地热场中“岩浆热场”的识别及其意义

Identification and implication of magma thermal field in the geothermal field

岩浆热场顾名思义是由岩浆活动引发的热场,与岩浆活动休戚与共.一旦岩浆停止活动冷却后,岩体的温度与围岩的温度差为0时,它将回归地热场.因此,岩浆热场是一种瞬间发生的、出现在局部地域的、等温线围绕岩体分布的、温度变化很快的一种地热场,是地壳内部热事件的一种反映.岩浆侵入和喷出活动可以出现在地质历史演化的各个阶段和不同的地区,因此,岩浆热场也可能发生在地球历史演化的不同阶段和地域.研究表明,从地热场中识别出某些岩浆热场的信息是可能的,文中列举了羊八井、腾冲现代岩浆热场和四川古岩浆热场的若干实例,指出从地热场中识别岩浆热场是很有意义的.现代岩浆热场是人类可以利用的稳定的自然资源之一,古岩浆热场则可能解释为什么大多数岩浆热液矿床是多金属成矿的问题.此外,岩浆热场还可以解释油气藏中烃源岩成熟度、煤化程度以及古代和现代的某些地热场异常问题等.因此,注意对岩浆热场的识别,探讨它的形成机制,引发的热场效应,是一个值得探索的新课题.

The magma thermal field in name is the thermal field caused by magmatic activity, and is relative with magmatic activity. Its temperature difference with the surrounding rock is equal to 0, and will return to the geothermal field once the magma is ceased and cooled down. Therefore, the magma thermal field is an instantaneous, appeared in the local area whose temperature field distributes around the intrusions, changes quickly, and indicates the crustal thermal event. Magrnatic intrusive and extrusive activity can appear in various geological evolution stages and different regions, therefore, the magma thermal field may also occur in the different evolution stages and geographical locations of Earth＇s. It is possible that the magma thermal field information can be identified in the geothermal field. We have cited Yangbajing, Tengchong present magmatic thermal field and Sichuan paleo- magmatic thermal field as examples, and pointed out that recognizing a magma thermal field from the geothermal field is of great significance. The present magmatic thermal field can be taken advantage as the stable natural resources, the paleo-magrnatic thermal field may be explained the most polymetallic mineralization of the magmatic hydrothermal deposits. In addition, the magma thermal field can also be explained the source rock maturity of hydrocarbon reservoirs, coal rank, and paleo and present abnormal geothermal field. Therefore, the identification of the magmatic thermal field, its formation mechanism and thermal effect is a worthy exploring new topic.