湖南慈利江垭剖面二叠系-三叠系界线层序的沉积微相类型、沉积环境和海平面变化

本文对湖南慈利江垭剖面二叠系-三叠系界线层序(大隆组顶部9.4m和大冶组底部7.5m)进行了详细的沉积微相分析,划分出八种微相类型,并结合露头和光面上的沉积特征,对每种微相的成因和沉积环境进行了分析和讨论。在此基础上,研究了界线附近的沉积环境和相对海平面变化。大隆组顶部层序沉积于相对海平面持续上升阶段,随着相对海平面的上升,沉积环境逐渐由盆地边缘向盆地内部迁移。在大隆组最顶部,相对海平面有一快速的大幅度下降,沉积环境由深水盆地突然转变为浅水台地。之后自大冶组底部向上,相对海平面又逐渐上升,沉积盆地依次经历了滞流盆地、半循环盆地和循环盆地的转换;在距离大冶组底部约7m处,相对海平面开始下降,气候变得极为干燥,沉积盆地转变为蒸发盆地。值得指出的是,大隆组-大冶组界线处的快速海退面正好对应于二叠纪末生物灭绝面,从而表明大海退很可能是造成二叠纪末生物大灭绝的重要原因。     

右江盆地二叠纪生物礁层序地层学研究

通过右江盆地二叠纪生物礁层序地层研究表明,在海平面升降旋回的各个时期,均有生物礁的发育,并呈现各自特征的层序内部构型及成因格架。低水位礁仅发育于台盆背景,以加积丘礁或点礁为特色,常与混屑浊积岩、硅灰岩、硅泥岩共生;陆棚边缘礁发育于台盆和斜坡背景,与低水位期的相比,礁体较大,数量较多,因为该期相对稳定的底质和水动力条件对生物礁的萌生更具诱导作用;海侵期表现为伴随海平面向陆超覆而形成的向陆年轻化的海侵型台盆礁、斜坡礁、台缘礁、台内礁组合,具加积-退积型堆积序列,礁顶发育硬底、生物挠动面、海底熔蚀面、淹没面、水下中止面等,礁盖包括硅岩、火山碎屑浊积岩、放射虫岩、骨针岩、深水遗迹相、生物密集层、浮游相灰岩、含锰磷酸盐灰泥岩等,生长方式主要是追补式和中止式,以宝塔礁、链状礁、点礁为主;高水位礁以进积礁、加积礁和混积礁组合为特征,广泛发育于台内、台缘、斜坡、台盆等环境,具向上变浅序列,礁顶发育暴露面、岩溶面、冲刷侵蚀面、钙化壳、白云岩帽等,礁盖主要有残积相、潮坪相、浊积相、丘滩相等,规模大、分布广,以堤礁、环礁、马蹄形礁为主。     

二叠纪海平面变化研究

在研究全球不同地区二叠纪沉积、层序及生物资料基础上,通过全球诸大陆典型剖面层序划分和对比表明,二叠纪至少有６次海平面升降事件具全球对比意义。二叠纪全球海平面旋回曲线,在不同板块不同成因盆地,其形态及结构不同,但总体可分为两种类型或分支：一是以海相→陆相沉积序列为主的反映主体海平面下降的经典型或欧美型;二是以海相碳酸盐岩→碳酸盐－硅质岩沉积序列为特征的揭示主体海平面上升的特拉斯型或华南型。这与二叠纪特定的全球构造－古地理密切相关。     

全球二叠系顶部白云岩与沉积相关系统计及其白云石化机制的意义

本文对全球范围内23个典型的研究程度较高的晚长兴期露头进行了研究,逐一检查了晚长兴期白云岩前身沉积的沉积相,结果发现所有白云岩的前身都是浅水相的(除汉中梁山一个剖面外)。相反,目前已经研究的深水相上二叠统碳酸盐沉积物都没有发生白云岩化。这一结果表明,世界范围内上二叠统顶部白云岩的形成机制可能都与海平面下降有关,很可能是蒸发成因的浓缩卤水使沉积物发生白云岩化。据此推断,四川盆地东北部长兴组白云岩也应当是此种成因。     

晚三叠世龙门山前陆盆地早期(卡尼期)碳酸盐缓坡和海绵礁的淹没过程与动力机制

晚三叠世龙门山前陆盆地分布于扬子克拉通西缘,属于印支期造山楔构造负载驱动的挠曲型前渊凹陷.其中卡尼期马鞍塘组是分布于底部不整合面之上的第一套地层单元,记录了前缘隆起边缘碳酸盐缓坡和海绵礁的构建和淹没过程.据钻孔揭示马鞍塘组的最大厚度超过250m,显示为西北厚东南薄的楔形结构,从北西向南东依次分布了深水盆地、碳酸盐缓坡和海绵礁和浅水滨岸带等沉积物类型.其中碳酸盐缓坡和海绵礁分布于前陆盆地的远端,呈面向西的条带状展布,其走向线与龙门山冲断带的走向大致平行.碳酸盐缓坡和海绵礁的厚度介于30～100m之间,由北西向南东变薄.在垂向上,马鞍塘组由3部分构成,下部为鲕粒滩和生物碎屑滩,中部为海绵礁,上部为黑色页岩,显示为向上变细、变深的沉积序列.在Li et al.(2003)盆地模拟的基础上,本次对卡尼期前陆盆地的沉降速率、沉积速率、海绵礁生长速率、相对海平面上升速率进行了定量计算,其中沉降速率为0.10mm·a-1、沉积速率为0.04mm·a-1、海绵礁生长速率为0.03mm·a-1、相对海平面上升速率介于0.01mm·a-1～0.05mm · a-1之间.研究结果表明:在卡尼期早期,相对海平面处于初始上升阶段,相对海平面上升速率较小,盆地处于欠补偿状态,沉积了碳酸盐缓坡型鲕粒滩和生物碎屑滩;在卡尼期中期,相对海平面上升速率等于海绵礁生长速率,海绵礁持续保持垂直向上的生长状态,形成了高度达100余米的塔礁;在卡尼期晚期,相对海平面上升速率大于海绵礁生长速率,礁顶的水深逐步变大,导致礁体被淹溺致死,从而在卡尼期形成了鲕粒灰岩滩-生物碎屑滩-海绵礁灰岩-页岩的向上变细、变深的沉积序列,显示了前陆盆地早期碳酸盐缓坡和海绵礁生长并被淹没的特有模式.本次研究成果表明龙门山前陆盆地的底部不整合面和碳酸盐缓坡、海绵礁的淹没过程是扬子板块西缘印支期造山楔逆冲构造负载的挠曲变形的产物,显示了在卡尼期松潘-甘孜残留洋盆的迅速闭合和造山楔构造负载向扬子板块的推进过程.     

贵州紫云二叠纪生物礁的基本特征及其发育规律

贵州紫云二叠纪生物礁是我国二叠纪发育最好的生物礁之一。该地区生物礁包括茅口阶堤礁、吴家坪阶珊瑚层、长兴阶堤礁和点礁。本文通过大比例尺地质填图和剖面测量，系统地研究了该地区生物樵的沉积学特征和古生物学特征，建立了成因模式。研究结果表明，紫云二叠纪生物礁类型较多。礁组合相带齐全，礁骨架结构极为典型，古岩溶十分发育。生物礁发育程度具有明显的旋回性，海平面的相对变化和古气候是控制生物礁发育的主要因素。     

南盘江盆地晚古生代盆地充填序列特征及生储盖组合划分

以米级旋回层序为基本工作单元 ,米级旋回层序在长周期三级层序中的有序叠加形式为基础 ,在南盘江盆地晚古生代地层中共识别出 2 5个三级层序 (沉积层序 ) ;以构造不整合面为准 ,又可进一步归为 4个二级层序 (构造层序 )。根据地层、沉积特征及构造地质涵义 ,把层序界面归纳为 4种类型 :构造不整合面、沉积不整合面、淹没不整合面以及它们的相关面 ,其中构造不整合面类似于类型 界面 ,沉积不整合面类似于类型 界面。晚古生代南盘江盆地存在两个明显的造礁期。于三级海平面上升阶段主要发育礁滩相灰岩构成的储层 ;而在与三级海平面下降相关的强迫型海退过程中则发育白云岩构成的储层。因此 ,可把南盘江盆地区域性的潜在生储盖组合拟定为 3个 :以孤立台地上泥盆系生物礁和加里东运动不整合面为主要勘探对象的下组合 ;以石炭系大埔组白云岩为主要勘探对象的中组合 ;以茅口组上部和长兴组生物礁及礁顶相白云岩、东吴运动不整合面为主要勘探对象的上组合     

中国中西部盆地海相白云岩主要形成机制与模式

塔里木、四川及鄂尔多斯盆地是中国中西部海相白云岩的主要发育地区。三大盆地重点层系海相白云岩新近的成因研究表明,大规模准同生白云岩和埋藏成因白云岩的发育均与蒸发台地密切相关。蒸发台地中由海水浓缩形成的富Mg~(2+)卤水一方面在准同生期,通过蒸发泵和下渗机制交代碳酸钙沉积物而形成与蒸发岩共生的准同生白云岩,另一方面作为富含Mg~(2+)的地层孔隙水,在准同生-浅埋藏期乃至中、深埋藏期,通过侧向渗透、侧向与垂向压实排挤和垂向热对流机制与粗结构的碳酸钙沉积物发生交代反应,在蒸发岩系周边和上下形成广泛分布的埋藏成因白云岩。与热流体作用有关的白云石化主要依靠构造断裂、裂缝、不同级次的层序界面、孔洞层等输导体系发生,分布较局限。热流体云化常表现为对先期白云岩进行叠加改造而形成热水改造白云岩。热流体性质不一,可以是深埋藏混合热水、深部循环水、地幔深部的岩浆热液等。白云石(岩)的生物成因不仅表现为微生物作用导致白云石直接沉淀,还表现为生物的存在与活动为白云石化作用提供Mg~(2+)和云化流体通道。由微生物和宏观藻释放出Mg~(2+),在埋藏期对方解石进行交代是各种富含藻类的灰岩中部分白云石的重要形成机制。生物扰动可明显改善岩石的孔渗性,从而显著促进白云石化作用的发生。     

复合海平面变化控制下的碳酸盐向上变浅层序──以贵阳地区三叠系大冶组灰岩为例

碳酸盐向上变浅层序形成的主因乃因在被动大陆边缘至克拉通盆地中，构造沉降速率一般要小于碳酸盐生产速率，而碳酸盐生产速率又要小于海平面变化相对上升速率。由此就形成了台地淹没事件形成的“淹没不整合”界面之上发育的碳酸盐向上变浅层序。这种低频率海平面变化快速上升超过碳酸盐生产速率形成的向上变浅层序，可由许多种类型的米级旋回层序有规律的垂直叠加所构成。在低频率海平面变化的上升阶段则以淹没节拍为主的米级旋回层序为特征，而在停滞至下降阶段则以暴露节拍的米级旋回层序为特征。而且组成向上变浅层序的下部单元──淹没事件形成的凝缩面具有从靠近盆地区到靠近台地区变薄的趋势。贵阳地区三叠系大冶组灰岩由两个向上变浅层序组成，每一层序包括若干个不同类型的米级旋四层序。     

影响沉积盆地相对海平面变化的多重因素和旋回层序响应

沉积盆地内相对海平面变化及沉积层序形成不仅受全球海平面变化旋回控制，而且沉积盆地所处的构造背景和相关因素，如：沉积物供给、盆底沉降和自然地理条件也对沉积层序及其内部组成——体系域具有极大的影响。对应于海平面变化发育的容纳空间旋回层序，沉积供给也可以形成特征的、可以鉴别的供给旋回层序。具有过渡性界线的三级或高频旋回层序受相对海平面变化和沉积供给双重因素控制。不同构造背景沉积盆地边缘发育不同的盆底沉降速率，相对海平面变化响应于盆缘沉降具有明显的构造－海平面分带，岸线在构造－海平面带中的地理位置决定了层序界面和层序堆叠样式，也同样影响着低位体系域的构成。深水盆地环境古地形特点及沉积物供给制约着深水沉积序列。构造运动显著地影响着沉积层序发育。碳酸盐缓坡和平顶镶边陆架的层序格架及体系域发育受其坡度、盆地深度及下降幅度的因素的作用。台地边缘和大陆边缘盆地浊积岩层序的发育和体系域组成受控于差异的沉积物源（平顶碳酸盐台地、镶边台地和陆源碎屑岩陆架）、古地理及构造活动性     

Permian

Summary Late in the Carboniferous Period or early in the Permian ice covered much of Tasmania (Fig. 30b). The sub‐Permian surface had a relief of several thousand feet with particularly low areas near Wynyard and Point Hibbs and high areas near Cradle Mountain, Devonport, Deloraine, Wylds Crag and Ida Bay and a peninsula in eastern Tasmania (Fig. 30a).

The glaciers from an ice centre north‐west of Zeehan diverged about a higher area near Cradle Mountain. One tongue occupied a deep valley near Wynyard and a lobe fanned out south of the high area to occupy parts of northern and central Tasmania and to override some parts of the east coast peninsula.

West of Maydena the ice scoured shell beds and dumped the shell fragments in the till on the Styx Range. Thus the base of the ice may well have been below sea‐level. Carey and Ahmad (1961) suggested that the Wynyard Tillite was deposited below a “wet‐base” glacier. David (1908, p. 278) suggested deposition from “land ice in the form of a piedmont or of an ice‐sheet” but that near Wynyard the ice came down very close to, if not actually to, sea‐level. The extent of the glaciation and the distribution of erratics of western Tasmanian origin in eastern Tasmania make it seem likely that either a piedmont glacier or an ice‐sheet rather than mountain glaciation was involved.

Following retreat of the glaciers the sea covered the till, probably to a considerable depth, eustatic rise of sea‐level being much more rapid than isostatic readjustment.

The Quamby Group is underlain by or passes laterally into thin conglomerates and sandstones in a number of places, but most of the group appears to be of deep water, partially barred basin origin. Marine oil shales accumulated close to islands. Shallowing of the sea during deposition of the upper part of the Quamby Group seems to be indicated by the fauna and increasing sandiness in marginal areas. Instability in the source areas is shown by the presence of turbidity current deposits in the higher parts of the group. The Golden Valley Group, of Upper Sakmarian and perhaps Lower Artinskian age, was deposited in a shallower sea than the Quamby Group but the deposits are more extensive along the east coast peninsula and on the flanks of the Cradle Mountain island. This anomaly may be explained if the rate of deposition exceeded the rate of rise of sea‐level. The sediments of the Golden Valley Group became finer‐grained upwards in most parts of Tasmania probably indicating reduction in relief of the source area. Some instability is indicated by turbidity current deposits. Uplift of source areas in north‐western Tasmania early in Artinskian time resulted in the spreading of sand over the shallow silts of the Golden Valley Group onto the east coast peninsula and over the Cradle Mountain area. The sand formed a wide coastal plain containing lakes and swamps and the sea was restricted to a small gulf in southern Tasmania during the deposition of the lower part of the Mersey Group. During deposition of this group the sea rose once to form a long, narrow gulf extending as far north as Port Sorell and then retreated. This inundation resulted in the development of two cyclothems in many parts of Tasmania.

A little later in Lower Artinskian time the sea rose and covered most of Tasmania except perhaps the far north‐west. This wide transgression probably resulted from down‐warping as an eustatic rise in sea‐level would be expected to produce thickest deposition over the old gulf in southern Tasmania and along the axis of Mersey Group inundation but the zone of thickest Cascades Group crosses these at a high angle. During deposition of the Cascades Group marine life became very abundant in the shallow sea over which a few icebergs floated. During the Artinskian tectonic instability increased as shown by the increasing number of turbidites in the upper part of the Grange Mudstone and the lower part of the Malbina Formation. The sea became less extensive and the source areas in north‐western and north‐eastern Tasmania were uplifted. The zone of thickest deposition of the Malbina Formation trended north‐north‐westerly. The rapid succession of turbidity currents killed the benthonic fauna and it was only during deposition of the upper part of the formation possibly in Lower Kungurian time that life became abundant again in the Hobart area. The sea spread a little over the east coast peninsula and further instability is recorded in the Risdon Sandstone. The resulting turbidity currents killed the benthonic fauna and it never became properly established again in any part of Tasmania during the Permian. A wide shallow sea covered much of Tasmania and was bordered by low source areas during deposition of the Ferntree Group. The axis of greatest thickness had an almost meridional trend and lay west of that of the Malbina Formation. Late in the Permian, probably in the Tartarian, rejuvenation of the source areas, particularly in western Tasmania, and withdrawal of the sea, resulted in deposition of sands and carbonaceous silts of the Cygnet Coal Measures. The zone of greatest thickness was almost parallel to but west of that of the Ferntree Group.

The thickness of the Permian System and the sheet‐like character of many of the members and formations suggest shelf rather than geosynclinal deposition. The average rate of deposition was of the order of 1 ft. in ten thousand years (about 0–003 mm./annum). However, the sediments differ markedly from those on stable shelves in that many of them are poorly‐sorted. Some of the poor sorting may be attributed to deposition from drifting icebergs but some is due to tectonic instability.

Uplift and downwarping and movement of zones of maximum thickness have been deduced above and it is probable that the tectonic instability started as early as Lower Artinskian and it may have started during Sakmarian (upper part of Quamby Group). Maximum instability seems to have occurred in Middle or Upper Artinskian time (Malbina Formation) and it is probably significant that this was a time of considerable orogenic movement in New South Wales (part of the Hunter‐Bowen Orogeny, Osborne, 1950). Progressive westward movement of zones of maximum thickness of units in Upper Permian time seems to have occurred and this again is reminiscent of the situation at the time in New South Wales (Voisey, 1959, p. 201) but seems to have started later. Uplift and development of a major synclinal structure with a trend approximately north‐north‐westerly occurred late in Permian time.     

Revision of the stratigraphy of Permian and supposed Permian rocks of Southern Scotland

The formal stratigraphy of the Permian basins of southern Scotland is described for the first time. These rocks consist of piedmont breccias and lavas, overlain by wadi-fan and dune complexes, and alluvial fan and floodplain sediments. The sequences are inferred to be Stephanian to Lower Permian in age and correlatable with similar continental sediments in England and with the Lower Rotliegendes of Germany and the North Sea.

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Zusammenfassung Erstmals wird hier eine stratigraphische Gliederung der permischen Beckensedimente im südlichen Schottland gegeben. Diese Gesteine bestehen aus Piedmont-Brekzien und Laven, die von Fanglomeraten und Dünenkomplexen überlagert werden. Alluviale Fächer und Schwemmflächen-Sedimente gehören hierzu. Diese Serien sollen ein Alter von Stephan bis Unter-Perm aufweisen und vergleichbar mit ähnlichen kontinentalen Sedimentfolgen in England und im Unter-Rotliegenden von Mitteleuropa sein.

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Résumé La stratigraphie des formations des bassins permiens du Sud de l'Ecosse est ici décrite pour la première fois. Ces roches sont des brèches de piedmont et des laves, surmontées par un complexe de dépôts d'épandage et de dunes, et par des cones et des dépôts alluviaux. Les couches seraient à rapporter au Stéphanien et au Permien inférieur, et à correler avec des sédiments continentaux semblables en Angleterre et avec le Rothliegend inférieur d'Allemagne et de la Mer du Nord.

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. Piedmont , . . - ; .

     

中国二叠系 的属带与国际二叠系的阶

中国已建立的二叠系各阶的(筵)的属带,对中国二叠系生物地层的研究曾起到重要的作用.由于二叠系的(筵)的属带时限都很长,定义不明确和地方性较强,中国二叠系的阶不宜再用(筵)的属带来确定.国际二叠系的主导化石门类是牙形刺.二叠系的3统9阶都是用牙形刺来确定的,而不是用(筵),更不是用(筵)的属带.进一步研究(筵)类各属内的种一级的谱系演化关系,参照牙形刺带确认(筵)的属种的时限,进行不同相区的对比,是今后二叠纪生物地层研究的重要任务.     

桂西地区二叠系合山组铝土岩的沉积环境*

桂西地区二叠系合山组铝土岩的沉积环境存在海相、陆相之争。通过对桂西二叠系铝土岩的区域调查及钻孔样品微量元素地球化学数据的分析,认为桂西二叠系铝土岩产出于陆相环境。从铝土岩分布情况看,桂西二叠纪各孤立碳酸盐岩台地上均广泛分布铝土岩沉积,该区域产出特征证明矿层是在碳酸盐岩台地全部暴露地表的环境下形成的。从铝土岩层与下伏茅口组灰岩的接触关系来看,铝土岩层底部存在茅口组灰岩砾石,在部分剖面尚见下伏茅口组灰岩中充填铝土岩等现象,说明铝土岩矿化过程直接于茅口组灰岩的古喀斯特面上完成。此外,在矿层中发现古植物根茎化石也是铝土岩形成于陆相环境的有力证据。从微量元素地球化学结果来看,来自铝土岩层样品的硼含量均小于10×10^-6,Sr/Ba值范围为0.29~1.61,平均值为0.92,Rb/K值范围为0.0011~0.0025,平均值为0.0017,以上指标结合V/Zr-Zr/Cu图解的判别,结果均指示铝土岩形成于陆相淡水环境。     

Oldhaminid brachiopods from the Permian of Transcaucasia

The Oldhaminoidea are classified as a suborder of the Productida, on the basis of the new genus Spinolyttonia which has productid spines, and on other morphological considerations. The Transcaucasian oldhaminoids are described in support of this position, with detailed treatment of the genera Keyseriingina Tschernyschev, Leptodus Kayser, Oldhamina Waagen, Gubleria H. and G. Termier, Spinolyttonia Sarycheva (nov.), and Poikilosakos Watson. The Transcaucasian fauna is Upper Permian (Guadalupian and Dzhulfian).—R. E. Grant     

Mineralogy of the Permian laterite of Northwestern Iran

Summary Laterite horizons of Permian age in NW Iran contain diagenetic and low grade metamorphic minerals. Chloritoid is ubiquitous in the metamorphic mineral assemblages. The chemical compositions of three meta-laterites satisfy the conditions for the formation of chloritoid. The comparison of the metamorphic mineral assemblages with experimental data indicates an equilibration temperature not exceeding 375–400°C.

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Zur Mineralogie permischer Laterite in Nordwest-Iran

Zusammenfassung Permische Laterithorizonte in Nordwest-Iran enthalten diagenetische und schwach metamorphe Minerale. Chloritoid kommt in den metamorphen Mineralparagenesen überall vor Die chemischen Zusammensetzungen dreier Metalaterite erfüllen die Bedingungen für die Bildung von Chloritoid. Der Vergleich der metamorphen Mineralvergesellschaftungen mit experimentellen Daten weist auf eine Gleichgewichtseinstellung bei einer Temperatur von nicht über 375–400°C hin.

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With 2 Figures     

Late Permian non-marine–marine transitional profiles in the central Southern Permian Basin, northern Germany

The transition from Rotliegend to Zechstein within the Southern Permian Basin is one from continental desert to a marine environment. During the Upper Rotliegend II a huge playa lake existed there. This lake was temporarily influenced by precursors of the Zechstein transgression. Therefore the mega-playa evolved into a sabkha system. One of these early marine ingressions is known from an outcrop in Schleswig-Holstein. Laminated silt- and claystones, deposited within a standing water body, are intercalated in siltstones of a salt-flat environment. The lake sediments are characterised by high frequency cyclicity, shown by the sedimentary record and also by palaeontological data. The section contains fresh water as well as brackish-marine and marine fauna. Climatically forced cycles interact with marine incursions. After the Zechstein transgression had flooded the basin completely, sedimentation was controlled by sea-level fluctuations. Two sections, in the southern North Sea and in Schleswig-Holstein, are presented in this paper. Cyclicities with different frequencies controlled the sedimentation of the Kupferschiefer (T1) and the Werra Carbonate (Ca1). Sediments of the North Sea sequence were deposited within a shallow bay at the margin of an elevation. Therefore, the high frequency cyclicity became obvious within the sedimentary patterns and in the faunal content.     

中国北方地区二叠纪岩相古地理

主要以实地踏勘和测量建立的87个标准剖面及529个辅助剖面为基础，通过对二叠系分布格局、岩石学特征、沉积构造特征、古气候、古生态、古环境等分析，来恢复中国北方地区二叠纪的古地理面貌。早二叠世：主要存在额尔古纳和佳木斯古陆，塔里木-敦煌-祁连-内蒙古古陆；海域主要分布在松辽海相区，华北残留海湾相区，柴西残留海湾相区和南准噶尔-吐哈-北山残留海湾相区；此外还有塔里木西部碳酸盐台地相区和准噶尔腹部河湖相区。中二叠世：早二叠世的古陆依然存在，但华北北部古陆范围明显缩小，而准噶尔南缘-吐哈地区已上升成为陆地；海域只局限在东北和南祁连地区，华北地区-北祁连地区大面积为河湖相发育区；塔里木盆地主要为陆相碎屑岩沉积；准噶尔地区发育河湖相沉积，北山残留海盆火山碎屑岩发育。晚二叠世：仅在南祁连地区有海相沉积，其他地区均为陆相沉积，东北地区陆相和湖泊相沉积占主导地位；华北地区-北祁连地区主体为河湖相沉积；塔里木盆地整体为河湖相沉积；准噶尔-吐哈盆地主体为河湖相沉积。