浙江桐村矿区裂变径迹分析与热历史模拟

发布时间：2018-06-23 02:16

  本文选题：桐村矿区 + 磷灰石　； 参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：桐村斑岩钼(铜)矿床位于江绍拼合带西南端,处于钦州-钱塘结合带内,邻近江南背斜,在钦州-杭州重点找矿带东段。通过野外调研和观察,总结并描述了研究区的基本地质特征,利用磷灰石和锆石进行裂变径迹测试,通过分析裂变径迹长度分布和年龄分布,对矿区进行热历史模拟,并分析了矿床的隆升剥蚀情况。取得认识如下:矿区主要见花岗岩、花岗岩闪长岩、和角岩,偶见石英岩;主要的含矿岩体有蚀变花岗岩和角岩;辉钼矿以细脉浸染状、黄铁矿和黄铜矿以星点状或团块状富集于岩体和矿脉中,岩体富集大量的含矿石英脉;矿床蚀变以青磐岩化为主,岩体中心向外依次是钾化硅化-青磐岩化(绢云母化)—高岭土化,其中矿化石英脉主要集中在青磐岩化带。分析岩体中磷灰石裂变径迹长度分布可知,其长度范围在11.9±2.4μm~13.2±2.0μm之间,相对较为集中,磷灰石裂变径迹长度分布直方图有两种类型,深部样品为无扰动基底型,浅部出现双峰型,表明桐村矿区磷灰石样品受到构造热活动影响而表现为两种分布状态,岩体整体受到两期热事件的作用,但岩体核部的样品则表现为简单的冷却过程。锆石裂变径迹年龄的范围在109-143 Ma之间,磷灰石裂变径迹年龄范围在17-31 Ma之间,为正态分布,其峰值年龄分别为137Ma和22Ma。利用He FTy软件对样品进行热历史模拟,得到时间-温度演化曲线,样品冷却轨迹相似,先进入冷却期,然后缓慢冷却期,最后进入加速冷却期。利用矿物对法分析剥蚀情况,岩体形成于晚侏罗世,从早白垩世-新近纪,剥蚀速率为0.0238km/Ma,剥蚀量为H1=2.732km,其中锆石裂变径迹与高程关系显示锆石记录了该时期的沉积信息,从新近纪-第四纪,岩体剥蚀速率为0.0383 km/Ma,剥蚀量为H2=0.842km,在45~25Ma期间和15~0.1Ma期间有两次明显的抬升,两次的冷却速率分别为3.75~5℃/km和3.21~6.67℃/km。岩体自137Ma至今,累计剥蚀量为3.579km。岩体的两次主要抬升剥蚀情况与华南地块燕山期和喜马拉雅阶段区域构造作用相吻合。
[Abstract]:The Tongcun porphyry molybdenum (copper) deposit is located at the southwest end of the Jiangshao assemblage belt, located in the Qinzhou-Qiantang junction belt, adjacent to the Jiangnan anticline, and located in the eastern section of the Qinzhou-Hangzhou key ore prospecting belt. Through field investigation and observation, the basic geological characteristics of the study area are summarized and described. The fission track is tested by apatite and zircon, and the thermal history of the mine is simulated by analyzing the length distribution and age distribution of the fission track. The uplift and denudation of the deposit are analyzed. They are: granite, granite diorite, and hornstone, occasionally quartzite; major ore-bearing rock bodies are altered granite and hornstone; molybdenum is disseminated in the vein, Pyrite and chalcopyrite are enriched in the rock mass and vein in the form of star or lump, and the ore-bearing veins are enriched in the rock mass. The center of the rock mass is in the order of potassium silicification-Qingiranlitization (sericite)-kaolinization, in which the mineralized quartz vein is mainly concentrated in the Qingiranlitization zone. By analyzing the length distribution of apatite fission track in rock mass, it can be seen that the length range of apatite fission track is between 11.9 卤2.4 渭 m and 13.2 卤2.0 渭 m, which is relatively concentrated. There are two types of apatite fission track length distribution histogram. The results show that the samples of apatite in Tongcun mining area are affected by tectonic thermal activity in two distribution states, the whole rock mass is affected by two thermal events, but the sample in core of rock mass shows a simple cooling process. Zircon fission track ages range from 109 to 143 Ma, apatite fission track ages range from 17 Ma to 31 Ma, which are normal distribution, their peak ages are 137 Ma and 22 Ma, respectively. He FTy software was used to simulate the thermal history of the sample, and the time-temperature evolution curve was obtained. The cooling trajectory of the sample was similar, which entered the cooling period first, then slowly, and finally the accelerated cooling period. From early Cretaceous to Neogene, the denudation rate is 0.0238km / Maand the denudation amount is H1 / 2.732km. The relationship between zircon fission track and height indicates that the sedimentary information of this period is recorded by the relationship between zircon fission track and height. From Neogene to Quaternary, the denudation rate of rock mass is 0.0383 km / Ma and the denudation amount is H _ 2O _ (0.842) km. There are two distinct uplift during 45~ 25Ma and 150.1Ma, the cooling rate of which is 3.75 ~ 5 鈩，

本文编号：2055297