火山温泉气体CO2／^3He比率与幔源气体的释放和成藏机制

CO_2/~3He RATIO OF VOLCANIC THERMAL SPRING GAS AND THE RELEASING AND RESERVOIR FORMATION MECHANISMS OF MANTLE GAS

我国五大莲池、云南腾冲、吉林长白等火山活动区温泉释放的幔源气体ＣＯ２／３Ｈｅ 比率受到幔源气体释放机制的控制，在深切岩浆房的断裂活动作用下，以断裂为通道直接自岩浆房中释放的幔源气体，以低于幔源气体脱离岩浆时的ＣＯ２／３Ｈｅ 比率为特征，其比率为１０７ ～１０９ 。同时，我国东部含油气盆地中受活动断裂控制的新生代形成的黄骅、济阳、苏北、三水等地的幔源ＣＯ２ 气藏，均以１０７ ～１０９ 的低ＣＯ２／３Ｈｅ 比率为特征，与火山区通过断裂通道释放的幔源气体的ＣＯ２／３Ｈｅ 特征完全一致。这表明，幔源气体以断裂为通道自岩浆房中直接释放的机制对于含油气盆地中幔源ＣＯ２ 气藏的形成、气源的补给和气体地球化学特征的塑造起着控制作用，同时也为ＣＯ２ 气藏的幔源成因提供了进一步的证据。

The CO 2/ 3He ratios of the mantle gas released from the thermal springs at the volcanic active regions as the Wudalianchi in Heilongjiang Province,the Tengcong in Yunnan Province and the Changbai Tianchi in Jilin Province are controlled by the releasing mechanisms of the mantle gas.Under the action of the active faults stretched deeply to magma chambers,the mantle gas released directly from the magma chambers by taking the faults as the paths is characterized by the CO 2/ 3He ratios of 10 7～10 9 which are lower than the ones of the original mantle gas just separated from basalt magma.Controlled by active faults and formed during Cenozoic,the mantle derived CO 2 reservoirs found in Huanghua,Jiyang,Subei and Sanshui regions of the oil and gas bearing basins in East China are also characterized by the lower CO 2/ 3He ratios of 10 7～10 9 which are fully corresponding with the ones of the mantle gas released through the fault paths in the volcanic active regions.It is shown that the mechanism of directly releasing mantle gas from the magma chambers by taking the faults as the paths controls mantle derived CO 2 reservoir formation,gas source supplement and the geochemical characteristics of the gas,providing further evidence for the mantle genesis of the CO 2 reservoirs at the same time.