二连盆地洼槽分类及其油气勘探意义

二连盆地已发现56个凹陷和21个凸起,每个凹陷按腾一段地层沉积中心的分割性可划分为2~3个洼槽。为开展洼槽地质分类及其与生烃潜力的相关性研究,通过对10个含油凹陷23个洼槽的地质和地球化学资料统计分析,发现各洼槽的古生界基底顶面(T_g)最大埋深、洼槽面积、阿尔善组及腾一段沉积期间的古水体盐度分别对阿尔善组和腾一段两套烃源岩的最大总厚度及成熟度、面积、有机质丰度及类型存在控制作用。据此提出按照基底埋深、深洼带面积和阿尔善组及腾一段的古水体盐度特征将洼槽划分为高熟型、成熟型和低熟型3大类14小类。结合洼槽生烃潜力评价,认为富生烃洼槽总体属于高熟大中型洼槽和成熟大中型咸水洼槽,咸水洼槽具有更优越的源储条件,更有利于致密油勘探。由于高熟咸水洼槽在马尼特坳陷和乌兰察布坳陷更发育,在勘探选区上应优先考虑这两个坳陷内的洼槽。     

Field tests of an improved sediment tracer including non-intrusive measurement of burial depth

Radio-frequency identification (RFID) transponders are now widely used to track sediment in a variety of environments. A recent innovation placed the transponder inside of a rotating inner mechanism that is designed to minimize missed detections due to burial and shielding or ‘signal collision’ effects between tracers, while also allowing a rapid measurement of the burial depth of the particle. Here we test a developed protocol for burial depth measurement and deploy the ‘Wobblestone’ tracers in the field for the first time. Results show that new tracers can be reliably positioned in the horizontal plane (median error ± 0.03 m) and that the burial depth can be accurately measured (~0.02 m maximum error). The field study was characterized by high mobility and travel lengths, and ~20% of the tracers were buried at depths up to 0.15 m. A comparison of exponential distributions for travel length of surface deposited and buried tracers indicate that the buried tracers on average traveled farther and earlier in the flood event. Tracers that did not move were also buried at one site as a result of sediment transport from upstream. Overall the technique has great potential for characterizing vertical mixing and understanding this rarely considered control on sediment transport. © 2020 John Wiley & Sons, Ltd.     

Isochron 26Al/10Be burial dating of the Lantian hominin site at Gongwangling in Northwestern China

The site of Gongwangling is among the most important early hominin sites in China due to the discovery of a partial Homo erectus cranium. Until recently the cranium has been widely accepted as ∼1.15 Ma (million years) in age based on magnetostratigraphy and loess/paleosol correlation. However, a revised magnetostratigraphic and pedostratigraphic study assigned a much older age of 1.63 Ma, making Gongwangling the second oldest hominin cranium-bearing site in Eurasia. Here we apply the isochron burial dating method as an independent check for the magnetostratigraphy. Samples from the top of a gravel bed ∼7 m below the fossil-bearing layer give an isochron burial age of 1.82 ± 0.12 Ma, in excellent agreement with the Olduvai subchron in the revised magnetostratigraphy, supporting the antiquity of the cranium.     

Possible climatic controls on the accumulation of Peru's most prominent alluvial fan: The Lima Conglomerate

Sediment accumulation can occur in response to a change in either tectonic or climatic driving forces. Here, we explore these controls on the deposition of the Lima Conglomerate, Peru. We use a combination of quantitative methods to explore the age of sediment accumulation, the provenance of the material and the paleo-erosion rates recorded by these deposits. Isochron burial dating with cosmogenic ¹⁰Be and ²⁶Al yield an age of c. 500 ka for the base (490 ± 70 ka) and the uppermost sample situated c. 30 m higher upsection (490 ± 80 ka). Results of paleo-erosion rate estimates with concentrations of in situ ¹⁰Be show a c. 60% increase from 105 ± 10 mm ka^-1 for the base to 169 ± 14 mm ka^-1 for the uppermost sample. Finally, provenance tracing with in situ U/Pb ages on detrital zircon implies that the material has been derived from the entire drainage basin. The combination of results suggests that sediment accumulation occurred in response to an erosional pulse, which affected the entire basin within a short time interval. Because ¹⁰Be data represents a large spatial record of erosion, we exclude the possibility where a breakout of a lake or a focused release of material in response to earthquakes, were responsible for the large material flux. Instead, the erosional pulse was likely to have occurred at the scale of the entire basin, supporting the idea of a larger-scale, most likely climate driven control. In this context, the accumulation age of c. 500 ka falls into an orbital cycle fostering the emerging picture in the literature that sediment routing in the Andes have most likely been driven by climate and cyclic changes. We suggest that the Andean mountain range offers an ideal laboratory to explore the erosional history in relation to climate patterns, at least in Peru. © 2018 John Wiley & Sons, Ltd.     

柴达木盆地西部埋藏史分析与油气关系类型

地层埋藏史研究是借助计算机恢复地层古厚度,动态的再现盆地的沉积发育过程,同时也是含油气系统研究的核心内容,是研究油气的生、运、聚及成藏过程的基础和关键。本文在区域概况分析的基础上,应用EASY％R。方法定量计算了柴达木盆地西部31口重点探井的剥蚀量,并应用实例详细论证了该方法恢复的剥蚀量是合理可靠的,然后应用回剥技术恢复原始地层厚度,做出了单井埋藏史图。并划分出了连续沉积型、中期剥蚀型和晚期强烈剥蚀型3种埋藏史类型。埋藏史与油气的关系密切：未遭受强烈抬升、剥蚀影响的地区能够较好的保存原生油气藏;而后期的强烈剥蚀使得早期的原生油气藏遭到破坏,同时又导致了浅层次生油气藏的形成。这对正确认识该地区沉积沉降演化历史和成藏机制,指导油气勘探具有重要作用。     

冀中坳陷孙虎地区沉积和剥蚀作用及其对油气生成聚集的影响

探讨了沉积和剥蚀作用对孙虎地区油气生成、聚集的影响,认为两者对于本区油气的生成、聚集和保存都不太有利。首先,在沉积演化中缺少深湖相沉积,只在孔店组和沙河街组发育干盐湖相和滨浅湖相沉积,使得本区的油源有机质丰度不高,类型较差。其次,在洼陷边缘发育的冲积体系由于距油源远,缺少连通通道而难以成为良好的储集岩。另外,本区地层在老、新第三纪之间遭受的强烈抬升剥蚀（最大剥蚀厚度达3000 m）,对本区的油气生成和聚集更是产生了严重的负面影响：一方面导致源岩层的温度、压力下降,油气生成、排出作用大大减弱;另一方面,使得已排出并聚集成藏的油气遭到破坏。强烈的构造活动导致了埋藏史的差异,本区可划分出3种类型的埋藏史,即持续沉降型、早期沉降型和二次沉降型。持续沉降型埋藏区地层埋藏较浅,只有沙三段局部地层进入生、排烃门限,生烃潜力不大;早期沉降型埋藏区地层埋藏较深,孔店组和沙三段均具有生排烃能力,但早期排出的烃存在一个保存问题;二次沉降型埋藏区经历了两次大幅度的沉降,均达到了生排烃门限,具有二次生排烃过程,是目前圈闭条件下寻找油气的较理想地区。     

Burial tolerances of reef-building Sabellariid worms from the east coast of Florida

Sabellariid worms, such as Phragmatopoma lapidosa, are sessile suspension feeders that attach to exposed hard bottom and serve as foundation species for worm reefs which are complex, multifaceted habitats. While worm reefs are adapted to dynamic sedimentary environments, burial of these habitats by beach nourishment projects is a concern. This study determined duration and depth of burial that can be tolerated by P. lapidosa without death. Worm rock samples were buried in sand at 1–10 cm (1-cm intervals), and at 15, 25 and 40 cm for the duration of 72, 144, and 216 h and then surveyed for initial mortality after burial and one week after removal of sediment (latent effects). Initial mortality was similar across all burial depths for the 72-h duration with values ranging from 8.3% (±0.8 SE) for 1 cm to 24.0% (±8.0 SE) for 10 cm of sediment. As burial duration increased to 144 h, mortality generally increased as burial depth increased with an average mortality for 2 cm of sediment of 23.5% (±5.3 SE) increasing to 96.0% (±14.3 SE) with 40 cm of sediment. The mean percent mortality for burial samples in the 216 h treatment varied from a low of 71.2% (±3.3 SE) for 1 cm depth to a high of 100% (±0 SE) for 10, 15, 25, and 40 cm depths. Mortality for most treatments also increased over time after removal of sediment indicating latent effects of burial stress.     

柴北缘西大滩矿区煤系沉降-埋藏史研究

虽然沉降-埋藏史模拟技术在油气地质研究中被广泛使用,但是却很少用于煤田地质研究。随着高产高效矿井和深部煤炭资源开采的展开,对煤田地质研究的要求也越来越高。迫切需要把沉降-埋藏史模拟等新技术引入到煤田地质研究中。以柴达木盆地北缘西大滩矿区的研究为例,根据煤田地质和沉降、埋藏史模拟技术的特点．介绍了用于煤盆地构造演化研究的沉降-埋藏史模拟技术方法,并对西大滩矿区侏罗纪煤系的沉降-埋藏史模拟结果进行了分析。认为研究区的构造演化可划分为中生代阶段（J1-J3）和新生代阶段（E—N）,其间被白垩纪时期的盆地抬升剥蚀所分开。实例研究表明,沉降史和埋藏史模拟技术为盆地构造演化研究提供了定量或半定量的技术手段。     

中扬子台地北缘灯影组白云岩研究

研究区白云岩成因类型可划分出准同生白云石化、回流渗透白云石化、混合水白云石化、压溶白云石化和埋藏白云石化。本文详细研了各成因类型的白云岩矿物岩石学特征和地球化学特征，重点探讨了埋藏白云石化Ｍｇ２＋来源及其搬运机理。认为埋藏白云石化Ｍｇ２＋来自粒间残留古海水，迁移机制与地下异常高压孔隙流体的驱动和襄樊－广济同沉积断裂的活动有关。五类白云岩中以混合水白云石化和埋藏白云石化的岩石类型储集性能最好。     

山东胜利油田第三系碎屑岩的埋藏成岩作用与储层评价

研究区在新生代为一持续下沉的断陷盆地,碎屑岩十分发育.有些埋藏成岩矿物,其出现深度的温度,等于或接近于其他学者对这些矿物的实测温度.这类成岩矿物包括石英(次生加大)、自生高岭石、自生石榴石、腐蚀状绿帘石及粘土矿物等.根据与温度有关的各种成岩作用,可划分出浅成、中成、深成和超深成四个岩带.业已查明,埋藏成岩带可用以划分和评价碎屑岩储油层.