东胜黄天棉图直罗组下段下亚段钙化木特征分析  

Feature of Calcified Wood in Lower Subinterval of Lower Zhiluo Formation,Huantianmiantu of Dongsheng

作　　者：贾正海 杨健 周旭 刘广宇 孙志伟 王光 

机构地区：[1]河北省地质调查院,河北石家庄050081

出　　处：《西北地质》2015年第1期72-78,共7页Northwestern Geology

基　　金：中央地质勘查基金东胜煤铀兼探会战项目(2008150013)

摘　　要：东胜黄天棉图北部山区直罗组下段岩层中,钙化木十分发育。笔者分析了钙化木赋存层位的沉积环境,描述了钙化木的岩石矿物学特征,并结合前人的研究成果,对该地区钙化木的成因进行了初步推测。研究发现:1该区木化石分两类,一类为钙化木,另一类为碳化-钙化木,其赋存层位的沉积环境为决口扇、决口河道与分流间湾的冲刷接触面。2钙化木中方解石以中晶-巨晶居多,含少量碳质成分,碳化-钙化木中方解石以隐晶—微晶为主,碳质成分含量较高。3钙化木是由富含Ca2+和CO32-的地下水进入树干中的孔隙,并在其中沉淀、结晶方解石形成的。认为Ca2+的来源为斜长石蚀变,CO32-的来源可能是碳酸铀酰络合离子([UO2(CO3)3]2-)。There are many calcified wood in lower subinterval of lower Zhiluo formation （J2z1-1 ） in the northern mountains of Huangtianmiantu town of Dongsheng. This paper analyzed the sedi- mentary environment of calcified wood, and described its petrological and mineralogical character- istics. Combined with previous research works, we preliminarily summarized the cause of forma- tion of calcified wood in this region. It is found that, firstly, there are two kinds of wood fossil in J2z1-1 formation of this district, respectively calcified wood and carbonized-calcified wood, and they occurred in the scouring surface between BA and CVS as well as CCH; secondly, the miner- al composition of calcified wood are mostly megacrystcalcite and very little carbonaceous frag- ments, but in carbonized-calcified wood the carbon content is higher and the calcite inside are mi- crolite; thirdly, the genesis of calcified wood is that the underground water with Ca2＋ and CO32- flowed into the pore of tree trunk and the calcite crystallized in it. It is considered that Ca2＋ is de- rived from anorthosite erosion, and CO32- probably comes from [UO2 （CO3）3]2-.

关 键 词：钙化木 岩矿特征 沉积环境 成因 

分 类 号：P66[天文地球—地质学]