湘西黔东寒武纪深水碳酸盐重力沉积

湘西黔东武陵山地区位于江南寒武纪边缘海的西北边缘[1],自早寒武世清墟洞期开始,本区主要表现为一呈北东-南西向展布的深水碳酸盐斜坡。其东南侧为深水盆地。西北侧为广阔的扬子碳酸盐台地。台地边缘区发育有以表附藻、葛万藻为主要造礁生物的蓝绿藻礁和鲕粒滩、砂屑滩。由于台地边缘的快速堆积及其向海推进,造成了台地边缘极大的不稳定性,在重力作用下,发生了大规模的沉积物横向位移。因此,自中寒武世开始，在斜坡带及盆地边缘形成了类型繁多的重力沉积物。     

鄂西桐梓组一段碳酸盐台洼重力流沉积特征及其研究意义

鄂西秭归、长阳、巴东等地奥陶系桐梓组一段中碳酸盐台洼重力流沉积主要有４种类型：塌积角砾岩、碎屑流砾屑灰岩、颗粒流含砾砂屑灰岩、近源浊积灰岩。沉积特征和时空分布情况表明它们发生在两河口期早期海侵背景下（ＴＳＴ）。最初的岩崩塌积沉积受控于被动大陆边缘板内应力作用产生的构造事件,后来的重力流沉积旋回明显受渐进式海侵海平面升降波动的影响。台洼重力流沉积提供了早奥陶世华南被动大陆边缘向前陆盆地演变之前奏幕式事件在碳酸盐台地内的地层记录。讨论鄂西乃至上扬子区奥陶纪两河口期碳酸盐台洼重力流沉积的背景、成因、受控因素及研究意义。     

湘南晚泥盆世佘田桥期碳酸盐块状流沉积特征

湘南晚泥盆世佘田桥期表现为东西两侧高而中部低陷的古地理面貌。两侧为碳酸盐台地,中间为深水台盆。在台盆、台地之间斜坡地带和台盆边缘,堆积了类型繁多的碳酸盐块状流沉积物。它们由两类在成因和分布上有密切联系的沉积体系组成,一类为重力崩落或滑移体系,包括岩崩、滑动和滑塌沉积,另一类为重力流体系,包括碎屑流、浊流和颗粒流沉积。在层序上它们虽作有规律的组合层序,但并不是完整的类型,而出现较大的变异性。已发现的组合层序有①滑塌沉积—碎屑流沉积,②碎屑流—高密度浊流—低密度浊流沉积,③变密度颗粒流—浊流沉积。它们沿近南北向的台盆的两侧边缘呈条带状分布,东侧位于临武香花岭至桂阳莲塘一带,重力流厚度可达150m左右,西侧位于道县虎岩坝至双牌县城一带,重力流厚只30—50m,反映了台盆边缘两侧构造活动强度不一致,东侧强,西侧弱。     

阿联酋下白垩统舒艾巴组生物礁沉积模式

本文在露头分析和钻井资料研究的基础上,结合区域地质背景,对阿联酋地区下白垩统舒艾巴组生物礁沉积特征进行了分析,确定了该区生物礁的沉积模式及有利储层发育相带。舒艾巴组沉积时期,具备优越的生物礁发育条件,造礁生物主要为厚壳蛤。研究区舒艾巴组碳酸盐台地具有"缓斜坡镶边台地"沉积特征,自盆地边缘向盆地内部,依次发育浅海低能碳酸盐陆架、浅海高能碳酸盐陆架、深水低能碳酸盐陆架、盆地斜坡相和深海盆地相。浅海高能碳酸盐陆架-盆地斜坡相带为生物礁发育带及油气富集区。其中浅海陆架边缘的高能相带为厚壳蛤生物礁发育的最有利区域,储层物性最好,厚壳蛤礁主要形成于早期存在的藻类粘结灰岩台地高点和台地边缘,礁核和礁前为优质储层发育带。研究该区生物礁的沉积模式与分布规律,对该区生物礁储层油气勘探具有重要的指导意义。     

深水碳酸盐沉积研究进展

深水碳酸盐沉积包括深水重力流作用形成的异地沉积和非重力流沉积，在非重力流沉积中又有深水牵引流(等深流、内波、内潮汐等)沉积和静态原地碳酸盐沉积。深水碳酸盐沉积与重力流及等深流活动有关，也受控于表层水碳酸盐产率、陆源物质的稀释作用及深水对碳酸盐的溶解作用。大量研究表明，深水碳酸盐沉积对海平面升降与气候变化响应明显，无论是重力流或非重力流沉积均有体现，通过深水碳酸盐沉积研究可以提取地质历史时期环境变化的信息，同时，某些深水碳酸盐沉积岩中蕴藏着丰富的石油、天然气和其他沉积矿产。由此开展此项研究具有重要的理论和实际意义。     

四川盆地东北部长兴期沉积特征与沉积格局

四川盆地东北部长兴组（大隆组）为海洋环境的产物,根据沉积特点,可以分为碳酸盐台地沉积体系和盆地沉积体系。碳酸盐台地沉积体系又可进一步分为局限台地、开阔台地、台地边缘礁滩及缓坡等沉积相。在详细研究分析各沉积体系的沉积特点的基础上,探讨了该期沉积相带的空间分布,提出了不存在“开江一梁平”海槽的认识。笔者等认为在“开江梁平海槽”区域内,长兴组只是水体相对台地较深环境（台棚环境）的产物,为碳酸盐缓坡,不宜称为海槽。指出台地边缘浅滩及生物礁是储层最有利相带,礁白云岩及颗粒白云岩等是储层的有利微相。研究区的生物礁为碳酸盐台地边缘缓坡点礁群,沿着台地边缘断续分布。     

文山古木街台地边缘泥盆纪斜坡碳酸盐沉积与环境意义

文山古木街台地东部边缘泥盆纪的斜坡碳酸盐沉积类型包括重力流和非重力流 ,重力流有碎屑流、滑移滑积层及浊流 ;常见的层序组合有 3种 ,整个斜坡体系在垂向上可划分 3个沉积旋回 ;建立 11个浮游生物化石带 ,沉积时代为早泥盆世晚期至中泥盆世早期。斜坡碳酸盐重力流的研究具有重要的古地理、古构造环境意义。     

城口-鄂西海槽西侧晚二叠世碳酸盐台地边缘发育新认识

基于城口-鄂西海槽西侧地区详细的露头调查、钻井资料分析,结合古生物、古生态以及地层对比,对研究区晚二叠世长兴期碳酸盐台地边缘沉积相及其演化进行详细解剖,得出区内台地边缘骨架礁-凝块石灰泥丘生态-沉积演化对碳酸盐台地边缘构筑具有积极作用的认识。研究表明区内长兴期碳酸盐台地边缘礁滩经历了三个演化阶段:第一阶段,碳酸盐台地边缘坡折带尚未形成,台地边缘礁滩欠发育,且台地前缘斜坡坡度较缓;第二阶段,碳酸盐台地镶边开始形成,发育骨架礁及滩相沉积,垂向上构成进积-加积组合序列,台地前缘斜坡变陡;第三阶段,微生物逐渐占据后生造礁生物生态空间,发育台地边缘凝块石灰泥丘,与上覆台地边缘滩构成垂向加积组合序列,促进了台地边缘正向地貌的发育,使区内台地边缘更加陡峭,台地前缘斜坡发育滑塌角砾岩。造礁生物生态演替及相对海平面变化共同影响并控制长兴期碳酸盐台地边缘构筑过程。     

川西北部泥盆系观雾山组沉积相新认识——以大木垭剖面与何家梁剖面为例

川西泥盆系观雾山组沉积相研究缺乏横向对比,沉积模式还存在争议。根据川西北部白家乡大木垭剖面与何家梁剖面实测成果,对中泥盆统观雾山组沉积相进行了分析,认为:大木垭剖面与何家梁剖面观雾山组为碳酸盐镶边台地沉积,期间发生短暂的碳酸盐缓坡化;桂溪剖面观雾山组同属碳酸盐台地边缘,观雾山组中段发育开阔台地深水沉积,并不是前人认为的潟湖沉积。研究区碳酸盐镶边台地包括台地边缘和前缘斜坡两种亚相,前缘斜坡亚相发育于何家梁剖面,以塌积岩沉积为标志。碳酸盐缓坡包括深水缓坡和浅水缓坡两种亚相。随着海平面变化,观雾山组碳酸盐岩发育三个沉积旋回,第一、第三沉积旋回为镶边台地沉积,第二沉积旋回为碳酸盐缓坡沉积。观雾山组沉积微相对储层的分布起控制作用:生物碎屑滩和上斜坡微相为有利储层发育相带;生物礁中在油气运移之前形成的溶蚀孔洞已被白云石和方解石充填,滩间微相泥质(泥晶)白云岩不利于溶蚀孔洞形成,这二者均不是有利储层发育相带。     

珠江口盆地东沙隆起生物礁地质及地震特征

东沙隆起珠江组生物礁是珠江口盆地重要的储层类型,礁灰岩主要为珊瑚藻灰岩,分为骨架岩、粘结岩及障积岩。研究区生物礁发育于开阔台地、台地边缘及台地前缘斜坡3类沉积相中,生物礁类型可分为台内点礁、台地边缘堡礁及台缘斜坡塔礁,以台地边缘堡礁为主。珠江组沉积早期,东沙隆起发育滨岸砂质沉积;中期海水逐渐淹没东沙隆起,形成镶边浅水碳酸盐台地,发育生物礁;晚期海侵台地逐渐淹没消亡,被浅海陆棚泥质沉积代替。流花台地厚度最大,最厚达563m,台地顶面地震强反射使外形轮廓清晰,台地内部中-弱振幅至空白反射,连续性降低;惠州台地厚度较流花台地薄,厚度多大于100m,顶界面强反射轮廓清晰,内部层状反射能量强-中振幅、高-中连续、中-低频,局部空白反射;陆丰台地厚约30m,只有一个高连续的强振幅。生物礁地震响应以丘形、箱型、低丘-透镜状为特征,礁顶常为强振幅,内部为波状、有时见前积结构,翼部可见上超和披覆现象等。     

贺兰拗拉槽胡基台地区中奥陶统樱桃沟组深海重力流沉积特征

结合国际上深海沉积研究最新动态,分析了鄂尔多斯盆地西侧胡基台地区中奥陶统樱桃沟组野外剖面。认为该地层块状内部无层理砂岩为砂质碎屑流沉积而不是前人认为的浊流沉积。研究区发育有垮塌沉积、颗粒流沉积、砂质碎屑流沉积、浊流沉积等重力流沉积。该区樱桃沟组重力流沉积类型的总体分布特征是:下部发育钙屑浊流与大规模灰岩垮塌沉积,见砂质碎屑流沉积;中部主要发育陆源碎屑浊流沉积,但在其下部有较为发育的颗粒流沉积;上部发育陆源碎屑浊流沉积。其中垮塌沉积和颗粒流沉积作为对古构造的沉积响应,反映了樱桃沟期该地区的古构造地形为陡坡。     

异地碳酸盐岩块体与碳酸盐岩重力流沉积研究及展望

异地碳酸盐岩块体是指已固结或半固结的、经过一定距离搬运再沉积而产于正常沉积地层中规模 较大的碳酸盐岩块,它和碳酸盐岩重力流沉积均属于再沉积碳酸盐岩。文章分析了岩崩、岩屑崩坍、海底滑坡、 滑塌和碎屑流沉积的过程,讨论了异地碳酸盐岩块体的沉积机制;归纳了异地碳酸盐岩块体形成的主要地质背 景,认为异地碳酸盐岩块体可见于活动大陆边缘、被动大陆边缘、海山和前陆盆地等地质环境中;着重介绍了 异地碳酸盐岩块体和碳酸盐岩重力流沉积的研究进展,即线源式的碳酸盐岩裙沉积和点源式的碳酸盐岩海底扇 沉积;最后,阐释了滑来岩块、滑塌堆积和碎屑流沉积的区别与联系,总结了孤立碳酸盐岩块体的搬运沉积机 制,对比区分了碳酸盐岩裙沉积和碳酸盐岩海底扇的沉积特征,认为它们在斜坡环境、沉积物类型和沉积特征 等方面存在诸多不同。     

东营凹陷滑塌型重力流沉积分布特征及三角洲沉积对其影响

三角洲沉积为滑塌型重力流的形成提供了物质来源,它对前端滑塌型重力流的沉积分布特征具有重要影响.以东营凹陷洼陷带沙三中亚段三角洲-前端滑塌型重力流沉积为研究对象,综合利用钻井岩心、三维地震、测录井及分析测试等资料,总结不同类型滑塌型重力流沉积特征、识别标志和分布特征,分析三角洲作为物源对滑塌型重力流的形成、沉积类型、沉积特征和分布特征的影响.研究表明,研究区滑塌型重力流沉积主要发育滑动岩、滑塌岩、碎屑流沉积和浊积岩4种类型,不同类型其沉积构造、粒度特征、地球物理特征差异显著.研究区砂质碎屑流沉积最为发育,滑动滑塌沉积次之,浊流沉积和泥质碎屑流沉积少量发育.不同地区重力流沉积发育程度及常见垂向序列存在差异,博兴南坡与辛133区块重力流类型以砂质碎屑流沉积为主,常见多期次砂质碎屑流沉积相邻或相间垂向组合;牛庄南坡与中央隆起带地区类似,由近及远,重力流类型及垂向序列存在较大差异;营11区块以砂质碎屑流沉积和浊流沉积为主,浊流比例相对其他区块较高;丰14区块单井重力流类型整体较单一,为砂质碎屑流沉积或滑塌沉积.三角洲砂泥百分含量控制了滑塌型重力流的沉积类型和沉积特征;三角洲沉积物粒径控制原始前积角大小,前积角越大,滑塌型重力流越发育,但滑移距离相对越近;三角洲的坡折点控制下,滑动滑塌沉积主要分布在斜坡坡脚和同沉积断层附近,浊流沉积主要分布在深水平原,碎屑流沉积在斜坡坡脚-深水平原均有分布;三角洲高的堆积速率通过减小内摩擦力促使滑塌型重力流的形成,其堆积速率与构造沉降速率的差异对滑塌型重力流沉积的垂向叠置和侧向连续性也具有重要影响.      

长江三峡东部地区震旦纪事件沉积?

长江三峡东部地区震旦纪先后发生了热事件、冷事件、重力事件等突发性灾变沉积。早震旦世发育由河流作用与陆地冰川作用形成的陆源碎屑沉积；晚震旦世则发育由两次台地-盆地-台地的海进-海退旋回形成的巨厚海相碳酸盐沉积。热事件沉积产物见于下震旦统莲沱组，夹于河流相沉积的砂岩及粉砂岩中。根据凝灰碎屑的岩石学特征，可将其分为降落型凝灰碎屑和水携型凝灰碎屑两类。冷事件沉积产物为下震旦统南沱冰碛层，属低纬度低高程的大陆冰川沉积。重力事件可分为滑塌事件和浊流事件，其沉积产物均分布于上震旦统，夹在大套的深水碳酸盐岩中。其中滑塌事件的沉积产物主要为滑塌角砾白云岩（石灰岩），浊流事件的沉积产物主要为浊积颗粒石灰岩（白云岩）。     

Mid-Cretaceous basin margin carbonates, east-central Mexico

Isolated, high relief carbonate platforms developed in the intracratonic basin of east-central Mexico during Albian-Cenomanian time. Relief on the platforms was of the order of 1000 m and slopes were as steep as 20–43°. Basin-margin debris aprons adjacent to the platforms comprise the Tamabra Formation. In the Sierra Madre Oriental, at the eastern margin of the Valles-San Luis Potosi Platform, an exceptionally thick (1380m) progradational basin to platform sequence of the Tamabra Formation can be divided into six lithological units. Basinal carbonate deposition that preceded deposition of the Tamabra Formation was emphatically punctuated by an allochthonous reef block 1 km long by 0·5 km wide with a stratigraphic thickness of 95 m. It is encased in Tamabra Formation unit A, approximately 360 m of peloidal-skeletal wackestone and lithoclastic-skeletal packstone that includes some graded beds. Unit B is 73 m of massive dolomite with sparse skeletal fragments and intraclasts. Unit C, 114m thick, consists of structureless skeletal wackestone passing upward into graded skeletal packstone. Interlaminated lime mudstone and fine grained bioclastic packstone with prominent horizontal burrows are interspersed near the top. Unit D is 126 m of breccia with finely interbedded skeletal grainstone and burrowed or laminated mudstone. The breccias contain a spectrum of platform-derived lithoclasts and basinal intraclasts, up to 10 m in size. The breccias are typically grain supported (rudstone) with a matrix of lightly to completely dolomitized mudstone or skeletal debris. Beds are up to several metres thick. Unit E is 206 m of massive, sucrosic dolomite that replaced breccias. Unit F is approximately 500 m of thick bedded to massive skeletal packstone with abundant rudists and a few mudstone intraclasts. Metre scale laminated lime mudstone beds are interspersed. The section is capped by El Abra Formation platform margin limestone, consisting of massive beds of caprinid packstone and grainstone with many whole valves. Depositional processes within this sequence shift from basinal pelagic or peri-platform sedimentation to distal, platform-derived, muddy turbidity currents with a large slump block (Unit A); through more proximal (coarser and cleaner) turbidity currents (Unit B?, C); to debris flows incorporating platform margin and slope debris (Units D, E). Finally, a talus of coarse, reef-derived bioclasts (Unit F) accumulated as the platform margin prograded over the slope sequence. Interspersed basinal deposits evolved gradually from largely pelagic to include influxes of dilute turbidity currents. Units containing turbidites with platform-derived bioclasts reflect flooding of the adjacent platform. Breccia blocks and lithoclasts were probably generated by erosion and collapse of the platform during lowstands. Laminated, black, pelagic carbonates, locally cherty, are interbedded with both breccias and turbidites. At least those interbedded with turbidites may have been deposited within an expanded mid-water oxygen minimum zone during relative highstands of sea level. They are in part coeval with mid-Cretaceous black shales of the Atlantic Ocean.     

Deposition and derivation of clastic carbonates on a Mesozoic continental margin, Othris, Greece

The Othris Mountains of eastern Greece contain a calcareous continental margin/ocean basin sequence exposed in a stack of Cretaceous thrust sheets. Upper Triassic to Lower Cretaceous shelf, submarine fan and basinal successions overlie shallow marine units of Lower Triassic and Permian age. In off-shelf sequences the older sediments are separated from the younger by a horizon of alkaline ‘early-rifting’ basalts. Ophiolites overthrust the marginal sequence. Pre-rifting sediments are represented by a varied suite of limestones and clastics resting on metamorphic basement and include distinctive, green lithic arenites. In the thrust sheet immediately over the para-autochthonous shelf sequence, pre-rifting sediments are separated from the rift basalts by an intermittent horizon of calcareous sandstones and conglomerates reworked from uplifted basement and older sediments. Textural and petrographic immaturity suggests that these are probably deposits derived from fault scarps, produced in an early phase of rifting. Above the basalts in the same sheet is a suite of calciclastic sediment-gravity-flow deposits, apparently sedimented on a submarine fan. Progressive downslope modification of calcirudites suggests deposition from evolving, high concentration flows. Massive calcarenite facies (? grain flows) are unusually abundant; a possible reflection of a shallow palaeo-shelf break since provenance and palaeocurrent evidence proves the clastic carbonates to have been derived from a calcareous shelf. In addition to limestone lithoclasts the calcirudites, but not the massive calcarenites, contain fragments of pre-rifting lithologies including the distinctive arenites. Since the shelf sequence in Othris is totally nondetrital these clasts imply derivation of coarse sediment from an off-shelf position; probably the walls of a submarine canyon. This may have occurred either by direct erosion of wall rock, or by reworking of material from an older clastic sequence. In the latter case the inferred fault-scarp deposits are a likely source.     

Depositional processes,triggering mechanisms and sediment composition of carbonate gravity flow deposits: examples from the Late Cretaceous of the south-central Pyrenees,Spain

Cenomanian through Coniacian strata near the town of Sopeira in the south-central Pyrenees (northern Spain) are composed of a variety of autochthonous and allochthonous carbonate slope lithologies that are divided into six depositional sequences based on facies distribution patterns and stratal relationships. The sequences record three major phases of platform margin evolution: rifting, burial, and exhumation. During the first phase (sequences UK-1, UK-2, UK-3, UK-4, and lower UK-5), deposition occurred on the edge of a wrench basin, and a normal fault located beneath the platform margin strongly influenced slope evolution. Background hemipelagic sediments on the slope were commonly redeposited by submarine slumps and slides. More intense reworking resulted in matrix-supported, slope-derived megaconglomerates (debrites).During the Cenomanian and Turonian, seismically triggered debris flows originated at the platform margin, bypassed the upper slope, and were deposited on the lower slope as polymictic, clast-supported, matrix-rich megabreccias. The megabreccias form channelized and sheet-like bodies with erosional basal surfaces. Shallow carbonate environments backstepped during the Late Turonian and Coniacian, but displacement along the fault at this time resulted in the development of a steep submarine scarp and the exposure of Cenomanian and Lower Turonian strata to submarine erosion. Matrix-poor, margin-derived megabreccias form a thick talus pile at the base of the scarp. Some of the breccias were transported into the basin as debris falls, forming sheet-like beds.Marl eventually buried the Coniacian scarp in sequence UK-5, resulting in the second major phase of platform slope evolution. The slope profile at this time was relatively gentle, and redeposited material is less common. In the third phase (sequence UK-6), tectonically induced bankward erosion during the Santonian resulted in a high (greater than 800 m) erosional scarp with a regional east–west trend that was subsequently onlapped by siliciclastic turbidites. Rejuvenation of erosion in the same vicinity suggests that long-term tectonism controlled the position of the slope, rates of erosion, and sediment type on the slope.Sediment gravity flow processes are laterally and temporally related. Submarine slide and slump deposits commonly grade laterally downslope into slope-derived megaconglomerates. Debris flows that originated at the platform margin appear to have initiated slumps, slides, and other debris flows on the slope. Debris fall deposits are commonly capped by coarse, graded, lithoclastic packstones that may represent turbidites generated by the debris falls.Sediment fabric exerted a profound impact on depositional processes, distribution of facies, and morphology of the slope. Fine-grained, mud-rich, lower slope deposits were unstable at even moderate slope angles, and have been extensively redeposited. Redeposition of grain-rich, upper slope facies was triggered by syndepositional seismic activity and upslope migration of instability and erosion. In the presence of mud, the transport mechanisms are typically cohesive debris flows, which were able to carry material onto the lower slope and into the basin. When no mud was available, rock falls and debris falls were the dominant sediment gravity flows, and their deposits are restricted to a position on the hanging wall proximal to the fault.     

河南省济源盆地下侏罗统鞍腰组重力流沉积特征及其构造意义*

在详细野外剖面工作的基础上,通过岩性特征、沉积构造及沉积序列等的系统观察研究,发现济源盆地下侏罗统鞍腰组重力流沉积由滑塌沉积、砂质碎屑流沉积和浊流沉积构成。滑塌沉积以砂岩和泥岩的混杂、岩层的滑动变形以及泥岩呈碎块被卷入砂岩层中为特征;砂质碎屑流沉积常呈厚层块状,颗粒分选和磨圆较差,杂基较多,可见漂浮于层内的石灰岩砾石;常见的浊流沉积分为2种类型: 具有明显正粒序结构的浊流沉积和砂泥岩薄互层的浊流沉积,可用鲍马序列来描述。鞍腰组重力流沉积可划分为3个沉积序列: 序列A记录了滑塌沉积→砂质碎屑流沉积→浊流沉积→深湖沉积的转换过程;序列B表现为砂质碎屑流与浊流沉积的叠覆;序列C由浊流及湖泊沉积构成,并经历了由序列A→序列B→序列C的沉积演化过程。重力流的形成受秦岭造山带于早侏罗世沿三门峡—鲁山—舞阳断裂发生逆冲推覆作用的控制,其沉积演化指示了秦岭造山带造山作用由强到弱的过程。     

‘Isolated base-of-slope aprons’: An oxymoron for shallow-marine fan-shaped,temperate-water,carbonate bodies along the south-east Salento escarpment (Pleistocene,Apulia, southern Italy)

This paper regards the lower Pleistocene temperate-water carbonate deposits disconformably overlying an escarpment made up of faulted Cretaceous to Miocene limestones of the Apulia Foreland (southern Italy). Study deposits discontinuously crop out along the present-day eastern Salento sea cliff, and form isolated fan-shaped bodies, up to 1 km wide and up to 40 to 50 m thick, each of them covering an area of a few square kilometres. The internal arrangement of beds is represented by up to 25° to 30° lobate, seaward dipping clinobeds thinning and onlapping onto a rocky foreslope in the proximal sector and passing to gently inclined to sub-horizontal strata in the distal sector. Seven facies were distinguished, mainly composed of coarse-grained skeletal carbonates made up of a heterozoan association including coralline algae, large and small benthic foraminifera, echinoids, molluscs, bryozoans and serpulids. Since clinobeds were formed thanks to hyperconcentrated density flows (grain flows) bypassing the upper part of the inherited escarpment, these skeletal grains represent ex situ deposits whose shallow-marine factory was located upward (landward) with respect to the bypassed zone, likely in the almost flat area on top of the Salento Peninsula. Clinobeds are often affected by tens of metres wide and long channel-like structures interpreted as landslide scars. Inside these gullies, contorted beds (slumps) or matrix-supported intra-bioclastic floatstone/rudstone (massive deposits) are present. The occurrence of supercritical-flow structures (for example, backset-bedded beds) indicates the development of hydraulic jumps along the steep slope of gullies. Since these clinostratified, fan-shaped carbonate bodies represent carbonate slopes, and that the latter are known as aprons, normally related to linear sourced sediments, an acceptable oxymoron for studied fan-shaped carbonate bodies is suggested: ‘isolated base-of-slope aprons’.