Effects of Variations in Subsidence and Sediment Supply on Parasequence Stacking Patterns

Author(s):  
F.L. Wehr
2019 ◽  
Vol 131 (9-10) ◽  
pp. 1643-1672 ◽  
Author(s):  
Simon A.J. Pattison

AbstractThe Campanian Desert Member and Lower Castlegate Sandstone in the Book Cliffs of east-central Utah to western Colorado, USA, has served as a foundational data set in the development of sequence stratigraphy. Contrary to previous work, no third-order sequence boundaries are recognized. These were originally thought to partition the neighboring coastal plain and shallow marine facies belts into separate systems tracts, unlinked in time or space. In contrast, adjoining channel-coastal plain and shallow marine facies belts are genetically-, temporally-, and spatially-related. Evidence includes the (i) synchronous, strongly progradational stacking patterns within each facies belt, (ii) gradational and conformable transitions between adjoining facies belts, accentuated by the ubiquity of flat-topped, rooted foreshore sandstones passing upwards into carbonaceous-rich-mudstone-dominated coastal plain, (iii) parasequence-scale interfingering of coastal plain-channel and foreshore-shoreface deposits, with channels, white caps and coals embedded within stacked shoreface parasequences, (iv) regional correlation of coals and flooding surfaces, and (v) near orthogonal paleocurrent relationship between channels and shorelines. Terminal channels incise into proximal foreshore-shoreface sandstones in most Desert-Castlegate parasequences. Incisions are generally confined to the parasequence in which the channels are nested, rarely cutting deeper. These shoreface-incised channels are cut and filled at a parasequence-scale, and are bounded above by the same flooding surface that caps each foreshore-shoreface package. The ubiquity of ascending regressive shoreface trajectories and near absence of descending regressive trajectories that intersect depositional slope argues against any significant sea level fall. Increased rates of sediment supply, driven by autogenic and/or allogenic processes, likely generated the strongly progradational Desert-Castlegate great tongue of sandstone.


2021 ◽  
Author(s):  
Nurul Syazwin Zamri ◽  
Ying Jia Teoh ◽  
Khalf Khiri AbuBakr ◽  
Meor Hakif Amir Hassan ◽  
Nur Azwin Ismail ◽  
...  

Abstract The purpose of this paper is to present information on the past sea-level fluctuations of sedimentary rock succession of the Perlis area that covers the Mempelam Limestone, Timah Tasoh Formation, Sanai Limestone, Telaga Jatoh Formation, Kubang Pasu Formation, and Chuping Formation at Bukit Tungku Lembu and Guar Sanai, Perlis, Malaysia. Based on sedimentology logging, cycle stacking patterns, and accommodation variations revealed by Fischer plots, 51 cyclic sequences of third-order depositional sequences are recognized. These sequences generally consist of transgressive and regressive events. As the thickness of the cycle column increases, it forms an increase in accommodation space and subsidence rate and results in rising sea level. As the thickness of the cycle column decreases, it will form a decrease in accommodation space and subsidence rate and resulting in sea-level fall. Generally, the facies of the cycle are vertically arranged, forming coarsening and fining upward patterns observed from sedimentology logging. The Silurian Mempelam Limestone-Carboniferous Chepor Member sequence is characterized by a progressive increase and decrease in accommodation space, indicating a rise and fall in sea level. In contrast, the Carboniferous Uppermost Kubang Pasu-Permian Chuping Limestone sequence is characterized by a progressive decrease in accommodation space, indicating a longer-term fall in sea level. The regressive-transgressive cycles recognize deviations in the accommodation space and sediment supply from the cyclic successions. In turn, these cycles are expressing the long-term of Perlis’s sea-level fluctuations. The results notably reflect the cycles consistent with the long-term rising and falling trend on different regions globally in Paleozoic times.


Geology ◽  
2019 ◽  
Vol 47 (11) ◽  
pp. 1011-1014 ◽  
Author(s):  
Daan Beelen ◽  
Christopher A.-L. Jackson ◽  
Stefano Patruno ◽  
David M. Hodgson ◽  
João P. Trabucho Alexandre

Abstract The geometry of basin-margin strata documents changes in water depth, slope steepness, and sedimentary facies distributions. Their stacking patterns are widely used to define shelf-edge trajectories, which reflect long-term variations in sediment supply and relative sea-level change. Here, we present a new method to reconstruct the geometries and trajectories of clinoform-bearing basin-margin successions. Our sequential decompaction technique explicitly accounts for downdip lithology variations, which are inherent to basin-margin stratigraphy. Our case studies show that preferential compaction of distal, fine-grained foresets and bottomsets results in a vertical extension of basin-margin strata and a basinward rotation of the original shelf-edge trajectory. We discuss the implications these effects have for sea-level reconstructions and for predicting the timing of sediment transfer to the basin floor.


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