基于钻井温的长白山天池火山北坡浅部岩浆房赋存深度研究

长白山火山区地壳热结构尚未建立, 目前基于地球物理探测手段获得的天池火山浅部岩浆房赋存深度存在差异. 通过对天池火山北坡CZK07钻孔测温情况的研究, 在资料评价与地温梯度计算的基础上, 结合全新世岩浆房温度资料, 估算了北坡浅部岩浆房的赋存深度. CZK07钻孔位于地球物理探测所推测的浅部岩浆房正上方, 靠近历史时期火山喷发火口, 在孔深约610 m处地温较高且稳定(102.5~106.8℃). 连续测温资料显示, 钻孔地温随深度呈一次正相关变化, 地温梯度主要变化于134~178℃/km之间(平均为153℃/km), 可大致代表浅部岩浆房上覆地壳的地温梯度. 基于前人浅部岩浆房的温度研究, 本次定量估算的天池火山北坡浅部岩浆房的赋存深度, 为天池水面下5.25~7.21 km, 与地球物理探测的反演结果相近.

COVERED DEPTH OF SUPERFICIAL MAGMA CHAMBER ON THE NORTHERN SLOPE OF TIANCHI VOLCANO IN CHANGBAI MOUNTAIN BASED ON BOREHOLE TEMPERATURE

The crustal thermal structure in Changbaishan volcanic area has not been established yet and there are differences about the covered depth of superficial magma chamber in Tianchi Volcano by means of geophysical exploration. The covered depth of superficial magma chamber on the northern slope of Tianchi Volcano is estimated through the temperature measurement of CZK07 borehole, data evaluation and geothermal gradient calculation, combined with the temperature data of Holocene magma chamber. The CZK07 borehole is located right above the superficial magma chamber speculated by geophysical exploration, close to the historic crater of volcanic eruption, with relatively high and stable temperature (102.5-106.8℃) at the depth about 610 m. The continuous temperature measurement data indicates that the borehole temperature shows a positive correlation with depth, with the geothermal gradient ranging from 134 to 178℃/km (averagely 153℃/km), roughly representing the geothermal gradient of the overlying crust of superficial magma chamber. Based on previous temperature studies of superficial magma chamber, the covered depth of superficial magma chamber on the northern slope of Tianchi Volcano is estimated to be 5.25-7.21 km below the surface of Tianchi Lake, which is similar to the inversion results of geophysical exploration.