【正文】 k of . The foreand many intradeeps are part of plate convergence plexes, which in view of their overwhelming quantitative, . 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 and 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, . whether they consist of oceanic or continental crust. According to Figs. and , there are three scenarios: 1. Subduction of oceanic crust beneatn oceanic crust (Fig. ). 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, posite 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 3000mthick Palaeogene succession of folded and faulted coal measures in the Hidaka Basin of central Hokkaido, described by Aihara (1986), is therefore a paratively rare case of a thick coal measure sequence formed and preserved in a forearc setting. 2. Subduction of oceanic crust underneath continental crust (). 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 pressional stress regime which causes it to subside under the weight of overriding thrust wedges. 3. Partial subduction of continental crust beneath continental crust (). 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. AC. Three possibilities of plate convergence. Continental crust。 ocanic crust。volcanics。 ??? molasses sediments。??? marine sediments 中文： 成煤構(gòu)造環(huán)境 在已知的煤沉積過程中，這種最終階段是與影響泥炭堆積外在的呈最高狀態(tài)的重要的沉積因素相聯(lián)系的。這是一個寬廣且復(fù)雜的領(lǐng)域，它吸收了聚集地球科學(xué)許多不同學(xué)科的知識。一部分領(lǐng)域已經(jīng)相當(dāng)迅速的普遍展開，而其他的一些在跟隨最近的科學(xué)革命處于一個結(jié)束期。在 20 世紀 70 年代早期的地槽假說被板塊構(gòu)造理論所替代就是后者中的一個例子。即使在經(jīng)過 20 年后，這種新的模式仍處于被改進或裝 備于概念的子集，同時在地形分析中被列為通用的重點的過程中。因此，在這個時期對于被選擇的題目做一個決定性的陳述是不可能的，但是，只是描述關(guān)于現(xiàn)代大地構(gòu)造因素方面的煤田分類是可以建立的。這種現(xiàn)代化目標的實現(xiàn)是充滿困難的，因為要從占優(yōu)勢的全球構(gòu)造學(xué)靜止地槽的觀點變?yōu)楝F(xiàn)代的，大量的活動論解釋使得一些煤田的構(gòu)造分類變得復(fù)雜。當(dāng)許多煤田的構(gòu)造情況，例如那些前淵或陸前盆地已經(jīng)相對改變一點，建立在內(nèi)部或山間的槽即造山的山脈上的煤田裝置，如果沒有仔細的學(xué)習(xí)是不能被適當(dāng)?shù)姆峙上氯ァ?根據(jù)該地槽的概念，幾乎所有的這些 內(nèi)淵，連同前淵 和 后淵 ，他們的超級造山帶對口，被視為一組穩(wěn)定地塊的一部分，其中伴隨著 “ 有機 終端地槽構(gòu)造” 的發(fā)展 （ Aubouin 1965）。 這 固定的并嚴格層 序的解釋（ Kay 所強調(diào)的“ 后成優(yōu)地槽” 1951） 并沒有發(fā)生在現(xiàn)代大地構(gòu)造分析 中，其中的大部分造山帶被作為拼貼的本地成因 和異地 成因的 地形，即作為構(gòu)造地層組合與可能同時代不均勻的 地層記錄，反映其原產(chǎn)地在不同的地質(zhì) 上或 地理 上的領(lǐng)域（ Monger and Price 1979, Monger et al. 1982）。 構(gòu)造環(huán)境，這也影響到形成一個異地巖層組合前的堆積 ，在遠離了物源地沉積下來后，在類型和形態(tài)上可能已經(jīng)非常不同。 它如下一個多 造山帶的巖層可能含有各種煤形成于不同時期之前和之后的巖層的堆積。 此外，當(dāng)代加積前形成的煤炭儲量在不同的地形很可能會有所不同，在煤的類型，煤化歷史和構(gòu)造樣式，所有這些將在來自不同加積后的 穩(wěn)定地塊 煤盆地，其中僅反映在造山帶本身條件普遍存在。 事實上，情況甚至可能會更加復(fù)雜，將在 討論 。 板塊構(gòu)造已創(chuàng)造了自己的名稱，其中只有基本術(shù)語將被用于在這里。 他們對輔助術(shù)語有的只是描述性的，因此獨立的大地構(gòu)造理論中，有的經(jīng)受了時間的 考驗，因為他們在通用的而 現(xiàn)在 已經(jīng)過時的概念中是有用的。舉例來說，詞“ 中新世 ”和“ 優(yōu)地槽組合”一直在用，涉及到淺海（主要是大陸架），和深海結(jié)核，濁積巖和蛇綠巖套，分別作為參考。 此外，提到“ 冒地向斜 ” ， 冒地槽已在北美文獻中成為一個標準的原地術(shù)語，沉積階地邊緣超覆了大陸邊緣。 同樣沉積物的構(gòu)造特征，如“ 同造山期的”復(fù)理石和“后期的同褶皺到造山期（沒有褶皺作用 )”的 穩(wěn)定地塊 ，分別地，仍然可以用在一個板塊構(gòu)造背景下，沒有不必要的混淆他們的相對精確的定義。 尤其是在討論煤田位于聚合的板塊邊緣， 穩(wěn)定地塊 的概念 用在造成破壞該隆起造山帶是十分有益的。由于在先前的討論，