| 洞庭盆地两护村孔孢粉组合及其气候与地层意义 |
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| 引用本文： | 柏道远,李长安,张文卿,陈渡平,周柯军.洞庭盆地两护村孔孢粉组合及其气候与地层意义[J].地质科学,2010,45(4):1125-1138. |
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| 作者姓名： | 柏道远 李长安 张文卿 陈渡平 周柯军 |
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| 作者单位： | 1.湖南省地质调查院 长沙 410011； 2.中国地质大学（武汉）地球科学学院武汉 430074；3.中国地质科学院水文地质工程地质方法研究所 河北保定 071051 |
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| 基金项目： | 中国地质调查局地质大调查项目，国家自然科学基金 |
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| 摘 要： | 两护村ZKC1孔位于洞庭盆地安乡凹陷的东南部,孔内第四系(底部跨上新世)厚达294 m,为河流和湖泊沉积,自下而上依次为上新世—早更新世华田组、早更新世汨罗组、中更新世洞庭湖组、晚更新世坡头组以及全新统等。对ZKC1孔第四系进行了详细的孢粉分析,自下而上划分出16个孢粉组合带。ESR年龄和孢粉组合及其反映的气候特征指示华田组下段形成于上新世末。根据孢粉组合特征,结合构造—沉积演化和区域气候背景,重塑洞庭盆地上新世末以来的气候演化过程:上新世末期由孢粉带Ⅰ和Ⅱ指示具暖干气候。早更新世经历了凉干(孢粉带Ⅲ、Ⅳ)→暖湿间凉干(孢粉带Ⅴ～Ⅶ)→冷干间温湿(孢粉带Ⅷ～Ⅹ)→暖较湿(孢粉带Ⅺ,Ⅻ)的气候演变过程。中更新世早期无孢粉样品(洞庭湖组下部砾石层),其沉积环境暗示冷干气候条件;中期由孢粉带ⅩⅢ反映出暖稍湿的气候特征;晚期因构造抬升缺失沉积,同期湿热化事件指示暖湿气候。晚更新世早期缺乏沉积,据区域对比应为寒冷气候;中期由孢粉带ⅩⅣ指示温较湿的气候特征;晚期缺失沉积,系寒冷气候下区域海平面下降所致。全新世经历了暖稍湿(孢粉带ⅩⅤ)→暖稍干(孢粉带ⅩⅥ)的演变。上述气候演变过程与ZKC1孔化学蚀变指数曲线反映的气候演变过程以及中国东部第四纪气候演化基本吻合。以孔深140 m为界,上部孢粉数量显著高于下部,种属也更为丰富。这一变化很可能对应于一次重要的地质事件,其成因有待今后深入研究。
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| 关 键 词： | 两护村孔 上新世 第四纪 孢粉 气候 洞庭盆地 |
| 收稿时间： | 2009-10-12 |
| 修稿时间： | 2010-03-26 |
Sporopollen assemblages of the core from Lianghucun borehole in Dongting Basin and their climatic and stratigraphic implications |
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| Bai Daoyuan,Li Chang'an,Zhang Wenqing,Chen Duping,Zhou Kejun.Sporopollen assemblages of the core from Lianghucun borehole in Dongting Basin and their climatic and stratigraphic implications[J].Chinese Journal of Geology,2010,45(4):1125-1138. |
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| Authors: | Bai Daoyuan Li Chang'an Zhang Wenqing Chen Duping Zhou Kejun |
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| Institution: | 1.Hunan Institute of Geology Survey|Changsha 410011； 2.Faculty of Earth Sciences； China University of Geosciences； Wuhan 430074； 3.Institute of Technologic Method of Hydrogeology & Engineering Geology|CAGS|Baoding|Hebei 071051 |
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| Abstract: | Lianghucun ZKC1 borehole is located in southeastern Anxiang sag of Dongting BasinQuaternary sediments(including bottom Pliocene deposits)with thickness of 294 m in the borehole are composed of alluvial and lacustrine deposits，and were composed of Pliocene Early Pleistocene Huatian Formation，Early Pleistocene Miluo Formation，Middle Pleistocene Dongtinghu Formation，Late Pleistocene Potou Formation and Holocene depositsDetailed sporopollen analysis on the Quaternary deposits from ZKC1 borehole was conducted and 16 sporopollen zones were identifiedESR age，sporopollen assemblages and corresponding climatic feature indicate that the lower part of Huatian Formation was formed at the end of PlioceneAccording to the features of sporopollen assemblages and combined with tectonic sedimentary evolution and regional climatic settings，the climatic evolution of Dongting Basin since the end of Pliocene was revealed as follows：Sporopollen zone Ⅰ and Ⅱ indicate that the climate at the end of Pliocene was tropical and dryFrom early to late，The climatic variations during Early Pleistocene are cool and dry(sporopollen zone Ⅲ and Ⅳ)，tropical and humid interposed with cool and dry(sporopollen zone Ⅴ～Ⅶ)，cold and dry interposed with warm and humid(sporopollen zone Ⅷ～Ⅹ)，tropic and weakly humid(sporopollen zone Ⅺ and Ⅻ).During Early Middle Pleistocene with no sporopollen sample the climate was cold and dry，which is suggested by sedimentary environment of gravels from lower part of Dongtinghu Formation； during middle Middle Pleistocene the climate was tropical and weakly humid which is indicated by sporopollen zone ⅩⅢ； during late Middle Pleistocene with no deposits formed for rise，the climate was tropical and humid which is indicated by tropical humid eventAccording to regional climatic feature，the climate was dry in early Late Pleistocene with no deposits formed； during middle Late Pleistocene the climate was warm and weak humid which is indicated by sporopollen zone ⅩⅣ； there were no deposits formed for cold climate and sea level droppedFrom early to late，The climatic variations during Holocene are tropical and weak humid(sporopollen zone ⅩⅤ)， and tropical and weak dry(sporopollen zone ⅩⅥ). This climatic evolution process coincide basically with climatic change indicated by CIA(chemical index of alteration)，and with Quaternary climatic variations of eastern ChinaThere exist a sporopollen boundary at depth of 140 m over which there were more pollen and spore then underThis variation was in all probability related with an important geological event，and the cause of formation await embedded research in future. |
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| Keywords: | Lianghucun borehole Pliocene Holocene Pollen and spore Climate Dongting Basin |
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