成煤构造环境外文翻译

Coal-Producing Tectonic Environments

This final chapter in the investigation of coal sedimentation is concerned with depositional aspects of the highest order of magnitude, namely, the influence of the crustal setting on peat accumulation. This is a broad and complex field which draws on information, gathered from many different disciplines of the earth sciences. Some of these are currently evolving quite rapidly, while others re in a “mopping up” stage, insensu Kuhn (1970) and Walker (1973), following recent scientific revolutions. An example of the latter is the replacement of the geosynclinal hypothesis in the early 1970s by the concept of plate tectonics. Even after a life span of 20 years, this new paradigm is still in the process of being refined and fitted out with conceptual subsets, as shown by the current emphasis on terrane analysis. It is therefore not possible at this stage to make a definitive statement on the chosen subject, but merely to outline the principle on which a modern geotectonic classification of coalfields can be established. Even this modest goal is fraught with difficulty, because the change from the predominantly static geosynclinal view of global tectonics to its modern, largely mobilistic interpretation has complicated the tectonic classification of some coalfields. While the tectonic status of many coalfields, e.g. those in foredeeps or foreland basins has changed relatively little, the setting of coals found in inter- and intramontane troughs, i.e. within orogenic cordilleras, cannot be properly assessed without very careful study. According to the geosynclinal concept, practically all of these intradeeps, together with fore- and backdeeps, their extra-orogenic counterparts, were regarded as part of a group of molasses basins, the development of which accompanies or follows “terminal geosynclinal tecto-orrgenic” (Aubouin 1965). This fixist and strictly sequential

interpretation (highlighted by the term “epieugeosyncline” of Kay 1951) has no place in modern geotectonic analysis, which views most orogenic belts as collages of autochthonous and allochthonous terranes, i.e. as tectono-stratigraphic assemblages with possibly coeval but heterogeneous stratigraphic records reflecting their origin in different geological and geographical domains (Monger and Price 1979, Monger et al. 1982). The tectonic setting, which influenced the formation of an allochthonous terrane assemblage before accretion, may have been very different in style and physically far removed from its resting place after docking. It follows that a multi-terrane orogen may contain a variety of coals formed at different times before and after terrane accretion. Moreover, contemporaneous pre-accretionary coal deposits formed in different terranes are likely to vary in coal types, coalification histories and tectonic styles, and all of these will in turn differ from the post-accretionary molasses coals, which alone reflect the conditiona prevailing in the orogen itself. Indeed, the situation may even be more complex, as will be discussed in Chap.9.3.2.2.

Plate tectonics has created its own nomenclature, of which only the essential terms will be used here. They will be supplemented by terms which are either descriptive, and therefore independent of geotectonic theory, or which have stood the test of time because they are useful in spite of their generic association with now obsolete concepts. For example, the expressions “mio-”and “eugeosynclinal assemblage”have been kept here as reference term for shallow water marine (mainly shelf), and ocean floor pelagite, turbidite and ophiolite associationa, respectively. Moreover, reduced to a “miogeocline”, the miogeosyncline has in the North-American literature become a standard term for

autochthonous, sedimentary terrace wedges onlapping continental margins. Also tectonic attributes of sediments, such as “synorogenic”flysch and “late syn- (folded) to postorogenic (non-folded)” molasses, respectively, can still be used in a plate tectonic context without unduly corrupting their relatively loose definitions. Particularly in the discussion of coalfields situated near convergent plate edges, the concept of molasses as the product of the destruction of the uplifted orogen is very useful. As in the previous discussion, it is not the purpose of this chapter to give detailed descriptions of a large number of cases but to select a few typical examples of coalfields and relate the essence of their architecture to their respective plate tectonic settings.

1 Early Examples of a Tectonic Classification of Coalfields

Large-scale coal formation can take place only in actively subsiding regions, for example in sedimentary basins. It is possible therefore to characterise the geotectonic environment occupied by a coal measure sequence in a manner similar to that which is applied to other sedimentary environments. Stutzer (1920) and Stille (1926) were among the first to recognise the genetic links between tectonism and the formation of coal. Stille, in particular, referred to the striking difference in terms of basin fill, number of coal seams present, their average thickness and proportion in relation to total coal measure thickness, which exist between the Carboniferous and Tertiary coal measures of Europe. He attributed such dissimilarities to contrasting degrees of crustal mobility in the areas affected by the two main European coal-forming periods. His results are summarized in Table 9. 1. Even if differences in compaction ratios between the Tertiary brown and Carboniferous bituminous coals are taken into account (to a lesser degree the compaction applies to inter-seam sediments) the contrast is

quite remarkable.

Later it was shown by von Bubnoff (1937) that the distribution of the world reserves of coal is also related to the geotectonic setting of coalfields. His conclusions are summarized in Table 9.2, which indicates that of all coal deposits known up to 1937, some 71% developed in former tectonically very active environments, particularly in the molasses foredeeps which develop adjacent to orogenic belts and receive much of the weathered debris washed down from the uplands.

Table 9.1. Stille’s (1926) comparison (slightly modified) between some characteristics of coal measures formed in tectonically mobile and cratonised parts of Europe, respectively

Table 9.2. The distribution of world reserves of coal in reference to the geotectonic setting of coalfields. (After von Bubnoff 1937)

The concentration of coal in the regions associated with orogenic belts is even more highlighted when the lateral extent of the deposits is considered. Coalfields situated within or on the shelf margins of cratons cover a wider area than the comparatively narrow foredeeps, but its areal restriction is compensated by the frequency of coal seams occurring in a thick stack of coal measures. As will be discussed later, this is related to the substantial and prolonged subsidence that the continental margin is subjected to near a subduction complex, as an orogenic belt is accreted onto the plate edge. It is not surprising, therefore, that

von Bubnoff (1937) found also a close temporal relationship between orogenies and coal formation in North America, Europe, Asia and Southern Continents. Of course, there are major orogenies known which are not associated with coal deposits. However, invariably, their absence is related to factors affecting the vegetable source. For example, all pre-Devonian orogenies occurred at a time when the plant kingdom was still insufficiently equipped by evolution to fulfil its role as an effective producer of peat.

The continental shelf environment, being less mobile, has produced fewer coal deposits than the orogenic domain. In this context it is important to define the term shelf. To the geographer, the shelf region is usually that part of the sea which extends between the strand-line and the continental slope. However, as von Bubnoff (1948a) noted, the position of the strandline is quite incidental depending on crustal movements and relative sea level positions.From the geological viewpoint, it appears therefore useful to extend the definition of the shelf so that the time factor can be accommodated. Shelf regions may then be regarded as those marginal but fuully integrated zones of continents which are occasionally affected by shallow marine transgressions. Typical areas are the trailing edges of continental plates and the cratonic margins of foredeeps. Commonly two types of shelf environments are distinguished, called stable and unstable, respectively (von Bubnoff 1948a; Krumbein and Sloss 1963). The majority for their associated coalfields is paralic in character, which is highlighted by the intercalation of coal measures with marine strata, a feature that is also common to the molasses foredeeps. However, marine strata may not always be recognized because of lack of fossils, which is related to the dilution of sea water by an excessive influx of fresh water from the nearby coastal

swamps (Duff and Walton 1962).

Intracratonic coalfields and those formed in intramontanc basins are frequently limnic in character, i.e. they have no hydrological connection to the sea, because they have been formed in land-locked basins above the then prevailing sea level. A spectacular modern example of intramontane peat formation occurs in the reed marshes on the shores of Lake Titicaca, 3810m above sea level in the South American Andes. Compared with their paralic counterparts limnic coalfields have small size and unstable position above depositional base level. However, as indicated above, the term intradeep may cover a complex array of depositional environments, some of which may be totally unrelated to the orogen in which they now occur.

The last group of coalfields mentioned in Table 9.2 occurs in the interior of continental areas. They owe their existence to a variety of events including epeirogenic sagging of continental crust and continental rifting. Many peat and coal deposits formed on consolidated basement have no tectonic origin at all, but are the result of paludification related to differential subsidence. Examples are subsidence due to salt migration and leaching in the subsurface, or the formation of sinks isolated coalfields are the result of the terrestrialisation of lakes. Most of these coalfields are limnic, but rare marine incursions may have occurred during their development.

The tectonic setting of a coalfield exerts a strong influence on the type of coal that is formed within its boundaries. Hacquebard et al. (1967), Mackowsky (1968), Shibaoka and Smyth (1975), Hunt (1982) and others have demonstrated that coal composition varies more in large paralic deposits than in limnic setting, because of the larger variety of factors influencing extensive continental shelf or

foredeep environments. Moreover, coals formed in rapidly subsiding foreland basins are more likely to have high vitrite, clarite and ash contents than coals formed on cratonic shelves or in slowly subsiding cratonic basins. These coals are likely to be rich in dull coals consisting mainly of durite inertite.

2 Basin Formation as Part of Plate Tectonics

The theory of plate tectonics, although primarily concerned with horizontal movements of the relatively rigid lithospheric plates (crust and uppermost mantle) over the softer asthenosphere (mantle), has also provided an explanation for the vertical movements that lead to subsidence and basin formation. The following crustal movements can be distinguished (after Dickinson 1974 and Fischer 1975):

1.Change in crustal thickness.According to the principle of isostasy thick

low-density continental crust floats higher on heavy mantle material than thin high-density oceanic crust. For example, an isostatically compensated continental crust of 50 km thickness extends 4 km above the sea, whereas a 6-km-thin oceanic crust is covered by approximately 5 km of water (Holmes, 1965). Plate tectonics provides several mechanisms for both crustal thickening and thinning. The latter, which is of immediate interest here, is often exemplified in areas of continental rifting, where in the early stages of plate separation the crust along the rift zone is attenuated by extensional step-faulting, thus forming rapidly subsiding grabens and half-grabens.

Erosional thining of anisostatically uplifted crustal portions also leads to subsequent subsidence. Uplift due to crustal thickening is of some interest in this context,because it creates potential source areas for coal measure sediments. This is particularly important in foredeeps, where basin formation

is invariably coupled with uplift in nearby orogenic belts. Most examples of uplift due to crustal thickening are related either to the injection of magma into the crust or to continental collision.

2.Change in thermal regime. Convection currents in the plastic asthenosphere

are responsible not only for horizontal plate movements but also for some vertical crustal motions which are independent of ceustal thickness.

Upwelling magma from the mantle may cause uplift by forming heat bulges in the overlying crust, and new oceanic crust is formed where such mantle material is extruded along mid-oceanic rift zones. The latter are elevated above the sea floor because of thermal expansion of the affected crust which becomes colder and denser with increasing age and distance fiom the rise crest. Areas of thermal tumescence within or along the margin of continental plates are subjected to erosional thinning, which accentuates their subsidence during the period of thermal decay.

3.Loading affects.When sediments accumulate on an isostatically

compensated crust the additional load will create a disequilibrium which will be balanced by subsidence. This means that, whatever the initial cause for the creation of a depositional site, once sediments are beginning to accumulate, their weight and compaction are in some measure responsible for the deposition of additional sediments. This, to some extent self-prepetuating process is particularly well shown by the flexural bending under load of the continental shelf margin (Walcott 1972). Other common geotectonic sites for load-induced subsidence and sedimentation are orogenic fordeep margins which are flexurally down-warped under the weight of the overriding thrust sheets generated in the adjacent fold belt

(Price 1973; Laubscher 1978; Beaumont 1981; Quinlan and Beaumont 1984).

Additional loading of the downwardly flexed crust is provided by the mass of molasses sediments produced in the fold belt and transported into the developing foredeep.

As has been discussed before, additional causes of sediment and coal formation are provided by subsurface salt migration and leaching, and eustatic sea-level changes, in particular by their interaction with crustal movements, which produce a variety of sedimentary responses in different tectonic domains. For example, rifting of oceanic crust has depositional consequences quite different from the separation of continental crust. The rifting of continental crust may lead to coal formation, but the rifting of oceanic crust is unlikely to lead to the formation of coal. A survey of the effects of the geotectonic setting of coalfields on peat accumulation and coal composition requires therefore an understanding of the major crustal elements of Earth and their principal motions.

A plate-tectonic interpretation of the main crustal elements in reference to their ability to provide suitable sites for the formation of coal is summarized in Fig.9.1. This interpretation is based on the notion that the creation of new lithospheric crust along mid-oceanic rifts and the lateral movement of the lithospheric slabs towards subductionzones, where oceanic crust is consumed, produce three types of plate junctures. These are (after Dickinson 1974):

1. Divergent plate edges, where plate separation takes place and the developing gap is filled by upwelling mantle material welding new oceanic crust to the separating plates.

2. Convergent plate edges, where old crust is subducted into the mantle underneath the leading edge of the overriding plate.

3. Transform plate edges, where adjacent plates are laterally displace by movement along strike-slip faults.

Fig.9.1. The geotectonic setting of coalfields in reference to Curray’s (1975) plate-tectonic subdivisions of the earth. The identification of countries is by international country code.

The tectonic subdivisions of coalfields used by von Bubnoff (1937) in Table 9.2 can be broadly accommodated within the plate tectonic framework of Fig.9.1. The fore-and many intradeeps are part of plate convergence complexes, which in view of their overwhelming quantitative, i.e. economic importance, will be

discussed first. The midplate continental margin is the setting of shelf deposits,

whereas the cratonic and rift valley settings refer to the interior of consolidated areas.

3 Coalfields Situated Near Convergent Plate Edges

The relationships between tectonic setting and coal content of a region inferred from Tables 9.1 and 9.2 suggest that coal can form more frequently in geological environments capable of offering a larger number and variety of crustal movements per unit time than less mobile areas. As mentioned above, this is a reature of foredeeps, which have been prolific coal producers in the pat. Mountain chains consisting of folded and often metamorphosed rocks are formed as linear and often arcuate welts along the edges of convergingplates by a number of tectonic and magmatic events, all of which appear to be primarily related to the process of subduction. However, not all former subduction zones have led to the formation of coalfields, which is a problem related to the nature of the converging plates, i.e. whether they consist of oceanic or continental crust. According to Figs. 9.1 and 9.2, there are three scenarios:

1.Subduction of oceanic crust beneatn oceanic crust (Fig. 9.2A). It is unlikely

that this situation will lead to significant coalfield formation because of the considerable water cover of the sea floor. Oceanic crust emerges above water only where it has been thickened by magmatic injection and may then produce isolated small coal occurrences. However, as long as only oceanic crust is involved, the lack of a strong nearby sediment source leaves the adjacent ocean basin starved and too deep for peat accumulation. Conversely, composite arc systems, in which several subduction zones are operating simultaneously in opposite directions and/or in which allochthonous crustal fragments (terranes) have been accreted to the arc system, may provide

suitable conditions for coal formation. An example are the Japanese islands, which contain coalfields of Tertiary age in both fore- and backarc positions (Aihara 1986). Forearc basins elsewhere are not known to be significant coal producers due to the tectonic instability during the basin stage and the subsequent destruction by tectonism. The occurrence of a 3000-m-thick Palaeogene succession of folded and faulted coal measures in the Hidaka Basin of central Hokkaido, described by Aihara (1986), is therefore a comparatively rare case of a thick coal measure sequence formed and preserved in a forearc setting.

2.Subduction of oceanic crust underneath continental crust (Fig.9.2B). There

are several past and present examples of extensive coal formation associated with this type of plate convergence. The main coalfields formed in the process occupy retroarc basins (Dickinson 1974) filled with thick sedimentary successions. The beginning of sedimentation is probably related to extensional tectonics in the backarc area, at a time when subduction is still in process. However, during and following the accretion of allochthonous terranes the retroarc basin is subjected to a compressional stress regime which causes it to subside under the weight of overriding thrust wedges.

3.Partial subduction of continental crust beneath continental crust (Fig.9.2C).

This type represents an example of continental collision. Because of its thickness and low density, continental crust can only partially be subducted which leads to tectonic stacking and overlap of the two plate margins. The conditions of coal formations in a retroarc basin are the same as in (2) for the overriding plate. In addition, at least two loci of potential peat accumulation are contributed by the consumed plate, one (usually destroyed by subsequent

orogenesis and metamorphism) in the form of the continental shelf margin which was formed before collision occurred, and the other in the form of a peripheral basin (Dickinson 1974) formed at the foot of the collision belt.

Retroarc and peripheral basins share the same basic foredeep architecture (Beaumont 1981), because both are the products of flexural downwarping of the underlying crust following loading by overriding thruet sheets.

Fig.9.2 A-C. Three possibilities of plate convergence. Continental crust; ocanic crust;volcanics; ??? molasses sediments;??? marine sediments

中文：

成煤构造环境

在已知的煤沉积过程中，这种最终阶段是与影响泥炭堆积外在的呈最高状态的重要的沉积因素相联系的。这是一个宽广且复杂的领域，它吸收了聚集地球科学许多不同学科的知识。一部分领域已经相当迅速的普遍展开，而其他的一些在跟随最近的科学革命处于一个结束期。在20世纪70年代早期的地槽假说被板块构造理论所替代就是后者中的一个例子。即使在经过20年后，这种新的模式仍处于被改进或装备于概念的子集，同时在地形分析中被列为通用的重点的过程中。因此，在这个时期对于被选择的题目做一个决定性的陈述是不可能的，但是，只是描述关于现代大地构造因素方面的煤田分类是可以建立的。这种现代化目标的实现是充满困难的，因为要从占优势的全球构造学静止地槽的观点变为现代的，大量的活动论解释使得一些煤田的构造分类变得复杂。当许多煤田的构造情况，例如那些前渊或陆前盆地已经相对改变一点，建立在内部或山间的槽即造山的山脉上的煤田装置，如果没有仔细的学习是不能被适当的分派下去。根据该地槽的概念，几乎所有的这些内渊，连同前渊和后渊，他们的超级造山带对口，被视为一组稳定地块的一部分，其中伴随着“有机终端地槽构造”的发展（Aubouin 1965）。这固定的并严格层序的解释（Kay所强调的“后成优地槽”1951）并没有发生在现代大地构造分析中，其中的大部分造山带被作为拼贴的本地成因和异地成因的地形，即作为构造地层组合与可能同时代不均匀的地层记录，反映其原产地在不同的地质上或地理上的领域（Monger and Price 1979, Monger et al. 1982）。构造环境，这也影响到形成一个异地岩层组合前的堆积，在远离了物源地沉积下来后，在类型和形态上可能已经非常不同。它如下一个多造山带的岩层可能含有各种煤形成于不同时期之前和之后的岩层的堆积。此外，当代加积前形成的煤炭储量在

不同的地形很可能会有所不同，在煤的类型，煤化历史和构造样式，所有这些将在来自不同加积后的稳定地块煤盆地，其中仅反映在造山带本身条件普遍存在。事实上，情况甚至可能会更加复杂，将在chap.9.3.2.2讨论。

板块构造已创造了自己的名称，其中只有基本术语将被用于在这里。他们对辅助术语有的只是描述性的，因此独立的大地构造理论中，有的经受了时间的考验，因为他们在通用的而现在已经过时的概念中是有用的。举例来说，词“中新世”和“优地槽组合”一直在用，涉及到浅海（主要是大陆架），和深海结核，浊积岩和蛇绿岩套，分别作为参考。此外，提到“冒地向斜”，冒地槽已在北美文献中成为一个标准的原地术语，沉积阶地边缘超覆了大陆边缘。同样沉积物的构造特征，如“同造山期的”复理石和“后期的同褶皱到造山期（没有褶皱作用)”的稳定地块，分别地，仍然可以用在一个板块构造背景下，没有不必要的混淆他们的相对精确的定义。尤其是在讨论煤田位于聚合的板块边缘，稳定地块的概念用在造成破坏该隆起造山带是十分有益的。由于在先前的讨论，也不是本章的目的给予详细说明了一大批例子，但要选择几个典型的涉及了本质和结构的煤田，以各自的板块构造建立。

1一个早期的煤田构造分类的例子

大型煤田的形成可以发生的地方，只有在活跃的下陷地区，例如在沉积盆地。因此，用一个煤系序列表征大地构造环境的方式表示其他适用的沉积环境是有可能的。Stutzer (1920) 和Stille (1926)第一次确认构造与成煤之间的成因关系。Stille，尤其是提到突出差异而言，欧洲盆地充填中煤层的平均厚度和的比例关系与总煤系厚度的联系，在这之间存在的石炭纪和第三纪煤的数量。他归因于这样的相似性，以对比程度的地壳的流动性，在欧洲的两个主要成煤期受影响地区。他的结果总结在表9 .1.中。即使在第三系褐色和石炭系沥青煤压实比率之间的不同的计算（在较小程度压实适用于跨煤层沉积物）的对比是相当显着的。后来结果表明，由von Bubnoff

(1937)表示，分布世界各地的煤的储量是与煤田的大地构造环境有关的。他的结论的摘要列于表9.2 ，这表明在1937年所有的煤炭储量都已经知道，约71 ％的是发展构造非常活跃的环境，特别是在稳定地块盆地前渊发展来的，其中毗邻造山带和从高地来的接收的许多风化碎片。

表9.1 . Stille’s（1926）一些比较（略作修改）

分述在构造移动盆地和欧洲部分克拉通盆地特征煤的数量

表9.2 .分布在世界储备煤中提到了大地构造环境的煤田。（von Bubnoff 1937 之后）

侧向范围的沉积被认为在与造山带相关的地区的煤的聚集中更是突出的。煤田位于沙洲的边缘或沙洲内古陆核的涵盖了更广阔的领域较相对狭窄的前渊，但其地域的限制，是补偿的频率煤层发生在一个一定数量厚的煤层。正如我们将在所后面讨论的，这是涉及到大量的和长期沉陷的被认为在大陆边缘受到附近俯冲的复杂的，作为一个造山带是与板块边缘共生的。这是不足为奇的，因此,在北美，欧洲，亚洲和南部大陆von Bubnoff (1937) 还发现一个山脉与成煤之间的相近关系。当然，那儿已知的山脉与煤的沉积是没有关系的。但是，往往他们的缺失是与影响植物来源有关的。例如，所有的前泥盆纪造山带发生的时候,植物界仍然不能满足作为生产泥炭的作用。大陆架的环境，缺少移动性，比造山作用产生的煤炭沉积少。在这方面是定义大陆架这个术语是很重要的。对于地理学来说，大陆架地区向海的部分通常在股线和大陆斜坡之间延伸。不过，由于von Bubnoff (1948a)指出，滨线的位置是相当偶然的，决定于地壳运动和海平面位置.从地质的角度来看，大陆架定义的扩大似乎是有用的，因此时间的因素可以忽略。大陆架地区可能被视为边缘的那些地区，但大陆的完整区域是偶尔受浅海的超覆。典型的地区是在大陆边缘的尾端，大陆板块和克拉通边缘的前渊。常见的两种类型是大陆架是显著的环境，分别为所谓的稳定和不稳定(von Bubnoff 1948a; Krumbein and Sloss 1963)。多数与它们相关的煤田是近海特征，这是所强调的插层煤在海相地层中的数量，其中一个特征是稳定地块盆地前渊普遍存在的。不过，因为缺少化石,海相地层不一定一直得到承认，这是与过量的新鲜水从沿海沼泽大量涌入有关的(Duff and Walton 1962)。

克拉通内的煤田和那些形成于山间盆地的煤田在特征上经常是湖泊相的，即它们对于海洋来说没有水文学的意义，因为他们在后来的海平面之上已经形成堵塞的内陆盆地。一个引人注目的现代的例子，山脉之间内泥炭的形成是发生在南美安第斯山脉高于海平面3810米芦苇沼泽对海岸的的

湖。与他们相比，在沉积基底的水平面之上近海成因的相对湖泊成因煤田有规模小和不稳定的特征。然而，如上文所示，术语内渊可能包括一个复杂系列的沉积环境，其中一些可能会与造山带现在发生的完全无关。

最后一批在表9.2提到的煤田发生在内部的大陆地区。他们应该归功于各种各样的活动，包括造陆下陷大陆地壳和大陆裂谷。许多泥炭和煤炭沉积的形成是基于没有构造的起源在所有，但泥炭化的结果是与不同的沉降有关的。这些例子是由于沉积物在地下迁移和过滤后沉淀，或下沉的孤立煤田的形成是由于该陆表的湖泊。大部分的这些煤田是湖泊相的，但罕见的海侵可能发生在他们的发展过程中。

在形成其边界过程中,煤田的构造环境有着重要的影响力。Hacquebard 等 (1967), Mackowsky (1968), Shibaoka and Smyth (1975), Hunt (1982)和其他人已经表明，煤的组成在很大程度上近海相比湖泊相呈现更大的不同，因为大量的不同因素影响宽广的大陆架或前渊盆地环境。此外，煤的形成在迅速下沉前陆盆地更可能有高含量的微镜煤，微亮煤和灰分比煤形成的稳定的边缘上，或在慢慢下沉克拉通盆地。这些煤很可能是丰富的暗煤为主的微惰性煤。

2盆地形成作为板块构造理论的一部分

板块构造理论，虽然主要关注相对刚性岩石圈板块（地壳与上地幔顶部在柔和的软流圈（地幔）的横向变动，但也提供了一个导致沉降和盆地的形成的垂直运动的解释。接下来的地壳运动，可以划分为(在Dickinson 1974 and Fischer 1975之后):

1.地壳厚度的变化根据该原则，均衡厚的低密度大陆地壳的漂浮物重的

地幔物质比薄的高密度大洋地壳高。举例来说，一个海平面之上均衡的大陆地壳50公里的厚度延伸4公里，而6公里的薄大洋地壳涵盖的约5公里的水(Holmes, 1965) 。板块构造提供了若干机制，为双方的地壳增厚和变薄。后者，这是对的切身利益，在这里，往往是体现在地区的大