海阳市招虎山一带崂山序列特征及成因类型分析

Analysis on the characteristics and genetic types of Laoshan sequence in Zhaohu Mountain area, Haiyang City

海阳市招虎山主峰一带发育二长花岗岩和正长花岗岩,呈半环状分布于海阳断裂西侧。岩石谱系单位划分为5个单元,归属于崂山序列,其中二长花岗岩归属于浮山亚序列,正长花岗岩归属于石门山亚序列。空间上侵入体按侵入时间由早到晚呈由外向内的环状分布。由早到晚,各单元岩石的碱性程度呈渐趋加强,且各亚序列中由早到晚,岩石粒度由粗变细;由早到晚,微量元素Sr、Ba呈渐趋降低、Rb略有增高趋势;轻稀土、重稀土及稀土总量均呈渐趋降低,铕亏损加强。通过对各单元岩石学、地球化学等特征分析,认为该区的崂山序列成因类型为SI型,其岩浆来源于上地幔,在上侵过程中与地壳同熔、混染。该序列成岩温度为800～274.04℃;成岩压力为(4～0.7)×108 Pa。推断其初始结晶深度为13 km,定位深度为7～10 km,后期单元定位向上,趋于浅成岩。

Admellites and Syenogranite developed along the main peak of Zhaohu Mountain area of Haiyang City. They are distributed in a semi-circular shape on the west side of the Haiyang Fault. The rock pedigree unit is divided into 5 units, Attributable to Laoshan sequenece, The admellites belong to the Fushan subsequence, syenogranite belongs to Shimenshan subsequence, The space intrusion is distributed from the outside to the inside according to the intrusion time. From early to late, The alkalinity of each sequenece rock is gradually strengthened, And the grain size of each subsequence is coarse and fine, Trace elements Sr and Ba are gradually decreasing and Rb is slightly increasing, The total amount of light rare earth element, heavy rare earth element and rare earth is gradually decreasing, and the loss of Eu is strengthened. Analysis of the characteristics of petrology and geochemistry of each sequenece, it is considered that the genetic type of the Laoshan super unit in this area is SI. The magma is derived from the upper mantle and is melted and mixed with the earth’s crust during the intrusion. The temperature of this sequenece diagenesis is 800~274.04℃;The diagenetic pressure is(4~0.7)×108 Pa. It is inferred that the initial crystal depth is 13 km and the depth of positioning is 7~10 km. Late unit positioning upwards, tending to shallow diagenesis.