地球物理学报
地毬物理學報
지구물이학보
2009年
11期
2788-2797
,共10页
南海扩张%浅俯冲%单方向漂移%挤压变形%手风琴风箱式地震相外形
南海擴張%淺俯遲%單方嚮漂移%擠壓變形%手風琴風箱式地震相外形
남해확장%천부충%단방향표이%제압변형%수풍금풍상식지진상외형
Sea-floor spreading of South China Sea%Shallow subduction%Way drifting%Extrusion metamorphism%Accordion-style seismic facies
南海的扩张、成因演化研究的成果主要基于深部速度研究及磁条带研究的基础上,但南海东北部边界的研究相对薄弱.本次通过对南海东北部边界的反射地震剖面973的综合研究,结合前人的天然地震震源研究及地质研究成果,得到南海形成与扩张是单方向向菲律宾吕宋岛弧-台湾岛地块漂移的结果.南海各块体处于一个统一的区域应力场作用之下,菲律宾吕宋岛弧-台湾岛地块限制了南海的扩张与发展;在此应力条件下,不同部位受力状态不同,就南海东北部973剖面地震波场特征,可划分为五个构造单元:AB段南海东北部大陆架张性盆地区;BC段大陆坡为伸展区,形成大量张性盆地;CD段中部深海沉积盆地为弱挤压区,深海沉积盆地弱变形,大陆坡张性盆地浅俯冲其下,深海沉积盆地西部翘起,向东倾斜;DE段东部为强挤压区,沉积盆地挤压变形,越向东挤压越强烈,深海沉积盆地浅俯冲其下,相对弱变形并西部翘起;E以东,菲律宾吕宋岛弧-台湾岛构造带为稳定地块.南海东北部在东或南东方向统一的区域应力场作用下,处于张性、弱挤压、强挤压不同压力状态,形成南海特有的由北西向东呈现拉张-弱挤压-强挤压构造格局,反射地震削面上显示两个浅俯冲点.每个块体构造层呈手风琴风箱式折曲并向东聚敛,近菲律宾吕宋岛弧-台湾岛构造带其折曲更为严重,沉积盆地由西向东,展现为不同阶段的沉积盆地,发育、成长、结束、消亡,块体俯冲方向以及各块体的区域性倾伏方向均与区域应力场方向一致.
南海的擴張、成因縯化研究的成果主要基于深部速度研究及磁條帶研究的基礎上,但南海東北部邊界的研究相對薄弱.本次通過對南海東北部邊界的反射地震剖麵973的綜閤研究,結閤前人的天然地震震源研究及地質研究成果,得到南海形成與擴張是單方嚮嚮菲律賓呂宋島弧-檯灣島地塊漂移的結果.南海各塊體處于一箇統一的區域應力場作用之下,菲律賓呂宋島弧-檯灣島地塊限製瞭南海的擴張與髮展;在此應力條件下,不同部位受力狀態不同,就南海東北部973剖麵地震波場特徵,可劃分為五箇構造單元:AB段南海東北部大陸架張性盆地區;BC段大陸坡為伸展區,形成大量張性盆地;CD段中部深海沉積盆地為弱擠壓區,深海沉積盆地弱變形,大陸坡張性盆地淺俯遲其下,深海沉積盆地西部翹起,嚮東傾斜;DE段東部為彊擠壓區,沉積盆地擠壓變形,越嚮東擠壓越彊烈,深海沉積盆地淺俯遲其下,相對弱變形併西部翹起;E以東,菲律賓呂宋島弧-檯灣島構造帶為穩定地塊.南海東北部在東或南東方嚮統一的區域應力場作用下,處于張性、弱擠壓、彊擠壓不同壓力狀態,形成南海特有的由北西嚮東呈現拉張-弱擠壓-彊擠壓構造格跼,反射地震削麵上顯示兩箇淺俯遲點.每箇塊體構造層呈手風琴風箱式摺麯併嚮東聚斂,近菲律賓呂宋島弧-檯灣島構造帶其摺麯更為嚴重,沉積盆地由西嚮東,展現為不同階段的沉積盆地,髮育、成長、結束、消亡,塊體俯遲方嚮以及各塊體的區域性傾伏方嚮均與區域應力場方嚮一緻.
남해적확장、성인연화연구적성과주요기우심부속도연구급자조대연구적기출상,단남해동북부변계적연구상대박약.본차통과대남해동북부변계적반사지진부면973적종합연구,결합전인적천연지진진원연구급지질연구성과,득도남해형성여확장시단방향향비률빈려송도호-태만도지괴표이적결과.남해각괴체처우일개통일적구역응력장작용지하,비률빈려송도호-태만도지괴한제료남해적확장여발전;재차응력조건하,불동부위수력상태불동,취남해동북부973부면지진파장특정,가화분위오개구조단원:AB단남해동북부대륙가장성분지구;BC단대륙파위신전구,형성대량장성분지;CD단중부심해침적분지위약제압구,심해침적분지약변형,대륙파장성분지천부충기하,심해침적분지서부교기,향동경사;DE단동부위강제압구,침적분지제압변형,월향동제압월강렬,심해침적분지천부충기하,상대약변형병서부교기;E이동,비률빈려송도호-태만도구조대위은정지괴.남해동북부재동혹남동방향통일적구역응력장작용하,처우장성、약제압、강제압불동압력상태,형성남해특유적유북서향동정현랍장-약제압-강제압구조격국,반사지진삭면상현시량개천부충점.매개괴체구조층정수풍금풍상식절곡병향동취렴,근비률빈려송도호-태만도구조대기절곡경위엄중,침적분지유서향동,전현위불동계단적침적분지,발육、성장、결속、소망,괴체부충방향이급각괴체적구역성경복방향균여구역응력장방향일치.
In this research,a comprehensive study of the 973 seismic profiles was conducted. Combined with previous studies of the geological and natural hypocenter,we proposed that the formation and expansion of the South China Sea is the result of the one-way drift to the Philippines Island of Luzon arc-Taiwan terrain. All the blocks of South China Sea are under the same regional stress field and its expansion and evolution were constrained by the Philippines island of Luzon arc-Taiwan terrain. Based on the stress conditions,and the characteristics of seismic wave field,five structural sections were distinguished in the 973 seismic profile of the northeastern South China Sea:AB section is a stretching area of the continental shelf;BC section is the expanded area of the continental slope,with many pull-apart basins;CD section is the deep sedimentary basin with weak compression and deformation. The extensional basins of the continental slope subducted underneath this section shallowly. The western deep-sea sedimentary basins was elevated,and inclined eastward; DE section is a strongly compressed sedimentary basin zone with stronger squeezing in the eastern part. The weak-deformed deep-sea sedimentary basins subducted shallowly underneath this section,and were lifted up in the western region. The east of E is the tectonic belt of Luzon-Taiwan island arc,and is a steady rigidity block. Under the eastern or southeastern uniform stress field,the northeastern part of the South China Sea underwent different stress state and formed unique structure patterns in South China Sea:extensional-weak compressive-strong compressive from north-west to east. Two shallow subduction zones were recognized in the seismic profiles. All the tectonic blocks have accordion-folds-style structures and converged in the east,with stronger folding near the Philippine island of Luzon arc-Taiwan Island. From west to east sedimentary basins showed different stages of the basins development:growth,mature and terminations. Block subduction and regional block inclining directions were all aligned with the directions of the regional stress field.