热力构造的概念分类特征及其研究进展

热力作用是与应力、重力相类同的一类地质作用力。以往对其研究多有忽视,近年来研究进展较大。热力作用是盆地发育演化和改造的主要因素,随着大陆动力学研究的深化,大陆垂向热力作用及其热力构造陆续被发现。对目前尚无公认统一分类方案的热力构造,根据现今构造、地貌形态分为三类:正向穹窿型、负向塌陷型和边隆核陷型;按岩浆-热力作用影响深度等分为五种类型:(古)地热异常群集区、表浅层火山喷发-热液活动-浅成斑岩侵入型、热力背斜(热穹隆)型、中深层侵入型(含壳内热柱型)、地幔热柱型。深度分类的第二类表浅层火山喷发-热液活动-浅成斑岩侵入型又可再分为许多亚类:火山-热力管道、环状断裂、破火山口和火山塌陷、中浅成侵入型(含变质核杂岩和浅层热穹隆)、隐伏热力构造。热力背斜(热穹隆型)实际为中成或中浅成岩浆侵入型;中深层侵入型多在盆地基底或中下地壳内活动或造山带内产出,可称为地壳热异常柱,在地壳内分布规模不大,盆地下部一般难以直接见到,要依靠地球化学、地球物理等技术手段来确认;岩浆岩体侵入的深度不一,热力构造类型和发育程度不同;地幔(或地壳)热柱型影响深度最大,没有明显的地貌显示,要依靠深部构造岩石学、地球物理学等间接研究方法确认。地质-地球物理-地球化学综合研究应该是一种有效的研究方法。盆地深部多层结构研究发现热力构造区多具有明显的垂向极低电阻率值区和壳内低阻层,应为地壳热异常柱,有其特殊的热力作用环境。盆地深部热力作用与热力构造的复杂性和较强烈活动性,对盆地能源研究与评价及煤油气铀成矿成藏的勘探评价等方面均具有重要的影响意义。

The concept ,classification and research progress on thermal structure

Thermal action is a kind of geological force similar to stress and gravity. Thermal action research has always been ignored in the past, but great advancement has been achieved in recent years. Thermal action is the main cause of basin development, evolution and reform. With the deepening of continental dynamics research, the continental vertical thermal action and its thermal structure were successively found. At present,there is still no universal classification method of thermal structure. According to present structural and geomorphic features,thermal structure can be divided into three types: (1) normal dome type; (2) reversed collapse type; (3) margin-swelled and core-sagged type. According to the influencing depth of magma-thermal action,thermal structure can be divided into 5 types: (1) (ancient) geothermal anomaly-concentrated area; (2) volcanic eruption of superficial or shallow layer-hydrothermal action-hypabyssal porphyry intrusion; (3) thermal anticline (thermal dome); (4) intermediate-deep intrusion (including crustal thermal plume type); (5) mantle thermal plume type. The second type of the classification by depth can itself be subdivided into many secondary types,among them: (a) volcanic-thermal pipe; (b) ring fracture; (c) caldera and volcanic collapse; (d) intermediate-shallow intrusion type (including metamorphic complex and shallow layer thermal dome); and (e) blind thermal structure. The thermal anticline (thermal dome) type is ,in fact of intermediate or intermediate-shallow magma intrusion type. The intermediate-deep intrusion type operates mainly in the basement of basins or in immoderately-deep parts of the crust;when it appears in orogenic belts,it can be called a crustal, thermal anomalous plume. To find it directly is usually difficult in the lower part of the basin; its identification depends on the use of methods such as geochemistry, geophysics, etc. The intrusive depth of rock magma and rock mass varies, so the thermal structural type and its developed degree are variable. The mantle (or crust) thermal plume has the deepest influencing depth, but has no distinct geomorphic indication; it must be identified by indirect investigation methods, e.g.geophysical methods. Comprehensive geological-geophysical-geochemical research should be an effective method. Research of multilayered structures in deep parts of basins clearly shows the existence of vertical areas with extremely low electrical resistance and of subbasin crustal layers with low electrical (resistance). They should be caused by crust thermal anomalous plumes and have their special thermal-action circumstances. Thermal action and thermal structure in the deep parts of basins are fairly strong and complex. They are of great importance for the research and evaluation of energy sources in basin, for the exploration and evaluation of mineralization of coal, oil, gas and uranium, and for oil-gas exploration and evaluation.