| 白云鄂博群哈拉霍疙特组滑塌堆积的
发现及其地质意义 |
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| 引用本文： | 张星,吕洪波,董晓朋,孙闯,陈林,柳建勇,章雨旭,王俊.白云鄂博群哈拉霍疙特组滑塌堆积的
发现及其地质意义[J].地质论评,2013,59(6):1199-1206. |
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| 作者姓名： | 张星 吕洪波 董晓朋 孙闯 陈林 柳建勇 章雨旭 王俊 |
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| 作者单位： | 中国石油大学地球科学与技术学院，山东青岛，266580;中国石油大学地球科学与技术学院，山东青岛，266580;中国石油大学地球科学与技术学院，山东青岛，266580;南京大学地球科学与工程学院，南京，200046；;包钢（集团）公司白云鄂博铁矿，内蒙古包头， 014080;包钢（集团）公司白云鄂博铁矿，内蒙古包头， 014080;中国地质科学院地质研究所，北京，100037；;香港大学地球科学系，香港 |
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| 基金项目： | 本文为国家自然科学基金资助项目（编号 41072074）的成果。 |
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| 摘 要： | 笔者等在白云鄂博矿田北西部查干楚鲁附近白云鄂博群哈拉霍疙特组上段发现了典型的滑塌堆积。重点研究了同一滑塌层位中的两个滑塌堆积露头。整个滑塌堆积层岩性单一，内部结构杂乱，不见原始沉积层理。根据野外观察和室内薄片鉴定结果，该处岩性主要有两种：形状不一、大小混杂的灰黄色白云岩岩块（滑积岩块）杂乱无序地分布在深灰色纹层状碳质微晶灰岩（本地沉积）中。最大的透镜状白云岩滑积岩块露头长27m，宽58m。深灰色纹层状碳质微晶灰岩岩层产状基本稳定，整体北倾，倾角较大。深灰色灰岩层与灰黄色白云岩的接触界面附近发育软沉积物变形构造，白云岩滑积岩块本身棱角不明显，两端有明显的细颈拉长现象，表明滑塌发生时，白云岩处于半固结和不完全成岩状态。滑积岩块位于不同的背景沉积层位中，揭示露头区存在多次的滑塌堆积事件。根据滑塌堆积的内部结构特征，初步判断其为被动大陆边缘靠近多岛洋或碳酸盐台地的深水盆地边缘，主要触发因素可能为地震活动。此外，白云鄂博群中滑塌岩块的发现表明白云鄂博群与腮林忽洞群沉积时具有相似的构造、古地理环境，这为白云鄂博群与腮林忽洞群相当（均为早古生代）提供了新的佐证。
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| 关 键 词： | 滑塌堆积 白云鄂博 白云鄂博群哈拉霍疙特组 软沉积物变形 震积液化脉 |
| 收稿时间： | 7/5/2013 12:00:00 AM |
| 修稿时间： | 2013/9/14 0:00:00 |
Olistostromes Discovered in the Halahuogete Formation, Bayan Obo Group
and Its Geological Significance |
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| Abstract: | The carbonate olistostromes found in the Upper Member of the Halahuogete Formation in the Bayan Obo Group were recognized in the field to the northwest of Bayan Obo Deposit, Inner Mongolia. We focus on the research of the two olistostrome outcrops in the field belong to the same horizon. The lithology of the entire olistostrome is monomictic, with chaotic internal structures, without showing the original sedimentary beddings. According to the data collecting in the field and thin sections, there are two major rock types: the dark gray laminated carbonaceous micrite, which represents the autochthonous deposition, and sallow dolostone olistolith. There are a lot of sallow dolostone blocks with different shapes and sizes distributed in the dark gray laminated carbonaceous micrite. The largest lenticular dolostone slump block is 27m in length, and 5.8m in width. The attitude of the dark gray laminated carbonaceous micrite layers is basically stable, north dipping with steep angle. We have recognized some soft sediment deformation structures from the outcrop near the contact interface of the autochthonous limestone and the olistostrome. The dolostone slump blocks do not show the sharp corners, and both ends of the large olistolith are obviously necking, indicating a soft or semi solidified state during transportation and deposition. The olistoliths in different autochthonous sedimentary beds reveal at least several slump events in this outcrop. We believe that the olistostrome should be deposited at the bottom of a hemipelagic pelagic ocean basin adjacent to the margin of carbonate platform where the dolostone was formed first in the shallow water and then cut and moved away by slumps. Seismic activities may be the major trigger factor. In addition, the olistostromes discovered in Bayan Obo Group suggest that when Bayan Obo Group and Sailinhudong Group deposited, they had similar tectonic environment and paleogeography, It provides new evidence that Bayan Obo Group is equal to Sailinhudong Group(both early Paleozoic). |
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