安徽宿松、繁昌地区武穴组沉积特征
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摘要
安徽宿松、繁昌、江西彭泽间长江两岸的武穴组呈透镜体展布,组成岩石类型①藻屑灰岩,②(?)灰岩,③海绵灰岩,④棘屑灰岩,⑤核形石白云岩;⑥白云岩。从四条剖面的研究曲线由下向上明显地区分出三个粒屑含量与基质含量百分比连续变化序列.这种序列称基本单元。一般的变化规律为由下向上,由粗变细的正向序列,但是其中也有由细一粗一细的反向序列,这种反向序列反映出较快的沉积过程,往往起着障壁作用;几乎全由棘屑灰岩、藻屑灰岩、海绵灰岩组成。并为亮品胶结,在每个基本单元的顶部或底部常伴有海绵粘结灰岩,并具巨一粗晶结构,显示出生物筑积作用的速度短暂地超过海平面上升的速度而处于极浅水域的产物。称这种类型的单元为生物建隆。依据其特征、所处位置。初步推断湖北广济、大冶、京山、南漳等地都有可能属于这种孤立的不连接的地质体存在。
The Wuxue Formation,a lenticular stratigraphic body distributed along the Yangtze River between Susong and Fanchang in Anhui and in the Pengze district,Jiangxi,consists of algal limestone,fusulinid limestone,sponge limestone,echinoderm limestone,oncolite dolostone and dolostone.According to the radios of elast to matrix in four sections,three sequences called basic units are easily recognized.These sequences are dominated by the normal fining-upward sequences from the base upwards.The inversely graded fine-coarse- fine sequence almost composed of the echinoderm limestone,algal limestone and sponge limestone cemented by sparite,however,is also found,which indicates a rapidly deposition- al process and a barrier environment.The sponge bindstone exhibiting mega-and coarse- crystallized grain textures observed at the base and on the top of these units represents the products in the extremely shallow-water environments where the rates of organic upbuild- ing were temporarily greater than those of sea-level,rise,This kind of depositional units is usually called organic buildups.It is inferred from tectonic settings and sedimentary char- acteristics that this kind of isolated geological bodies may come into existence in Guangji, Daye,Jingshan,Nanzhang and other places in Hubei.
The Wuxue Formation,a lenticular stratigraphic body distributed along the Yangtze River between Susong and Fanchang in Anhui and in the Pengze district,Jiangxi,consists of algal limestone,fusulinid limestone,sponge limestone,echinoderm limestone,oncolite dolostone and dolostone.According to the radios of elast to matrix in four sections,three sequences called basic units are easily recognized.These sequences are dominated by the normal fining-upward sequences from the base upwards.The inversely graded fine-coarse- fine sequence almost composed of the echinoderm limestone,algal limestone and sponge limestone cemented by sparite,however,is also found,which indicates a rapidly deposition- al process and a barrier environment.The sponge bindstone exhibiting mega-and coarse- crystallized grain textures observed at the base and on the top of these units represents the products in the extremely shallow-water environments where the rates of organic upbuild- ing were temporarily greater than those of sea-level,rise,This kind of depositional units is usually called organic buildups.It is inferred from tectonic settings and sedimentary char- acteristics that this kind of isolated geological bodies may come into existence in Guangji, Daye,Jingshan,Nanzhang and other places in Hubei.
引文
1魏家庸等著.沉积岩区1:50000区域地质填图方法指南.中国地质大学出版社,1991
2Wilson,J.C.Carbonate facies in geologic history.New York,Springer-Verlag,1975,471 pp.
3冯增昭等著.中下扬子地区二叠纪岩相古地理.地质出版社,1991
4赵时久等.中南地区二叠纪岩相古地理及沉积矿产远景预测.《岩相古地理文集》第七集。地质出版社,1991
5杨振强等.“江南古陆”两侧早二叠世海泡石的形成环境及成矿预测.《岩相古地理文集》第七集,地质出版社,1991
2Wilson,J.C.Carbonate facies in geologic history.New York,Springer-Verlag,1975,471 pp.
3冯增昭等著.中下扬子地区二叠纪岩相古地理.地质出版社,1991
4赵时久等.中南地区二叠纪岩相古地理及沉积矿产远景预测.《岩相古地理文集》第七集。地质出版社,1991
5杨振强等.“江南古陆”两侧早二叠世海泡石的形成环境及成矿预测.《岩相古地理文集》第七集,地质出版社,1991
目录
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