| 西秦岭北带泥盆纪遗迹群落在浊积岩系中的分布特征 |
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| 引用本文： | 晋慧娟,李育慈.西秦岭北带泥盆纪遗迹群落在浊积岩系中的分布特征[J].沉积学报,1997,15(1):13-19. |
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| 作者姓名： | 晋慧娟 李育慈 |
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| 作者单位： | 中国科学院兰州地质研究所, 兰州 730000 |
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| 摘 要： | 本文重点研究内容是:1）舒家坝组时代的厘定和层序叠置关系；2）遗迹群落总体概况以及各遗迹属确定的依据；3）浊流沉积作用控制遗迹群落的形成及其分布特征。通过本文研究不难看出，舒家坝组的43个遗迹化石属可划分为两大类。一是形成于浊流间歇期缓慢沉积的泥岩层面，主要为“深水型”遗迹分子；另一是产于浊流突然事件来临及其后快速堆积的砂岩内，包括“浅水型”和“穿相型”分子。就其分异度和丰度而言，虽均以前者最高，但这两类遗迹化石组合共生在一个沉积剖面，这恰是浊积岩系（复理石相）遗迹化石分布的独有特征。
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| 关 键 词： | 分布特征 遗迹群落 西秦岭北带泥盆系 |
| 收稿时间： | 1996-04-01 |
Distribution Characteristics of Trace Forssil Group in Turbidite Measure (Devonian) in the Northern Belt of West Qinling Mountains |
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| Jin Huijuan and Li Yuci.Distribution Characteristics of Trace Forssil Group in Turbidite Measure (Devonian) in the Northern Belt of West Qinling Mountains[J].Acta Sedimentologica Sinica,1997,15(1):13-19. |
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| Authors: | Jin Huijuan and Li Yuci |
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| Institution: | Lanzhou Institute of Geology Chinese Academy of Sciences Lanzhou 730000 |
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| Abstract: | 43 trace fossil ichnogenera have been found in Devonian Shujiaba Formation distributed in thenorthern belt of West Qinling Mountains, and they areAcanthorhaphe Arthophcus, Belorhaphe，Bostri -cophyton, Buthotrephis, Cochilidznus, Chondrites, Cosmorhaphe, Dictyodora，Fucusopsis, Glockeria，Gordia，Gran ula ria，Helicolithus, Helminthoida，Helminthopsis, Lennea，Loph octen ium，Megagrap tort，Neonereites, Nereies, Palaeohelminthoida，Paleod ictyon，Planolites, Protopaleodictyon,,Protovirgular-is，Rhabdoglyphus, Rhobdoichnus, Rusophycus(?)，Saerichnites, Sagittichnus, Scolicia，Skol ithos,Spirophycus,Spirorhaphe,Squamodictyon,Subloren,Subularia,Subhyllochorda，Taphrhelminthoida, Taphrhelminthopsis, Tuberculichnus, Urohelminthoida.All the host rocks of trace fossils mentioned aboveare to rbidi to depo sit s, s o i t iseasy toseethere exists a close link between the formation of trace fossil and turbidity process. According tothatthetime of pre- and post-turbiditynized, and they are current event, twsharply different fossil assemblages canbe recog-1) Trace fossil assenblag a fo rmed befo re turbidi ty ev entThey are produced in a low-energy abyssal environment in the interval of tubidity process, with twotypical feature① animals live and seek for food horizontally in the surface deposits,and trace fossil sa remainly preserved in the Te mudstone surfac of the Bouma sequence;②Generally, they appear incurve,snake and network shapesof which overAnd they are the typical members of "Nereites”features.70% ichnogeneraareformed before the turbidity event.fades with high degree of differentiation and abundance2) Trace fossil assemblage formed after turbidity eventThey are of lowabundance and degreespanning fadesty peof differentiation, and are characterized by the irregular”shalloww ater”and”members, generally preserved in the sandstone parts of thesequence or piercing sandstone. They are not in the leading role among the fossils discovered.Although the abundance and degree of differentiation of trace fossils formed before the turbidityevent :ire g ready higher than that formed after the event, they are of equivalently important role in theturbidite measure for their appearrance reflects the replacement of "fastlow-fast”sedimentation rate,i. e the whole process of the formation is a complete turbidite depositional sequence. Thus we canlink the two sharply lifferent trace fossil assemblages in accordance with their origin, and use them as apaleoichnological indicator of bethyal byssal turbidite measure. |
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| Keywords: | characteristics of distribution trace fossil group devonian northern belt of west Qinling mountains |
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