| 陇东三叠系延长组主要油源岩发育时期的古气候特征 |
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| 引用本文： | 吉利明,吴涛,李林涛.陇东三叠系延长组主要油源岩发育时期的古气候特征[J].沉积学报,2006,24(3):426-431. |
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| 作者姓名： | 吉利明 吴涛 李林涛 |
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| 作者单位： | 中国科学院地质与地球物理研究所 兰州 730000 |
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| 基金项目： | 2002年度中国科学院“西部之光”人才培养计划，2003年度甘肃省中青年科技基金资助. |
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| 摘 要： | 鄂尔多斯盆地西南部陇东地区延长组长8段和长7段分别发现以Aratisporites- Punctatisporites和Asseretospora-Walchiites为代表的孢粉组合,时代分别为中三叠世晚期与晚三叠世早期。通过现生主要植物类型生态环境分布规律的讨论和孢粉植物群已知亲缘关系类型的地层分布特征研究,推测陇东地区中晚三叠世气候温暖潮湿,雨量充沛,植被茂盛。孢粉植物群反映的古气候为温带—亚热带暖湿或湿热气候。孢粉植物群特征与孢粉化石分异度曲线都表明,本地区长8—长7段沉积时期为持续温暖潮湿的适宜期, 与湖泊发展的长8期大规模湖进和长7期的最大湖泛相一致。孢粉植物群具有北方植物群的明显特征,由于本地区当时濒临大型湖泊,而且长8—长7段沉积时期正处于湖泊扩张的鼎盛期,因此显示出更为湿润的古环境特征。正因为长期稳定温暖潮湿气候和广大的深水湖泊环境为水生藻类的大规模发育创造了条件,从而为本地区长7期优质烃源岩的形成提供了母质来源。
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| 关 键 词： | 鄂尔多斯盆地 延长组 孢粉组合 古气候 |
| 文章编号： | 1000-0550（2006）03-0426-06 |
| 收稿时间： | 2005-07-14 |
| 修稿时间： | 2005-09-20 |
Paleoclimatic Characteristics During Sedimentary Period of Main Source Rocks of Yanchang Formation (Triassic) in Eastern Gansu |
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| JI Li-ming,WU Tao,LI Lin-tao.Paleoclimatic Characteristics During Sedimentary Period of Main Source Rocks of Yanchang Formation (Triassic) in Eastern Gansu[J].Acta Sedimentologica Sinica,2006,24(3):426-431. |
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| Authors: | JI Li-ming WU Tao LI Lin-tao |
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| Institution: | Institute of Geology and Geophysics, Chinese Academy of Science, Lanzhou 730000 |
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| Abstract: | A great number of sporopollen fossils have been discovered in Chang 8 and Chang 7 intervals of Yanchang Formation from drilling cores of Longdong area in the southwestern Ordos Basin,and they were named as Aratisporites-Punctatisporites assemblage and Asseretospora-Walchiites assemblage,respectively.Their characteristics are similar to the sporopollen assemblages of Tongchuan Formation and Yanchang Formation discovered in the southeast of thebasin,and the geologic times of the assemblages are Ladinian of the late Middle Triassic and Carnian of the early Late Triassic.Based on the environmental distribution of main plant types at present and the analysis of the content of types to recognize the relationship between palynological flora and the characteristics of stratagraphic distribution,we can infer that the climate was warm and moist then,rainfall was plentiful,and the vegetation was luxuriantduring Middle Triassic and Late Triassic in Longdong area.The paleoclimate reflected by palynological flora was warm-wet or hot-wet in temperateto subtropical.The ecological types of palynological flora and the diversity curves of palynoflora indicate that the Chang 8 and Chang 7 phases were suitable period of continuously warm and humid in the area,and the extensive lacustrine transgression occurredin Chang 8 phrase during the development of lake as well as sustaining maximum flooding in Chang 7 phase.It was semi-humidity temperate to subtropical climate during Middle Triassic and Late Triassic in northern China.The palynological flora discovered from the Chang 8 and Chang 7 intervals in Longdong area is obviously characteristic of the northern China flora. However,becausethearea was close to the large-scale lake at that time,and the Chang 7 and Chang 8 phases werethe great prosperous period that lake wasbeing expanded,so the characteristics of moister paleoenvironment was indicated.It was just because of long-term stable warm and wet climate and the extended deep lake environmentthat created conditions for large-scale growth of hydrophilousalga,consequently they provided organic matter for the high-quality source rocks of Chang 7 section in thearea. |
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| Keywords: | Ordos Basin Yanchang Formation sporopollen assemblage paleoclimate |
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