| 胜利油田惠民凹陷辉绿岩地球化学及成因 | |
| Alternative Title | The Geochemistry and Genesis of Diabase from |
| 刘洪文 | |
| Subtype | 博士 |
| 2006-11-07 | |
| Degree Grantor | 中国科学院地球化学研究所 |
| Place of Conferral | 地球化学研究所 |
| Degree Name | 博士 |
| Keyword | 胜利油田（济阳拗陷） 惠民凹陷 新生代辉绿岩和火山岩 地球化学和成因 异常地幔 地壳物质混染作用 |
| Abstract | 济阳拗陷（胜利油田）为我国仅次于大庆油田的石油生产基地，区内新生代火成岩广泛发育，且为重要的油气藏储层之一，有关该区火成岩与油气藏的成因联系一直是国内外地学工作极为关注的课题和生产部门亟待解的问题。前人对该区火成岩的研究主要集中在火山岩分布、岩石类型、储层性质等方面，很少涉及对火成岩地球化学、形成构造环境、地幔源区特征、岩浆演化以及在油气形成过程中的作用等方面的研究，对与之时空密切共生的次火山岩——辉绿岩研究相对较少，尤其是岩石地球化学的研究工作尚未开展，无法探讨其成岩动力学背景、地幔地球化学、壳幔相互作用以及与火山岩之间的成因联系等一系列问题。本论文主要对济阳拗陷惠民凹陷钻孔揭露的辉绿岩进行了系统的矿物学和地球化学研究，以此探讨了该区辉绿岩的成岩动力学背景、地幔源区特征、岩浆形成与演化，同时通过与区内沙三段中的火山岩（与辉绿岩时空密切共生）地球化学对比，揭示了辉绿岩与火山岩的成因联系。论文获得的主要认识如下： ① 研究区辉绿岩主要矿物为单斜辉石和斜长石，次要矿物主要为橄榄石、斜方辉石、云母、角闪石、钾长石和方解石等，副矿物主要为磷灰石、金属矿物，同时还出现种类繁多的次生矿物，常见的有蛇纹石、绿泥石、钠长石、高岭石、碳酸盐以及形态不则的云母和金属矿物等；光性测定和探针分析结果表明，各种矿物的化学成分变化范围较宽，可能主要与岩浆结晶分异作用和岩浆期后不同程度的热液蚀变作用有关。 ② 岩石的主要元素、微量元素和稀土元素（REE）的含量范围变化较大，富集高场强元素（HFSE）、具有异常Sr、Nd同位素组成（相对高87Sr/86Sr（0.704094～0.708223）和相对高143Nd/144Nd（0.512604～0.512856））是本区辉绿岩重要的地球化学特征。相关分析结果表明，该区辉绿岩HFSE和REE的含量受磷灰石含量控制，HFSE和REE之间存在较好的正相关关系，证实其HFSE高含量与岩浆地壳物质混染作用有关。 ③ 在一系列岩石分类和类型划分图解上，岩石为钠质碱性系列岩石；岩石具有相似的过渡元素、不相溶元素和REE配分模式，其大离子亲石元素（LILE）、HFSE和REE明显高于原始地幔（PM）和洋中脊玄武岩（MORB）；Sr、Nd同位素组成在87Sr/86Sr－143Nd/144Nd图中偏离典型地幔演化趋势，位于DMM与EM2地幔端元之间；成岩环境为大陆板内拉张环境；这些特征均表明本区辉绿岩具有异常地幔源区, 为DMM、EM1和EM2三端元混合的混合地幔。 ④ 研究区辉绿岩与区内沙三段中的火山岩具有相似的主要元素、微量元素、稀土元素和Sr-Nd同位素组成，过渡元素、不相容元素和REE配分模式不具明显区别，微量元素之间的比值变化范围重叠、且与交代富集地幔端元（EM1和EM2）相近，这些均表明两类岩石为同源不同岩相的产物，辉绿岩为火山岩为次火山岩相。 ⑤ 结合有关模拟计算结果，初步建立了研究区辉绿岩成因模式。新生代，随着太平洋板块向西俯冲，引发北东向郯庐深大断裂带的重新活动，俯冲进行地幔楔中的沉积物脱水形成的流体和沿郯庐深大断裂带上升的地幔深部流体与亏损地幔相互作用，形成该区具DMM、EM1和EM2三端元混合特征的异常地幔；这种异常地幔部分熔融形成的熔体（原始岩浆）在岩浆房（或上升过程中）遭受地壳物质的混染作用，形成本区辉绿岩和火山岩的母岩浆；大部分母岩浆沿区内构造薄弱地带快速喷发形成本区的火山岩，少量喷发速度较慢的岩浆结晶形成次火山岩相的辉绿岩。 |
| Other Abstract | The Jiyang downwarp (this is the Shengli Oilfield) is the second largest oil base in China, less than the Daqing Oilfield. In this area, the Cenozoic igneous rock is widely developed, and is one of the most important oil-gas reservoirs. Many researchers are great concern the relationship between the igneous rock and oil-gas reservoirs in this area. Previous study have focused mainly on the distribution, rock types and reservoir property etc. of the Cenozoic volcanic rock, and rarely on their geochemistry, tectonic setting, mantle source feature, magmatic evolution and genetic relationship and oil-gas generation etc.. On the other hand, previous researchers did not study the geochemistry of diabase which is the Cenozoic subvolcanic rock in this area, and had not discuss their tectonic setting, mantle geochemistry, crust-mantle interaction and genetic relationship and the Cenozoic volcanic rock. This paper study on mineralogy and geochemistry of diabase from the Huimin depression in the Jiyang downwarp, discuss their tectonic setting, mantle source feature and magmatic evolution, and bring to light the genetic relationship between diabase and volcanic rock in this area. The main conclusions are listed as follow. (1) The essential minerals of diabase in this area are clinopyroxene and plagio- clase, minor minerals are olivine, orthopyroxene, mica, hornblende, K-feldspar and calcite etc., accessory minerals mainly are apatite and metallic minerals. In addition, many kinds of secondary minerals can also be observerd in diabase, such as serpentine, chlorite, albite, kaolinite, carbonate, anhedral mica and metallic minerals etc.. The optical determination and analytical results of electron microprobe show that all of minerals in the diabase have wide ranges of chemical compositions, which is mainly related to magmatic crystal fractionation and later hydrothermal alteration. (2) The diabase in this area are characterized by wide ranges content of major, trace, and rare earth element (REE), enrichment of high field strength element (HFSE) and abnormal Sr and Nd isotopic compositions which relatively high 87Sr/86Sr (from 0.704094 to 0.708223) and 143Nd/144Nd (from 0.512604 to 0.512856) ratios. The results of correlation analysis indicate that the contents of HFSE and REE are mainly controlled by the contents of apatite, and the good positive correlation between HFSE and REE also demonstrates that enrichment of HFSE is due to crustal contamination in the processes of magmatic evolution. (3) In the rock classification diagrams, the diabase in this area belong to sodium- rich alkaline rock. All of rocks have similar distribution patterns of transition elements, incompatible elements and REE, and their contents of large ion lithophile element (LILE), HFSE and REE are obviously higher than those of primary mantle (PM) and mid-ocean ridge basalt (MORB). In 143Nd/144Nd vs 87Sr/86Sr diagram, all of samples are deviated from the evolution line of mantle array and plotted in the area between DMM and EM2. Combination with that they were emplaced in a intra-plate tensional environment, we can conclude that diabase in this area were derived from a abnormal mantle source which may be a mixture of DMM, EM1 and EM2. (4) The diabase and the Cenozoic volcanic rock in the strata of the Shasan member in the Jiyang downwarp have similar contents of major, trace and REE and Sr-Nd isotopic compositions. They are also similar in the distribution patterns of transition, incompatible and REE. Those features show that both of rock-types have homologous source and different lithofacies. That is to say, the diabase is subvolcanic rock of the Cenozoic volcanic rock in the Jiyang downwarp. |
| Pages | 147 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.gyig.ac.cn/handle/352002/3264 |
| Collection | 研究生_研究生_学位论文 |
| Recommended Citation GB/T 7714 | 刘洪文. 胜利油田惠民凹陷辉绿岩地球化学及成因[D]. 地球化学研究所. 中国科学院地球化学研究所,2006. |
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