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Discovery of a 400 km 2 honeycomb structure mimicking a regional unconformity on three-dimensional seismic data
Geology ( IF 5.8 ) Pub Date : 2019-12-01 , DOI: 10.1130/g46484.1
Rosine Riera 1 , Julien Bourget 1 , Victorien Paumard 1 , Moyra E.J. Wilson 1 , Jeffrey Shragge 2 , Annette D. George 1 , Jean Borgomano 3 , Thomas Wilson 4
Affiliation  

Recognition of seismic unconformities is crucial for interpreting basin history from seismic reflection data sets in both siliciclastic and carbonate settings. While it is well established that non-erosional changes in sedimentary facies can create seismic reflections that mimic seismic unconformities (i.e., pseudo-unconformities), these features are generally considered to be localized and uncommon, and, therefore, are largely overlooked during interpretation. Diagenetic alteration of strata can also affect the morphology of seismic reflectors and mislead seismic interpreters. This study is based on a three-dimensional (3-D) seismic data set and documents a 400 km2 honeycomb structure (HS) masquerading as a regional erosional unconformity in the Oligocene–Miocene carbonate strata of Australia’s North West Shelf. This HS is located at the transition between the topsets and the foresets of clinoforms of carbonate to marly composition. The HS expression in 3-D seismic data cross sections is irregular, giving the HS the appearance of a truncated surface that could erroneously be interpreted as a regional seismic unconformity. Closer examination reveals that the HS crosscuts chronostratigraphic clinoform reflectors, and frequency extraction processing shows that the HS dominantly falls within a lower-frequency band than the clinoform reflectors. The morphology of the HS (i.e., continuous with densely packed cells) and its time-transgressive nature suggest that it has a burial diagenetic origin. This suggests that creation of pseudo-unconformities at basin scale by burial diagenesis may lead to surface misidentification, with negative consequences for paleoenvironmental studies and petroleum exploration activities.

中文翻译:

发现了一个400 km 2的蜂窝结构,该结构模仿了三维地震数据上的区域不整合

识别地震不整合面对于从硅质碎屑岩和碳酸盐岩环境中的地震反射数据集中解释盆地历史至关重要。公认的是,沉积相的非侵蚀性变化会产生模仿地震不整合面(即伪不整合面)的地震反射,但这些特征通常被认为是局部且不常见的,因此在解释时会被忽略。地层的成岩作用改变也可能影响地震反射器的形态并误导地震解释器。这项研究基于三维(3-D)地震数据集,并记录了400 km 2在澳大利亚西北大陆架的渐新世—中新世碳酸盐岩地层中,蜂窝结构(HS)伪装成区域侵蚀不整合面。该HS位于碳酸盐的斜形至马里组成的顶部和前缘之间的过渡处。3-D地震数据横截面中的HS表达式是不规则的,使HS出现截断面的外观,这可能被错误地解释为区域地震不整合。仔细检查发现,HS横切了年代地层斜面反射器,而频率提取处理表明,HS明显落在比斜面反射器更低的频带内。HS的形态(即连续紧密堆积的细胞)及其随时间变化的性质表明,它具有埋藏成岩作用。
更新日期:2019-11-20
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