How do carbonate factories influence carbonate platform morphology? Exploring production−transport interactions with numerical forward modelling     

Daniel Sultana  Peter Burgess  Dan Bosence 《Sedimentology》2022,69(1):372-393

Understanding how carbonate factories influence platform evolution is either based on qualitative conceptual models or quantitative numerical stratigraphic forward models. This study establishes new production depth profiles for four Cenozoic carbonate factories and uses two-dimensional stratigraphic forward models to explore how interactions between sediment production and transport within carbonate systems influence carbonate platform development. Newly established production/depth profiles are used to model photozoan and heterozoan carbonate grain associations, and the associated carbonate producing factories, and results are compared with well-studied outcrop successions. Sediment production from photozoan and heterozoan grain associations is also equalized, so that the total sediment production is the same but the depth/production profiles retain their distinctly different form. Thus, the effect of the different production profiles can be assessed. Ramps form when sediment diffusional transport rates are high relative to production rates and flat-top steep-margin platforms form when sediment diffusional transport rates are low relative to production rates, whether they are photozoan or heterozoan grain associations. The control exerted by sediment production and transport is expressed as a sediment transport–production ratio where transport ratio is a diffusional sediment transport in two-dimensions and production ratio is the total sediment production rate which is the product of a production profile that varies in depth and laterally. The transport–production ratio is a key control on the evolution and geometry of carbonate platforms. This is the case with different production profiles (both euphotic and oligophotic) and in mixed grain-size and mixed transport-rate systems. Carbonate producing factories significantly influence the rate of sediment production, the depth distribution of sediment production (production profiles), as well as the type of grain sizes produced (influencing resistance to erosion). Thus, different types of carbonate grain associations, and the associated carbonate producing factories, can produce the critical differences between carbonate platform geometries.  相似文献   

Response of large benthic foraminifera to climate and local changes: Implications for future carbonate production     

Gita R. Narayan  Claire E. Reymond  Marleen Stuhr  Steve Doo  Christiane Schmidt  Thomas Mann  Hildegard Westphal 《Sedimentology》2022,69(1):121-161

Large benthic foraminifera are major carbonate components in tropical carbonate platforms, important carbonate producers, stratigraphic tools and powerful bioindicators (proxies) of environmental change. The application of large benthic foraminifera in tropical coral reef environments has gained considerable momentum in recent years. These modern ecological assessments are often carried out by micropalaeontologists or ecologists with expertise in the identification of foraminifera. However, large benthic foraminifera have been under-represented in favour of macro reef-builders, for example, corals and calcareous algae. Large benthic foraminifera contribute about 5% to modern reef-scale carbonate sediment production. Their substantial size and abundance are reflected by their symbiotic association with the living algae inside their tests. When the foraminiferal holobiont (the combination between the large benthic foraminifera host and the microalgal photosymbiont) dies, the remaining calcareous test renourishes sediment supply, which maintains and stabilizes shorelines and low-lying islands. Geological records reveal episodes (i.e. late Palaeocene and early Eocene epochs) of prolific carbonate production in warmer oceans than today, and in the absence of corals. This begs for deeper consideration of how large benthic foraminifera will respond under future climatic scenarios of higher atmospheric carbon dioxide (pCO₂) and to warmer oceans. In addition, studies highlighting the complex evolutionary associations between large benthic foraminifera hosts and their algal photosymbionts, as well as to associated habitats, suggest the potential for increased tolerance to a wide range of conditions. However, the full range of environments where large benthic foraminifera currently dwell is not well-understood in terms of present and future carbonate production, and impact of stressors. The evidence for acclimatization, at least by a few species of well-studied large benthic foraminifera, under intensifying climate change and within degrading reef ecosystems, is a prelude to future host–symbiont resilience under different climatic regimes and habitats than today. This review also highlights knowledge gaps in current understanding of large benthic foraminifera as prolific calcium carbonate producers across shallow carbonate shelf and slope environments under changing ocean conditions.  相似文献   

鄂尔多斯盆地上三叠统延长组长7富有机质页岩中藻类化石的发现及地质意义     

袁伟  柳广弟  袁红旗 《地质论评》2022,68(3):2022062024-2022062024

鄂尔多斯盆地上三叠统延长组长7段富有机质页岩是该盆地中生界含油系统的主力烃源岩,其有机质丰度高,类型好,具有巨大的生烃潜力。该套烃源岩中有机质的富集很大程度上取决于长7期的高古生产力及其提供的充足的有机质。长7期藻类勃发的存在已被多数学者所接受,但是目前还缺乏直观、有力的证据。笔者等通过薄片和扫描电镜观察、能谱分析,在长7段的脉状黄铁矿附近和碳酸盐结核中发现了属种单一、分布丰度高的藻类化石,它们呈现出近似球状的轮廓,在中部分布着一条裂缝。这些藻类化石的发现具有重要的地质意义,它为长7期的藻类勃发提供了很好的证据,也为该时期热液活动的重要作用提供了有力的支撑。  相似文献   

天津东丽湖深部岩溶热储探测与储层参数研究及其开发利用潜力分析          下载免费PDF全文

李胜涛  岳冬冬  冯昭龙  宋健  刘东林  宋志彬  和国磊  龙慧  郝文杰  张秋霞 《中国地质》2022,49(6):1732-1746

【研究目的】天津市地热资源储量丰富、开发利用程度高,蓟县系雾迷山组三、四段白云岩热储是目前的主力开采层位,随着开发强度不断增大,部分地区开采潜力已达极限。探测深部地热资源、增加可开采资源量,成为保障天津地区地热可持续开发的有效途径之一。【研究方法】本次研究以东丽湖为重点研究区,开展深部热储地球物理探测,实施地热科学钻探CGSD-01井。【研究结果】主要结果包括：（1）CGSD-01井在3715m钻遇雾迷山组二段,上覆雾迷山组三段底部发育一套紫红色泥质白云岩夹浅灰色细晶白云岩,厚度约73m,裂隙不发育,具有隔水-弱透水性质;（2）CGSD-01井成井深度4051.68m,孔底温度105℃,单位涌水量1.53m³/h·m,渗透系数0.40m/d,导水系数48.69m²/d;（3）雾迷山组二段地热水类型为Cl·SO₄·HCO₃-Na型,矿化度1.7g/L,初步推断地热水来源于大气降水,主要发生混合、阳离子交替吸附、碳酸盐岩溶解、硫酸盐还原等作用,且未达到平衡;（4）蓟县系雾迷山组二段单井最大涌水量可达130m³/h,出水温度100℃,单井可满足约30万m2建筑物供暖需求。【结论】在天津地区深部热储第二空间首次探获高产能雾迷山组二段新储层,探明了热储结构和主要参数,显示出良好的资源前景。  相似文献   

塔河油田碳酸盐岩油藏古岩溶洞穴层状结构与形成机理     

陈华鑫  康志宏  康志江 《现代地质》2022,36(2):695-708

随着岩溶型碳酸盐岩油藏开发实践的不断深入,层状洞穴储层结构特征和流体同层连通特点逐渐被学者重视。层控岩溶结构、形成要素和过程等是本类油藏有效开发的关键。通过原始地层组构对比和野外溶洞特点,认为:塔河奥陶系岩溶层具较好的对比标志层和岩性差异,为层状岩溶洞穴发育奠定了物质基础;野外顺水平层理多层溶洞和受控于层理缝的管道型古暗河等地质现象,证实了层控岩溶普遍存在。在岩溶洞穴单井识别、连井测井对比、单井动态及地震波形特征的基础上,以典型溶洞带为例,识别出3个主要洞穴层,建立了全新的3层洞穴储集体地质结构剖面:第1层洞穴以砂砾岩充填为主要特点,第2层洞穴呈现洞穴规模大且泥质充填严重,第3层规模较小,主要发育于岩溶地貌高地。运用现代岩溶理论,探讨了层控岩溶的形成机制:碳酸盐岩原岩组构差异是岩溶作用的物质基础和主控因素之一;潜流带岩溶水(饱含CO₂)控制着岩溶洞穴的横向发育,岩溶古地貌控制同层洞穴的横向差异;平缓地层条件下的潜水面水位垂向带迁移控制洞穴的岩溶期次及层状结构。基于各岩溶要素认识,构建了层状岩溶储层发育模式。  相似文献   

鄂尔多斯盆地中上三叠统延长组长7段碳酸盐结核成因讨论     

朱如凯  崔景伟  罗忠  李森  毛治国  葸克来  苏玲 《地质学报》2021,95(11):3442-3454

鄂尔多斯盆地南部铜川地区露头区中三叠统延长组长7段细砂岩、粉砂岩、泥质粉砂岩、粉砂质泥岩层序中发育有大量圆球状、椭球状、扁球状碳酸盐岩结核,对于其成因存在争议.对铜川地区多个剖面的结核开展宏观描述,在微观薄片观察基础上开展岩石矿物组成、稳定同位素、簇同位素以及微区同位素等分析,特别是选取一个结核开展了详细的解剖.结果显示结核成分以方解石为主,少量白云石;内部结构有差异,在球体横切面上明显分为两个圈层;碳同位素值正偏,由内部圈层向外部圈层降低;氧同位素与碳同位素变化趋势一致,计算结核形成古温度变化区间为28.6～76.5℃;簇同位素揭示结核中部形成温度为42.9℃.认为该类结核为早期发酵带内细菌参与甲烷生成作用形成,甲烷菌活动引起有机质碳同位素分馏,碳酸盐结核中方解石和白云石圆球粒可能是蓝细菌细胞方解石化或白云石化的结果.根据埋藏史,认为该类结核形成于成岩作用早期,后期在成岩过程中叠加生长,同心环层结构明显.  相似文献   

塔河油田奥陶系生物扰动型碳酸盐岩储集层特征及其孔隙度计算样本检验模型     

赵佳如  牛永斌  王敏  徐资璐  崔胜利  王培俊 《沉积学报》2021,39(2):482-492

塔河油田奥陶系一间房组和鹰山组生物扰动型碳酸盐岩储集层非常发育。在岩芯观测的基础上,通过薄片显微镜观测与柱塞孔隙度、渗透率分析,对研究区生物扰动型碳酸盐岩储集层宏、微观特征和成因机制进行了研究,并基于岩芯资料和常规测井数据提出了一种新的孔隙度计算样本检验模型。结果表明:1）研究区奥陶系生物扰动储集层在岩芯上多呈不规则状或绸带状分布的含油斑块,潜穴充填物以白云石为主,储集空间主要是晶间孔。随着生物扰动指数的增加,平均孔隙度呈先增大后减少趋势,平均渗透率则一直增大;2）在早—中奥陶世的沉积过程中,（古）生物在碳酸盐沉积物表面或内部建造了大量形态各异的潜穴,生物扰动使得潜穴充填物和围岩基质在成分、结构上出现差异,这些差异伴随着其后的成岩过程逐步增大,这对储集层的储、渗能力具有重要影响;3）在总结前人测井孔隙度计算方法的基础上,将生物扰动指数引入密度测井孔隙度计算模型中,提出了一种基于岩芯资料和常规测井数据的孔隙度计算样本检测检验模型,并用岩芯柱塞测试结果验证了该孔隙度计算模型的有效性和准确性;该模型弥补了现有常规孔隙度模型的不足,其计算产生的拟岩芯数据可为下一步建立的通用生物扰动碳酸盐岩储集层孔隙度计算模型提供可靠的样本训练数据,也对这类储层的储量估算与油藏描述有一定的借鉴意义。  相似文献   

华北地台中—新元古界烃源岩沉积特征及生烃潜力          下载免费PDF全文

张文浩  汤冬杰  杨烨  张交东  刘旭锋  王丹丹  曾秋楠  刘卫彬 《中国地质》2021,48(5):1510-1523

随着近年来元古宇商业性原生油气藏在全球范围的不断发现,元古宙地层已逐渐成为了油气勘探重点。华北地台燕山地区是中国中-新元古界最为发育的地区之一,中-新元古界总厚可达9553 m,虽油苗等油气显示发现已久,但多年来一直未取得油气突破。为了下一步开展更具针对性的油气调查及勘探,从中、新元古代这套巨厚的沉积地层中优选出油气勘探的有利烃源岩层段就有着非常重要的意义。本文分析了华北中元古代地层中发育的暗色泥岩与微生物碳酸盐岩这两类烃源岩层的沉积特征,并初步评价了它们的生烃潜力。串岭沟组、洪水庄组与下马岭组均发育有厚层的暗色泥、页岩,总有机碳含量TOC平均值分别为0.89%、2.54%、2.82%,有机质的镜质体反射率Ro（采用为镜状体反射率Ro_vl）值分别为2.03%、1.05%、0.63%。微生物碳酸盐岩在高于庄组、雾迷山组及铁岭组中普遍发育,其内富含微生物群落等丰富的有机质残留,发育TOC>0.2%的优质烃源岩层段。  相似文献   

不同赋存环境下碳酸盐岩溶蚀过程试验模拟研究          下载免费PDF全文

林云  任华鑫  武亚遵  贾方建  刘朋  梁家乐 《水文地质工程地质》2021,48(2):15-26

目前,有关碳酸盐岩溶蚀过程的研究多集中在单一环境平衡状态下,不同赋存环境、微观尺度上的研究较少。鉴于此,为探讨不同赋存环境下碳酸盐岩溶蚀过程及微观变化特征,借助研制的岩溶水系统不同赋存环境下水岩相互作用模拟装置,选取典型岩溶水系统开放环境、半封闭环境与封闭环境的岩样,以CO₂溶液为酸性流体介质,开展室内溶蚀模拟试验,研究岩溶水中特征组分的变化规律进行模拟实验,并从宏观和微观尺度,研究岩溶水系统不同赋存环境下的碳酸盐岩溶蚀变化特征。结果显示:不同赋存环境下Ca²⁺、HCO3^-含量、饱和指数及pH值空间变化特征不同,各特征组分均呈现出随径流方向、溶蚀时间逐渐增大的趋势。不同赋存环境下,碳酸盐岩受水溶液中CO₂含量的影响,在补给区的开放环境下溶蚀性最强,形成连通性较高的溶孔、溶隙。碳酸盐岩总溶蚀率均值是半开放环境的1.43倍,是封闭环境的2.70倍,半封闭与封闭环境下碳酸盐岩溶蚀后的微观结构介于孤立微孔与完全连通性溶隙之间。此外随深度的变化溶蚀量呈逐渐减弱的趋势,且浅部的变化更为明显。碳酸盐岩的溶蚀作用还受岩性控制,其随岩石中CaO/MgO比值的增大而增强。  相似文献   

Origin of Phosphate-bearing Carbonate Concretions in the Upper Triassic Lacustrine Black Shales of the Southern Ordos Basin,China     

ZHANG Long  LIU Chiyang  ZHANG Dongdong  QU Shaodong  MA Huanhuan  JIANG Chong  LEI Kaiyu 《《地质学报》英文版》2021,95(3):883-894

Carbonate concretions are conspicuous in organic-rich shales and are generally related to decomposition of organic matter.The black shales from the Chang 7 Member of the Upper Triassic Yanchang Formation of the southern Ordos Basin host abundant carbonate concretions,which provide a unique record of depositional and early diagenetic conditions of the paleo-lake sediments.However,little attention has been given to the genesis and growth processes of the concretions in these lacustrine petroleum source rocks.New petrographic observations and geochemical analysis show that the concretions are composed of calcite,phosphate fossil fragments,K-NH_4-feldspar,quartz,bitumen,and minor Fedolomite.Phosphate minerals,mainly carbonate fluorapatite (CFA),show pervasive replacement by calcite,most of which contains phosphorus,ranging in concentration from 0.26 to 2.35 wt%.This suggests that the phosphate minerals are the precursors for concretion growth.Positiveδ~(13)C (+5.6 to+12.4‰V-PDB) signatures and the absence of pyrite indicate that microbial methanogenesis was the dominant driver for concretion growth,rather than bacterial sulfate reduction.Quartz,bitumen,and Fe-dolomite are the last cements that occurred,at deep burial depths and high temperatures.The formation of phosphate minerals might have been induced by upwelling of phosphate-enriched deep water in the Late Triassic paleolake,which promoted phytoplankton blooms and further enrichment of organic matter.Extremely slow sedimentation rates of fine-grained detrital minerals,relative to dead organism accumulation,led to the high permeabilities of the organic-rich sediments and rapid concretion growth during shallow burial.The close association of phosphate-bearing carbonate concretions and organic-rich shales reflects that upwelling played a critical role in the formation of the high-quality petroleum source rocks in the Triassic paleo-Ordos lake.  相似文献