Evaluating new fault-controlled hydrothermal dolomitization models: Insights from the Cambrian Dolomite,Western Canadian Sedimentary Basin     

Ardiansyah Koeshidayatullah  Hilary Corlett  Jack Stacey  Peter K. Swart  Adrian Boyce  Hamish Robertson  Fiona Whitaker  Cathy Hollis 《Sedimentology》2020,67(6):2945-2973

Fault-controlled hydrothermal dolomitization in tectonically complex basins can occur at any depth and from different fluid compositions, including ‘deep-seated’, ‘crustal’ or ‘basinal’ brines. Nevertheless, many studies have failed to identify the actual source of these fluids, resulting in a gap in our knowledge on the likely source of magnesium of hydrothermal dolomitization. With development of new concepts in hydrothermal dolomitization, the study aims in particular to test the hypothesis that dolomitizing fluids were sourced from either seawater, ultramafic carbonation or a mixture between the two by utilizing the Cambrian Mount Whyte Formation as an example. Here, the large-scale dolostone bodies are fabric-destructive with a range of crystal fabrics, including euhedral replacement (RD1) and anhedral replacement (RD2). Since dolomite is cross-cut by low amplitude stylolites, dolomitization is interpreted to have occurred shortly after deposition, at a very shallow depth (<1 km). At this time, there would have been sufficient porosity in the mudstones for extensive dolomitization to occur, and the necessary high heat flows and faulting associated with Cambrian rifting to transfer hot brines into the near surface. While the δ¹⁸O_water and ⁸⁷Sr/⁸⁶Sr ratios values of RD1 are comparable with Cambrian seawater, RD2 shows higher values in both parameters. Therefore, although aspects of the fluid geochemistry are consistent with dolomitization from seawater, very high fluid temperature and salinity could be suggestive of mixing with another, hydrothermal fluid. The very hot temperature, positive Eu anomaly, enriched metal concentrations, and cogenetic relation with quartz could indicate that hot brines were at least partially sourced from ultramafic rocks, potentially as a result of interaction between the underlying Proterozoic serpentinites and CO₂-rich fluids. This study highlights that large-scale hydrothermal dolostone bodies can form at shallow burial depths via mixing during fluid pulses, providing a potential explanation for the mass balance problem often associated with their genesis.  相似文献   

Provenance of sediment in the Labrador Current: a record of hinterland glaciation over the past 125 ka          下载免费PDF全文

LONGJIANG MAO  DAVID J. W. PIPER  FRANCKY SAINT‐ANGE  JOHN T. ANDREWS  MARKUS KIENAST 《第四纪科学杂志》2014,29(7):650-660

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塔里木盆地和田河气田周缘寒武系盐下白云岩油气勘探潜力分析          下载免费PDF全文

曾昌民 李 勇范秋海  冯晓军张 亮 陈 才朱礼春  陈延贵李向云 《地质科学》2018,(4):1413-1439

塔里木盆地塔西南地区和田河气田周缘寒武系中统发育厚层膏盐岩,其下白云岩溶蚀裂缝-孔洞型储层发育条件好。多个层系具备烃源岩发育条件,除寒武系下统玉尔吐斯组外,震旦系、南华系也是可能的重要生油层系,油气资源丰富。盐下发育多个规模较大的构造圈闭,且由于膏盐岩层的滑脱作用,断裂很难断穿盐层,后期保存条件好。因此,寒武系中统膏盐岩与下伏白云岩组成本区重要的储盖组合,勘探领域具有非常好的前景。  相似文献   

川西中三叠统雷口坡组三段-四段白云岩特征与成因——来自于岩相学及地球化学的约束   总被引：1，自引：0，他引：1  

钱一雄  武恒志  周凌方  黄康俊  邓美洲  李勇  董少峰  王琼仙 《岩石学报》2019,35(4):1161-1180

白云岩化是影响储层发育是否的重要沉积-成岩过程。作者通过在对川西地区的中三叠统雷口坡组的雷三至雷四段的岩相学,碳、氧、锶、镁同位素以及元素地球化学等综合研究,划分出含膏的泥晶云岩AD0、泥晶云岩D0、泥粉晶云岩D1、粉细晶云岩D2、微生物云岩MD、含灰质藻云岩CD(交代结构)以及去云化的泥粉晶云岩(CD0CD1)等七类白云岩。白云石有序度及铁、锰含量较低。阴极发光以暗紫、暗紫红、蓝紫为主;次为玫瑰红、橙红及橙黄红色。δ~(13)CPDB=1. 95‰～2. 46‰,δ~(18)OPDB=-4. 05‰～2. 70‰;~(87)Sr/~(86)Sr=0. 70778～0. 70807,δ~(26)Mg=-1. 872‰～-2. 124‰,其中δ~(13)C_(PDB)、~(87)Sr/~(86)Sr的平均值与中三叠世全球海水相似;δ~(18)O_(PDB)为弱负漂及正偏移。从D2、D1至D0、AD0,Sr、Na和大部分微量元素含量及比值和δ~(18)O_(PDB)逐渐增加; AD0、少量D0或MD相对富含硅、铝,并与高(低镁)方解石、黏土、有机质等共生。离子组成反映出白云石的前驱物以方解石型为主,少量为文石、原白云石结构。存在广盐、稍咸和超盐度的碱性等沉积环境。白云岩形成主要受向上变浅米级旋回序列,干燥、炎热为主、偶夹潮湿古气候以及古地貌-古水文条件等因素影响。存在浅潟湖的萨勃哈(AD0或D0)、环潮缘至局限台地(D0-D1、微生物诱导MD)、潮间-潮下的微生物礁(席)构成的障壁的台缘带(MD-CD1-CD)、潮坪-开阔台地(D0-D2-CD1、MD)等环境,以萨勃哈和受蒸发泵-密度差驱动的"渗透-回流白云石化"模式为主。  相似文献   

二元同位素测温技术及其在白云岩储层成因研究中的应用——以塔里木盆地中下寒武统为例     

郑剑锋  李晋  季汉成  黄理力  胡安平  马明璇 《海相油气地质》2017,22(2)

作为近年来新兴的实验技术,二元同位素(D47)测温技术已被应用于碳酸盐岩成岩环境的研究中。简要介绍了二元同位素测温技术的原理及应用方法,并以塔里木盆地中下寒武统白云岩为例,优选11块样品,测试其D47值和白云石的碳氧同位素,并计算出样品的成岩温度和古流体的δ~(18)O值。综合分析认为:样品中,颗粒白云岩形成于低温准同生—浅埋藏环境,成岩流体为海水;细晶白云岩为深埋藏成岩环境中原岩受到了高温重结晶作用的改造,成岩流体为地下热卤水;孔缝中的白云石胶结物是深埋藏成岩环境富镁热卤水沉淀作用的产物。研究证明二元同位素测温技术可以较好地恢复白云岩的成岩温度,减少储层成因的多解性,它为今后储层成因研究提供了一种新的手段和依据。  相似文献   

MIS 3时期青藏高原东南部稻城古冰帽冰进事件研究   总被引：1，自引：1，他引：0  

张志刚  王建  何元庆  何则  齐翠姗  李盼盼 《冰川冻土》2017,39(5):957-966

深海氧同位素3阶段(Marine Isotope Stage 3,MIS 3)是全球气候演化过程中特殊的时期,对深入认识区域古气候、古环境演变具有重要意义。青藏高原东南部稻城古冰帽是第四纪冰川作用历史和古气候研究的理想区域,许多学者在该区进行了冰川地貌学和年代学研究。目前,该区域在MIS 3阶段是否存在冰川前进事件仍存在争论。现着重从洞穴石笋、高原冰芯、海洋沉积、古湖孢粉等记录来总结我国MIS 3阶段的气候环境状况,并搜集高原及周边地区MIS 3阶段冰进事件的记录,结合稻城古冰帽区已发表的MIS 3阶段的年代数据来探讨稻城古冰帽区MIS 3阶段的冰川前进的可能性。结果表明:稻城古冰帽区MIS 3阶段(43~53 ka)发生了大规模冰进事件,这可能是由于该冰帽区处于相对冷湿环境且受到了西南季风的影响。本研究可为区域气候重建与环境演变提供新的依据。  相似文献   

Neoproterozoic (Cryogenian) stromatolites from the Wolfe Basin,east Kimberley,Western Australia: Correlation with the Centralian Superbasin     

K. Grey  D. H. Blake 《Australian Journal of Earth Sciences》2013,60(3):329-341

Linella avis, an early to middle Neoproterozoic (Tonian to Cryogenian) stromatolite, occurs in the Eliot Range Dolomite, part of the Ruby Plains Group in the Wolfe Basin, east Kimberley. Previously, this dolomite was assigned to the Mesoproterozoic Bungle Bungle Dolomite in the Osmond Basin, which contains a different suite of stromatolites. Linella avis, which also occurs in the Neoproterozoic Bitter Springs Formation of the Amadeus Basin, central Australia, appears to be restricted to rocks aged around 850 to 800 Ma. The presence of L. avis indicates that the Ruby Plains Group is a probable correlative of the Heavitree Quartzite and Bitter Springs Formation, and is probably much younger than the Bungle Bungle Dolomite. If the correlation suggested here is correct, the Wolfe Basin, together with the Amadeus and Ngalia Basins, formed part of the Centralian Superbasin.  相似文献   

稻城冰帽库照日冰碛垄的宇生核素¹⁰Be年代测定   总被引：1，自引：0，他引：1  

张志刚  王建  徐孝彬  赵志军  白世彪 《海洋地质与第四纪地质》2012,(1):85-91

沙鲁里山南端的稻城冰帽在第四纪曾发生过大规模的冰川作用,然而,关于冰川作用的年代数据相对较少。选择稻城冰帽南缘库照日附近的3套冰碛垄进行宇生核素10Be的暴露年代测定,研究结果表明:(1)库照日最老冰碛垄(E)的暴露年代为(714±8.0)～(529±8.0)kaBP,D垄的暴露年代为(121±2.9)～(114±2.9)kaBP,DC垄的暴露年代为(47±1.3)～(43±1.3)kaBP。由于宇生核素暴露年代所反映的是冰川消退时的年代,因此,我们结合深海氧同位素的气候特征以及其他测年数据推断,E垄、D垄、DC垄可能是MIS16、MIS6以及MIS3b阶段冰川作用的产物;(2)冰川退却是一种逐步退却的模式。样品E的两次测验结果比较吻合,表明宇生核素10 Be暴露测年方法对冰碛垄形成年代的测定是可靠的,该方法在地貌学和第四纪年代学研究中有着巨大的潜力。  相似文献   

Storm-driven shelf-to-canyon suspended sediment transport at the southwestern Gulf of Lions     

A. Palanques  J. Guillén  P. Puig  X. Durrieu de Madron 《Continental Shelf Research》2008

Shelf-to-canyon suspended sediment transport during major storms was studied at the southwestern end of the Gulf of Lions. Waves, near-bottom currents, temperature and water turbidity were measured on the inner shelf at 28-m water depth and in the Cap de Creus submarine canyon head at 300 m depth from November 2003 to March 2004. Two major storm events producing waves H_s>6 m coming from the E–SE sector took place, the first on 3–4 December 2003 (max H_s: 8.4 m) and the second on 20–22 February 2004 (max H_s: 7 m). During these events, shelf water flowed downcanyon producing strong near-bottom currents on the canyon head due to storm-induced downwelling, which was enhanced by dense shelf water cascading in February 2004. These processes generated different pulses of downcanyon suspended sediment transport. During the peak of both storms, the highest waves and the increasing near-bottom currents resuspended sediment on the canyon head and the adjacent outer shelf causing the first downcanyon sediment transport pulses. The December event ended just after these first pulses, when the induced downwelling finished suddenly due to restoration of shelf water stratification. This event was too short to allow the sediment resuspended on the shallow shelf to reach the canyon head. In contrast, the February event, reinforced by dense shelf water cascading, was long enough to transfer resuspended sediment from shallow shelf areas to the canyon head in two different pulses at the end of the event. The downcanyon transport during these last two pulses was one order of magnitude higher than those during the December event and during the first pulses of the February event and accounted for more than half of the total downcanyon sediment transport during the fall 2003 and winter 2004 period. Major storm events, especially during winter vertical mixing periods, produce major episodes of shelf-to-canyon sediment transport at the southwestern end of the Gulf of Lions. Hydrographic structure and storm duration are important factors controlling off-shelf sediment transport during these events.  相似文献   

南方震旦系灯影组热液白云岩化及其对储层形成的影响研究——以黔中隆起为例   总被引：1，自引：0，他引：1       下载免费PDF全文

朱东亚  金之钧  孙冬胜  彭勇民  张荣强  袁玉松 《地质科学》2014,(1):161-175

我国南方地区,特别是四川盆地震旦系灯影组是我国当前高演化天然气勘探的热点,以黔中隆起为例,新揭示了其中发育的热液白云岩化现象,并探讨了其对储层形成的影响。研究区灯影组白云岩溶蚀孔洞或裂缝中见有白云石、石英、沥青充填,其中一种充填的粗晶白云石具有弯曲晶面、波状消光特征,在岩石学特征上初步反映热液成因。地球化学特征进一步揭示了这种热液成因。不同采样位置热液白云石样品中流体包裹体均一温度平均为157.5 ℃～205.8 ℃,最高为253.5 ℃。热液白云石具有较轻的氧同位素组成,δ¹⁸O_PDB 位于 -15.3‰～-8.6‰之间,平均值为 -11.2‰;较高的⁸⁷Sr/⁸⁶ Sr比值（0.709 445～0.713 131）,其平均值为0.710 843,在稀土元素组成上,热液白云石具有典型的Eu正异常的特点,δEu值为1.11～7.46,平均值为2.37。因此,灯影组热液白云石发育。热液活动对储层形成具有积极影响,主要体现在对充填在早期岩溶孔洞和构造裂缝中的白云石产生了溶蚀作用,溶蚀孔中见沥青充填,反映为油气运移通道和聚集空间。因此,热液溶蚀改造作用对我国南方地区震旦系灯影组及下古生界碳酸盐岩储层发育可能具有重要意义,值得加强探索研究。  相似文献