some geologists，however，on the basis of observations concerning mantle xenoliths， argue that the mantle is not layered，but that heterogeneity is created by fluids rich in "incompatible elements" (elements tending toward liquid rather than solid state)percolating upward and transforming portions of the upper mantle irregularly，according to the vagaries of the fluids' pathways. (4+)

但是，某些地質(zhì)學(xué)家，以對(duì)地幔捕虜巖體(xenolith)所作的觀察為依據(jù)，指出地幔并非是分層排列的，相反，地幔的異質(zhì)性是由那些富含“不相容成分”的流質(zhì)構(gòu)成的，這些成分趨向于流體而非固體的狀態(tài)，自下而上滲透擴(kuò)散，并依照這些流質(zhì)流向的任意性，不規(guī)則地將上部地幔的某些部分予以改變。

難句類(lèi)型：

復(fù)雜修飾、插入語(yǔ)

解釋：

本句的主句中有一個(gè)長(zhǎng)插入語(yǔ)however,on the basis of observations concerning mantle xenoliths,割裂了主謂，但句子的主要難度還是在that引導(dǎo)的賓語(yǔ)從句中，從句中有由but 所連接的兩個(gè)句子，一起延續(xù)到句末。

首選是rich in incompatible elements修飾fluids;后面又有一個(gè)同位語(yǔ)和一個(gè)分詞結(jié)構(gòu)，都是修飾incompatible elements的，最后還有一個(gè)狀語(yǔ)來(lái)修飾那個(gè)分詞結(jié)構(gòu)，層層修飾，比較復(fù)雜。

意群訓(xùn)練：

some geologists，however，on the basis of observations concerning mantle xenoliths， argue that the mantle is not layered，but that heterogeneity is created by fluids rich in "incompatible elements" (elements tending toward liquid rather than solid state)percolating upward and transforming portions of the upper mantle irregularly，according to the vagaries of the fluids' pathways.