華北克拉通北緣中段龍王廟巖體和上莊巖體的巖石成因及構(gòu)造指示
發(fā)布時(shí)間：2018-07-29 17:29
【摘要】：華北克拉通北緣中段的大陸巖石圈地幔在奧陶紀(jì) 三疊紀(jì)時(shí)逐步在蒙古洋板塊多階段俯沖的影響下變得活躍。本文選取的龍王廟巖體和上莊巖體的形成時(shí)代分別是~399 Ma和~123?128 Ma,屬于中泥盆世和早白堊世。本文在重點(diǎn)論述二者巖石學(xué)成因和構(gòu)造指示意義的基礎(chǔ)上,結(jié)合前人對(duì)華北克拉通北緣中段二者時(shí)間區(qū)間的其他巖體研究,最后綜合論述晚古生代到晚中生代華北克拉通北緣中段巖石圈地幔在中生代大規(guī)模減薄之前的構(gòu)造演化過程。主要取得的成果和創(chuàng)新性認(rèn)識(shí)如下:1、龍王廟巖體同時(shí)具備弧和后碰撞的地化特征,是弧擠壓到弧后伸展過渡環(huán)境的產(chǎn)物,其弧后伸展環(huán)境對(duì)應(yīng)的弧 陸碰撞是晚志留世的白乃廟島弧體與華北克拉通北緣的碰撞。與同時(shí)期的紅石砬和二道溝?下哈叭沁雜巖體比較,可以得出該階段的大陸巖石圈地幔并沒有受到蒙古洋系統(tǒng)大規(guī)模的影響,僅表現(xiàn)為大陸巖石圈地幔的不均一富集。2、上莊巖體的形成時(shí)代與華北克拉通中部和東部中生代巖石圈減薄機(jī)制下的伸展作用事件吻合。母巖漿等同的細(xì)粒輝長巖地化特征(比如低Dy/Yb值:3.48?3.55;La/Yb值:50.83?53.22)顯示其來源為含尖晶石二輝橄欖巖相巖石圈富集地幔的部分熔融,且它們的Zr/Nb(8.03?9.09),Zr/Y(13.0?15.1)和Nb/Y(1.62?1.66)值顯示源區(qū)有少量軟流圈地幔等深部物質(zhì)的加入。軟流圈上涌帶來足夠熱量,加上同時(shí)期源于太平洋板片俯沖而來的水份,共同促成上莊巖體母巖漿的形成。太平洋俯沖板片給北緣的大陸巖石圈地幔提供了一定的水份,但沒有造成該區(qū)域大陸巖石圈地幔的進(jìn)一步富集。3、綜合華北克拉通北緣其他階段的基性-超基性巖體以及其他幔源巖體的各種特征,得出華北克拉通北緣的大陸巖石圈地幔在遭受中生代大規(guī)模的巖石圈破壞和減薄事件之前,曾受蒙古洋板塊階段性俯沖的影響。它們的Hf同位素和地化特征表明大陸巖石圈地�？傮w表現(xiàn)為越來越富集。4、在蒙古復(fù)合地體與華北克拉通北緣于晚二疊世發(fā)生碰撞后,北緣受到后碰撞/后造山作用,引起巖石圈的拆沉,隨即出現(xiàn)的基性-超基性巖體兼具軟流圈地幔和巖石圈地幔的混合特征。而后這一拆沉作用逐步向克拉通內(nèi)部發(fā)展,引起更大規(guī)模的巖石圈拆沉作用,以華北克拉通內(nèi)部出現(xiàn)大規(guī)模的晚侏羅世(~160 Ma)高鎂安山巖、英安巖和埃達(dá)克巖達(dá)到頂峰。上莊巖體表明早白堊世時(shí)期北緣巖石圈破壞和減薄的機(jī)制是熱/化學(xué)侵蝕。
[Abstract]:The continental lithospheric mantle of the northern margin of the North China Craton became active during the Ordovician Triassic under the influence of multi-stage subduction of the Mongolian oceanic plate. The age of formation of the Longwangmiao and Shangzhuang pluton in this paper is 399Ma and 123128Marespectively, belonging to the Middle Devonian and early Cretaceous. Based on the emphases on the petrogenesis and tectonic indication of the two rocks, this paper studies other rock masses in the time interval of the northern margin of the North China Craton in combination with previous studies. Finally, the tectonic evolution of the lithospheric mantle in the northern margin of the North China Craton from the late Paleozoic to the late Mesozoic before the large-scale thinning of the Mesozoic is comprehensively discussed. The main achievements and innovative understandings are as follows: 1. The Longwangmiao rock mass has geochemistry characteristics of both arc and rear collision, which is the product of the transition environment from arc compression to back-arc extension. The arc-continent collision corresponding to its back-arc extensional environment is a collision between the late Silurian Bainaimiao island arc body and the northern margin of the North China Craton. With the same period of Hongshila and Erdaogou? A comparison of the Lower Hapeqin complex shows that the continental lithospheric mantle at this stage was not affected by the Mongolian oceanic system on a large scale. The formation age of the Shangzhuang rock body coincides with the extensional events under the Mesozoic lithospheric thinning mechanism in the central and eastern North China Craton. The geochemical characteristics of the mother magma equivalent fine-grained gabbro (for example, low Dy/Yb value: 3.48 ~ 3.55 / Lap / Yb = 50.83 / 53.22) indicate that it originated from the partial melting of the mantle enriched by the lithospheric lithosphere containing spinel. Their Zr/Nb (8.03 ~ 9.09) and Nb/Y (1.62 ~ 1.66) values indicate that a small amount of deep materials such as the asthenospheric mantle are added into the source region. The upwelling of the asthenosphere brought enough heat together with the water from the Pacific plate subduction in the same period which contributed to the formation of the mother magma of the Shangzhuang rock mass. The Pacific subduction plate provides a certain amount of water to the continental lithospheric mantle in the northern margin. However, it has not resulted in further enrichment of the continental lithospheric mantle in the region, and the various characteristics of the basic-ultrabasic rock bodies and other mantle-derived rocks in other stages of the northern margin of the North China Craton have been synthesised. It is concluded that the continental lithospheric mantle in the northern margin of the North China Craton was affected by the stage subduction of the Mongolian ocean plate before the Mesozoic large-scale lithospheric destruction and thinning events. Their HF isotopic and geochemical characteristics indicate that the continental lithospheric mantle is more and more enriched in general. After the collision between the Mongolia composite terrane and the North China Craton occurred in the late Permian, the northern margin was subjected to post-collision / post-orogeny. The basic-ultrabasic rock body, which caused the lithosphere to desink, has the mixed characteristics of the asthenospheric mantle and the lithospheric mantle. Then the desinking gradually developed to the interior of the craton, resulting in a larger lithospheric desubsidence, with the large scale late Jurassic (160Ma) high mafic andesite within the North China craton, with the dolomite and adakite reaching its peak. The Shangzhuang rock mass indicates that thermal / chemical erosion was the mechanism of lithospheric destruction and thinning in the northern margin of early Cretaceous.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：P581;P542
，
本文編號(hào)：2153457
[Abstract]:The continental lithospheric mantle of the northern margin of the North China Craton became active during the Ordovician Triassic under the influence of multi-stage subduction of the Mongolian oceanic plate. The age of formation of the Longwangmiao and Shangzhuang pluton in this paper is 399Ma and 123128Marespectively, belonging to the Middle Devonian and early Cretaceous. Based on the emphases on the petrogenesis and tectonic indication of the two rocks, this paper studies other rock masses in the time interval of the northern margin of the North China Craton in combination with previous studies. Finally, the tectonic evolution of the lithospheric mantle in the northern margin of the North China Craton from the late Paleozoic to the late Mesozoic before the large-scale thinning of the Mesozoic is comprehensively discussed. The main achievements and innovative understandings are as follows: 1. The Longwangmiao rock mass has geochemistry characteristics of both arc and rear collision, which is the product of the transition environment from arc compression to back-arc extension. The arc-continent collision corresponding to its back-arc extensional environment is a collision between the late Silurian Bainaimiao island arc body and the northern margin of the North China Craton. With the same period of Hongshila and Erdaogou? A comparison of the Lower Hapeqin complex shows that the continental lithospheric mantle at this stage was not affected by the Mongolian oceanic system on a large scale. The formation age of the Shangzhuang rock body coincides with the extensional events under the Mesozoic lithospheric thinning mechanism in the central and eastern North China Craton. The geochemical characteristics of the mother magma equivalent fine-grained gabbro (for example, low Dy/Yb value: 3.48 ~ 3.55 / Lap / Yb = 50.83 / 53.22) indicate that it originated from the partial melting of the mantle enriched by the lithospheric lithosphere containing spinel. Their Zr/Nb (8.03 ~ 9.09) and Nb/Y (1.62 ~ 1.66) values indicate that a small amount of deep materials such as the asthenospheric mantle are added into the source region. The upwelling of the asthenosphere brought enough heat together with the water from the Pacific plate subduction in the same period which contributed to the formation of the mother magma of the Shangzhuang rock mass. The Pacific subduction plate provides a certain amount of water to the continental lithospheric mantle in the northern margin. However, it has not resulted in further enrichment of the continental lithospheric mantle in the region, and the various characteristics of the basic-ultrabasic rock bodies and other mantle-derived rocks in other stages of the northern margin of the North China Craton have been synthesised. It is concluded that the continental lithospheric mantle in the northern margin of the North China Craton was affected by the stage subduction of the Mongolian ocean plate before the Mesozoic large-scale lithospheric destruction and thinning events. Their HF isotopic and geochemical characteristics indicate that the continental lithospheric mantle is more and more enriched in general. After the collision between the Mongolia composite terrane and the North China Craton occurred in the late Permian, the northern margin was subjected to post-collision / post-orogeny. The basic-ultrabasic rock body, which caused the lithosphere to desink, has the mixed characteristics of the asthenospheric mantle and the lithospheric mantle. Then the desinking gradually developed to the interior of the craton, resulting in a larger lithospheric desubsidence, with the large scale late Jurassic (160Ma) high mafic andesite within the North China craton, with the dolomite and adakite reaching its peak. The Shangzhuang rock mass indicates that thermal / chemical erosion was the mechanism of lithospheric destruction and thinning in the northern margin of early Cretaceous.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：P581;P542
，
本文編號(hào)：2153457
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