川北下寒武统仙女洞组台缘斜坡碳酸盐岩重力流沉积
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摘要
基于重力流剖面的野外观察、露头解剖及镜下鉴定等分析手段,对四川盆地北部下寒武统仙女洞组台缘斜坡碳酸盐岩重力流沉积及发育机制进行了研究。研究区位于仙女洞组,主要沉积粉砂质泥岩、生屑泥晶灰岩、藻灰岩等3种岩石类型;根据层面上产出形态的不同,将该区碳酸盐岩重力流沉积分为似瘤状碳酸盐岩重力流沉积和角砾型碳酸盐岩重力流沉积2类。结合露头区重力流沉积物粒度及岩性变化,将碳酸盐岩重力流沉积由下至上划分出5个发育期次,期次内部重力流沉积物由细变粗,纵向上呈现出明显的叠置关系,与仙女洞组时期所经历的海退环境大致吻合。地震、风暴浪等触发机制导致台缘斜坡上部松散沉积的灰泥丘块体发生破碎并沿斜坡发生滑塌,伴随水体注入,大块砾石在沉积物—水体混合的环境中发生破碎搅动,形成大小不等的块体,深水底流等作用对未固结或弱固结的砾屑灰岩进行溶蚀、改造,最终形成了层面形态特征不同的2类似瘤状碳酸盐岩重力流沉积。角砾型碳酸盐岩重力流沉积则主要是未破碎的巨型灰泥丘块体经搬运和短距离滑塌,最终与似瘤状砾屑灰岩共同沉积而成。
Based on field survey, outcrop analysis and microscopic observbation, we report the basic characteristics of the carbonategravity flow in platform margin in the lower Cambrian Xiannvdong Formation of the Northern Sichuan Basin and address itsdevelopmental mechanism in this paper. Results show that the Xiannvdong Formation typically developed an environment of diamicticcarbonate platform marginal slope in shallow water. The bottom of this formation is mainly composed of three rock types, i.e., siltymudstones, bioclastic micritic limestones and algal limestones. According to the planar morphologies, two types of carbonate gravity flow deposits were classified, including nodular-like and brecciated. Based on the grain size and lithological variation of the gravity flowsediments in outcrops, five developmental stages were divided, which show an obvious superposition relationship vertically. The grainsize of these sediments roughly changes from fine to coarse within sedimentary cycles, consistent with the regressive environment of theXiannvdong period in general. In the vicinity of the platform marginal slope, slide and slump events occurred due to the triggering ofgeological events, e.g., earthquake and storm. The mound and shoal mass moved down along the slope, and some of the blocks migratedand deposited here, which formed the brecciated carbonate gravity flow deposits. With the increasing injection of water, the amount ofsediment-water mixture and the decomposition of the material rose, and some of the mass were broken and flowed as similar forms ofdebris flow along the slope, and then the debris transformed into carbonate gravity flow deposits with plastic rheological characteristics.Then, these deposits might be reworked by bottom current or experienced corrosion from seawater after deposition to form two types ofnodular-like carbonate gravity flow sediments. In contrast, the brecciated carbonate gravity flow sediments were products of transportationand short-distance slumping of mega unbroken carbonate mound mass. They are co-deposited with the nodular-like calcirudites.
Based on field survey, outcrop analysis and microscopic observbation, we report the basic characteristics of the carbonategravity flow in platform margin in the lower Cambrian Xiannvdong Formation of the Northern Sichuan Basin and address itsdevelopmental mechanism in this paper. Results show that the Xiannvdong Formation typically developed an environment of diamicticcarbonate platform marginal slope in shallow water. The bottom of this formation is mainly composed of three rock types, i.e., siltymudstones, bioclastic micritic limestones and algal limestones. According to the planar morphologies, two types of carbonate gravity flow deposits were classified, including nodular-like and brecciated. Based on the grain size and lithological variation of the gravity flowsediments in outcrops, five developmental stages were divided, which show an obvious superposition relationship vertically. The grainsize of these sediments roughly changes from fine to coarse within sedimentary cycles, consistent with the regressive environment of theXiannvdong period in general. In the vicinity of the platform marginal slope, slide and slump events occurred due to the triggering ofgeological events, e.g., earthquake and storm. The mound and shoal mass moved down along the slope, and some of the blocks migratedand deposited here, which formed the brecciated carbonate gravity flow deposits. With the increasing injection of water, the amount ofsediment-water mixture and the decomposition of the material rose, and some of the mass were broken and flowed as similar forms ofdebris flow along the slope, and then the debris transformed into carbonate gravity flow deposits with plastic rheological characteristics.Then, these deposits might be reworked by bottom current or experienced corrosion from seawater after deposition to form two types ofnodular-like carbonate gravity flow sediments. In contrast, the brecciated carbonate gravity flow sediments were products of transportationand short-distance slumping of mega unbroken carbonate mound mass. They are co-deposited with the nodular-like calcirudites.
引文
陈志明.1991.扬子地区早古生代碳酸盐重力流沉积的地质背景探讨[J]地质科学,4:337-345.
高振中,段太中.1985.湘西黔东寒武纪深水碳酸盐重力沉积[J].沉积学报,3(3):7-22.
韩作振,陈吉涛,张晓蕾,等.2009.鲁西寒武系第三统张夏组附枝菌与附枝菌微生物灰岩特征研究[J].地质学报,83(8):1097-1103.
郭建华,高振中,工正允,等.1997.鄂东南大沙坪下奥陶统碳酸盐岩重力流及自发振动成因机理[J].岩石学报,13(2):245-253.
靳学斌,李壮福,陆鹿,等.2014.下扬子巢湖地区下三叠统瘤状灰岩成因再探讨[J].高校地质学报,20(3):445-453.
李皎,何登发.2014.四川盆地及邻区寒武纪古地理与构造一沉积环境演化[J].古地理学报,16(4):441-460.
李相博,卫平生,刘化清,等.2013.浅谈沉积物重力流分类与深水沉积模式[J].地质论评,59(4):607-614.
刘宝裙,叶红专,蒲心纯.1990.黔东、湘西寒武纪碳酸盐岩重力流沉积[J].石油与天然气地质,11(3):235-246.
刘登忠,魏显贵,杜思清,等.1997.米仓山西段地质研究新进展[J].矿物岩石,17:1-8.
牟传龙,梁薇,周恳恳,等.2012.中上扬子地区早寒武世(纽芬兰世-第二世)岩相古地理[J].沉积与特提斯地质,32(3):41-53.
牛新生,王成善.2010.异地碳酸盐岩块体与碳酸盐岩重力流沉积研究及展望[J].古地理学报,12(1):17-30.
沈骋,谭秀成,李凌,等.2015.川北早寒武世碳酸盐岩台缘斜坡沉积特征及变形构造形成机制探讨[J].古地理学报,17(3):321-334.
沈骋,谭秀成,周博,等.2016.川北旺苍唐家河剖面仙女洞组灰泥丘沉积特征及造丘环境分析[J].地质论评,62(1):1-14.
王一刚.1986.黔南桂西早三叠世大陆斜坡碳酸盐岩重力流沉积[J].沉积学报,4(2):91-100.
张满郎,谢增业,李熙喆,等.2010.四川盆地寒武纪岩相古地理特征[J].沉积学报,28(1):128-139.
张廷山,兰光志,沈昭国,等.2005.大巴山,米仓山南缘早寒武世礁滩发育特征[J].天然气地球科学,16(6):710-714.
朱洪发,王恕一.1992.苏南、皖南三叠纪瘤状灰岩、蠕虫状灰岩的成因[J].石油实验地质,14(4):454-460.
Bouma A H.1962.Sedimentology of some flysch deposits[J].Amsterdam:Elsevier Pub.:168.
Coniglio M and Dix G R.1992.Carbonate Slopes[M]//Facies Models:Response to Sea Level Change.Edited by Walker R G and James N P.Geological Association of Canada,St.John's:349-374.
Khan K and Al-Shayea N A.2000.Effect of specimen geometry and testing method on mixed mode I-II fracture toughness of a limestone rock from Saudi Arabia[J].Rock Mechanics and Rock Engineering,33(3):179-206.
Kuenen Ph H and Migliorini C I.1950.Turbidity currents as a cause of graded bedding[J].Journal of geology,58:91-127
Mutti E.1977.Distinctive thin-bedded turbidite facies and related depositional environments in the Eocene Hecho Group(southcentral Pyrenees Spain)[J].Sedimentology,24:107-131.
Normark W R.1978.Fan valleys channels and depositional lobes on modern submarine fans characters for recognition of sandy turbidite environments[J].American Association of Petroleum Geologists Bulletin,62:912-931.
Shanmugam G.1996.High-density turbidity currents;are they sandy debris flows?[J].Journal of Sedimentary Research,66(1):2-10.
Shanmugam G.2000.50 years of the turbidite paradigm(1950s-1990s):deep-water processes and facies models-a critical perspective[J].Marine&Petroleum Geology,17(2):285-342.
Shanmugam G.2006.Deep-Water processes and facies models:Implications for Sandstone Petroleum Reservoirs[M].Amsterdam:Elsevier:Handbook of Petroleum Exploration and Production,5:476.
Shanmugam G.2013.New perspectives on deep-water sandstones:Implications[J].Petroleum Exploration&Development,40(3):316-324.
Vail P R,Audemard F and Bowman S A,et al.1991.The Stratigraphic Signatures of Tectonics,Eustacy and Sedimentology:An overview[M]//Einsele G,Ricken W,Seilacher A,eds.Cycles and Events in Stratigraphy.Berlin:Springer-Verlag:618-659.
Walker R G.1978.Deep-water sandstone facies and ancient submarine fans:Models for exploration for Stratigraphic Traps[J].American Association of Petroleum Geologists Bulletin,62:932-966.
高振中,段太中.1985.湘西黔东寒武纪深水碳酸盐重力沉积[J].沉积学报,3(3):7-22.
韩作振,陈吉涛,张晓蕾,等.2009.鲁西寒武系第三统张夏组附枝菌与附枝菌微生物灰岩特征研究[J].地质学报,83(8):1097-1103.
郭建华,高振中,工正允,等.1997.鄂东南大沙坪下奥陶统碳酸盐岩重力流及自发振动成因机理[J].岩石学报,13(2):245-253.
靳学斌,李壮福,陆鹿,等.2014.下扬子巢湖地区下三叠统瘤状灰岩成因再探讨[J].高校地质学报,20(3):445-453.
李皎,何登发.2014.四川盆地及邻区寒武纪古地理与构造一沉积环境演化[J].古地理学报,16(4):441-460.
李相博,卫平生,刘化清,等.2013.浅谈沉积物重力流分类与深水沉积模式[J].地质论评,59(4):607-614.
刘宝裙,叶红专,蒲心纯.1990.黔东、湘西寒武纪碳酸盐岩重力流沉积[J].石油与天然气地质,11(3):235-246.
刘登忠,魏显贵,杜思清,等.1997.米仓山西段地质研究新进展[J].矿物岩石,17:1-8.
牟传龙,梁薇,周恳恳,等.2012.中上扬子地区早寒武世(纽芬兰世-第二世)岩相古地理[J].沉积与特提斯地质,32(3):41-53.
牛新生,王成善.2010.异地碳酸盐岩块体与碳酸盐岩重力流沉积研究及展望[J].古地理学报,12(1):17-30.
沈骋,谭秀成,李凌,等.2015.川北早寒武世碳酸盐岩台缘斜坡沉积特征及变形构造形成机制探讨[J].古地理学报,17(3):321-334.
沈骋,谭秀成,周博,等.2016.川北旺苍唐家河剖面仙女洞组灰泥丘沉积特征及造丘环境分析[J].地质论评,62(1):1-14.
王一刚.1986.黔南桂西早三叠世大陆斜坡碳酸盐岩重力流沉积[J].沉积学报,4(2):91-100.
张满郎,谢增业,李熙喆,等.2010.四川盆地寒武纪岩相古地理特征[J].沉积学报,28(1):128-139.
张廷山,兰光志,沈昭国,等.2005.大巴山,米仓山南缘早寒武世礁滩发育特征[J].天然气地球科学,16(6):710-714.
朱洪发,王恕一.1992.苏南、皖南三叠纪瘤状灰岩、蠕虫状灰岩的成因[J].石油实验地质,14(4):454-460.
Bouma A H.1962.Sedimentology of some flysch deposits[J].Amsterdam:Elsevier Pub.:168.
Coniglio M and Dix G R.1992.Carbonate Slopes[M]//Facies Models:Response to Sea Level Change.Edited by Walker R G and James N P.Geological Association of Canada,St.John's:349-374.
Khan K and Al-Shayea N A.2000.Effect of specimen geometry and testing method on mixed mode I-II fracture toughness of a limestone rock from Saudi Arabia[J].Rock Mechanics and Rock Engineering,33(3):179-206.
Kuenen Ph H and Migliorini C I.1950.Turbidity currents as a cause of graded bedding[J].Journal of geology,58:91-127
Mutti E.1977.Distinctive thin-bedded turbidite facies and related depositional environments in the Eocene Hecho Group(southcentral Pyrenees Spain)[J].Sedimentology,24:107-131.
Normark W R.1978.Fan valleys channels and depositional lobes on modern submarine fans characters for recognition of sandy turbidite environments[J].American Association of Petroleum Geologists Bulletin,62:912-931.
Shanmugam G.1996.High-density turbidity currents;are they sandy debris flows?[J].Journal of Sedimentary Research,66(1):2-10.
Shanmugam G.2000.50 years of the turbidite paradigm(1950s-1990s):deep-water processes and facies models-a critical perspective[J].Marine&Petroleum Geology,17(2):285-342.
Shanmugam G.2006.Deep-Water processes and facies models:Implications for Sandstone Petroleum Reservoirs[M].Amsterdam:Elsevier:Handbook of Petroleum Exploration and Production,5:476.
Shanmugam G.2013.New perspectives on deep-water sandstones:Implications[J].Petroleum Exploration&Development,40(3):316-324.
Vail P R,Audemard F and Bowman S A,et al.1991.The Stratigraphic Signatures of Tectonics,Eustacy and Sedimentology:An overview[M]//Einsele G,Ricken W,Seilacher A,eds.Cycles and Events in Stratigraphy.Berlin:Springer-Verlag:618-659.
Walker R G.1978.Deep-water sandstone facies and ancient submarine fans:Models for exploration for Stratigraphic Traps[J].American Association of Petroleum Geologists Bulletin,62:932-966.