长白山天池火山双岩浆房岩浆作用与互动式喷发

广义的长白山火山在我国境内包括天池火山、望天鹅火山、图们江火山和龙岗火山,是我国最大的第四纪火山岩分布区。长白山各个火山区的火山活动具有此起彼伏的穿时性特征,天池火山之下地壳和地幔两个岩浆房具有上下呼应、互动式喷发之特点。一方面来自地幔的钾质粗面玄武岩浆直接喷出地表,在天池火山锥体内外形成诸多小火山渣锥;另一方面钾质粗面玄武岩浆持续补给地壳岩浆房,发生岩浆分离结晶作用和混合作用,形成双峰式火山岩特征并触发千年大喷发。西太平洋板块俯冲-东北亚大陆弧后引张是长白山天池火山喷发的动力学机制。

The Magmatism and Interactive Eruption of the Two Magma Chambers in The Tianchi Volcano, Changbaishan

Generally,the Changbaishan volcanic province(CBVP) includes the Tianchi volcano,the Wangtian'e volcano,the Tumen volcano and the Longgang volcano.It is the biggest Quaternary volcanic province in China.The volcanism in the various volcanic areas in the CBVP is characterized with various chronological intervals.It is believed that two magma chambers,one in mantle and one in crust,were occurred beneath the Tianchi volcano.Magmatism of the two magma chambers is characterized with temporal inter-correlation and interactive magma eruption.In one hand,a part of the potassic trachybasalt magma,which was derived from the chamber in mantle,erupted directly on the surface to form many small cinder cones in the outer zone of the Tianchi Volcano cone.In the other hand,another part of the potassic trachybasalt magma had filled consistently into the magma chamber in crust from the chamber in mantle.Then the evolved magmas through the fractional crystallization in the magma chamber in crust had erupted on the surface lasting over one thousand years with the characteristics of the distribution of bimodal volcanic rocks.The geodynamic interpretation indicates that the volcanism of the Tianchi volcano in the CBVP was caused by the subduction of the western Pacific Plate and the subsequent back-arc extension of the northeast Asia subcontinent.