| 宋普洪,陆跃荣,魏世鹏,刘波,徐东,周永康,白宇.黔中大湾磷矿区早震旦世“盖帽”白云岩对a矿层的影响及其地质意义[J].贵州地质,2021,38(2):201-207 |
| 黔中大湾磷矿区早震旦世“盖帽”白云岩对a矿层的影响及其地质意义 |
| Influence and Geological Significance of Cap Dolomite to A Seam of Early Sinian in Dawan Phosphorite Mining Area in Central Guizhou |
| 投稿时间：2021-01-30 |
| DOI： |
| 中文关键词: 大湾磷矿 陡山沱组 盖帽白云岩 贵州中部 |
| 英文关键词:Dawan Phosphorite Ore Central Guizhou Doushantuo Formation Cap Dolomite Central Guizhou |
| 基金项目: |
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| 中文摘要: |
| 大湾矿区陡山沱组底部为上覆于南华系冰碛岩之上的盖帽白云岩，主要由微晶白云石组成的泥-微晶结构、薄层状构造灰色细晶白云岩。局部地区，岩石为铁质侵染，为褐红色。见方解石及少量石英充填于裂隙中。水平层理发育，与上覆矿层整合接触。盖帽白云岩在全球各地广泛分布。大湾矿区震旦系陡山沱二段(a矿层产出层位)厚度及其品位受沉积基底(陡山沱一段“盖帽”白云岩)起伏程度的制约，当盖帽白云岩厚度增大时，沉积的陡山沱组a矿层厚度减薄，相应的磷块岩P2O5含量相对增高，相反，沉积的陡山沱组含磷层厚度大，磷块岩P2O5含量相对较低。矿区北4-8号勘探线及9-27号勘探线a矿层矿石品位相对较高，a矿层厚度相对减小。指示大湾矿区北东部及南西部a矿层沉积环境海水相深度相对较浅，水动力环境相对较强。同样，大湾矿区中部a矿层底板盖帽白云岩很薄或这未发育，但出现粉砂质泥岩，矿石品位相对较低，矿层厚度相对变厚。a矿层沉积环境海水相深度相对较深，水动力环境相对较弱，推测大湾矿区中部a矿层沉积底板存在一条东西向凹陷。从盖帽白云岩到陡山沱二段a矿层是持续海侵过程，地层连续沉积。盖帽白云岩沉积环境为介于潮间带至深水区的缓坡，指示a矿层同样为潮间带至深水区之间的缓坡沉积。 |
| 英文摘要: |
| The base of Doushantuo formation in GrandBaie mining area is cap dolomite overlying Nanhua Moraine，which is mainly composed of microcrystalline dolomite with mudmicrocrystalline structure and thinlayered structureIn some areas，the rocks are ironcolored and brownishredcalcite and a small amount of quartz filled in the fractureHorizontal bedding is developed and contacts with overlying strataCap Dolostone is widely distributed all over the worldThe thickness and grade of the second member of the Sinian Doushantuo formation in the GrandBaie mining area are controlled by the fluctuation of the sedimentary basement(cap dolomite of the first member of the Doushantuo formation)，the thickness of a deposit of the sedimentary doushantuo formation is thinner，and the P2O5 content of the corresponding phosphate rock is relatively higher，on the contrary，the thickness of the sedimentary Doushantuo formation is larger，and the P2O5 content of the phosphate rock is relatively lowerThe ore grade of ore layer a is relatively high and the thickness of ore layer a is relatively small in the north 48 exploration line and 927 exploration lineIt indicates that the depth of marine facies is relatively shallow and the hydrodynamic environment is relatively strong in the northeast and southwest parts of the GrandBaie mining areaSimilarly，in the central part of the GrandBaie mining area，the floor cap dolomite is very thin or not developed，but silty mudstone appears，the ore grade is relatively low and the thickness of the ore layer is relatively thickThe sedimentary environment of a deposit is relatively deep in Marine facies and weak in hydrodynamic environmentIt is inferred that there is an eastwest depression in the sedimentary floor of a deposit in the central part of GrandBaie mining areaFrom Cap Dolomite to a deposit of the second member of doushantuo formation is a continuous transgression process and continuous sedimentary strataThe Cap Dolomite sedimentary environment is a gentle slope between the intertidal zone and the deep water zone，indicating that the a deposit is also a gentle slope between the intertidal zone and the deep water zone |
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