广西桂林南边村上泥盆统沉积灰岩脉研究
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摘要
沉积灰岩脉广泛发育在桂林及桂西北右江盆地晚古生代碳酸盐岩台地边缘。广西桂林南边村泥盆纪—石炭纪(层55～56)国际副层型剖面中,沉积灰岩脉分别出现在层50(为多条栉壳状方解石细脉标示拉张的构造背景)和层45(为液化颗粒灰岩脉)。层45中的液化颗粒灰岩脉与在桂林庙头剖面和桂西北右江盆地晚古生代地层中广泛发育的沉积灰岩脉有较大差异:桂林庙头和右江盆地晚古生代碳酸盐岩台地边缘的沉积灰岩脉中充填物大多数为与围岩有时差的后期正常海水沉积物,而层45内的沉积灰岩脉中充填物为上覆软沉积物液化颗粒流。由砂屑、生物屑颗粒组成:砂屑成分为含铁泥质、破碎方解石晶体及细小生物屑,呈暗色,彼此紧密接触,几乎没有填隙物,并常因挤压而变形,表明砂屑为非正常海水沉积物;生物屑主要为腕足类和海百合茎,挤在砂屑颗粒之间,且海百合茎纤细侧剌保存完好、腕足壳完整,被缓慢挤压变形几近U型合拢并原地寸断——佐证颗粒为非正常海水沉积物。脉顶端显示上宽下稍窄V字型,脉壁无侵蚀但贴有红色铁质泥皮(表明短暂间断);而且在周围岩层中找不到与脉内岩性结构相同的沉积地层。因此脉中颗粒物应来源于上覆弱固结沉积物流。晚泥盆世晚期,在拉张的构造背景下,桂林及右江盆地各台地边缘同沉积正断层活动并伴生张裂隙,同时诱发地震;桂林庙头剖面和右江盆地各含沉积灰岩脉剖面多数处在陡峭的台地边缘,是无沉积刚性正地形(bypassing),因此同沉积正断层及地震只在此形成伴生刚性张裂隙,并在下次海侵时接受正常海水沉积物;桂林南边村剖面处于靠近台缘的斜坡位置,因此具有上覆软沉积物;当台缘同沉积正断层及地震活动波及时,形成少量张裂隙,而上覆软沉积物,如准同生灰泥、砂屑、生物屑、亮晶胶结物、铁泥质等,与孔隙水混合形成粘稠的液化颗粒灰岩流,灌入这些张裂隙。二者裂隙成因均与台缘同沉积断层的构造—地震活动密切相关。即:同沉积断层发生时,在南边村剖面层45中产生刚性张裂隙,而其上覆地层的沉积物还处在弱固结的塑性状态,发生混合、颗粒化形成塑性液化颗粒流灌入下伏裂隙中。因此,南边村剖面层45中的沉积灰岩脉是软硬岩层对同沉积断层活动诱发地震的不同响应。而南边村剖面晚泥盆世所处的台缘靠近斜坡的古地理位置是其沉积灰岩脉的内部结构构造与众不同的原因。
Carbonate neptunian dykes occurred commonly in Late Palaeozoic carbonate plateform margins in Guilin and Northwestern Youjiang basin, Guangxi Autonomous Region. In the Nanbiancun International Devonian— Carboniferous (bed 55~56) Boundary (DCB) Parastratotype Section of Guilin of Guangxi, carbonate neptunian dykes are identified in Bed 45 (a liquefied grainstone vein) and Bed 50 (some fine crystal fiber calcite veins, as signal of tension structure background) and is considered far different from those in the Miaotou section of Guilin and Youjiang Basin. In the Miaotou section of Guilin and the Youjiang Basin, the infillings of neptunian dyke are afterwards normal sea water sediments, while in the Nanbiancun section of Guilin are simultaneous overlain liquefied soft-sediment-flow, shown as skeletals and non-skeletal grains ( with dark Fe-bearing clays, fine calcites and fine skeletals) mixture. The non-skeletal grains deformed and impinged each other with very few cements among them That means they are not normal sea water deposits. The skeletal grains are mainly brachiopod and crinoid stems crowded floating in non-skeletal grains. A single Brachiopods shell are folded as "U" shape and then cut into several continuous parts in situ. That means a slowly soft press surrounding and wholly flowing. The upper part of the carbonate neptunian dyke shaped "V" and the inside wall of the dike are solid and covered with thin Fe-film (means an instant unconformity). Additional evidence is that no rock, same as the fillings inside the dykes in contains and structure, are reported in surrounding beds. Therefore the infillings are from overlain soft-sediments-flow. In the later Late Devonian, the Miaotou section and those of sections with neptunian dykes in Youjiang basin located in high cliff margin without overlain sediments (bypassing). When the normal fault movement and earthquake had taken place, the cracks occurred here and then filled by next transgression normal sea water sediments instead of following mentioned "overlain soft-sediment-flow". Whereas the Nanbiancun section was located in slope and covered with sediments. When the normal fault movement and earthquake had taken place, the crack occurred in solid Bed 45, and seismic liquefying occurred in overlain. Those half-solid sediments, such as lime, skeletal grain, non-skeletal grain, or spar cement were in situ liquefied to become liquefied soft-sediment-grain-flow and fill in the cracks. Those carbonate neptunian dykes were all caused by the syn-sedimentary normal faults and earthquakes. So the neptunian dyke in the Nanbiancun section is the different response of solid and soft beds to the earthquake. It is the special location of the Nanbiancun section that make the different characteristics of the carbonate neptunian dykes.
Carbonate neptunian dykes occurred commonly in Late Palaeozoic carbonate plateform margins in Guilin and Northwestern Youjiang basin, Guangxi Autonomous Region. In the Nanbiancun International Devonian— Carboniferous (bed 55~56) Boundary (DCB) Parastratotype Section of Guilin of Guangxi, carbonate neptunian dykes are identified in Bed 45 (a liquefied grainstone vein) and Bed 50 (some fine crystal fiber calcite veins, as signal of tension structure background) and is considered far different from those in the Miaotou section of Guilin and Youjiang Basin. In the Miaotou section of Guilin and the Youjiang Basin, the infillings of neptunian dyke are afterwards normal sea water sediments, while in the Nanbiancun section of Guilin are simultaneous overlain liquefied soft-sediment-flow, shown as skeletals and non-skeletal grains ( with dark Fe-bearing clays, fine calcites and fine skeletals) mixture. The non-skeletal grains deformed and impinged each other with very few cements among them That means they are not normal sea water deposits. The skeletal grains are mainly brachiopod and crinoid stems crowded floating in non-skeletal grains. A single Brachiopods shell are folded as "U" shape and then cut into several continuous parts in situ. That means a slowly soft press surrounding and wholly flowing. The upper part of the carbonate neptunian dyke shaped "V" and the inside wall of the dike are solid and covered with thin Fe-film (means an instant unconformity). Additional evidence is that no rock, same as the fillings inside the dykes in contains and structure, are reported in surrounding beds. Therefore the infillings are from overlain soft-sediments-flow. In the later Late Devonian, the Miaotou section and those of sections with neptunian dykes in Youjiang basin located in high cliff margin without overlain sediments (bypassing). When the normal fault movement and earthquake had taken place, the cracks occurred here and then filled by next transgression normal sea water sediments instead of following mentioned "overlain soft-sediment-flow". Whereas the Nanbiancun section was located in slope and covered with sediments. When the normal fault movement and earthquake had taken place, the crack occurred in solid Bed 45, and seismic liquefying occurred in overlain. Those half-solid sediments, such as lime, skeletal grain, non-skeletal grain, or spar cement were in situ liquefied to become liquefied soft-sediment-grain-flow and fill in the cracks. Those carbonate neptunian dykes were all caused by the syn-sedimentary normal faults and earthquakes. So the neptunian dyke in the Nanbiancun section is the different response of solid and soft beds to the earthquake. It is the special location of the Nanbiancun section that make the different characteristics of the carbonate neptunian dykes.
引文
丁道桂,邓模,朱文利.2010.大南盘江地区晚古生代拗拉槽盆地的改造变形.石油与天然气地质,31(4):393～402.
杜远生,黄虎,杨江海,黄宏伟,陶平,黄志强,胡丽沙,谢春霞.2013.晚古生代—中三叠世右江盆地的格局和转换.地质论评,(1):1～11.
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.1988.广西壮族自治区区域地质志.北京:地质出版社,P59～66.
侯明才,陈洪德,朱西养,田景春.2006,被动陆缘裂陷盆地的层序充填动力学模型——以早泥盆世—中泥盆世早期右江盆地为例.地质学报,80(4):606～614.
黄宏伟,杜远生,陈志强,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):723～724.
吕洪波,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——一类新的沉积构造的归类、命名和构造意义探讨.地质论评,49(5):449～456.
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.
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(5):613～619.
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(6):736～742.
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):43～48.
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.
Beavon R V.1998.Archean Neptunian fissures and early history of theDestor—Porcupine fault zone,Timmins,Ontario,Canada.Canadian Journal of Earth Sciences,35(12):1402～1407.
Hunt D V,Fitchen W M,Kosa E.2002.Syndepositional deformation ofthe Permian capitan reef carbonate platform,Guadalupe Mountains,New Mexico,USA.Sedimentary Geology,154(3～4):89～126.
Chen Jitao,van Loon A J,Han Zuozhen,Chough S K.2009.Funnel-shaped,breccia-filled clastic dykes in the Late CambrianChaomidian Formation(Shandong Province,China).SedimentaryGeology,221:1～6.
Whitmore J H,Strom R.2010.Sand injectites at the base of theCoconino Sandstone,Grand Canyon,Arizona(USA).SedimentaryGeology,230:46～59.
Basilone L,Morticelli M G,Lena G,2010,Mesozoic tectonics andvolcanism of Tethyan rifted continental margins in western Sicily.Sedimentary Geology226:54～70.
Meretti M.2000.Soft-sediment deformation structures interpreted asseismites in middle—late Pleistocene seolian deposits(Apulianforeland,southern Italy).Sedimentary Geology,135:167～179.
Pratt B R.2001.Oceanography,bathymetry and syndepositionaltectonics of a Precambrian interactationic basin:integratingsediments,storms,earthquakes and tsunamis in the Belt Supergroup(Helena Formation,ca.1.45Ga).western North American.Sedimentary Geology,141～142:371～394.
Schroeder S,Adams E W,Grotzinger J P,McCormick D S,Amthor J E,Smith D W,Wood R.2001.Fabrics and genesis of microbial reefsin the terminal Neoproterozoic Nama Group(central Namibia).In:Geological Society of America,2001annual meeting.PB:Geological Society of America(GSA).Boulder,CO,UnitedStates.
杜远生,黄虎,杨江海,黄宏伟,陶平,黄志强,胡丽沙,谢春霞.2013.晚古生代—中三叠世右江盆地的格局和转换.地质论评,(1):1～11.
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.1988.广西壮族自治区区域地质志.北京:地质出版社,P59～66.
侯明才,陈洪德,朱西养,田景春.2006,被动陆缘裂陷盆地的层序充填动力学模型——以早泥盆世—中泥盆世早期右江盆地为例.地质学报,80(4):606～614.
黄宏伟,杜远生,陈志强,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):723～724.
吕洪波,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——一类新的沉积构造的归类、命名和构造意义探讨.地质论评,49(5):449～456.
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.
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(5):613～619.
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(6):736～742.
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):43～48.
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.
Beavon R V.1998.Archean Neptunian fissures and early history of theDestor—Porcupine fault zone,Timmins,Ontario,Canada.Canadian Journal of Earth Sciences,35(12):1402～1407.
Hunt D V,Fitchen W M,Kosa E.2002.Syndepositional deformation ofthe Permian capitan reef carbonate platform,Guadalupe Mountains,New Mexico,USA.Sedimentary Geology,154(3～4):89～126.
Chen Jitao,van Loon A J,Han Zuozhen,Chough S K.2009.Funnel-shaped,breccia-filled clastic dykes in the Late CambrianChaomidian Formation(Shandong Province,China).SedimentaryGeology,221:1～6.
Whitmore J H,Strom R.2010.Sand injectites at the base of theCoconino Sandstone,Grand Canyon,Arizona(USA).SedimentaryGeology,230:46～59.
Basilone L,Morticelli M G,Lena G,2010,Mesozoic tectonics andvolcanism of Tethyan rifted continental margins in western Sicily.Sedimentary Geology226:54～70.
Meretti M.2000.Soft-sediment deformation structures interpreted asseismites in middle—late Pleistocene seolian deposits(Apulianforeland,southern Italy).Sedimentary Geology,135:167～179.
Pratt B R.2001.Oceanography,bathymetry and syndepositionaltectonics of a Precambrian interactationic basin:integratingsediments,storms,earthquakes and tsunamis in the Belt Supergroup(Helena Formation,ca.1.45Ga).western North American.Sedimentary Geology,141～142:371～394.
Schroeder S,Adams E W,Grotzinger J P,McCormick D S,Amthor J E,Smith D W,Wood R.2001.Fabrics and genesis of microbial reefsin the terminal Neoproterozoic Nama Group(central Namibia).In:Geological Society of America,2001annual meeting.PB:Geological Society of America(GSA).Boulder,CO,UnitedStates.
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