华北克拉通中生代幔源岩浆岩放射性元素生热率的时空差异与主控因素

Temporal-spatial differences and controlling factors in radioactive heat generation rates of Mesozoic mantle-derived magmatic rocks in the North China Craton

华北克拉通地热资源与中生代岩浆活动关系密切。然而,地热资源的成因、分布与岩浆作用之间的内在联系尚不明确。为研究华北克拉通中生代岩浆活动对地热资源的影响,在厘清中生代幔源岩浆岩期次、岩性、成因和分布的基础上,利用632组幔源岩浆岩的U、Th、K生热元素数据,计算不同时期岩石放射性生热率,探究华北克拉通中生代幔源岩浆岩放射性生热率时空差异及其主控因素。结果表明:幔源岩浆岩岩石类型是影响生热率的直接因素,霞石正长岩、辉石岩、正长岩和煌斑岩的生热率高于辉长岩、辉绿岩和玄武岩;幔源岩石成因是放射性生热率高低的基础,与伸展构造背景相比,碰撞环境下岩石生热率较高;不同破坏机制下岩石生热率差异较大,热-化学侵蚀岩石圈破坏地区的岩石生热率普遍高于拆沉作用地区。

Geothermal resources within the North China Craton have a strong association with Mesozoic magmatic activities.However,the precise link between the origin,distribution,and magmatism of these geothermal resources remains elusive.To investigate the influence of Mesozoic magmatic activity on the geothermal resources within the North China Craton,this study calculated the radioactive heat generation rates of rocks during various periods by utilizing data on U,Th and K heat generation elements from 632 sets of mantle-source magmatic rocks.This calculation was conducted on the basis of clarifying the period,rock type,genesis,and distribution of Mesozoic mantle source magmatic rocks.The research aimed to investigate the temporal-spatial disparities and primary controlling factors behind the radioactive heat generation rates of Mesozoic mantle-derived magmatic rocks within the North China Craton.The outcomes highlight that the type of mantle-derived magmatic rocks serves as a direct determinant of the heat generation rate.Specifically,nepheline syenite,pyroxene,syenite and lamprophyre display higher heat generation rates compared to gabbro,diabase,and basalt.Moreover,the origin of mantle-derived rocks emerges as the foundamental basis for the high radioactive heat generation rate,and the thermal generation rate of rocks within the collision environment surpasses that within the extensional tectonic setting.Substantial variations in the heat generation rate are observed among magmatic rocks formed under different destructive mechanisms.The rocks within the lithosphere damaged area by thermal-chemical erosion typically exhibit higher heat generation rates than those affected by delamination in the lithosphere.