摘要
对中国大陆科学钻探主孔100—2000m区间岩心样品磁化率与钻孔原位测井磁化率进行系统时比研究。结果表明,控制岩石磁化率的主要因素是岩性和退变质作用,其中蛇纹石化石榴石橄榄岩的磁化率最大,样品平均磁化率为86．277×10-3SI,正片麻岩,退变质榴辉岩,榴辉岩,副片麻岩次之,角闪岩的磁化率最小,样品平均磁化率为1．698×10-3SI。不同退变质程度榴辉岩的磁化率特征具有明显的差异:中-强程度退变质榴辉岩由于退变质过程所产生的磁铁矿和钛铁矿-钛磁铁矿,其磁化率最大;随着退变质作用的进一步加剧,这些磁铁矿和钛铁矿-钛磁铁矿被完全分解,导致完全退变质榴辉岩的磁化率最小;新鲜榴辉岩的磁化率介于两者之间。在该深度区间,约70％岩心样品磁化率与测井磁化率的比值小于4．0,其中以<2．0为主,相同岩性岩石(如榴辉岩,退变质榴辉岩和副片麻岩)磁化率的比值随深度变化较小。岩心样品磁化率和测井磁化率之间的欧氏距离位于3．0-6．4范围,且随深度变化不明显,如在100～600m和1500～2000m两个深度范围的欧氏距离分别为3．0-5．2和3．2～5．3,表现出相似的变化特征,显示了在此区间深度范围内,地层压力对磁化率的基本没有影响。
The characteristics of magnetic susceptibility of core samples and logging susceptibility from the depth of 100 - 2000m mainhole of Chinese Continental Scientific Drilling （CCSD） are systematically compared. The results indicate that lithology and retrograded metamorphic process are the main factors controlling susceptibility of rocks. Susceptibility of rocks with different lithology in their decreasing order are serpentinized garnet peridotite, orthogneiss, retrograded eclogite, eclogite, paragneiss and amphibolite. Marked differences in susceptibility of eclogite with different retrograded degree were observed. Due to the formation of magnetite and ilmenite during the retrograded process, the susceptibility of the moderately to strongly retrograded eclogite is the largest. However, that of the totally retrograded eclogite is the smallest resulting from the decomposition of the magnetite and ilmenite with the further retrograded effects, and the susceptibility of the fresh eclogite is intervenient. The ratio between susceptibility of core samples （ κlog） and logging susceptibility （κlog） keep steady value within the depth of 100 - 2000m, most of κcore/κlog are lower than 4. 0, which accounts for about 70%, and the values lower than 2. 0 are preponderant. With the increasing depth, there is no obvious variation in κcore/κlog of rocks with same lithology, such as eclogite, retrograded eclogite and paragneiss. In addition, the Euclid distance between κcore and κlog range from 3.0 to 6. 4, no evident variations with depth. At the depth range of 100 - 600m the Euclid distance changes from 3.0 to 5.2, while at the depth range of 1500 - 2000m, it changes from 3. 2 to 5.3. The Euclid distance range both at depth ranges of 100 -600m and 1500 - 2000m are similar, showing that the susceptibility measured on core samples and at the logging approximate have the same variational characteristics in the whole borehole. Susceptibility of core samples was measured in laboratory with normal temperature and pres
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第7期2089-2094,共6页
Acta Petrologica Sinica
基金
国家重点基础研究发展规划项目(2003CB716506)
中国地质大学(武汉)自然科学基金项目。
关键词
测井磁化率
岩心磁化率
退变质
压力
中国大陆科学钻探(CCSD)
东海
Logging susceptibility, Susceptibility measured on core samples, Pressure, Chinese Continental Scientific Drilling （ CCSD）, Donghai
