广西田东布兵石炭纪水下沉积灰岩脉及其地质意义
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摘要
笔者等首次在德保台地边缘上泥盆统灰岩中发现大量多期次下石炭统杜内阶之灰岩岩脉;通过调查,查明岩脉的形态、沉积物特征、时代及其分布规律,首次在沉积岩脉中采获早石炭世早期牙形刺及Gnathodus与Siphnodella大量混生的现象。经过调查研究,对岩脉的成因有新的认识:其形成是构造与地震相结合的产物,地震造成台地的隆升、沉降,使上泥盆统已成岩的刚性灰岩发生断裂,形成较深层的张性(拉张)裂隙,早石炭世未成岩的软沉积物及碎屑灌入裂隙中,形成灰岩脉。多期次的构造运动、拉张,造成张性裂隙的多次的张裂,多期次灌入则形成似直立产状的岩墙。这一成因模式既能合理解释岩脉中具有地震造成的液化脉之现象,又能解释形成如此深度岩脉的动力因素,也能解释台地边缘相中有深水相的沉积物及生物之物质来源。通过对岩脉的调查及研究,对理解右江盆地的构造演化具有重要的意义。
On the Debao platform margin,writers firstly discover numerous multi-phased limestone dikes of the Lower Carboniferous Tournaisian stage in the Devonian limestone.The shapes,sedimentary characteristics,age and distribution pattern of the dikes are made clear.Writers have found many conodonts of Early Carboniferous as well as the phenomena that Gnathodus and Siphnodella mixed in sedimentary dikes.Writers get a new understanding for the genesis of the dikes.The dykes are the incorporation products of tectonic movements and earthquakes.In Early Carboniferous,the Upper Devonian solidified limestones splited when the platform uplifted and settled down by the earthquake,formed deep tensile cracks,thus the Early Carboniferous soft sediments and fragments injected into the cracks,formed the dikes.Multi-phased tectonic movements and tension,result in the tensile fractures repeatedly opening,lead to formation of the multi-phased vertical dikes.This genesis pattern can reasonablly explain the seismic liquefied veins appear in the dikes and the dynamic factors of such deep-seated dikes as well as the sources of the deep-water facies sediments and bio-clastics in the dikes on a platform margin.It is important for understanding the tectonic evolution of the Youjiang basin to investigate and study the limestone dikes.
On the Debao platform margin,writers firstly discover numerous multi-phased limestone dikes of the Lower Carboniferous Tournaisian stage in the Devonian limestone.The shapes,sedimentary characteristics,age and distribution pattern of the dikes are made clear.Writers have found many conodonts of Early Carboniferous as well as the phenomena that Gnathodus and Siphnodella mixed in sedimentary dikes.Writers get a new understanding for the genesis of the dikes.The dykes are the incorporation products of tectonic movements and earthquakes.In Early Carboniferous,the Upper Devonian solidified limestones splited when the platform uplifted and settled down by the earthquake,formed deep tensile cracks,thus the Early Carboniferous soft sediments and fragments injected into the cracks,formed the dikes.Multi-phased tectonic movements and tension,result in the tensile fractures repeatedly opening,lead to formation of the multi-phased vertical dikes.This genesis pattern can reasonablly explain the seismic liquefied veins appear in the dikes and the dynamic factors of such deep-seated dikes as well as the sources of the deep-water facies sediments and bio-clastics in the dikes on a platform margin.It is important for understanding the tectonic evolution of the Youjiang basin to investigate and study the limestone dikes.
引文
广西壮族自治区地质矿产局.1988.桂林市区域地质调查报告.广西桂林市瓦窑印刷厂.
广西壮族自治区地质局第八地质队,淮南煤炭学院.1978.广西凌云早二叠世沉积灰岩脉和沉积灰岩体的发现及其对研究古构造的意义.见:国际交流地质学术论文集(一).北京:地质出版社:272～278.
广西壮族自治区地质矿产局.1992.广西的泥盆系.武汉:中国地质大学出版社.
黄宏伟,杜远生,黄志强,陈海.2007.广西丹池盆地晚古生代震积岩及其构造意义.地质论评,53(5):577～585.
邝国敦,吴浩若.2002.桂西晚古生代深水地层.地质科学,37(2):152～164.
邝国敦.2001.桂西晚古生代深水沉积研究的新进展.广西地质,14(3):1～6.
陆刚,胡贵昂,张能,张耿,潘艺文,彭阳.2006.右江盆地二叠纪生物礁时空分布和沉积构造演化新知.地质论评,52(2):190～197.
吕洪坡,章雨旭,夏邦栋,方中,周伟明,彭阳,吴智平,李伟.2003.南盘江盆地中三叠统复理石中的同沉积挤压构造.地质论评,49(5):449～456.
彭阳,李岩,胡贵昂,陆刚,乔秀夫.2007.广西桂林庙头上泥盆统融县组中的灰岩脉和角砾灰岩体及其成因.地质论评53(5):736～743.
彭阳,陆刚,胡贵昂,周敏,乔秀夫,章雨旭.2009.广西凌云下甲二叠纪沉积灰岩墙和角砾灰岩体的成因及地质意义.地质论评,55(1):731～737.
彭阳,胡贵昂,陆刚,章雨旭,乔秀夫.2004.桂西北晚古生代地层中的沉积灰岩墙研究进展.地质论评,50(6):613～619.
乔秀夫,彭阳,高林志.2002.桂北二叠纪灰岩墙(脉)的地震成因解释,地质通报,21(2):102～104.
张继淹.1995.广西水下沉积岩脉群特征及形成机理,中国区域地质,(4):309～311.
广西壮族自治区地质局第八地质队,淮南煤炭学院.1978.广西凌云早二叠世沉积灰岩脉和沉积灰岩体的发现及其对研究古构造的意义.见:国际交流地质学术论文集(一).北京:地质出版社:272～278.
广西壮族自治区地质矿产局.1992.广西的泥盆系.武汉:中国地质大学出版社.
黄宏伟,杜远生,黄志强,陈海.2007.广西丹池盆地晚古生代震积岩及其构造意义.地质论评,53(5):577～585.
邝国敦,吴浩若.2002.桂西晚古生代深水地层.地质科学,37(2):152～164.
邝国敦.2001.桂西晚古生代深水沉积研究的新进展.广西地质,14(3):1～6.
陆刚,胡贵昂,张能,张耿,潘艺文,彭阳.2006.右江盆地二叠纪生物礁时空分布和沉积构造演化新知.地质论评,52(2):190～197.
吕洪坡,章雨旭,夏邦栋,方中,周伟明,彭阳,吴智平,李伟.2003.南盘江盆地中三叠统复理石中的同沉积挤压构造.地质论评,49(5):449～456.
彭阳,李岩,胡贵昂,陆刚,乔秀夫.2007.广西桂林庙头上泥盆统融县组中的灰岩脉和角砾灰岩体及其成因.地质论评53(5):736～743.
彭阳,陆刚,胡贵昂,周敏,乔秀夫,章雨旭.2009.广西凌云下甲二叠纪沉积灰岩墙和角砾灰岩体的成因及地质意义.地质论评,55(1):731～737.
彭阳,胡贵昂,陆刚,章雨旭,乔秀夫.2004.桂西北晚古生代地层中的沉积灰岩墙研究进展.地质论评,50(6):613～619.
乔秀夫,彭阳,高林志.2002.桂北二叠纪灰岩墙(脉)的地震成因解释,地质通报,21(2):102～104.
张继淹.1995.广西水下沉积岩脉群特征及形成机理,中国区域地质,(4):309～311.
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