第24卷第3期 2010年6月
现代地质 GEOSCIENCE
Vol. 24No.3 0z
南海北部陆坡海底火山活动对天然气水合物
成藏的影响
栾锡武"，张亮12，岳保静！2
(1.中国科学院海洋研究所海洋地质与环境重点实验富，山东青岛266071；2.中国科学院研究生院，北京100049）
摘要：南海北部陆坡发育海底火山。海底火山的发育是否有利于天然气水合物的成藏是该区进行水合物勘探首先要考虑的一个关键问题。通过地展面解释、建立地质模型，并通过模型温度场计算，认为发生岩浆底侵时，高温岩浆使水合物稳定域的厚度变薄。随着热量的散失，水合物稳定域的厚度逐新恢复。底侵的深度较浅时，水合物稳定域减薄的幅度增大，恢复周期变短。对海底火山喷发的情况，水合物稳定域将完全不存在，但其恢复的时间更短。岩浆底侵深度为6km时，其对水合物稳定域的影响周期为1Ma左右。南海北部东沙运动和流花运动都伴随着规模性的火山活动，两次构造运动期间岩浆侵人、侵出引起的热效应到目前为止已对该区水合物稳定域的发育没有影响，但海底火山活动对增大地层的孔隙与通道，从而对甲烷气体的运案和水合物的成藏都能起到积极的作用。火山活动引起的高地温梯度，对生物甲烷的产生也将起到一定的帮助，从而有利于水合物的形成。南海北部陆坡火山区仍是天然气水合物勘探的有利杷区。
关键词：南海北部陆坡；火山活动；天然气水合物；成藏；影响
中图分类号：P744.4
文献标志码：A
文章编号：1000-8527(2010)03042409
InfluenceonGasHydratesFormationProducedbyVolcanicActivity
onNorthernSouthChinaSeaSlope LUAN Xi-wu',ZHANG Liang"2,YUE Bao-jing "2
(1. Key Laboratory of Marine Gelogy and Eaironment, lnustitude of Oceanology, Chinexe Academy of Sciences, Qingdao, Shandong266071
Chine; 2. Graduaite Unitersity, Chinese Academy of Sciences, Bejing100049, China)
Abstract : There are volcanoes developed on the northerm South China Sea slope. The influence on gas hydrates formation produced by those volcanic activities is the key problem which should be considered first before field exploration conducted. Based on seismic line interpretation and geological themal model calculation, this paper concluded that the thickness of gas hydrates stability zone would be influenced by magma intrusion. The shallo wer the magma intrusion depth is, the bigger the influence to the thickness of the gas hydrates stability zone is, but the shorter the thickness of gas hydrates stability zone recover period time is. When volcanic eruption oc-curred on the seafloor, the gas hydrate stability zone would be destroyed totally at first, however, it would also recovered after a shortest period of time as comparing to the case of magma intrusion. As to the case of magma intrusion depth of 6 km, the total recover time for the gas hydrates stability zone is about 1Ma. There had been volcanic activities during both Dongsha movement and Liuhua movement. Up to now the influences on gas hy-drates stability zone produced by those volcanic activities during those two tectonic movements have been disap peared. Finer sediment grain and lower porosity usually developed on slope area are unfavorable factors for the formation of gas hydrates. As the volcanic activity can both enlarge the sediment porosity and accelerate the mi-
收稿日期：2010-05-15；改回日期：2010-05-30；责任编辑：楼亚儿。
基金项目：中国科学院创新I"程重要方向项目（KZCX2-YW-211-01)；科技部"973"项目(2007CB411702）；国家自然科学基
金项目（40776032）。
作者简介：案锡武，男，资任研究员，1966年出生，海洋地球物理专业，主要从事海洋地球物理调查研究工作。
Email: xluan@ ms qdio ac. cne