considered to be of (late) Pragian age. Through comprehensive analyses of plant, bivalve and fish assemblages and the lithology, the upper part of the Xujiachong Formation is dated to be of early Emsian age. The Xujiachong flora belonged to the northeastern Gondwana palaeophytogeogr     

Two Zosterophyll Plants from the Lower Devonian (Lochkovian) Xitun Formation of Northeastern Yunnan, China

Abstract: Two zosterophyll plants are described from the Lower Devonian (Lochkovian) Xitun Formation of Qujing, Yunnan, China. Xitunia spinitheca gen. et sp. nov. has stalked sporangia laterally attached on the axis in a helical arrangement. Sporangia are dorsoventrally flattened and composed of two unequal valves; the adaxial valve is round in face view, while the abaxial valve is larger than the former, triangular or wedge-shaped, and radially bears long spiny appendages along the distal margin. Xitunia shows new variation of sporangial morphology within the zosterophylls. Zosterophyllum minorstachyum sp. nov. has K-shaped branchings at the basal parts and small-sized terminal spikes, which consist of round to elliptical sporangia arranged helically. This paper provides new data on the diversity of plant types during Lochkovian when rare vascular plants were reported. As for various species of Zosterophyllum in South China, their apparent evolutionary trend of features from the Late Silurian to Early Devonian (Emsian) is discussed.     

广西南宁下泥盆统华南鱼类化石新发现及其地层和古地理意义*

笔者描述了广西南宁下泥盆统布拉格阶那高岭组下部盔甲鱼类的新发现,建立了华南鱼科2个新种——丘比特华南鱼(Huananaspis cupido sp. nov.)和梁氏亚洲鱼(Asiaspis liangi sp. nov.)。前者以头甲个体较小、不发育中背棘、两角末端超出头甲后缘等特征区别于属型种武定华南鱼(H. wudingensis),后者以头甲长大于宽、角向头甲侧后方延伸、角后缘发育锯齿、中背孔呈纵长椭圆形等特征区别于属型种宽展亚洲鱼(A. expansa)。广西南宁地区那高岭组具有可靠的地质时代证据,其中所产的徐家冲鱼类化石组合能够为华南地区早泥盆世地层的对比研究提供鱼类化石标准,而华南鱼属(Huananaspis)和亚洲鱼属(Asiaspis)在那高岭组的发现,丰富了华南鱼类的多样性,扩大了徐家冲鱼类组合的化石内容,并为云南武定坡松冲组与广西南宁那高岭组之间的对比提供了直接化石证据。广西南宁莲花山组与那高岭组过渡层中的徐家冲鱼类化石组合物种多样性最高,几乎涵盖了其他地区该组合的所有属种,说明广西南宁地区可能是盔甲鱼类辐射和扩散的中心之一。该地区早泥盆世布拉格期的古鱼类、早期维管植物和腕足动物均表现出显著的地方性色彩,可能跟华南海是一个半封闭的陆表海湾有关,即由于封闭海效应,鱼类在这个封闭的环境中独立演化,表现出很高的多样性和很强的土著性,最终在华南板块上形成一个独立的动物区系——“盔甲鱼—云南鱼”动物区系。     

A New Zosterophyll Plant, Ramoferis gen. nov., from the Posongchong Formation of Lower Devonian (Pragian) of Southeastern Yunnan, China

A new genus and species,Ramoferis amalia gen.et sp.nov.,is described from the Early Devonian(Pragian)Posongchong Formation,Wenshan district of southeastern Yunnan,China.This plant has isodichotomous major axes,which also divide anisotomously distally to produce closely spaced lateral branches,often within fertile regions.The stalked round to reniform sporangia,borne laterally and spirally over several levels of branches,are distantly to moderately spaced or aggregated into distinct spikes.The stalks incr...     

云南早泥盆世植物稳定碳同位素特征及其古气候意义*

受到植物化石材料局限性与时代久远性的限制,目前用古生代植物化石δ¹³C值来反演古环境的研究程度较低。文中通过对云南省曲靖市下泥盆统徐家冲组和文山州下泥盆统坡松冲组的部分植物化石进行稳定碳同位素测试,分析了早泥盆世植物的光合作用途径以及古环境。结果表明: 徐家冲组镰蕨属(Drepanophycus)δ¹³C值为-29.0‰~-22.8‰,平均值为-24.5‰,其中镰蕨属茎轴的δ¹³C值高于叶片0.1‰~0.3‰;坡松冲组工蕨属(Zosterophyllum)和始叶蕨属(Eophyllophyton)δ¹³C值分别为-24.8‰~-22.1‰和-23.0‰~-22.6‰,平均值分别为-23.2‰和-22.7‰;三者的δ¹³C值分布范围都与现代C3植物一致。自徐家冲组第57至第79沉积旋回,δ¹³C值总体呈上升趋势,达到2‰左右,推测可能与早泥盆世大气CO₂浓度下降和气候变冷相关。镰蕨属和工蕨属的C_i/C_a值较为稳定,说明这2种植物可能对大气CO₂浓度变化较为敏感,曲靖市古气候可能为当今的热带疏林草原气候或热带季风气候。     

Chemical characterization of Lower Devonian vascular plants

Vegetative remains of three coalified Lower Devonian vascular plants (Zosterophyllum, Psilophyton, Renalia) were analyzed using flash pyrolysis-gas chromatography-mass spectrometry. The distributions of pyrolysis products are compared with those from younger vascular plant fossil xylem (Cordaixylon, Callixylon) and cuticle (Pachypteris). The likelihood of the chemical preservation of characteristic higher plant macromolecules (e.g., lignin and cutan) in the Lower Devonian plant fossils is considered in light of this comparison and associated thermal maturity assessments. Reflectance values from vitrinite-like macerals, which may not be vitrinite sensu stricto in the Lower Devonian host rocks for the fossils selected for this study, are shown to provide a reasonable assessment of the thermal maturity of these early vascular plant fossils. Although lignin altered through burial maturation is the most likely source of the prominent alkylphenols and aromatic hydrocarbons in the Lower Devonian tracheophyte flash pyrolysates, a contribution from thermally modified tannins cannot be ruled out. Comparison of the highly aliphatic pyrolysates from the Zosterophyllum and Psilophyton axes with that of a thermally mature fossil gymnosperm leaf revealed that cutan was an important component in the Devonian plant remains. This is the earliest chemical evidence for the presence of cutan in vascular plants.     

新疆北部下中泥盆统层序及其界线讨论

新疆北部是中国北方下中泥盆统出露最全地区之一,1977年曾作为中国北方槽区典型剖面.笔者根据最新资料研究,重新选定了下中泥盆统标准层序(自下而上):下泥盆统:乌吐布拉克组、曼格尔组.芒克鲁组;中泥盆统:乌鲁苏巴斯套组、纸房组.并根据岩性变化及床板珊瑚化石资料,对乌吐布拉克组进行了重新审定,将原沙尔布尔提山剖面乌吐布拉克组下2层归入上志留统.重点讨论了下泥盆统的底界及下与中泥盆统间的界线.     

The oldest flora of the South China Block, and the stratigraphic bearings of the plant remains from the Ngoc Vung Series, northern Vietnam

Several outcrops of the Late Silurian and Devonian of the Ngoc Vung Series, northern Vietnam, yielded plant remains. The Late Silurian localities delivered the earliest known flora of the South China block. Although the fossils are fragmentary, they complement our knowledge about the global composition of the flora. The major components of the flora are plants with dichotomous habit and terminal bivalvate sporangia, which are close relatives to zosterophylls, and zosterophylls. Plants with possible euphyllophyte affinities and bryophytes are occasionally present. This floral composition is similar to that of the rich, younger South China block assemblages from the Posongchong and Xujiachong Formations of China, considered Pragian in age. The South China block flora is therefore likely to have been dominated by zosterophylls and pre-zosterophylls at least from the Late Silurian to the Pragian (i.e. a 20 million years long period). It also strengthens the hypothesis that more derived plants were present on eastern Gondwana earlier that elsewhere, in the first steps of tracheophyte evolution. The Devonian localities of the Ngoc Vung Series delivered a thick fibrous stem fragment and a basal euphyllophyte. These latter plant remains provide some stratigraphic data. The large stem fragment is consistent with an Eifelian age for the Duong Dong Formation (part of the Ngoc Vung Series), as suggested by the brachiopod fauna. The accompanying basal euphyllophyte displays a combination of characters (axes 3-4 mm wide and lateral branchings) that is also consistent with an Eifelian age, but possibly more characteristic of the Emsian flora. It is therefore suggested that the stratigraphic range of the Duong Dong Formation might be extended down to the Emsian.     

新疆哈密地区早泥盆世珊瑚动物群及其地质意义

新疆哈密地区下泥盆统发育,南部图拉尔根地区下泥盆统为大南湖组,北部三道白杨沟地区为卓木巴斯套组。在大南湖组中共发现四射珊瑚2属5种,床板珊瑚7属12种,并建立四射珊瑚组合Syringaxon moriense和床板珊瑚组合Pseudofavosites giganteus;在卓木巴斯套组共发现四射珊瑚5属7种,床板珊瑚2属2种,并建立四射珊瑚组合Orthopaterophyllum junggarense和床板珊瑚组合Pachyfavosites junggarensis。通过珊瑚在地层中的分布及组合的时代对比,确定前者的时代为早泥盆世埃姆斯期早期,后者的时代为埃姆斯期中晚期。通过与国内外典型的早泥盆世埃姆斯期珊瑚动物群的对比,认为哈密地区的珊瑚动物具有典型的早泥盆世温带动物群特征,在生物古地理区系上属于北方大区准噶尔-兴安省。     

新疆北塔山晚志留—早泥盆世苔藓虫

本文描述的上志留统一下泥盆统的苔藓虫标本产自新疆东准噶尔北塔山地区。上志留统考克赛组中包括6属7种,它们是:Fistulipora granulosa Astrova, Hallopora xinjiangensis Lu, Semicoscinium pyramidatum Kopaevich, Sem. fragilis Astrova, Chasmatopora sp., Orthopora sp., Sceptropora sp.; 下泥盆统托让格库都克组中包括2属3种:Fistulipora Sp., Semicoscinium baytikensis Wang et Lu(sp. nov.), Sem. kurjensis Nekhoroshev.根据上述苔藓虫组合特征,可建立两个苔藓虫组合,上志留统为Fistulipora granulosa-Hallopora xinjiangensis组合;下泥盆统为Semicoscinium baytikensis-Sem. kurjensis组合。     

云南华宁盘溪几种泥盆纪四射珊瑚

云南省华宁县盘溪地区的泥盆纪浅海相地层发育,珊瑚化石丰富,研究历史悠久,是中国南方重要的泥盆系剖面之一,它在国内外地层古生物学界久负盛名。1948年王鸿祯教授首次描述了盘溪等地泥盆纪的四射珊瑚19属36种(包括变种、未定种等),其中有19新种,自下而上建立了G、C、K、E、T、P、D等7个珊瑚层(horizon),奠定了滇东泥盆纪生物地层研究的基础,该文至今仍一直被国内外地层古生物学界同行所引用和参考。文中描述了盘溪泥盆纪四射珊瑚13属13种(包括未定种和近似种)及其上覆下石炭统的四射珊瑚1属2种。文章还着重讨论了泥盆系的南盘江组、一打得组和在结组的地质时代以及泥盆—石炭系界线等地层问题。     

A New Lycopsid, Zhenglia radiata gen. et sp. nov., from the Lower Devonian Posongchong Formation of Southeastern Yunnan, China, and Its Evolutionary Significance

A new plant, Zhenglia radiata gen. et sp. nov., from the Posongchong Formation （Early Devonian, Pragian age） of the Wenshan District of southeastern Yunnan Province, China is a small herbaceous lycopsid. The aerial branches divide into foliar and fertile stems. The arrangement of the leaf bases on the stem shows lepidodendroid-like phyllotaxy. Possibly the leaf base bears a ligulate pit. The microphyll consists of a swollen, decurrent base, and an entire, linear lamina. The fertile axis is composed of sporophylls arranged helically, forming a compact area similar to cone-like structure. Each sporophyll consists of a widened lateral extension and a distal lamina. The ovoid-elongate sporangia are attached adaxially on the surface of sporophylls. Based on morphological similarities, especially the undivided microphylls, the style of phyllotaxy, the form of the cone-like structures and sporangia, the new lycopsid Zhenglia radiata is placed in the order Protolepidodendrales and a possible evolutionary relationship with the arborescent lycopsids of the Late Devonian and Carboniferous is considered.     

四川盐边稗子田志留系与泥盆系的界线划分及地质意义

四川省盐边县北部稗子田地区的专留系发育良好,牙形刺化石极为丰富,与上覆泥盆系连续沉积,并呈整合接触。该剖面为我国扬子区较为理想的志留纪地层剖面,其代表和反映了扬子区西部一种新的断陷盆地碳酸盐岩沉积类型,丰富了区内志留系的研究内容。笔者详细记述了稗子田专留系至下泥盆统下部剖面的岩性特征和生物化石的垂直分布状部,在此基础上建立和完善区内新的地层系统,提出地层划分的对比依据和建议。新方案除对志留系底的黑     

西藏申扎地区下泥盆统达尔东组珊瑚化石新材料

系统描述了采自藏北申扎地区下泥盆统达尔东组的部分珊瑚类化石。其中，皱纹珊瑚7属5种(含1新种Hunanaxonia xizangensis sp．nov．)及2个未定种；床板珊瑚形珊瑚4属4种，含2个新种(Pachycanalicula sparcula sp．nov．，Paraheliolites zakangensis sp．nov．)。这些珊瑚化石的发现将有助于进一步了解本区早泥盆世珊瑚动物群的共生组合、演化以及珊瑚的古生物地理区系。     

北疆沙尔布尔提山地区早泥盆-早石炭世沉积相、物源演变及其意义

准噶尔西北部沙尔布尔提山地区下泥盆统到下石炭统的沉积可划分为滨海相和海岸平原相。其中下泥盆统和布克赛尔组底部的乌图布拉克亚组为滨海碎屑岩相,曼格尔亚组为滨海碎屑岩和碳酸盐岩相,芒克鲁亚组为滨海碳酸盐岩相。中泥盆统呼吉尔斯特组为海岸平原相。上泥盆统洪古勒楞组底部为海岸平原相,向中部过渡为滨海碳酸盐岩相,顶部为滨海碎屑岩相。下石炭统黑山头组为滨海碎屑岩相。下泥盆统和下石炭统的古流向总体从北向南,显示研究区以北地区为物源区,即成吉斯-塔尔巴哈台褶皱带。结合沉积相的研究成果,本区可能属成吉斯-塔尔巴哈台褶皱带以南的晚古生代陆缘区。物源演变趋势分析揭示早泥盆世成吉斯-塔尔巴哈台带中的早古生代岛弧发生隆起,为乌图布拉克亚组提供成熟度很低的碎屑物质。随着岛弧被剥蚀殆尽,中、晚泥盆世呼吉尔斯特组和洪古勒楞组沉积时转而接受岩屑型再旋回造山带的物源供应,而早石炭世的物源则为过渡型再旋回造山带区。这种物源变化反映了成吉斯-塔尔巴哈台褶皱带的建造特征和隆起过程。     

内蒙占珠斯楞海尔罕地区中、晚泥盆世地层及四射珊瑚群的古地理意义

前人(张研等,1983)曾将珠斯愣海尔罕地区的泥岔系分为4个组:珠斯楞组、依克乌苏组、卧驼山组和西屏山组,分别属于埃姆斯期、艾菲尔期、吉维特期和弗拉斯期。本文描述了该区中、上泥盆统4个剖面,将其划分为4个沉积旋网,每个旋回构成一组,自下而上依次为依克乌苏组、卧驼山组、下西屏山组和上西屏山组。根据四射珊瑚组合和其它共生化石,把依克乌苏组上部到下西屏山组下部归入吉维持期,下西屏山组上部相上西屏山组的时代为弗拉斯期,木区缺乏法门期的沉积。 关于珠斯楞海尔罕地区所在的北方槽区泥盆纪的生物地理区系特征尚无统一认识。作者根据四射珊瑚动物群的地方性分子含量,Otsuka相似性系数和构造古地理,将中同泥岔纪的珊瑚分为3个大区:北方大区、北特提斯大区和南特提斯大区。这种划分方案也非常适用于吉维特期和弗拉斯期。 吉维持期到弗拉斯期,巴丹吉林区和扬子区珊瑚群的关系最为密切,与北天山——准噶尔区和内蒙古——兴安区共同的属很少。因此,广大的北方槽区属于两个不同的生物大区,北方大区和北特提斯大区,二者的界线是居延海——林西地壳对接带。这种认识与王鸿祯(1981)所划分的中国大地构造单元一致。     

新疆哈巴河县阿舍勒泥盆—石炭纪四射珊瑚

笔者1990—1991年在新疆哈巴河县阿舍勒采集和描述的四射珊瑚,经研究鉴定计有8属3新种和6未定种:Sinospongophyllum habaheens(sp. nov.), S. sp.,Orthophyllum sp.,Tryplasma Sp.,Cystophrentis achelenensis (sp. nov.), Siphonaphyllia habaheensis (sp. nov.),Clavilasma?sp.,Bifossularia?sp.,Amplexizaphrentis sp.等,它们分别归属于托克萨雷组、阿舍勒组和红山嘴组。     

甘蒙北山地区下石炭统绿条山组 时代修正及其构造意义

甘肃—内蒙古北山地区位于中亚造山带中段,其晚古生代洋盆最终闭合时间倍受关注且久有争议。早石炭世是该区洋陆转换的关键时期之一,下石炭统下部绿条山组与下伏的下、中泥盆统之间的角度不整合被认为是该区构造隆升的主要证据之一。但由于研究程度限制,绿条山组的时代尚有争议,一定程度上制约了该区构造演化的深入分析。北山北部甜水井北与碎石山剖面绿条山组火山岩的LA-ICP-MS锆石U-Pb年龄分别为296.8±3.5Ma与311.1±3.2Ma,产出晚石炭世巴什基尔期(Bashkirian)菊石Gastrioceras和Branneroceras,时代应修订为晚石炭世—早二叠世早期。研究区下泥盆统—上石炭统沉积充填及生物群落特征表明该区可能在晚石炭世由大陆边缘浅海演化至裂谷盆地,上石炭统与下、中泥盆统之间的角度不整合代表洋陆转化造成的长时间隆升剥蚀。     

Hamatophyton from the Late Devonian of Anhui Province, South China and Evolution of Sphenophyllales

Abstract: Well-preserved specimens of Hamatophyton verticillatum collected from the Upper Devonian (Famennian) Wutong Formation of Chaohu district, Anhui Province, South China, display more complete fertile axes in three orders and multiple divisions. Comparisons indicate that Hamatophyton possibly does not have palmate planate sterile leaves but hook-like linear ones with rare divisions. We propose seven definitive characters of Sphenophyllales: (1) completely whorled lateral organs; (2) sterile leaves; (3) strobili; (4) “sporangiophores” or stalks with reflexed tips bearing sporangia; (5) three- or four-ribbed primary xylem; (6) exarch maturation of primary xylem; and (7) secondary xylem. The Sphenophyllales probably originated from the Iridopteridales based on similarities in whorled lateral organs, ribbed primary xylem and peripheral protoxylem strands. In transition from Iridopteridales to Sphenophyllales, morphological changes involve partially whorled to completely whorled lateral organs, sterile ultimate appendages to leaves, and fertile ultimate appendages to “sporangiophores”/stalks with bracts; anatomical modifications include configuration and maturation of primary xylem, and presence of secondary xylem.