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1.
《Sedimentary Geology》1999,123(1-2):81-102
In strike-slip basins, proximal stratal patterns are a function of displacement on basin-bounding faults. In order to better understand factors that control changes in sedimentary facies and stratal patterns of the northeastern part of the Jinan Basin (Cretaceous), a strike-slip basin, we made a detailed analysis of sedimentary facies, depositional architecture and paleoflows. The sedimentary successions can be grouped into five facies associations representing five depositional environments: (1) facies association FA I (alluvial fan); (2) FA II (small-scale Gilbert-type delta); (3) FA III (large-scale, steep delta slope); (4) FA IV (base of large-scale, steep delta slope and prodelta); and (5) FA V (lacustrine plain). The successions are divided into two distinct sedimentary fills on the basis of facies associations, depositional architecture and paleocurrents: (1) marginal fill and (2) longitudinal fill. The marginal fill (ca. 3.2 km thick) is present along the strike-slip basin-bounding fault. The lower part of the marginal fill (ca. 1.3 km thick) consists of alluvial-fan deposits (FA I) along the bounding fault which are transitional northward to small-scale Gilbert-type delta (FA II) and lacustrine plain (FA V) deposits. The upper part of the marginal fill (ca. 1.9 km thick) contains large-scale, steep delta slope (FA III) and base of delta slope/prodelta (FA IV) deposits accompanied with a northward change in facies associations. In the marginal fill, the successive alluvial fan, small-scale Gilbert-type delta and large-scale, steep delta/prodelta deposits are overlapped (shingled) northeastward. The longitudinal fill (ca. 2 km thick) is characterized by eastward overlapped stacks of large-scale, steep delta slope (FA III) and base of delta slope/prodelta (FA IV) deposits with a westward progradation. The longitudinal fill was overstepped by the marginal fill. The northeastward shingled geometry of the marginal fill was most likely caused by sinistral strike-slip displacements on the basin-bounding fault. The slightly oblique (northward) progradation of the marginal fill was due to the northward basin-floor tilting. In the marginal fill, the progressive changes in facies and depositional architecture from the lower alluvial fan/small-scale Gilbert-type delta to the upper large-scale, steep delta/prodelta are suggestive of increase in basin subsidence along the strike-slip basin margin that was closely related to the variation in displacement on the basin-bounding fault. The sinistral strike-slip movements on the bounding fault also caused the eastward overlapping of the longitudinal fill. 相似文献
2.
Shoal‐water deltas in high‐accommodation settings: Insights from the lacustrine Valimi Formation (Gulf of Corinth,Greece) 
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下载免费PDF全文 The stratigraphic architecture of shoal‐water deltaic systems developed in low‐accommodation settings is relatively well‐known. In contrast, the features of shoal‐water deltas developed in high‐accommodation settings remain relatively poorly documented, especially when compared with the available data sets for Gilbert‐type deltaic systems developed in the same settings. The lacustrine Valimi Formation (Gulf of Corinth, Greece) provides an opportunity to investigate the facies assemblage and architectural style of shoal‐water deltaic systems developed in high‐accommodation settings. The studied interval accumulated during the Pliocene and Pleistocene and represents part of the early syn‐rift Gulf of Corinth succession. Six facies associations, each described in terms of depositional processes and geometries, have been identified and interpreted to represent a range of proximal to distal deltaic sub‐environments: delta plain, distributary channel, mouth‐bar, delta front, prodelta and open lake. The facies associations and their architectural elements reveal characteristics which are not common in traditionally described shoal‐water deltas. Of note, different facies arrangements are observed in the distributary channels in different sectors of the delta, passing from thick single‐storey channel fills embedded within delta‐plain fines in landward positions, to thin, amalgamated and multi‐storey channels closer to the river mouth. This study proposes a new depositional model for shoal‐water deltas in high‐accommodation settings documenting, for the first time, that shoal‐water delta deposits can form a substantial part of stratigraphic successions that accumulate in these settings. The proposed depositional model provides new criteria for the recognition and interpretation of these deposits; the results of this study have applied significance for reservoir characterization. 相似文献
3.
泌阳断陷湖盆陆相层序水进体系域以退积型扇三角洲为其沉积主体，靠近构造枢纽的陡坡带边缘，冲积扇相域越来越窄，而向盆内则由滨浅湖逐渐过渡为半深湖。断陷湖盆水体属水进型湖泊。水进体系域中油气潜在储集体包括冲积扇的辫状河道砂体及扇三角洲的分流河道、水下分流河道、河口砂坝和前缘席状砂体。但由于它们形成的古环境及物理化学条件的不同，其砂砾岩中所含粘土矿物类型及数量亦有显著差异，对其储集性能将产生不同程度的影响。 相似文献
4.
在简略回顾扇三角洲的背景信息、研究历史和介绍了经典的一牙买加。阿拉斯加、吉尔伯特三大模式基础上,总结了国外对扇三角洲的一些新认识有：构造沉降,相对海平面升降和断层运动等因素对扇三角洲沉积的影响;提出由陆架进积至斜坡坡折的大型吉尔伯特型扇三角洲和堆叠于活动断层之上的吉尔伯特三角洲两种新沉积模式;前积层中砾质舌状体,特殊叠覆构造与大型槽状交错层理的研究;裂缝,胶结和碎屑流等具体沉积特征与机理的分析;对扇三角洲相带储层模型的建立等。最后提出未来扇区三角州的研究方向为：之前各项研究争议较大,难以定论的机理,且局限性较强,无法适用于实际情况的储层模型等。 相似文献
5.
Abstract The Kyokpori Formation (Cretaceous), south‐west Korea, represents a small‐scale lacustrine strike‐slip basin and consists of an ≈ 290 m thick siliciclastic succession with abundant volcaniclasts. The succession can be organized into eight facies associations representing distinctive depositional environments: (I) subaqueous talus; (II) delta plain; (III) steep‐gradient large‐scale delta slope; (IV) base of delta slope to prodelta; (V) small‐scale nested Gilbert‐type delta; (VI) small‐scale delta‐lobe system; (VII) subaqueous fan; and (VIII) basin plain. Facies associations I, III and IV together constitute a large‐scale steep‐sloped delta system. Correlation of the sedimentary succession indicates that the formation comprises two depositional sequences: the lower coarsening‐ to fining‐upward succession (up to 215 m thick) and the upper fining‐upward succession (up to 75 m thick). Based on facies distribution, architecture and correlation of depositional sequences, three stages of basin evolution are reconstructed. Stage 1 is represented by thick coarse‐grained deposits in the lower succession that form subaqueous breccia talus and steep‐sloped gravelly delta systems along the northern and southern basin margins, respectively, and a sandy subaqueous fan system inside the basin, abutting against a basement high. This asymmetric facies distribution suggests a half‐graben structure for the basin, and the thick accumulation of coarse‐grained deposits most likely reflects rapid subsidence of the basin floor during the transtensional opening of the basin. Stage 2 is marked by sandy black shale deposits in the upper part of the lower succession. The black shale is readily correlated across the basin margins, indicating a basinwide transgression probably resulting from large‐scale dip slip suppressing the lateral slip component on basin‐bounding faults. Stage 3 is characterized by gravelly delta‐lobe deposits in the upper succession that are smaller in dimension and located more basinward than the deposits of marginal systems of the lower succession. This lakeward shift of depocentre suggests a loss of accommodation in the basin margins and quiescence of fault movements. This basin evolution model suggests that the rate of dip‐slip displacement on basin‐margin faults can be regarded as the prime control for determining stacking patterns of such basin fills. The resultant basinwide fining‐upward sequences deviate from the coarsening‐upward cycles of other transtensional basins and reveal the variety of stratigraphic architecture in strike‐slip basins controlled by the changes in relative sense and magnitude of fault movements at the basin margins. 相似文献
6.
Quaternary sedimentology of the Rose Creek fan delta, Walker Lake, Nevada, USA, and implications to fan-delta facies models 总被引：1，自引：0，他引：1
The 3·2 km long Rose Creek fan delta of west‐central Nevada is prograding from an active rift margin into the 32 m deep Walker Lake. A case study of the forms, processes and facies of this fan delta reveals that the proximal and medial zones mainly are of sub‐aerial origin, and the distal zone is of lacustrine origin. Pebbly to bouldery rock‐avalanche mounds >100 m thick (Facies A) and muddy to bouldery debris flow levées 0·5 to 2·0 m thick (Facies B) dominate the proximal zone, whereas mostly matrix‐supported cobbly pebbly debris flow lobes 0·1 to 1·0 m thick (Facies C) typify the medial zone. Surficial pebble lags and gully fills (Facies D) are widespread in both zones but, in exposures, comprise only partings or lenticles between debris flow units. The distal fan delta mainly consists of lakeshore to lake‐bottom tracts formed by extensive wave reworking of debris flow facies. Nearshore deposits include erosional cobbly boulder lag beaches (Facies E), pebbly constructional beaches attached at headcuts or on barrier spits (Facies F), pebbly upper shoreface (Facies G) and sandy lower shoreface (Facies H) tracts positioned lakeward of the beach, and pebbly landward‐dipping foresets (Facies I) and backshore‐pond sand and mud (Facies J) present landward of the spits. Erosional lag beaches fringe the windward north side of the fan‐delta front, attached constructional beaches characterize the central zone, and southward‐elongating barrier spits typify the leeward south side, extending from the zone of greatest projection of the fan delta into the lake. Shoreline facies asymmetry results from largely unidirectional longshore drift caused by high fetch to the north and minimal fetch to the south, combined with the arcuate shape of the fan‐delta front. The spits overlie a platform deposited below common wave base consisting of south‐east‐trending cones of pebbly Gilbert foresets (Facies K) and sandy toesets (Facies L). Typically slumped silt and mud (Facies M) fringe both this platform and lower shoreface sand in deeper water. This case demonstrates facies types and patterns that are inconsistent with the widely promoted fan‐delta facies model having a front consisting of an apron of radially directed Gilbert foresets deposited where sub‐aerial flows enter the lake. The Rose Creek fan‐delta front instead features a sharp contact between sub‐aerial and lakeshore facies formed where waves erode, sort and redistribute heterogeneous debris flow sediment into the various shallow‐to‐deep lake facies. Gilbert foresets are present only in the lee of the fan delta where sediment moving by longshore drift reaches the brink of the spit front. This facies scenario results from the infrequency of fan‐building events versus nearly constant wind‐induced waves, a scenario that, in contrast to the popular Gilbert model, probably is the norm for fan deltas. The level of Walker Lake, and thus the position of wave reworking on the Rose Creek fan delta, fluctuated over a range of ～157 m during the last 18 kyr, producing complex interfingering between sub‐aerial and lakeshore facies across a 1700 m wide radial belt, typifying a wave‐modified, freestand lacustrine fan delta. 相似文献
7.
滇西洱源县位于扬子地块西南缘丽江拗陷盆地南侧。在详细野外剖面测量和室内分析的基础上,对研究区下三叠统青天堡组地层的宏观特征（颜色、原生沉积构造）、物质组分、岩石结构及古生物特征等进行了系统研究,划分出冲积扇、河流、三角洲3类沉积相,并进一步划分出河道充填、三角洲前缘和前三角洲3个沉积亚相及辨状河道、洪泛平原、水下分流河道、分流河道间、河口砂坝、席状砂6个沉积微相。研究表明,军马场下三叠统青天堡组垂向上表现为冲积扇—河流—三角洲的退积型沉积特征,表明在早三叠世青天堡时期盐源-丽江盆地发生了大规模海侵,盆地水体加深,军马场地区经历了由陆相到海相的沉积演化序列。 相似文献
8.
The Uhangri Formation forms part of the Cretaceous sedimentary sequence deposited in a series of inland basins in the south-western Korean Peninsula. It comprises an approximately 400-m-thick epiclastic sequence of conglomerate, (gravelly) sandstone, cherty mudstone and black shale. The entire sequence can be represented by 16 distinctive sedimentary facies organized into four facies associations. Facies association I is characterized by thick homogeneous brownish siltstone, wedge-shaped disorganized conglomerate and thinly interlayered gravelly sandstone units. The siltstone units were formed by large floods submerging the alluvial fan fringe (floodplain), whereas the conglomerate and gravelly sandstone units were deposited by sheetfloods and debris flows. Facies association II consists of stratified conglomerate — gravelly sandstone, laminated sandstone and sandstone/siltstone couplets which form fining-upward cycles. Some facies units are low-angle trough cross-bedded and show broad channel geometries. This association represents subaqueous delta lobes fed by high- and low-concentration turbidity currents in the distal delta realm. Facies association III is characterized, by wedged conglomerate and gravelly sandstone facies with interfingered massive sandstone bounded by scoured bases. It represents a delta front where distributary channels and mouth bars are dominant. Facies association IV consists of laterally continuous sequence of laminated black shale, crudely stratified sandstone and convoluted sandstone/cherty mudstone. This facies association is suggestive of depositional processes controlled by chemical equilibrium resulting from an interaction between density inflows and lake water. The cherty mudstone resulted from inorganic precipitation from siliceous solution provided by acidic volcanism. The Uhangri sequence generally shows a fining-upward trend with a transition from alluvial fan fringe, coarse-grained subaqueous delta, to shallow lake. The retrogradation was probably due to continuous subsidence related to continental rifting in the oblique-slip mobile zone. 相似文献
9.
鄂尔多斯盆地西缘上三叠统延长组沉积相特征研究 总被引：3，自引：0，他引：3
通过对鄂尔多斯盆地西缘北部汝箕沟剖面、南部阎家庄剖面和中部环78、环52、演40井岩芯的详细观察,并结合前人的研究资料及岩性和岩相组合、沉积相分析,探讨了研究区延长组沉积相特征与演化过程。研究结果表明:鄂尔多斯盆地西缘延长组发育12种岩相类型,7种岩相组合。延长组时期为扇三角洲—湖泊、辫状河三角洲、冲积扇沉积体系,其中也充分发育筛状沉积、水上分流河道、分流河道间、水下分流河道、河口坝、远砂坝、等沉积微相和亚相类型。北部汝箕沟地区在延长组沉积早期主要为扇三角洲相,进入中期由湖泊相过渡为扇三角洲相,晚期则发育深湖相;中部环县—演武地区在延长组早期为辫状河三角洲相,中期发育辫状河三角洲相和湖泊相,晚期过渡为三角洲相并受到抬升剥蚀作用;南部阎家庄在延长组则发育冲积扇相,随后便受到抬升剥蚀作用。 相似文献
10.
梅河盆地为典型的断陷型含煤、油页岩盆地。通过岩芯、测井和地震的层序标志识别,在梅河盆地梅河组识别出1个巨层序、2个超层序和4个三级层序。其中,砂砾岩段、下部含煤段、中部泥岩段、上部含煤段分别对应着三级层序I、II、III和IV。通过对层序地层格架的认识,结合构造、沉积分析,揭示了研究区梅河组沉积层序演化规律,三级层序地层格架内沉积演化分别为:层序I发育了盆地初始裂陷阶段的冲积型和扇三角洲沉积;层序II发育了盆地裂陷扩张阶段扇三角洲、沼泽和浅水湖泊沉积;层序III发育了盆地最大扩张阶段深水湖泊沉积;层序IV发育了盆地萎缩阶段扇三角洲和湖泊沉积。因此,梅河盆地梅河组的层序I到层序IV的演化揭示了中国东部伸展环境下断陷盆地从初始裂陷阶段到盆地萎缩阶段完整的不同沉积层序演化特征。 相似文献
11.
羌塘盆地地处藏北高原,其南、北边界分别为班公错一怒江缝合带与拉竹龙一金沙江缝合带,盆地面积约18×104km2,可进一步分为羌北坳陷、中央隆起带和羌南坳陷3个二级构造单元.双湖托纳木地区地处羌北坳陷南部,与中央隆起带毗连,广泛发育上侏罗统雪山组沉积,垂向上由3个沉积旋回组合构成,总体显示为一个向上变粗的充填序列.雪山组发育扇三角洲相和冲积扇相,其中雪山组一段为前扇三角洲亚相沉积;二段为扇三角洲前缘亚相和扇三角洲平原亚相沉积,扇三角洲前缘亚相分为水下分流河道、河口坝和远砂坝沉积,扇三角洲平原亚相发育天然堤和分流河道沉积;三段为冲积扇相沉积,包括扇端和扇中沉积.雪山组沉积的物源来自西南部的中央隆起带. 相似文献
12.
琼东南盆地崖南凹陷海湾扇三角洲体系沉积构成及演化模式 总被引：3，自引：0，他引：3
本文以琼东南盆地崖南凹陷陵水组三段扇三角洲体系为例，详细讨论了进积于海湾背景环境下扇三角洲体系的岩性相、成因相及其空间配置关系。研究区海湾扇三角洲体系自下而上潮汐作用越来越强，其垂向演化可划分为三个阶段，早期为以河流作用占优势阶段，中期为河流和潮汐混合作用阶段，晚期为以潮汐作用占优势逐渐过渡为以潮汐作用占优势。 相似文献
13.
中国东部箕状断陷湖盆扇三角洲与辫状河三角洲对比研究 总被引：1，自引：0，他引：1
中国东部箕状断陷湖盆短轴方向,常常发育扇三角洲和辫状河三角洲,二者均可形成良好的油气储集体,但在岩芯以及地球物理资料的识别上常常容易混淆。通过对它们沉积特征、地球物理资料特征、含油气性和控制因素的对比研究和分析认为:扇三角洲是陡坡带冲积扇直接入湖形成,地震反射特征为楔形前积,沉积物成分成熟度和结构成熟度均低于辫状河三角洲,沉积特征反映重力流和牵引流双重作用;辫状河三角洲是缓坡带辫状河入湖形成的三角洲,向湖盆方向推进较远,地震反射特征为叠瓦前积,沉积特征反映牵引流作用。扇三角洲易形成构造-岩性油气藏和岩性油气藏,有利相带为扇三角洲前缘水下分流河道、席状砂以及前扇三角洲容易发育的滑塌浊积扇;辫状河三角洲易形成地层-岩性油气藏和岩性油气藏,有利相带为辫状河三角洲平原辫状分流河道,辫状河三角洲前缘水下分流河道、河口坝、席状砂以及半深湖中的浊积岩体。古气候变化、构造-古地貌以及湖平面变化速率三者共同作用于扇三角洲和辫状河三角洲的沉积特征,其中构造-古地貌是主控因素。结合二者沉积特征差异,建立了中国东部箕状断陷湖盆扇三角洲和辫状河三角洲沉积模式图,以期能对相似构造背景下扇三角洲和辫状河三角洲的分析与研究提供一定的指导作用。 相似文献
14.
The Triassic deposits of Cerro Puntudo in the San Juan province of western Argentina constitute the northernmost exposures of the northern portion of the nonmarine Cuyo rift basin, also known as the Las Peñas-Tamberías half-graben. The local column, with an exposed thickness of approximately 400 m, consists of abundant basal and topmost coarse alluvial fan conglomerates and breccias (facies associations I and II) and a relatively thin (approximately 50 m) intervening sequence of marginal, shallow lacustrine deposits characterized by stromatolitic (domal) limestones, tuffaceous mudstones, and fine-grained sandstones (facies association III). Subaerial exposure in the lacustrine deposits is evidenced by desiccation cracks and brecciation. A very thin (0–6 m), laterally, discontinuous succession of lacustrine deposits with similar characteristics is interbedded with the basal conglomerates. Laterally, this lacustrine interval was eroded by overlying conglomerates. The basal conglomerates commonly show crude normal grading, faint cross-bedding, and b-axis clast imbrication. The predominance of coarse deposits and paleocurrents from NW to SE, indicative of an axial flow pattern, suggest that these exposures correspond to the northern end of the Cuyo basin, which is characterized by a shallow, alluvial fan-encased, carbonate-rich lake margin. This lacustrine interval can be correlated with the thicker lacustrine section exposed to the south at Quebrada del Tigre and Ciénaga Larga along the border fault margin of a nonmarine half-graben. The correlation with these sections suggests that the Cerro Puntudo lacustrine deposits are the shallowest equivalent of more profundal, organic-rich lacustrine sediments exposed in the deepest segment of the border fault margin. These thickness and facies variations are the result of differential subsidence along the border fault margin between the low accommodation, fault tip end represented by the Cerro Puntudo section and the high accommodation, central segment located to the south. 相似文献
15.
Lake Hazar lies within a small pull-apart basin along the East Anatolian Transform Fault in south-eastern Turkey. Deltas are formed where streams debouch into the low-energy lacustrine environment. The facies constituting the deltas include delta plain debris flow, braided stream, and marginal lacustrine deposits; delta front foreset and mouth bar deposits; prodelta and lacustrine deposits. The facies are spatially restricted with sharp transitions. Facies sequences and relationships indicate two distinct styles of deltaic sedimentation. Fan deltas with a tripartite structure characteristic of Gilbert-type deltas comprise the marginal drainage system and form along the basin margins. Mouth bar deltas develop where the axial drainage system of the basin debouches into the lake. The distribution of the two deltaic types is thought to be a function of gradient and controlled by position relative to faults within the basin. 相似文献
16.
通过野外地质露头和钻孔岩心观察以及对大量钻孔岩心编录和测井解释资料的综合统计分析,笔者将伊犁盆地南缘西段中下侏罗统水西沟群划分出4个大的沉积体系:八道湾组(J1b)的冲积扇沉积体系、三工河组—西山窑组一段的辫状河三角洲沉积体系、西山窑组二段至三段的浅湖沼泽沉积体系和西山窑组四段至五段的曲流河三角洲沉积体系。文中详细讨论了伊犁盆地南缘西段水西沟群各沉积体系的沉积相特征,研究了水西沟群沉积体系及沉积相与砂岩型铀矿的成矿关系,指出辫状河三角洲沉积体系是砂岩型铀矿成矿最有利的沉积体系,三角洲前缘河口坝及席状砂亚相、三角洲平原辫状河流亚相、扇中-扇端亚相及三角洲平原分流河道亚相是砂岩型铀矿主要的控矿沉积相。 相似文献
17.
自浅水三角洲的概念提出以来,已经历了60多年的研究历史。虽然在诸多方面取得了较大的研究进展,但在浅水三角洲的概念内涵、砂体成因类型及沉积构型样式等方面仍存在一定的分歧。本文探讨了浅水三角洲概念的内涵,并总结和分析了其沉积构型特征和样式。根据浪基面和河-盆水深比(初始河道深度与河口盆地水体深度比值),可将三角洲分为极浅水三角洲、较浅水三角洲和较深水三角洲。典型的浅水三角洲为极浅水三角洲,发育于河-盆水深比值大于或等于1的浅水水体,分流河道可下切至下伏的前三角洲沉积。根据三角洲前缘分流河道与河口坝的组合样式,将河控浅水三角洲的端元类型分为分流砂坝型和指状砂坝型。分流砂坝型三角洲为河道入海(湖)后形成的多级分叉的河口坝与分流河道系统,平面上呈扇状,河—坝组合呈现“河在坝间”的样式,而指状砂坝型三角洲为指状砂坝与分流间湾相间分布的系统,平面上呈枝状,河—坝组合呈现“河在坝内”的样式。 相似文献
18.
鄂尔多斯盆地三叠系延长组主要发育东北和西南两大沉积体系,东北的河流三角洲体系已为大量的勘探研究资料所证实,而西南体系因受勘探程度限制,目前研究不够。本文通过最新钻探成果,结合盆地西南部露头资料,确立盆地西南地区三叠系延长组为冲积扇-扇三角洲沉积体系,发育冲积扇、扇三角洲、湖泊（浊积）相。冲积扇以西南缘平凉崆峒山和汭水河剖面为代表,扇三角洲及湖泊（浊积）相为区内钻井剖面所证实。长6-长8为区内主力油层组,地层保存完整,钻探程度相对较高。扇三角洲前缘砂体类型以水下分流河道为主,局部发育河口坝,浊积体以厚层块状为主。长8亚期为扇三角洲前缘亚相最发育期,横向形成自西南向东北延伸的三支前缘砂体带,是石油聚集的重要区带;长7亚期随着湖盆沉降,周边抬升强烈,湖岸较陡,大量发育浊积体系;长6亚期湖退导致扇三角洲再次发育,但规模较长8亚期弱。扇三角洲前缘砂体单层厚度大,砂岩粒度较粗,颗粒分选及物性好,是石油富集的最有利相带。 相似文献
19.
K. Stingl 《International Journal of Earth Sciences》1994,83(4):811-821
The Eibiswald Bucht is a small subbasin of the Western Styrian Basin exposing sediments of Lower Miocene age. In the past the entire sequence exposed in the Eibiswalder Bucht has been interpreted as being of fluvial/lacustrine origin; here, results are presented of detailed sedimentological investigations that lead to a revision of this concept. The lowermost siliciclastic sedimentary unit of the Eibiswalder Bucht sequence is the Radl Formation. It is overlain by the Eibiswald Beds, which are subdivided into the Lower, Middle and Upper Eibiswald Beds. The Radl Formation and the Lower Eibiswald Beds are interpreted as a fan delta complex deposited along NNW-SSE striking faults. Based on the sedimentary facies this fan delta can be subdivided into a subaerial alluvial fan facies group, a proximal delta facies group and a distal delta/prodelta facies group. The Radl Formation comprises the alluvial fan and proximal delta facies groups, the Lower Eibiswald Beds the distal delta/prodelta facies group. The alluvial fan and the proximal delta consist of diverse deposits of gravelly flows. The distal delta/prodelta consists of wave-reworked, bioturbated, low density turbidites intercalated with minor gravelly mass flows. The prodelta can be regarded as as the basin facies of the small and shallow Eibiswalder Bucht, where marine conditions prevailed. The basin was probably in part connected with the Eastern Styrian Basin, the contemporary depositional environment of the Styrian Schlier (mainly turbiditic marine offshore sediments in the Eastern Styrian Basin). Analysis of the clast composition, in conjunction with the paleotransport direction of the coarse delta mass flows of the Radl Formation, shows that the source rocks were exclusively crystalline rocks ranging from greenschists to eclogites. 相似文献
20.
The Älvestorp conglomerates, deposited in an alluvial fan setting, form part of the Svecofennian orogenic belt in west Bergslagen, south central Sweden and are estimated to be as old as c. 1.85 Ga. Reaching a thickness of one kilometre, their architecture and form suggest an alluvial origin. Along sections, massive conglomerates often grade into pebbly mudstones and greenschist facies slates, while pure slates with dolomite concretions and olistolites occur in dark slatey mudstones on the eastern shore of lake Brunnsjön. Inner fan trenches are filled with massive, clast‐supported conglomerates that contain more than 80 percent epiclastic tuffaceous material. The Älvestorp conglomerate is therefore classified as the product of a Proterozoic stream‐flow channel and debris flow, or alluvial fan. The Grythyttan Basin to the north originated by extension after the first of two orogenic stages of Bergslagen. 相似文献