渭河裂谷盆地的构造特征分析     

王全庆  裴先治 《地球科学与环境学报》1990,(1)

渭河裂谷盆地是汾渭裂谷系构造的重要组成部分,是喜山期以来秦岭造山带北缘在环太平洋构造域与特提斯构造域联合作用的产物。它的演化经历了前燕山期挤压收缩所造成的正扇形断褶隆起;早喜山期初始扩张断陷;中喜山期的强烈伸展裂陷和晚喜山期的联合扭动改造作用,而形成现渭河裂谷盆地。  相似文献   

Geology and tectonics of the Boa Vista Basin (Paraíba, northeastern Brazil) and geochemistry of associated Cenozoic tholeiitic magmatism     

Zorano Srgio de Souza  Marcos Antonio Leite do Nascimento  Rogrio Vidal Nunes Barbosa  Luis Gustavo da Silveira Dias 《Journal of South American Earth Sciences》2005,18(3-4):391-405

The Boa Vista Basin (BVB) is located approximately 60 km southwest of Campina Grande, Paraíba, northeastern Brazil. It has a half-graben geometry controlled by dip-slip normal faults striking NE–SW. From the base to the top, the BVB is composed of (1) a lower volcanic unit of altered basalts and basaltic andesites overlying Precambrian basement rocks, (2) an intermediate unit of bentonitic shales that pass upward to medium- to coarse-grained sandstones and conglomerates and downward to sandstones and siltstones, and (3) an upper volcanic unit of massive to vesiculated basaltic flows grading to pillowed or autobrecciated basalts. These basalts show porphyritic (olivine and augite microphenocrysts), glomeroporphyritic, intersetal, pilotaxitic, and variolitic textures. They are medium-K, Fe-rich tholeiites with SiO₂ of 50.2–53.3 wt%, magnesium number of 50.54–60.21 wt%, total alkali of 2.15–3.92 wt%, and TiO₂ of 1.8–1.9 wt% and are related by low-pressure fractionation of olivine, plagioclase, magnetite, ilmenite, and apatite. They are LREE-enriched (La_N/Yb_N=8.54–44.14) with no significant europium anomaly. Trace element modeling suggests a garnet-bearing metasomatised lherzolite as their source. The geological context and geochemistry of the basalts suggest a close connection between reactivated deep-rooted Precambrian shear zones, which channeled mantle-derived Tertiary tholeiitic magmas, and continental rifting in northeastern Brazil.  相似文献   

陆相断陷盆地湖平面变化曲线与层序地层学框架模式讨论   总被引：4，自引：1，他引：4  

郭建华  朱美衡  刘辰生  王明艳 《矿物岩石》2005,25(2):87-92

陆相断陷盆地形成于控凹断层长期稳定的下沉过程中，因此，湖平面的升降变化主要是受控凹断层的活动速率与活动特点、海侵及气候的控制。由于控凹断层活动的幕式性与阶段性，以及突发的海侵事件，导致湖平面升降变化轨迹为两段折线式，即快速的湖侵与缓慢的湖退。在一个湖平面升降旋回过程中，形成了下部的湖侵体系域和上部的湖退体系域，可称之为T-R旋回沉积层序。层序的边界可能是由于幕式性的构造活动所反映出的局部的沉积间断与缺失，或者是由于突发性的海侵而造成的“沉没”。很显然，这种T-R旋回层序地层学格架模式缺乏大面积的暴露而形成的Ⅰ型层序边界。在其内部的构成上，由于没有明显的侵蚀不整合，也难以将“低位体系域”和“高位体系域”区分开。尤其是在湖盆萎缩或“低位期”，湖水退至湖盆中心，水体较浅，很难形成“低位期”的湖底扇。  相似文献   

Fluid focusing and back-reactions in the uplifted shoulder of the Rhine rift system: a clay mineral study along the Schauenburg Fault zone (Heidelberg, Germany)     

A. M. Schleicher  L. N. Warr  B. A. van der Pluijm 《International Journal of Earth Sciences》2006,95(1):19-33

A retrograde sequence of fluid-controlled, low-temperature mineral reactions has been preserved along an east-west striking, dextral-oblique-slip fault in the uplifted Rhine Graben shoulder. This fault (the Schauenburg Fault, near Heidelberg), juxtaposes Permian rhyolite against Carboniferous (Variscan) granite and shows syn- or post-rift displacement of the north–south trending, eastern boundary fault of the rift basin. Both mineral texture and rock fabric indicate that the fault forms a site of high rock permeability and fluid flow, and records the exhumation and fluid-rock history of the rift shoulder since the Mesozoic. The reaction sequence and mineral compositions of the clay minerals within the cataclasite, and adjacent granite and rhyolite lithologies, document progressively decreasing fluid temperatures, with back-reactions of pure 2M₁ illite to 1M_d (R3) illite-smectite, and eventually smectite and kaolinite assemblages. Compositional variations are attributed to Tertiary to Recent fluid flushing of the fault zone associated with rift flank uplift, and with progressive dilution of the electrolyte-rich, acidic to neutral hydrothermal brines by down-flowing electrolyte-poor, meteoric waters.  相似文献   

藏北若拉岗日C-P1裂谷带的发现及构造意义     

穆利修  王宏运  罗宏伟 《新疆地质》2006,24(1):16-23

若拉岗日裂谷带位于拉竹龙-西金乌兰-金沙江结合带的中段,该带作为一条重要的大地构造分界线已被地学界所注目.在西金乌兰地区发现了蛇绿混杂岩带,在金沙江、甘孜理塘等地保留有较完整的洋壳残片(蛇绿混杂岩套)和岛弧火山岩建造,其西延的若拉岗日一带,没有见到这些地质体.基性岩(脉)和少量超基性岩脉是三叠纪热侵位的产物,地球化学等特征表明,它们不是MORB型基性岩,更多地体现板内裂谷特征;石炭系—下二叠统基性火山岩以碱性系列玄武岩为主,具裂谷型双峰式特征,岩石地球化学等特征表明,它们形成于板内或板内裂谷;酸性花岗岩类侵入岩极不发育,构造岩浆带不发育.  相似文献   

贝加尔裂谷带通京盆地新生代火山岩石学与地球化学特征及其构造意义   总被引：1，自引：0，他引：1  

李益龙  周汉文  Лабацкая  严溶  曾广策 《矿物岩石》2006,26(3):56-63

位于贝加尔裂谷带西南端通京盆地的尚加泰火山玄武岩由高拉长石—中长石、贵橄榄石、次透辉石、火山玻璃组成,据对S iO2与全碱(N a2O K2O)的关系判断,均为碱性橄榄玄武岩,微量元素、稀土元素分布型式与板内碱性玄武岩一致,推测原始岩浆来源于上地幔距地表200 km~250 km深度处,在距地表约40 km处即莫霍面附近开始冷却结晶,该火山活动区可能成因于异常地幔凸起中的物质-能量流沿着断裂在通京盆地内的上升。  相似文献   

若尔盖-九寨沟裂谷构造与金成矿     

张成忠  刘增达 《地质找矿论丛》2006,21(Z1):58-61

若尔盖-九寨沟地区产有30余处金矿床(点),另有铜、锑、铁等金属矿产;金矿石分石英脉型和微细浸染型,成因类型可分为构造热液型和构造岩浆热液接触交代型.金成矿与裂谷的演化息息相关,金矿主赋于裂谷强烈期的三叠系地层中,分布受裂谷带控制,金矿化具明显的岩性-岩相选择并与一定的围岩蚀变相伴产出.  相似文献   

A stratigraphical-geochemical study on the Chaco Paraná continental rift basin- An approach study based on regional sedimentology and drill-hole core analyses,South América     

Roberto Torra 《中国地球化学学报》2006,25(3)

This paper is focused on a geologic "regional rift basin system pattern" and its stratigraphical-geochemical relationship. This is mainly based on the littoral shallow marine sedimentary succession paleogeography and deposits. These successions characterize the large extensional intracratonic Chaco rift basin system evolved from the Upper Cretaceous ( Late Campanian-Senonian-Maastrichtian-Early Paleocene) to Quaternary time. The siliciclastic littoral shallow marine successions were deposited from Early Senonian-Maastrichtian to Late Miocene during three main successive littoral shallow marine transgressions of continental extension.These transgressions happened over the wide pediplanized terrains of South America. These lands exist west of the more positive areas, between the Brazilian Shield and the foreland massifs that were settled in the more westernwards areas. Later, these regional foreland massifs were coupled and raised to the Andean Orogen Belt during the last 5 million years.The extensive intracratonic pediplanized low topographic relief areas were the reservoirs of siliciclastic littoral shallow marine succession deposits during the three successive widespread vast continental littoral shallow marine transgressions.The first transgression began at the Latest Campanian-Senonian and/or Early Maastrichtian time. After this episode, the sedimentary depositional systems continued during the Cenozoic until the Latest Miocene. These successions constitute a major allostratigraphic unit.The limit with underlying units is the regional unconformity between the regional volcanic event (Jurassic-Cretacic and interleaved eolianite sandstones) at the base and the undifferentiated Quaternary sediments (called as the Pampeano and Post-Pampeano Formations sensu lato). Based on many facies analyses there had been checked out different levels in the eustatic sea level variations within the allostratigraphic unit.Three major stages of extensional climax were recognized and related to the stages of conspicuous eustatical sea-level variations. They happened during the Latest Senonian-Paleocene, Eocene and Miocene.The first transgression occurred during the Upper Cretaceous-Paleocene although the sedimentary deposits related to this event are scarce, which are only a few meters in thickness. However, the Upper Cretaceous-Paleocene succession is very well recognized in the actual pre-Andean zone in the north-west of Argentina and Bolivia (the Sierras Subandinas and the meridional imbricated fault systems just joint to the actual orogen, I.e. , Quebrada de Humahuaca outcrops).During the Eocene and Middle to Latest Miocene occurred the second and third extensive regional littoral shallow marine transgressions. They are present either in well log registers as in most widespread outcrops on the entire Southamerican continent.The regional analysis led to the deduction of long periods of tectonic quiescence, at least three of them. They may be inferred and synchronously related with eustatic highstand sea level variations that occurred during the Late Paleocene-Early Eocene, Latest Eocene-Early to Mid Oligocene and Middle-to-Late Oligocene-Early Miocene.The structural style is related with major extensional N-S strike faultings (regional tilted and faulting blocks). On the other hand, quite a number of strike-slip faults (mainly of regional characteristic) are present crossing the area. They have a clear influence on the accommodation and transfer zones of the rift basin system. The strike is north-west to south-east on the border of the basin, to the west, in the contact with the Pampean Ridges and the narrow-meridionally-extense Sub-Andean folded trend ( mainly Paleozoic units belonging to the so-called Sierras Subandinas geological province). Also, at the western edge of the studied area, there exist many large shear zones and upthrust faults. The strike-slip regional faults dislocated the Pampean and Sub-Andean blocks due to the interaction of crossing regional tilted and fault blocks.For this reason, an en echelon regional block model is characteristic. Incipient contaminated igneous activities were associated with this cortical weak zones. Domes, needles and necks of volcanic and sub-volcanic origin appear as the landscape of the region.A part of the igneous activity was dated on Latest Pliocene although mainly corresponding to Pleistocene and Holocene. This deduction is obvious because their morphological constitution was never eroded. The volcanic aparatous are morphologically unmodified from their extrusion to present days.All the studied successions seem to resemble a long persisting erosive, transportation and deposition episode. This phenomenon is linked to a large regional (continental) unconformity dated at Late Cretaceous. The entire analyzed sedimentary succession deposits and their siliciclastic facies associations correspond clearly to a "heterolithic facies succession" which is very common within persisting tide-dominated depositional systems (passive margins). In fact, this is what happened during Cenozoic times (Torra,1998b, 2001a). The heterolithic Miocene facies deposits constitute one of the best continental exposed examples.Paleogeographical evidence showed that the Paranense and Amazonic Sea transgressions had been a littoral shallow marine connection during long time from Middle to Late Miocene. During the Late Cretaceous and Eocene periods marine connections were also active in the region. This fact is strongly supported by the tectonic and geomorphological framework of the proto-Southamerican continent, fossil remains and similar sedimentary deposits.The geochemical results showed an outstanding similarity among the three sandy-muddy successions herein studied. Both major and trace elements always show the same geochemical patterns. Specially mentioned are the elements gallium, cesium, chromium, barium, vanadium, thorium, zirconium, rubidium and strontium because they present very constant values through all successions.The Paranense and Amazonic epicontinental seas had been connected to the Pacific Ocean during the three marine episodes. The connections were formed by narrow inter-mountain valleys, present in the preAndean foreland massifs. These events occurred prior to the main orogenesis elevation of the Andean orogen belt in the last 5 to 1 Ma ( Pliocene-Latest Pleistocene).This paper shows, for the first time, a synthetic stratigraphical-geochemical "regional model" for the carries many unexamined-unexplored natural resources which need more regional and local studies for their evaluation. This is in spite of the area that has the problem of a significative vegetation coberture and scarce good outcrops. The development of modern techniques of dataacquisition will help to overcome these difficulties.  相似文献   

伊通盆地莫里青断陷烃源岩特征及生排烃史     

邓守伟  曹强  叶加仁 《地质科技情报》2007,26(6):66-70

为了综合确定伊通盆地莫里青断陷的主力烃源岩,深化油气成藏动力学过程研究,在烃源岩分布特征及有机质丰度、类型和成熟度分析的基础上,应用含油气盆地数值模拟技术,定量恢复了研究区主要烃源岩层系的生排烃史.研究表明,莫里青断陷主要发育始新统双阳组、奢岭组和永吉组3套烃源岩系,其中双阳组泥岩为主力烃源岩,具较高的有机质丰度、成熟度、生烃强度与排烃效率;以双阳组为烃源岩的油气系统应是该区油气勘探的主要目标.  相似文献   

攀西裂谷内陆盆地自由热对流应力分析及盆地沉降   总被引：2，自引：0，他引：2       下载免费PDF全文

尹福光 《沉积与特提斯地质》2003,23(4):79-83

康滇地区裂谷作用已得到证实,但形成这种地堑地垒的格局有多种解释,以传统的地质力学分析为主。笔者借以热力学的自由热对流原理来加以论述：攀西巨厚的火山岩体在下覆异常地幔热作用下,发生自由热对流,引起热量散失,使地壳沉降与隆起不均衡,生成地堑地垒的格局。自由对流单元的侧向迁移,使盆地形成非对称性。  相似文献