摘要
桐柏—大别山地区西起随州三合店,南东至黄梅县,分布有不同规模的中生代深成侵入体30余个,以酸性岩为主。上世纪90年代以来的区域地质调查,依据同源岩浆演化序列的理论和等级体制原则,初步建立了本区侵入岩岩石谱系单位,划分了单元,归并了超单元。侵入岩体及超单元的岩石类型主要为二长花岗岩、碱长花岗岩、钾长花岗岩、花岗闪长岩、闪长岩、石英二长闪长岩、正长岩等。侵入体同位素年龄值均在120 Ma上下,其时代为白垩纪。侵入体与围岩多为不协调侵入接触,超单元及序列之间为超动接触,超单元内部各单元之间为涌动接触或脉动接触。就位机制多为强力就位,它们在平面上多呈圆形或椭圆形,具同心环状构造,其就位模式以热轻气球膨胀为主,且多受断裂控制或沿两组断裂的复合部位就位。岩石成因类型主体为构造期后"I"型花岗岩,部分为构造期"I"型花岗岩,它们既有时间上的先后序列,又具空间上有规律的展布,平面多呈环带状分布;在结构上由早单元至晚单元呈细粒→中粒→粗粒→斑状,斑晶由少至多,斑晶颗粒由细至粗作规律性变化,岩石化学显示为钙碱性→碱性系列、弱铝→过铝系列,由此构成了各超单元系统的演化序列。
Intrusion isotopic ages were 120Ma,those of the Cretaceous era.Intrusive rocks are mostly incompatible intrusive contact with wall rock.Beveling intrusive contact is between the super-unit and sequence,each unit of super-unit elements is surge intrusive contact or pulsating intrusive contact.Emplacement mechanisms are mostly strong,they were round or elliptical in the plane,with concentric ring structure.Emplacement model is dominated by expansion of thermal light balloons,controlled by faults or along the two faults composite parts in place.Genetic types of rocks is constructed of "I"-type granite after tectonic epoch,part structure of "I"-type granite,which has not only temporal sequence,but also a space on a regular distribution,with zonal distribution in plane.Petrochemistry shows calc-alkaline→alkaline series,weak aluminum→peraluminous series,which constitutes the super-cell system of sequence evolution.
出处
《资源环境与工程》
2010年第4期341-347,358,共8页
Resources Environment & Engineering