| 云南省鹤庆小天井锰矿赋矿地层的时代及其找矿意义 |
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| 引用本文：张翼飞,杨学雄,王岩.2025.云南省鹤庆小天井锰矿赋矿地层的时代及其找矿意义[J].地球学报,46(1):88-92. |
| DOI：10.3975/cagsb.2024.111102 |
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| 基金项目:中国地质调查局“中国矿产地质志”项目(编号: DD20221695; DD20190379)；“战略新兴产业地质调查工程”项目(编号: DD20230034)和科技部科技基础资源调查专项“中国战略性新兴产业矿产资源数据整编及图集编纂”课题(编号: 2022FY101702) |
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| 中文摘要:云南省鹤庆小天井锰矿长期存在赋矿地层时代的争论, 找矿至今无大的进展。笔者在鹤庆小天井锰矿主矿体的顶板和底板均采到牙形刺化石, 顶板获Clarkina leveni leveni (Kozur, Pjatakova et Mostler)(莱文克拉科刺)、Clarkina liangshanensis(Wang)(梁山克拉科刺)、Clarkina bitteri(Kozu)(比特克拉科刺)、Xaniognathus elongatus Sweet(细长梳颚刺)4个种的克拉刺带化石。这4个种的牙形刺为晚二叠世吴家坪期中期Clarkina leveni leveni带; 底板获得Diplognathodus sp. A(双颚齿刺未定种A), 其时代属中晚二叠世(P2-3), 该化石在中国主要见于中二叠统茅口组上部, 上二叠统相应地层也有见及。基于这些牙形刺化石特征, 确定了鹤庆锰矿赋矿地层时代为晚二叠世, 应归属上二叠统吴家坪组, 解决了对含锰矿地层时代的争论。同时, 钻孔深部取出的岩矿芯和地表观察均证实, 原含锰矿上部的“飞来峰”灰岩(T2b)与下伏的含锰矿地层为整合接触关系, 说明该区不存在推覆构造形成的飞来峰。本区含锰矿地层时代已清楚, 对该区进一步寻找锰矿的地层也从原“上三叠统松桂组(T3sg)”转向上二叠统吴家坪组寻找新的锰矿产地。值得注意的是, 小天井锰矿石中有蜡硅锰矿, 这是与火山有关的一种锰矿石, 应重视火山沉积盆地中远离喷发区的火山沉积边缘小盆地寻找锰矿。 |
| 中文关键词:小天井锰矿 飞来峰 牙形刺 晚二叠世 |
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| Age and Prospecting Significance of the Ore-bearing Strata in the Xiaotianjing Mn Deposit, Heqing, Yunnan Province |
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| Abstract:There has long been controversy over the stratigraphic age of the ore-bearing formations in the Xiaotianjing manganese mine in Heqing County. We collected gondolella fossils from both the roof and floor of the main orebody in the Xiaotianjing manganese deposit. In the roof, four species of Clarkina-bearing fossils were identified: Clarkina leveni leveni, Clarkina liangshanensis, Clarkina bitteri, and Xaniognathus elongatus Sweet, belonging to the Clarkina leveni leveni zone of the middle Wujiapingian age of the Late Permian. From the floor, Diplognathodus sp. A was obtained, which dates to the Middle–Late Permian (P2-3). This fossil is mainly found in the upper part of the Maokou Formation of the Middle Permian in China and also occurs in corresponding formations of the Upper Permian. Based on the characteristics of these gondolella fossils, the stratigraphic age of the ore-bearing formations in the Xiaotianjing manganese deposit was determined to be the Late Permian and should be attributed to the Upper Permian Wujiaping Formation. Meanwhile, both the rock cores obtained from deep drilling and surface observations confirmed that the “klippe” limestone (T2b) originally located above the manganese-bearing formations is in conformable contact with the underlying manganese-bearing formations, indicating that there is no tectonic nappe forming the “klippe” in this area. With the stratigraphic age of the manganese-bearing formations in this area now clarified, further manganese ore prospecting has shifted to the Late Permian Wujiaping Formation. It is noteworthy that there is cerussite in the Xiaotianjing manganese ore, which is a type of manganese ore related to volcanism. Attention should be paid to prospecting for manganese ore in small volcanic sedimentary basins located on the volcanic sedimentary margins far from the eruption zones within volcanic sedimentary basins. |
| keywords:Xiaotianjing Mn deposit klippe gondolella Late Permian |
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