首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
For example, an atom of radioactive rubidium decays to form an atom of strontium (another element) by converting a neutron in it
For example, an atom of radioactive rubidium decays to form an atom of strontium (another element) by converting a neutron in it
admin
2011-01-04
53
问题
For example, an atom of radioactive rubidium decays to form an atom of strontium (another element) by converting a neutron in its nucleus to a proton and releasing an electron, generating energy in the process. The radiogenic daughter products of the decay—in this case strontium atoms-—diffuse away and are lost above a certain very high temperature. So by measuring the exact proportions of rubidium and strontium atoms that are present in a mineral, researchers can work out how long it has been since the mineral cooled below that critical "blocking" temperature. The main problems with this dating method are the difficulty in finding minerals containing rubidium, the accuracy with which the proportions of rubidium and strontium are measured, and the fact that the method gives only the date when the mineral last cooled below the blocking temperature. Because the blocking temperature is very high, the method is used mainly for recrystallized (igneous or metamorphic) rocks, not for sediments—rubidium-bearing minerals in sediments simply record the age of cooling of the rocks which were eroded to form the sediments, not the age of deposition of the sediments themselves.
选项
答案
例如,放射性的铷的一个原子衰退后,把一个中子转变成一个质子并释放出一个电子,形成一个锶(另外一种元素)原子,在这个过程中产生能量。衰退后的放射性子产品——在这里就是锶原子——会以一个极高的温度分散化解。所以测量一下现在矿物中铷原子和锶原子的确切比例,研究人员就会推导出该矿物在冷却到凝结温度以下之后又埋没了多少年。这种回溯方法具有弊端,因为很难发现含有铷元素的矿物、测量铷元素和锶元素的精确比例,而且推断出的时间只是矿物最后冷却到凝结温度之下的时间。因为凝结温度很高,这种方法只适用于再结晶岩石(火成岩或变质岩),不适合沉积岩——含铷元素的矿物,它能记载岩石腐化成沉积物的冷却时间,而不是沉积物自己的蜕变年龄。
解析
转载请注明原文地址:https://kaotiyun.com/show/vcHO777K
0
在职攻硕英语联考
相关试题推荐
Inthelate19thcentury,JulesVerne,themasterofsciencefiction,foresawmanyofthetechnologicalwondersthatare______to
Theintellectually______enterpriseofsciencedependsonfreecommunication.
Thewaythatpeoplespendtheirmoney,andtheobjectsonwhichtheyspendit,arethelastareaswherefreechoiceandindividu
Thewaythatpeoplespendtheirmoney,andtheobjectsonwhichtheyspendit,arethelastareaswherefreechoiceandindividu
Thewaythatpeoplespendtheirmoney,andtheobjectsonwhichtheyspendit,arethelastareaswherefreechoiceandindividu
Thewaythatpeoplespendtheirmoney,andtheobjectsonwhichtheyspendit,arethelastareaswherefreechoiceandindividu
Thewaythatpeoplespendtheirmoney,andtheobjectsonwhichtheyspendit,arethelastareaswherefreechoiceandindividu
Thewaythatpeoplespendtheirmoney,andtheobjectsonwhichtheyspendit,arethelastareaswherefreechoiceandindividu
Ifitwereonlynecessarytodecidewhethertoteachelementarysciencetoeveryoneonamassbasisortofindthegiftedfewan
随机试题
HJ431属于____型焊剂。
现病史不包括
出入液量的记录内容下列正确的是
依据《建设项目环境影响评价资质管理办法》,评价范围是农林水利类的环境影响评价机构不可以提供环评服务的项目是( )。
某保税仓库2006年6月1日进库储存一批转口的货物,到2007年5月底因故没有出运出库,经向海关批准延期3个月,但到期仍未出运,按规定海关可以提取变卖的时间为:
当市场价格高于行权价格时,公司发行在外的股份总数()。
德育过程是对学生知、情、意、行的培养和提高过程,其实施顺序是()。
(2016·河北)下列各项属于经典条件反射理论关于学习的基本观点的是()
某数据库中有关系:供应商(供应商号,供应商名,地址)零件(零件号,零件名,重量)项目(项目编号,项目名称,开工日期)供应(供应商号,项目编号,零件号,零件数)其中一个供应商能提供多种零件和多个项目,一种零件能供给不同
HowmanytimeswillshapeTfitintoshapeS?
最新回复
(
0
)