本文關鍵詞： 渭北隆起 裂變徑跡 中-新生代 構造-熱演化 差異隆升　出處：《西北大學》2017年碩士論文　論文類型：學位論文

【摘要】：渭北隆起與秦嶺造山帶隔渭河斷陷相鄰,其構造熱演化尤其是晚中生代以來的差異隆升過程一直是鄂爾多斯盆地南緣“盆-山”關系研究和油氣勘探關注的熱點問題。本文主要采用野外地質構造剖面勘察、地震剖面解釋與構造熱年代學分析相結合的研究方法,綜合分析了渭北隆起區(qū)加里東晚期與燕山中期擠壓沖斷變形的疊加復合關系、構造分區(qū)特征和晚中生代的構造熱事件及其后期差異抬升冷卻過程-剝蝕改造狀況,探討闡釋了渭北隆起后期差異隆升過程與相鄰構造帶活動的關系。主要取得如下成果認識:(1)野外露頭剖面勘察與地震剖面解釋相結合的構造分析結果表明,渭北隆起區(qū)至少經(jīng)歷了受控于北秦嶺加里東晚期和燕山中期兩次不同性質造山事件的擠壓沖斷變形,加里東晚期韌-脆性褶斷變形層系主要殘存于圣人橋-潼關斷裂以南,燕山中期脆性褶斷變形層系可向北擴展至靈臺-黃陵斷裂;后期的差異抬升和渭河斷陷的疊加改造作用最終鑄成了渭北隆起區(qū)東、西分段和南、北分帶的構造單元分區(qū)特征。(2)鏡質體反射率數(shù)據(jù)分析與井剖面沉降埋藏-熱演化史模擬的研究結果表明,渭北隆起區(qū)經(jīng)歷了早白堊世(140～120Ma)與盆地區(qū)域近乎同步的燕山中期構造熱事件,相應的地溫梯度達到40～50℃/km,明顯大于現(xiàn)今地溫梯度(29.4℃/km);研究區(qū)前新生代沉積埋藏條件與構造熱事件的共同作用,不僅造成該區(qū)上古生界烴源巖層系普遍達到了高或過成熟熱演化階段(Ro1.8～2.4%),同時表現(xiàn)出“中北部高、東南緣低和西段局部構造-巖漿活動熱異�！钡臒嵫莼潭炔町惙謪^(qū)特征。(3)裂變徑跡年齡統(tǒng)計分布及其差異分區(qū)特征的研究結果表明,渭北隆起區(qū)晚中生代以來至少經(jīng)歷了三期構造抬升冷卻事件,主要發(fā)生在早中侏羅世174～168Ma的燕山早期、早白堊世晚期116～100Ma的燕山中晚期和始新世-漸新世39～27Ma以來的喜山中晚期;晚中生代以來的構造抬升冷卻過程總體表現(xiàn)出西南部較早(155～65Ma)、東北部較晚(66～32Ma)的時-空差異分區(qū)特點。(4)磷灰石裂變徑跡熱史模擬與差異抬升速率分析結果表明,渭北隆起燕山中晚期以來的構造抬升過程總體呈現(xiàn)出早期(120～65Ma)較快(56～61m/Ma)、中期(65～30Ma)緩慢(5～10m/Ma)和晚期(30～5Ma以來)最快(67～85m/Ma)的差異抬升特點。其中,渭北隆起內帶的早期(120～110Ma)、中期(110～40Ma)和晚期(40～17Ma以來)的抬升速率分別接近56m/Ma、5m/Ma和67m/Ma;渭北隆起外帶的早期(120～65Ma)、中期(65～30Ma)和晚期(30Ma～5以來)的抬升速率分別接近61m/Ma、10m/Ma和85m/Ma。
[Abstract]:The Weibei uplift is adjacent to the Qinling orogenic belt across the Weihe fault depression. The tectonic thermal evolution, especially the differential uplift process since the late Mesozoic, has always been a hot issue in the study of the "basin-mountain" relationship in the southern margin of the Ordos basin and in oil and gas exploration. By combining seismic section interpretation with tectonic thermochronology analysis, the superimposed composite relationship between late Caledonian and mid-Yanshanian extrusion and thrust deformation in Weibei uplift region is comprehensively analyzed. The characteristics of tectonic zoning and the late Mesozoic tectonic thermal events and their late differential uplift and cooling process-denudation and transformation, The relationship between the differential uplift process in the late Weibei uplift and the activity of adjacent tectonic zones is discussed. The Weibei uplift area experienced at least two extrusion and thrust deformation controlled by two different orogenic events of late Caledonian and mid-Yanshanian orogenic events in the North Qinling Mountains. The late Caledonian ductile-brittle fold deformation strata mainly remained south of the Saint-Qiao-Tongguan fault. In the middle Yanshan period, the deformed series of brittle fold faults can extend northward to Lingtai-Huangling fault, and the late differential uplift and the superposition transformation of Weihe fault depression finally cast the east, west and south of Weibei uplift area. The analysis of vitrinite reflectance data and the simulation of the subsidence and burial history of well sections show that, The Weibei uplift area experienced an early Cretaceous tectonic heat event in the middle Yanshanian period, which was nearly synchronized with the basin area. The corresponding geothermal gradient is 40 ~ 50 鈩，

本文編號：1525606