| 陕南奥陶系宝塔组灰岩网状裂缝成因 |
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| 引用本文： | 王安东,周瑶琪,仲岩磊,段竟,王子阳,张振凯.陕南奥陶系宝塔组灰岩网状裂缝成因[J].地球科学,2012,37(4):843-850. |
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| 作者姓名： | 王安东 周瑶琪 仲岩磊 段竟 王子阳 张振凯 |
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| 作者单位： | 1.中国石油大学地球科学与技术学院，山东青岛 266555 |
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| 基金项目： | 国家自然科学基金40872095 |
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| 摘 要： | 为了研究奥陶系宝塔组灰岩网状裂缝的形成原因，利用古生物鉴定、野外露头对比及镜下薄片观察等方法进行分析.古生物以头足类、三叶虫、介形类和棘皮类为主，偶见腕足类，未见藻类.裂缝延伸到生物化石时停止，贯穿地层顶底面但未穿透相邻地层，平面呈瘤状、龟裂纹和S曲线等，锯齿状缝合线切穿裂缝.镜下发现灰质基块内散布着泥质团块，泥质团块通过微裂隙互相连通或连通主裂缝，泥质内夹的灰质碎屑长轴沿裂缝展布，新鲜剖面灰质基块与泥质裂缝无明显界限.提出宝塔期扬子板块处于稳定克拉通沉积环境，网状裂缝是在较深水缓慢沉积的低能开阔台地环境下，由于化学分异作用灰质质点聚集、压实作用胶态粘土矿物脱水收缩、泥质随水排出时充填裂缝而形成的，为非构造成因裂缝.
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| 关 键 词： | 宝塔组灰岩 网状裂缝 泥质含量 收缩裂缝 沉积学 构造 |
| 收稿时间： | 2012-03-05 |
Causes of Reticular Cracks in Ordovician Baota Formation Limestone in Southern Shaanxi |
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| Abstract: | Through Paleontology appraisal, outcrop contrast and under mirror slice observation methods, this paper analyzes the causes of reticular cracks, Baota Formation limestone, Ordovician. Paleontology is mainly of cephalopods (Sinoceras chinensis), trilobites, ostracoda and echinodermata (Metacrinus), occasionally including Brachiopoda, noalga. The formation is divided into two units: the lower purple and the upper celadon. The crack, stretching from the surface and bottom without penetrating the adjacent formation, stops when extended to the biological fossils. The patterns are of nodular, tortoise shell and the S curve, etc; dentate suture lines cut through the crack. Microscopic study shows that shale mass spreads in the limy matrices, with shale mass connected each other or connected to the main crack by the micro crack, the macroaxis of the limy chipping in shale exhibited along the crack. There are no obvious boundaries between limy matrices and shale crack in fresh profile. It is concluded that the Yangtze plate, Baota period was in a stable craton sedimentary environment, and reticular cracks formed due to limy particles by chemical differentiation and clay mineral syneresis in compressions with shale filling cracks with no-flow periods in a deep water(more than euphotic zone) slow deposition low-energy open platform environment, which indicates that cracks formed because of the non-structural causes. |
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