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Late Mesozoic sandstone volumes recorded in Gulf of Mexico subsurface depocentres: Deciphering long-term sediment supply trends and contributions by paleo river systems
Basin Research ( IF 3.2 ) Pub Date : 2022-01-28 , DOI: 10.1111/bre.12659
John W. Snedden 1 , Harry L. Hull 2 , Timothy L. Whiteaker 3 , Jon W. Virdell 3 , Catherine H. Ross 2
Affiliation  

Quantitative assessment of terrigenous sediment flux to the deep basin has mainly been limited to the Cenozoic Era, given challenges with reconstruction of more ancient source to sink systems. Subsurface mapping in the northern Gulf of Mexico basin, where there is a robust database of wells and seismic data, allows estimation of sand-size grain volumes within 12 chronostratigraphically defined Late Mesozoic supersequences. Five subsurface depocentres with thicknesses of >400 m are identified, revealing a history of sediment routing via major fluvial axes (paleo rivers) southward from a mid-continent drainage divide. The interpreted paleo-rivers are further confirmed by compilation and synthesis of published and novel detrital zircon provenance data showing combinations of age peak subsets that vary considerably between depocentres. This study quantifies sediment volumes within each depocentre by inverting porosity over defined gross rock volumes derived from subsurface well logs and 2D seismic mapping. Two temporal trends of progressively increasing grain volume can be related to climatic effects on fluvial discharge and sediment delivery to the depocentres: (1) Late Jurassic to Early Cretaceous (Oxfordian to early Aptian) and (2) Late Cretaceous (Late Aptian to Coniacian). The first temporal trend probably reflects the local climate becoming less arid with northward drift of the North American Plate into higher latitudes. The second trend mirrors increasing Cretaceous paleotemperatures and rising global sea levels. This second trend is also marked by increased shelf margin bypass of sand indicated by deep basin drilling. Partitioning of Late Mesozoic grain volume by fluvial axes shows that the Paleo-Apalachicola and Paleo-Mississippi rivers, sourced from Appalachian basement terranes, generated the largest and longest terrigenous sediment flux into the Gulf of Mexico basin in the Late Mesozoic. Overall, Late Mesozoic siliciclastic grain volumes are estimated to be an order of magnitude less than those previously documented for the Cenozoic Era.

中文翻译:

墨西哥湾地下沉积中心记录的中生代晚期砂岩体积:破译古河流系统的长期沉积物供应趋势和贡献

考虑到重建更古老的源汇系统面临挑战,对流向深盆地的陆源沉积物通量的定量评估主要局限于新生代。墨西哥湾盆地北部的地下测绘有一个强大的井和地震数据数据库,可以估计 12 个年代地层定义的晚中生代超层序内的沙粒大小。确定了五个厚度大于 400 m 的地下沉积中心,揭示了沉积物从大陆中部排水分界线向南通过主要河流轴(古河流)的历史。已发表的和新的碎屑锆石来源数据的汇编和综合进一步证实了解释的古河流,这些数据显示了在沉积中心之间差异很大的年龄峰值子集的组合。本研究通过反演从地下测井和二维地震测绘得出的定义的总岩石体积的孔隙度来量化每个沉积中心内的沉积物体积。颗粒体积逐渐增加的两种时间趋势可能与气候对河流排放和沉积物输送到沉积中心的影响有关:(1)晚侏罗世至早白垩世(牛津纪至早阿普提亚)和(2)晚白垩世(晚阿普提亚至科尼亚纪) . 第一个时间趋势可能反映了随着北美板块向北漂移到高纬度地区,当地气候变得不那么干旱。第二个趋势反映了白垩纪古温度的增加和全球海平面的上升。第二个趋势的特点还在于深盆地钻探表明陆架边缘绕流砂的增加。通过河流轴划分晚中生代颗粒体积表明,源自阿巴拉契亚基底地体的古-阿巴拉契科拉河和古-密西西比河在晚中生代产生了进入墨西哥湾盆地的最大和最长的陆源沉积物通量。总体而言,估计晚中生代硅质碎屑颗粒体积比先前记录的新生代要少一个数量级。
更新日期:2022-01-28
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