滇东北及其邻区石炭纪—二叠纪紫松阶下部层序地层学及古地理演化研究

发布时间：2017-12-31 10:43

本文关键词：滇东北及其邻区石炭纪—二叠纪紫松阶下部层序地层学及古地理演化研究　出处：《昆明理工大学》2016年博士论文　论文类型：学位论文

【摘要】：本文研究区位于云南省东北部与贵州西部交界位置,处于小江断裂、紫云垭都断裂和弥勒师宗断裂所围成的近似三角形构造范围中。本文的主要目标是针对滇东北及其相邻地区石炭纪海相碳酸盐岩为主的沉积地层,开展以层序地层为主的综合地层学研究,建立并完善适用于全区的地层划分系统；建立区内石炭系-二叠系下统马平组年代格架与海平面变化旋回曲线关系,进而深刻认识研究区石炭纪-早二叠世地层发育的特征与沉积体系的空间分布规律。结合地球化学等手段,在地层年代格架的基础上,编制滇东北地区石炭纪-二叠纪早期层序岩相古地理图,进一步揭示研究区沉积演化过程与特征。本文取得的主要成果和认识如下。(1)重新整理划分研究区内岩石地层,并总结岩石地层穿时性规律。研究区及周边邻区石炭系-二叠系下统发育较完全,涉及区域广。在前人研究成果的基础上,本文对研究区22条剖面进行详细野外观测,重新厘定区内石炭纪的岩石地层单位,建立了统一的地层划分方案,即将石炭系原来的三分(上统、中统、下统)调整为二分(上统、下统),原石炭系岩关组下部的革老河组划分到泥盆系中,原石炭系顶部马平组为跨系地层；将石炭系-二叠系下统划分为6个岩石地层单位,即：汤耙沟组、万寿山组、大塘组、摆佐组、威宁组、马平组。同时总结石炭系-二叠系底部穿时性的规律,万寿山组和大塘组在盆地边缘出现向上穿时的现象,摆佐组在盆地中部出现向下穿时的现象。(2)对各个地层的岩石学特征、显微镜下微相特征、碳酸盐岩沉积地球化学测试结果和空间展布规律进行分析。(1) Sr/Cu比值法研究表明会泽地区环境整体表现为逐渐干热,雨碌地区环境整体表现为先干热后温湿而毛坪地区环境变化比较明显,整体为先是干热气候后为温湿气候；(2) Sr/Ba比值法研究表明会泽和雨碌地区整体为咸水环境,毛坪地区水体盐度变化较大,整体处于微咸水到半咸水环境,个别时期水体盐度有明显升高的变化；(3)V/(V+Ni)比值法和U/Th比值法综合分析表明本区石炭纪-二叠纪早期总体上呈现出一种还原条件下的沉积环境,整体为贫氧环境(缺氧环境),威宁期水体中氧含量较低,水体中含氧量呈先下降后略上升的趋势,推测海平面属于先上升后下降的变化趋势。总结出区内不同时期的沼泽相、开阔台地相、局限台地相、台内浅滩相、台地边缘斜坡相分布格局,并在前人研究的基础上新识别出台沟相和生物礁相。(3)在研究区石炭系-二叠系底部,共识别出SQ14、SQ15、 SQ16、 SQ18、SQ19共5个三级层序,相当于晚古生代25个三级层序中的SQ14-SQ19。由于受到黔桂运动第一幕构造抬升,海平面下降,风化剥蚀的影响,缺失SQ17。同时识别出石英砾石层(SQ14与SQ15和SQ15与SQ16界面)、沉积相变面(如SQ18与SQ19界面)、古风化壳(如SQ16与SQ18界面及它们的相关面)。通过古生物特征及海平面变化特征,建立了研究区石炭纪-二叠纪早期年代地层格架和层序地层格架。反映了三级层序的基本层序地层格架特征：具空间上相序的有序性和时间上环境变化的同步性。由于受到黔桂运动第一幕构造抬升、海平面下降及风化剥蚀的影响,确实SQ17层序。(4)根据等时层序地层格架,结合生物组合特征、沉积体系及体系域等研究成果,以单因素作图、多因素分析的方法,选择三级层序为单元绘制5幅层序岩相古地理图,并对研究区石炭纪-二叠纪早期层序岩相古地理演化进行了分析。①汤耙沟期,研究区继续表现为海退,大部分地区暴露在海平面之上,沉积范围极小,主要为沿北西南东向的开阔台地相沉积,在红路脚和二官营两处为局限台地相沉积,矿山厂与者兴上两地为古岛；②从万寿山期开始,整个研究区进入一个大范围、长时间的海进阶段,主要沉积陆源碎屑物,该时期气候温湿,非常适合植物生长,特别是高大乔木,该时期地层多出现煤层。该时期以滨海沼泽相、混合潮坪相和局限台地相沉积为主,沼泽相主要分布在万寿山组研究区东北部毛坪-白腊厂一带和西南部初奈一带,岩关阶时期的开阔台地相地区变为了局限台地相,范围有所缩小,其余的广大地区为混合潮坪相,此时在威宁阻基出现一处古岛。③大塘期基本继承了万寿山期的沉积格局,海平面继续向西北方向扩张,康滇古陆和扬子古陆范围缩小,开阔台地大为发育；④摆佐期-威宁期,海平面达到石炭纪-早二叠纪时期的最大值,海侵范围在区内也达到最广。由于受到构造运动的影响,此时研究区内海底地形复杂,整体表现为由西到东海水逐渐变深,东部深水台盆位置为区内最深,台盆相、台地相、礁滩相等沉积模式均有体现,并以威宁-水城地区东南方向的深水台盆为中心向两边对称分布,从古陆向台盆方向出现局限台地、开阔台地、台地边缘斜坡三个相带,在这三个相带中阻基、二官营、桃园表现为孤立台地沉积环境；⑤达马平期的海退阶段始于黔桂运动第一幕构造运动,由于受到构造运动的影响,陆地开始抬升,出现明显的海平面下降的现象；由于黔桂运动第二幕构造运动影响较大,陆地出现了一个明显的抬升,沉积环境发生了明显的变化,海陆格局发生了重大的变化,沉积环境由之前的海相环境转变为了陆相环境。⑥在威宁期,沉积相带分布变化不大,在靠近古陆地区出现了浅滩相,阻基与桃园古岛消失,二官营孤立台地依然存在。⑦在小独山阶-紫松阶时期,海平面下降,北部海改地以北地区暴露在海平面以上,矿山厂大竹园、二官营、初奈-秧田冲一带为浅滩相,台盆消失变为开阔台地,大部分地区由于海平面的下降变为局限台地相。(5)根据构造控盆、盆控相理论,结合古地理及构造演化查明了盆地演化过程。研究区受到紫云-罗甸-南丹裂陷带构造的控制,导致盆地内部地形及古环境受到一定的影响。该构造带在石炭纪-二叠纪早期处于较明显的拉张陷落期。研究区盆地演化主要分为两个阶段：①第一个阶段拉张陷落期。继泥盆纪海退之后,该裂陷带再次拉张,地壳因拉张而再度沉陷,研究区处于同构造带上,亦保持了北西向展布。受此影响,在威宁地区出现了地壳拉张陷落,形成威宁台沟,在大塘组顶部出现的玄武岩说明此时该构造带正处于拉张期。此时期海侵扩大,区内主要由局限台地、开阔台地、台缘斜坡和台沟相组成。②第二阶段为拉张静止的断陷填充期。由于受到外界构造影响,加之海平面下降,断陷台沟被沉积物充填,使得函内沉积区范围减小,台沟表现不明显,台内浅滩相和生物礁相发育。区内主要由局限台地、开阔台地、颗粒台内浅滩、生物礁及台沟相组成。
[Abstract]:In this paper, the study area is located in the northeast of Yunnan province and Guizhou at the junction of the western position in the Xiaojiang Fault, similar to Ziyun yadu fault and Maitreya Shizong fault surrounded by the triangle area. The main goal of this paper is aimed at the sedimentary strata of Carboniferous marine carbonate rocks in northeastern Yunnan Province and its adjacent areas mainly, carry out a comprehensive study on stratigraphic sequence stratigraphy. The stratigraphic division, establish and perfect the system for the establishment of the region; Permian in Carboniferous - lower Ma Ping group's framework and sea-level change cycle curve, and a profound understanding of the research area of Carboniferous Early Permian strata characteristics and sedimentary system development spatial distribution. Combined with the geochemical means. Based on the stratigraphic framework, establishment of Carboniferous Early Permian in Northeast Yunnan sequence paleogeography, further reveal the sedimentary modeling The process and characteristics. The main achievements are as follows. (1) re division of the study area of rock strata, and summed up the rock strata wear regularity. Study on Carboniferous Permian area and the surrounding neighborhood system under the system development is complete, involving a wide area. On the basis of previous research results in this paper. Detailed field observations of 22 profiles in study area, the redefinition of lithostratigraphic units in Carboniferous, established the stratigraphic division of the Carboniferous is uniform, the original three points (upper, middle, lower) was adjusted to two points (upper and lower), the original stone carbon rock group is closed the old leather group into the Devonian, Carboniferous Maping stone top cross strata; the Carboniferous Lower Permian is divided into 6 lithostratigraphic units, namely: tangbagou group, longevity hill group, Datang Group, baizuo group, Weining group, Ma Ping group. At the same time of Carboniferous - two The regularity of Triassic bottom wear, longevity hill group and Datang Group at the edge of the basin to wear on the phenomenon of baizuo group down wear phenomenon in the central basin. (2) the petrological characteristics of each stratum under the microscope, micro facies characteristics, sedimentary geochemistry of carbonate rock and test results the spatial distribution was analyzed. (1) study Sr/Cu ratio method show that the Huize region environment for the overall performance of dry heat environment gradually, Yu Lu region as a whole for the first performance after the dry temperature and humidity and Maoping regional environmental change is more obvious, the overall for the first climate after a warm and humid climate; (2) research shows that Sr/Ba ratio method the whole Huize and Yu Lu area water environment. The Maoping area water salinity is larger, overall in the brackish water to brackish water environment, water salinity has increased significantly during the period of individual changes; (3) V/ (V+Ni) synthesis ratio method and U/Th ratio method Analysis shows that the area of Carboniferous Early Permian shows a sedimentary environment under the condition of reduction, the whole oxygen poor environment (hypoxia), Weining water in lower oxygen content decreased first and then increased slightly the oxygen content in the water, it is concluded that the change trend of sea level is increased first and then decreased summed up the area in different periods. The swamp facies open platform facies, restricted platform facies, platform shoal facies, platform margin slope facies distribution pattern, and on the basis of previous research to identify new introduction channel facies and reef facies. (3) in the study area of Carboniferous Permian bottom, and identified SQ14. SQ15, SQ16, SQ18, SQ19 a total of 5 three level sequence, equivalent to 25 three level sequence of Late Paleozoic in SQ14-SQ19. due to the movement of the first scene in Guizhou and Guangxi tectonic uplift, sea-level fall, effects of weathering and erosion, loss of SQ17. and identify the quartz gravels (SQ14 and SQ 15 and SQ15 and SQ16 interface), sedimentary facies change surfaces (such as SQ18 and SQ19 interface), palaeoweathering crust (such as SQ16 and SQ18 interface and their associated surface). By palaeobio characteristics and sea level changes, the study area was established in Early Carboniferous Permian stratigraphic framework and sequence stratigraphic framework. Reflects the basic sequence stratigraphic characteristics of the three grade sequence: simultaneous environmental changes in order and time with space sequence. Due to the movement of the first act of tectonic uplift, sea-level decline and weathering and denudation, indeed SQ17 sequence. (4) according to the isochronous stratigraphic framework, combined with biological a combination of features, sedimentary systems and system tracts and other research results, using single factor mapping method of multi factor analysis, three grade sequence draw 5 pieces of sequence paleogeographic map as a unit, and the research area of Carboniferous Early Permian sequence paleogeographic evolution. The analysis of the tangbagou period. The study area, continue to behave as regressive, most areas exposed above the sea level, the deposition scope of minimum, mainly for the open platform along the North East to southwest sedimentary facies of the two battalion is restricted platform facies in the Red Road foot and two officer, and Xing mining factory the two ancient island; from the beginning of the longevity hill, the entire study area into a large range of transgression stage a long time, the main sedimentary period of terrigenous detritus, the climate is moist, very suitable for the growth of plants, especially the tall trees, the formation period appeared in this period in coal seam. The coastal marsh dominated. Mixed tidal flat facies and restricted platform facies and swamp facies are mainly distributed in the northeast region of Longevity Hill Group Mao Ping - white wax factory area and southwest area at the beginning of Nai yanguanian period, open platform facies are area to restricted platform facies, has narrowed the scope of the rest Large areas of mixed tidal flat facies, appears in Weining base resistance of an ancient island. The Tang period basically inherited the sedimentary pattern of Longevity Hill period, sea level continued to expand to the northwest, Kangdian ancient land and Yangtze narrow, open platform for development; the baizuo during Weining period. The maximum sea level reached in the Carboniferous Early Permian period, the transgression of the sea in the region has reached the most widely. Under the influence of the tectonic movement, the study area of seabed topography, the overall performance from west to east sea becomes deep gradually, the eastern area in the deep-water basin location for deep basin facies, platform facies. Reef facies patterns are reflected, and to the southeast of Weining Shuicheng area of deep-water basin as the center to symmetrical distribution, from the land to the direction of basin restricted platform, open platform, platform margin slope facies in three, the three phase belt In the resistance group, two battalion officer, Taoyuan showed isolated platform sedimentary environment; the regression stage began in the period of Ma Ping Qiangui movement the first act of tectonic movement, under the influence of the tectonic movement, the land began to rise, the sea decreased significantly due to movement of the phenomenon; Guizhou second episodic tectonic movement affected land a significant uplift, change of sedimentary environment, major changes in sea land, sedimentary environment before the marine environment changes to the terrestrial environment. In Weining period, sedimentary facies distribution changed little in the near ancient regions of the shoal facies, base resistance and Taoyuan ancient island disappeared two, Guan Ying isolated platform still exists in Dushan. The stage of small order - Purple pine, sea-level fall, North sea change in north area exposed above sea level, Dazhu mining plant garden, two Guan Ying, early seedling - Chong Nai The area disappeared into shallow facies, basin open platform, most areas due to the fall of sea level into the restricted platform (5). According to the tectonic control basin, basin facies controlling theory, basin evolution process to identify the combination of Palaeogeography and tectonic evolution. The study area by the Ziyun - Luodian - Nandan rift zone structure control the interior of the basin, resulting in topography and ancient environment influenced. The tectonic belt in the Carboniferous Early Permian in obvious extensional collapse. The basin evolution is mainly divided into two stages: the first stage of extensional collapse following the Devonian period. After regression, the rift belt tension again, the crust due to a re subsidence, the study area in the syntectonic belt, also keep the NW trending. Affected by this, in the Weining area of the crustal extension collapse, Weining Taiwan ditch, appeared on the big pond at the top of the Xuan Wuyan group In extensional tectonic belt. The transgression zone expanded, mainly by the restricted platform, open platform, platform margin slope and ditch. The second stage is composed of static tension faulted filled period. Due to the external structure influence, coupled with sea-level fall, faulted sedimentary filling by Taiwan ditch the letter, deposited in the zone reduced, Taiwan ditch performance is not obvious, Taiwan facies and reef shoal facies. The area is mainly composed of restricted platform, open platform, platform particles shoal, reef and Taiwan ditch.

【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P539.2;P534.4

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