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1.
Carlos J. P. Rosa Jocelyn McPhie Jorge M. R. S. Relvas Zélia Pereira Tomás Oliveira Nelson Pacheco 《Mineralium Deposita》2008,43(4):449-466
In the Iberian Pyrite Belt, volcanic rocks are relatively scarce, accounting for approximately only 25% of the geologic record,
with the remaining 75% consisting of sedimentary units. This association is very clear in the host succession to the Neves
Corvo massive sulfide deposit in Portugal. The Neves Corvo host succession comprises the products of explosive and effusive
rhyolitic eruptions intercalated with mudstone that records a submarine below-wave-base environment and provides precise biostratigraphic
age constraints. The first and second volcanic events involved eruptions at local intrabasinal vents. The first event generated
thick beds of fiamme breccia that are late Famennian in age. The fiamme were originally pumice clasts produced by explosive
eruptions and were subsequently compacted. The second event was the late Strunian (latest Famennian) effusion of rhyolitic
lava that was pervasively quench-fragmented. The third and final event is younger than the massive sulfide deposits poorly
represented in the mine area and minor compared with the two other events. The integration of biostratigraphic data with the
volcanic facies architecture indicates that the Neves Corvo ore deposits are similar in age to the late Strunian rhyolitic
lava. Although regionally the Iberian Pyrite Belt is essentially a sedimentary succession, ore formation at Neves Corvo can
be closely linked to discrete volcanic events that produced a relatively narrow range of volcanic facies. 相似文献
2.
J. T. Oliveira C. J. P. Rosa Z. Pereira D. R. N. Rosa J. X. Matos C. M. C. Inverno T. Andersen 《Mineralium Deposita》2013,48(6):749-766
The lithostratigraphic sequence in the Rosário–Neves Corvo antiform comprises the Phyllite–Quartzite Group, whose top is of Famennian age, the Volcanic Sedimentary Complex, of Strunian to upper Visean age, and the Mértola Formation (the lower unit of the Baixo Alentejo Flysch Group) of upper Visean age. The volcanic sedimentary complex comprises a lower sequence of Strunian (Late Famennian) age and an upper sequence of lower to upper Visean age. Detailed mapping of the antiform towards NW of the Neves Corvo mine, supported by palynological dating, identified two new lithostratigraphic units: the Barrancão member (upper Famennian) ascribed to the Phyllite–Quartzite Group and made up of laminated dark shales with siliceous lenses and nodules, and the Ribeira de Cobres Formation of the Volcanic Sedimentary Complex, containing shales, siltstones and fine volcaniclastic rocks. Based on zircon U–Pb isotope dating, five discrete felsic magmatic events were identified at approximately 354, 359, 365, 373 and 384 Ma. This suggests that the volcanic activity in the area has extended for about 30 Ma, in a context of high regional heat flow as indicated by the geochemical signatures of the felsic volcanic rocks. The characteristics of magmatism and the depositional environment indicated by the sedimentary record should therefore have been highly favourable for massive sulphide formation. However, evidence of massive sulphide mineralization in the study area is still to be found. Moreover, reconstruction of the volcanic facies architecture demonstrated that the volcanic units in the Rosário area are strongly dominated by coherent facies typical of the inner part of thick lavas/domes. In fact, most of their external part, the more favourable location for possible massive sulphide mineralization, is missing. Palynological dating indicates a significant hiatus, recognised between the lower and upper sequences of the volcanic sedimentary complex, which implies erosion of the top of the volcanic centre, where VHMS deposits could possibly have formed. However, lateral areas of this volcanic centre, eventually preserved at depth, have good potential to host massive sulphide mineralization. 相似文献
3.
对葡萄牙Neves Corvo Cu.Sn多金属矿床锡矿石，富铜硫化物矿石和贫铜硫化物矿石中锡石的微量元素电子探针分析结果的综合研究表明，该矿床存在高温（＞300度），富W的早期锡矿化阶段，钞晚的贫W，富Cu，温度略低（245－295度）的Cu,Sn主矿化阶段，以旬晚的贫W，贫Cu温度更低（约200度）的Cu,Sn矿化阶段，结合Pb同位素研究可以推测矿床中Sn可能来源于矿体下部深处未出露的，与板块俯冲有关的富Sn古老地壳岩石，与其他类型锡矿床的微量元素对比表明，Neves Corvo矿床属于处于火山岩容矿（VHMS）型和沉积岩容矿（SHMS）型块状硫化物矿床之间的一种过渡类型－－伊比利亚型。 相似文献
4.
祁连山北缘旱峡地区发育完整的下白垩统下沟组-中沟组沉积序列;以陆源碎屑岩为主,发育砾岩、砂岩、钙质粉砂岩和页岩等;其中砾石分选差、磨圆一般、成分以灰白色砂岩为主,砂岩成分、结构成熟度中等-差。岩石组合、沉积序列和综合沉积特征研究表明,下沟组和中沟组主要由湖泊、扇三角洲、河流等3种类型沉积相、亚相与微相类型组成,发育了一系列重力流成因的沉积类型;湖泊沉积主要发育在下沟组底部和中沟组,扇三角洲沉积分布在下沟组中-上部,中沟组发育河流沉积。研究区早白垩世中期古流向以EN向为主,早白垩世晚期以W向为主,表明沉积沉降中心也由早期的旱峡西移至研究区西南侧。在综合分析的基础上,建立了研究区下白垩统下沟组-中沟组沉积相模式。 相似文献
5.
J. Schäfer H. Neuroth H. Ahrendt W. Dörr W. Franke 《International Journal of Earth Sciences》1997,86(3):599-611
The Saxothuringian flysch basin, on the north flank of the Central European Variscides, was fed and eventually overthrust by the northwestern, active margin of the Tepla-Barrandian terrane. Clast spectra, mineral composition and isotopic ages of detrital mica and zircon have been analyzed in order to constrain accretion and exhumation of rocks in the orogenic wedge. The earliest clastic sediments preserved are of early Famennian age (ca. 370?Ma). They are exposed immediately to the NW of the suture, and belong to the par-autochthon of the foreland. Besides ultramafic (?ophiolite) material, these rocks contain clasts derived from Early Paleozoic continental slope sediments, originally deposited at the NW margin of the Saxothuringian basin. These findings, together with the paleogeographic position of the Famennian clastics debris on the northwestern passive margin, indicate that the Saxothuringian narrow ocean had been closed by that time. Microprobe analyses of detrital hornblendes suggest derivation from the “Randamphibolit” unit, now present in the middle part of the Saxothuringian allochthon (Münchberg nappes). Detrital zircons of metamorphic rocks formed a little earlier (ca. 380?Ma) indicate rapid recycling at the tectonic front. The middle part of the flysch sequence (ca. early to middle Viséan), both in the par-autochthon and in the allochthon, contains abundant clasts of Paleozoic rocks derived from the northwestern slope and rise, together with debris of Cadomian basement, 500-Ma granitoids and 380?Ma (early Variscan) crystalline rocks. All of these source rocks were still available in the youngest part of the flysch (c. middle to late Viséan), but some clasts record, in addition, accretion of the northwestern shelf. Our findings permit deduction of minimum rates of tectonic shortening well in excess of 10–30?mm per year, and rates of exhumation of ca. 3?mm/a, and possibly more. 相似文献
6.
准噶尔盆地东北缘卡姆斯特地区下侏罗统中的放射虫硅质岩砾石及其放射虫动物群 总被引：1，自引：0，他引：1
克拉麦里造山带位于准噶尔盆地东北缘,是中亚构造框架中一个非常重要的构造单元,研究工作较多,但对其演化历史一直存在不同认识。本文报道了阿勒泰卡姆斯特地区下侏罗统三工河组中的紫红色放射虫硅质岩砾石及其放射虫动物群,其中最新的放射虫化石年代为维宪早期,据此推论克拉麦里洋盆封闭于早石炭世晚期,克拉麦里造山带在侏罗纪早期发生快速隆升。 相似文献
7.
云南楚雄前陆盆地晚三叠世沉积建造及盆地演化 总被引：6，自引：1，他引：5
根据沉积建造的类型、系列和体态认为楚雄盆地在晚三叠世经历了３个明显的发育阶段：第一阶段为早期聚敛碰撞阶段,发育了黑色页岩建造和碳酸盐复理石建造;第二阶段为构造相对静止期,发育了火山复理石建造和陆源复理石建造;第三阶段为盆地充填阶段,发育了海相磨拉石建造和陆相磨拉石建造。３个阶段中的沉积建造属于次稳定型和非稳定型两大类。 相似文献
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9.
广东省海丰地区是下侏罗统长埔组良好的出露区。长埔组为一套浅海碎屑岩沉积,主要为陆棚泥质沉积背景下的临滨砂坝和浊流沉积。粒度分析显示临滨砂坝沉积的概率累积曲线为两段式,频率直方图为单峰。浊流沉积的概率累积曲线为三段式,频率直方图为双峰。岩相序列为海进-海退过程的岩相组合,砂岩层向上变厚。海进-海退的序列显示出长埔时期海丰地区总体上经历了两次海平面变化。浅海泥质沉积和浊流沉积构成一套复理石序列。马尔科夫链分析显示长埔组具有明显的向上变粗序列。地球化学数据显示长埔组沉积物兼具被动大陆边缘性质和活动大陆边缘性质。砂岩样品成分的Dickinson图解显示,沉积物来源于再旋回造山带,与岩浆弧造山带和俯冲带杂岩体有关,海丰地区靠近逆冲造山带。因此早侏罗世盆地处于挤压下的弧后前陆构造背景,沉积物受再旋回造山带和陆块双物源控制。 相似文献
10.
Detailed studies on Late Devonian to Early Carboniferous carbonate rocks in central Hunan, southern China have led to the recognition of 25 lithofacies which can be grouped into:(1) inner ramp peritidal platform,(2) inner ramp organic bank and mound.(3) mid ramp,(4) outer ramp,and(5) shelf basin fades associations.The peritidal platform fades association dominates the Zimenqiao Formation (Namurian A or late Datangian) and is characterized by gypsum and dolostone-containing sequences, indicating a peritidal platform environment.The other four fades associations dominate the Menggongao Formation(late Famennian).Liujiatang Formation(Tournaisian or Yangruanian).Shidengzi Formations (early Visean or early Datangian).Five upward-shallowing cycles were distinguished in these three Formations.The predominant fades associations developed in each Formation demonstrate an overall transgression-regression cycle in the Late Devonian to Early Carboniferous in central Hunan.The overall transgressive sequence was preserved in the Shaodong.Menggongao.and Liujiatang Formations,and the overall regressive sequence was preserved in the Liujiatang.Shidengzi.Ceshui and Zimenqiao Formations. 相似文献
11.
Cephalopod limestone deposition on a shallow pelagic ridge: the Tafilalt Platform (upper Devonian, eastern Anti-Atlas, Morocco) 总被引：1，自引：0，他引：1
As a result of early Variscan tectonic movements and of differential subsidence, a platform and basin topography was created along the northern margin of the Sahara Craton during the late Devonian. In the Moroccan Anti-Atlas Mountains, the Tafilalt Platform is an approximately N-S running ridge which developed since the late Middle Devonian. It separated a slowly subsiding shallow basin in the east (Tafilalt Basin) from a rapidly subsiding furrow in the west (Mader Basin). Platform deposits are characterized by highly reduced thicknesses, shallow subtidal to supratidal deposits in the late Frasnian and by unconformities at the Lower/Upper Frasnian and the Frasnian/Famennian boundaries. After a local transgression over emergent areas in the north, water depth probably never reached more than several tens to about 100 m in the lower Famennian. Cephalopod limestones of this age, deposited on the platform, represent a very diverse facies pattern comprising quartz-rich brachiopod coquinas, crinoidal limestones, thick-bedded cephalopod limestones and nodular limestones. Sedimentation rates ranged from 1 to 5 mm/ 1000 yr. In the late Famennian more uniform marl and nodular limestone facies suggest slightly deeper environments. Platform margins are characterized by higher rates of subsidence, debris flow deposits and slump structures. In the relatively shallow Tafilalt Basin, marls with intercalated nodular limestones were deposited. In the Mader Basin, sandy and calcareous turbidites suggest deeper water conditions in the late Devonian. During the Strunian/Tournaisian the whole area was overwhelmed by a thick deltaic sequence. The general facies distribution is in agreement with depositional models of other Upper Devonian and Lower Carboniferous cephalopod limestones in the European Variscan orogenic belts. In all these cases, condensed cephalopod limestones occupy a distinct palaeogeographic position in predictable facies sequences that reflect pre-orogenic phases in the Variscan geodynamic cycle. Moreover, close parallels exist with condensed sequences in the Triassic and Jurassic that occur in a very similar position within the Alpine orogenic cycle. 相似文献
12.
甘肃省景泰正路下志留统复理石杂砂岩沉积地球化学特征 总被引：5，自引：3，他引：2
位于北祁连造山带东段甘肃省景泰正路一带的下志留统肮脏沟组为一套巨厚的浊流相陆源碎屑岩,以杂砂岩为主,夹有板岩,属典型的浊流沉积。薄片的镜下观察结果表明,其粒度为0.05~4.00 mm,岩性为细粒-中、粗粒砂岩、含砾砂岩。对5块采集于复理石中的杂砂岩样品进行岩性组合判定和主要元素地球化学分析结果表明,w(SiO2)为61.83%~69.90%,w(K2O)/w(Na2O)为0.89~1.46。利用数据对比及w(K2O)/w(Na2O)—w(SiO2)等判别图的分析结果对其物源区的性质及沉积大地构造背景进行分析和判别的研究结果表明,北祁连造山带东段甘肃省景泰正路一带下志留统肮脏沟组的陆源碎屑主要来源于活动大陆边缘岩浆岛弧源区和造山带源区,反映了卷入造山带的岛弧、活动大陆边缘的弧后盆地的物源背景。沉积地球化学特征揭示的沉积大地构造背景为弧后前陆盆地背景,与碰撞后的大地构造背景相吻合。 相似文献
13.
The isolated outlier of Visean (Mid Mississippian) limestones and sandstones near Corwen, North Wales, UK, provides a critical constraint on regional tectonic and palaeogeographical models. The late Asbian to Brigantian succession comprises a series of shoaling‐upwards cycles (parasequences). These were the product of forced, glacioeustatic regressions and have boundaries that testify to emergence, karstic dissolution and soil formation on a low gradient carbonate platform prior to flooding and the resumption of marine deposition. The recognition of two of the main marker beds within the North Wales Visean succession (Main Shale and Coral Bed) together with a newly applied foraminiferal and algal biozonation allow the outlier succession to be correlated with other Visean outcrops in the region and more widely throughout the British Isles. In revealing regional thickness and facies variations, these comparisons show that the outlier succession was deposited landward of the early Asbian shoreline in a region of enhanced subsidence localized along the Bala Lineament. The Corwen Outlier suggests that, within narrow gulfs associated with the region's major tectonic lineaments, Mississippian carbonate facies extended farther south into the contemporary hinterland of older rocks and that, in response to Brigantian climate change, these topographic features likely also influenced fluvial catchments supplying siliciclastic sediment to the platform's landward margin and, subsequently, Namurian deltas. Contrary to earlier suggestions, Visean outcrop patterns, facies distributions and thicknesses in the vicinity of the Bala Lineament can be explained without the need to invoke extensive post‐depositional lateral displacements. BGS © NERC 2013. Geological Journal © John Wiley & Sons Ltd. 相似文献
14.
桂中坳陷经历了原特提斯早期裂陷成盆、晚期褶皱造山,古特提斯阶段再度裂陷成盆与新特提斯阶段造山改造3个盆地世代的构造演化过程。自早泥盆世开始的大规模海侵作用,使得本区堆积了从台沟相到斜坡相沉积的深色泥页岩、到滨海沼泽相的含煤建造,主要分布下泥盆统塘丁组、中泥盆统罗富组和下石炭统岩关组3套黑色泥页岩。研究表明,本区上古生界海相页岩有机质丰度高、类型好、处于高-过成熟演化阶段,具有页岩气形成与富集的有利地质条件,是南方页岩气探采值得关注的重点区域。目前已在该坳陷上古生界页岩中发现了较多气显示,具有与美国东部典型页岩气盆地(阿巴拉契亚、福特沃斯、密执安等盆地)相似的地质条件;经采用类比法预测初步估算,全坳陷上古生界页岩气资源量约为12.34×1012m3,表明该区具有巨大的页岩气资源潜力。 相似文献
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16.
为明确松辽盆地北部古龙地区登娄库组沉积与构造演化的耦合关系,本文利用古龙地区的地震、钻井、测井和岩心等资料,通过古龙地区登娄库组的构造演化特征、层序地层格架和沉积特征综合研究,对古龙地区登娄库组构造演化对沉积充填特征的控制作用进行分析,结果表明,古龙地区登娄库组沉积时期为断坳转换期,可进一步划分为断陷盆地萎缩阶段早期和晚期、坳陷盆地孕育阶段早期和晚期4个构造演化阶段,分别对应4个三级层序(Sq1-Sq4); 古龙地区登娄库组主要发育冲积扇、扇三角洲、湖底扇、河流相、辫状河三角洲、浅水三角洲、湖泊沉积等沉积体系; 登娄库组构造演化控制着沉积充填演化,各构造演化阶段沉积体系分布特征及沉积演化模式具有明显的差异性,即沉积充填特征与构造演化过程具有良好的耦合关系。具体表现为:断陷盆地萎缩阶段早期(Sq1)和晚期(Sq2)下部地层受断陷作用控制,沉积充填特征符合陆相断陷湖盆沉积演化模式; 断陷盆地萎缩阶段晚期(Sq2)上部、坳陷盆地孕育阶段早期(Sq3)和晚期(Sq4)地层具有坳陷层序地层特征,其中萎缩阶段晚期(Sq2)上部和坳陷盆地孕育阶段早期(Sq3)属于坳陷盆地"河流-浅水三角洲"沉积模式; 坳陷盆地孕育阶段晚期(Sq4)发育干旱背景下的坳陷湖盆"洪水-河漫湖"沉积模式。 相似文献
17.
在赣中地区开展的1：5万区调工作中，于南华纪早世古家组之上新发现一套变沉凝灰岩、变余砂岩、千枚岩夹灰岩组合，其层位与南华纪晚世下坊组相当，但岩性组合差异很大，两者属同时异相的沉积产物。早期工作中由于认识上的原因，将这套岩性组合及其下伏古家组合砾岩石组合统称源里组。新厘定的源里组是将原定义的源里组下部含砾的岩石组合划归古家组，其上部不含砾的这套岩石组合才归属于重新厘定的源里组。鉴于新厘定的源里组分布于扬子板块与华南板块对接带的南缘，代表古家组冰碛岩之上沉积的一套斜坡相浊积岩，与下坊组盆地相复理石建造明显不同，其空间展布及其边界对确定两大板块的分界线具有重要的大地构造意义，故本文作者将该套岩性组合重新厘定为源里组，时代归属于南华纪晚世． 相似文献
18.
Žarko Ž. Jovanovíc 《Sedimentary Geology》1973,9(2):117-147
In the Turonian and Maastrichtian, the “Diabase-chert Formation” and the “Volcanogenic flysch” were formed as two specific rock series, due to the synchronous basic volcanism of the Drenica area in Kosovo (Yugoslavia). Comparison with other localities of the Inner Dinarides has proved that, regardless of their different stratigraphic position, each of these two formations exhibits in individual localities great lithological and structural similarities. Both formations are associated with large tectonic zones with ophiolitic occurrences which extend from the Alps through the Yugoslav Inner Dinarides, northern and northeastern Greece, part of Turkey (Asia Minor) and further southeast.The Diabase-chert Formation is a lateral facies of Turnonian limestone. It is represented by a characteristic regime of a specific geochemical character, brought about by synchronous basic volcanism, and by the introduction of volcanogenic components — these factors are responsible for great lithological diversity and very rapid lateral and vertical changes. A certain consistency in the lithological composition is only noticable in the closing horizons of this formation at its transition into limestone sediments.The volcanogenic flysch was formed as a result of subvolcanic activity synchronous with flysch sedimentation whereby semi-consolidated flysch sediments acquired certain volcanogenic-sedimentary characteristics. The most intensively disturbed parts around submarine flows of diabase have been recognized as the “zone of highly disturbed flysch”. The zone is conformably overlain by the stratified cherty-clayey zone. This continues into the “zone of ball sandstone”, and ends with the “zone of normal flysch”. Their newly acquired characteristics resulting from synchronous basic volcanism distinguish them clearly from normal flysch and make them a special type of flysch — the volcanogenic flysch. 相似文献
19.
沔阳—当阳前陆盆地自北而南可划分为五个构造单元 :桐柏山—大别山基底卷入推覆构造带、南大巴山—大洪山叠瓦逆冲断裂构造带、沔阳—当阳拗陷变形带、宜昌—沙市前陆斜坡带、黄陵—松滋前缘隆起带。盆地的形成与南大巴山—大洪山造山带的发育密切相关。盆地经历了加里东期、海西—印支期南秦岭洋盆、北华南洋盆的两次“开 (降 )、合 (升 )” ,燕山早期陆内俯冲造山成盆及燕山晚期—喜马拉雅期陆内伸展断陷的演化。盆地油气资源丰富 ,具三套有效烃源岩 :晚奥陶世—早志留世广海陆棚相泥页岩 ,二叠纪滨岸沼泽相含煤泥岩 ,晚三叠世—早侏罗世湖泊—沼泽相暗色泥页岩、煤系泥岩和煤岩。中三叠世—早第三纪为油气生成高峰期。油气运移指向主要为南西方向的前缘隆起 相似文献
20.
广西柳州地区石炭系一个新的岩石地层单位——北岸组 总被引：1，自引：0，他引：1
在1∶5万地质测量中,广西柳州地区石炭系鹿寨组与“寺门组”之间的地层曾被称为“黄金组”,但其与典型地区的黄金组在岩性、岩相、古地理位置等方面均存在显著差异。根据新的研究与前人的资料综合分析,将柳州地区所谓的“黄金组”命名为一个新的组——北岸组。该组主要分布于广西中北部柳州市、柳江县、鹿寨县、柳城县、环江县等地,在古地理上位于黔南-桂中台槽的北缘。该组岩性以灰—深灰色薄—厚层生物碎屑粉晶灰岩、含生物碎屑泥晶灰岩为主,夹硅质岩、泥岩和砂岩,可划分为3个沉积旋回,属斜坡-盆地相沉积。下伏鹿寨组,上覆新圩组,均为整合接触。时代为石炭纪维宪期晚期—谢尔普霍夫期。 相似文献