【作者】 周方；

【导师】 胡斌；

【作者基本信息】 河南理工大学 ， 古生物与地层学， 2010， 硕士

【摘要】 本文在对野外剖面及岩心观察描述的基础上,通过详细的岩石学、沉积学和遗迹学分析,将豫西早二叠世太原组划分为以下五种沉积相带:(1)远岸浅海相;(2)近岸浅海相;(3)海湾-泻湖相;(4)潮坪-沼泽相;(5)障壁岛(砂质滩、坝)相。远岸浅海相以深灰色泥晶生物屑灰岩、生物屑泥晶灰岩和泥灰岩沉积为主,形成在台地相区浪基面之下、水体相对较深的沉积环境中。近岸浅海相以发育五种不同类型的碳酸盐岩风暴沉积为特征,代表了台地相区浪基面之上、海水动荡环境的沉积记录。海湾-泻湖相包括障壁岛、泻湖、混合坪、泥炭坪和泥坪等沉积类型,形成在较闭塞、水体较平静且还原程度较高的环境中。潮坪-沼泽相由潮道、潮沟、砂坪、混合坪、泥坪、泥炭坪等沉积类型组成,反映了水体较浅,并且周期性暴露水面的沉积环境。障壁岛(砂质滩、坝)相以发育成熟度较高的中-细粒石英砂岩为主,反映了滨岸地带强水动力条件下的沉积特征。豫西地区下二叠统太原组中的遗迹化石主要产于上、下灰岩段,少量见于中部碎屑岩段。遗迹化石丰度、分异度都较高,已识别出遗迹化石10属11种,包括Zoophycos brianteus,Zoophycos villae, Teichichnus rectus,Nereites isp., Chondrites isp., Rhizocorallium isp.,Thalassinoides suevicus,Ophiomorpha nodosa,Gordia marina,Taenidium satanassi和Planolites isp.等。根据上述遗迹化石组成及其在地层中的分布以及围岩的沉积特征,豫西地区早二叠世太原组识别出三种遗迹群落:(1)Zoophycos—Nereites遗迹群落,出现在水体相对较深、浪基面之下且沉积底层贫氧的远岸浅海沉积环境中;(2)Zoophycos—Taenidium遗迹群落,产生于水体相对较浅浪基面之上的近岸浅海沉积环境中;(3)Ophiomorpha—Thalassinoides遗迹群落,发育于海岸带潮坪或海湾泻湖沉积环境中。其中Zoophycos—Nereites遗迹群落仅出现在太原组下部灰岩段L5灰岩中部,代表了在整个太原组沉积期水体最深时留下的遗迹群落;而Ophiomorpha—Thalassinoides遗迹群落和Zoophycos—Taenidium遗迹群落在太原组上、下灰岩段均大量发育,表明豫西太原组是以浪基面之上的高能浅海风暴沉积与低能泻湖潮坪沉积交互出现为特征的沉积格局。更多还原

【Abstract】 On the basis of description and observation of outcrops and cores, and the detailed analysis on petrology, sedimentology and ichnology,the Early Permian Taiyuan Formation of Western Henan can be divided into five sedimentary facies in this paper: (1)distal shallow marine facies, (2)proximal shallow marine facies, (3)bay and lagoon facies, (4)tidal flat and peat swamp facies, and (5)barrier island (sandy shoal and bar)facies. The distal shallow marine facies is dominated by dark muddy biolastic limestone, biolastic micrite and marl and is formed in deep carbonate platform environment under storm wave base. The proximal shallow marine facies includes five different types of carbonate storm deposits and represents high energy carbonate platform environment under fair weather wave base. The bay and lagoon facies consists of barrier island, lagoon, bay, mixed tidal flat, peat flat and muddy flat deposits and is preserved in low energy restricted sedimentary environment at high reducibility condition. The tidal flat and peat swamp facies comprises tidal channel, tidal creek, sandflat, mixed flat,mudflat and peat flat deposits and occurs in periodically exposed shallow tidal environment. High maturity medium and fine quartzose sandstone is dominant in the barrier island (sandy shoal and bar)facies and is deposited in high energy coastal environment.The trace fossils in the Early Permian Taiyuan Formation of Western Henan Province are mainly from the Upper Limestome Member and the Lower Limestome Member, only a little in the Middle Clastic Member. They display a higher ichnoabundance and ichnodiversity and include 10 ichnogenera and 11 ichnospecies such as Zoophycos brianeus,Zoophycos villae, Teichichnus rectus,Nereites isp., Chondrites isp., Rhizocorallium isp.,Thalassinoides suevicus,Ophiomorpha nodosa,Gordia marina,Taenidium satanassi, Planolites isp. and so on. Three ichnocoenose can be recognized from the Taiyuan Formation according to the composition and distribution of trace fossils and sedimentology of the host rock. Zoophycos—Nereites ichnocoenosis is formed in distal shallow marine environment below storm wave base and indicates low oxygen level in the interstitial waters within the sediments at the site of trace emplacement. It only occurs in L5 of the Lower limestone Member and represents the sedimentary record when marine transgression reached its maximum within depositional period of the Taiyuan Formation. Zoophycos—Taenidium ichnocoenosis is preserved in proximal shallow marine environment above storm wave base and is commonly made in high energy storm deposits. Ophiomorpha—Thalassinoides ichnocoenosis is formed in the marlite or calcareous siltstone and thin-bedded fine sandstone in tidal flat and lagoon sedimentary environments. The last two ichnocoenose are widely distributed in Lower and Upper Limestone Members, which indicating the dominating depositional framework of alternating occurrence between high energy shallow marine storm deposits and low energy lagoon and tidal flat deposits above storm wave base in the Taiyuan Formation of Western Henan Province.更多还原