燕山南缘盘山岩体的热历史与构造-地貌演化过程

THERMAL HISTORY AND TECTONO GEOMORPHIC EVOLUTION OF PANSHAN PLUTON AT SOUTHERN MARGIN OF THE YANSHAN OROGENIC BELT

应用热年代学方法，揭示了燕山南缘盘山岩体的热历史与隆升过程。结果表明， 盘山岩体的侵位深度约为 １０ｋｍ 。岩体侵位以后， 经历了快速冷却过程，在２２６４８ Ｍａ～２０４９５ Ｍａ 期间，岩体温度由 ５２０℃冷却至 ３００℃， 平均降温速率为１０２２℃／ Ｍａ。２０４９５ Ｍａ～１１８ Ｍ ａ 期间为盘山岩体的缓缦隆升时期，平均隆升速率约为 ００２８ｍ ｍ ／ａ，隆升幅度约 ２５ｋｍ 。１１８ Ｍａ～９６ Ｍａ 为盘山岩体较快速隆升时期，隆升速率为００３５ｍ ｍ ／ａ，隆升幅度约０７７ｋｍ 。９６ Ｍａ～３５ Ｍａ 为盘山岩体与盘山山脉的快速隆升时期，隆升速率约为０１１５ｍ ｍ ／ａ，隆升总幅度达７ｋｍ 。３５ Ｍａ 以来，盘山岩体的隆升速率很小，仅约００１４ｍ ｍ ／ａ，隆升幅度约为０５ｋｍ 。盘山周缘环状构造系统的形成时代略早于 ２２６４８ Ｍａ。

The thermal history and uplifting of the Pangshan pluton at the southern margin of the Yanshan orogenic belt were studied in detail by thermochronological dating.It was revealed that the Panshan pluton was intruded at a depth of about 10km before 226 48Ma.This was followed by a rapid cooling at a rate of 10 22℃/Ma during 226 48～204 95 Ma subsequently,it was uplifted 2 5km in the period of 204 95～118Ma at a rate of 0 028mm/a,1 33km in the period of 118～80Ma at a rate 0 035mm/a,approximately 7km during 80～35 Ma at a rate of 0 08 mm/a, and about 0 5km since 35Ma at a rate of 0 014mm/a.The ring structures system surrounding the pluton formed a little earlier than 226 48Ma,and the boundary normal fault between it and the North China Basin was formed and became active mainly during 80～35Ma.