Grain size analysis and depositional environment of shallow marine to basin floor, Kelantan River Delta

Author(s):  
M. R. Nurul Afifah ◽  
A. Che Aziz ◽  
M. Kamal Roslan

Grain size analysis of Turonian Amasiri Sandstone in southern Benue Trough has been undertaken to determine the controversial depositional environment of the formation. The formation was first studied on outcrops and 26 representative samples were collected and subjected to particle size analysis in line with standard procedures for dry sieving. Various methods of environmental interpretation of grain size distribution data were applied to constrain the depositional of the sandstones. The result indicates that the sands are medium and coarse-grained with mean size ranging from 0.15 to 1.87φ and averaging 0.96 φ. The sandstones are moderately to poorly sorted with standard deviation values ranging from 0.72 to 1.38 φ and averaging 1.07 φ. They exhibit a wide range of distribution from strongly coarse skewed to strongly fine skewed with skewness values ranging from -2.31 to 1.52 φ and averaging -0.04 φ but indicate a narrow range of kurtosis from mesokurtic to leptokurtic distribution with values ranging from 0.99 to 3.49 φ and an average of 2.06 φ. The sediments have bimodal with minor polymodal and unimodal distribution with primary modal size of 1.2 φ. The bivariate plots of size statistical parameters indicate fluvial environment of deposition. However, linear discriminant function analysis and the interpretations of log-probability plots indicate deposition in a fluvial, beach, and shallow marine settings, and thus suggesting a possible deposition in high-energy transitional environment. The C-M pattern of the samples indicates that sediments were transported mainly by rolling and suspension with subordinate fractions moved by rolling as well as suspension. Thus, it is deduced that Amasiri Sandstone was deposited in fluvial, beach, and agitated shallow marine environments.


2021 ◽  
Vol 11 (6) ◽  
pp. 2799
Author(s):  
Yanping Chen ◽  
Wenzhe Lyu ◽  
Tengfei Fu ◽  
Yan Li ◽  
Liang Yi

The Huanghe River (Yellow River) is the most sediment laden river system in the world, and many efforts have been conducted to understand modern deltaic evolution in response to anthropological impacts. However, the natural background and its linkage to climatic changes are less documented in previous studies. In this work, we studied the sediments of core YDZ–3 and marine surface samples by grain-size analysis to retrieve Holocene dynamics of the Huanghe River delta in detail. The main findings are as follows: The mean value of sediment grain size of the studied core is 5.5 ± 0.9 Φ, and silt and sand contents are 5.2 ± 2.3% and 8.2 ± 5.3%, respectively, while the variance of clay particles is relatively large with an average value of 86.4 ± 8.5%. All grain-size data can be mathematically partitioned by a Weibull-based function formula, and three subgroups were identified with modal sizes of 61.1 ± 28.9 μm, 30.0 ± 23.9 μm, and 2.8 ± 1.6 μm, respectively. There are eight intervals with abrupt changes in modal size of core YDZ–3, which can be correlated to paleo-superlobe migration of the Huanghe River in the Holocene. Based on these observations, the presence of seven superlobes in the history are confirmed for the first time and their ages are well constrained in this study, including Paleo-Superlobes Lijin (6400–5280 yr BP), Huanghua (4480–4190 yr BP), Jugezhuang (3880–3660 yr BP), Shajinzi (3070–2870 yr BP), Nigu (2780–2360 yr BP), Qikou (2140–2000 yr BP), and Kenli (1940–1780 and 1700–1650 yr BP). By tuning geomorphological events to a sedimentary proxy derived from core YDZ–3 and comparing to various paleoenvironmental changes, we proposed that winter climate dominated Holocene shifts of the Huanghe River delta on millennial timescales, while summer monsoons controlled deltaic evolution on centennial timescales.


2018 ◽  
Vol 5 (1) ◽  
pp. 183-199
Author(s):  
K. Deepthi ◽  
Usha Natesan ◽  
A. L. Muthulakshmi ◽  
Vincent A. Ferrer ◽  
S. V. Narasimhan ◽  
...  

2021 ◽  
Vol 38 (2) ◽  
pp. 79-84
Author(s):  
Indrajit Patra ◽  
William Prasad ◽  
A Y Rao

The concentration of heavy mineral placer deposits along the coastal tracts are function of various favourable factors i.e. hinterland geological formations, prevalence of favourable climatic condition, their transportation through intricate drainage systems and various coastal processes, which operated during the geological past. Textural analysis of the available unconsolidated sediments from the present deposits is of vital importance to decode the prevailing depositional environment while grain size analysis is the major parameter used. Present study highlights the grain size analysis of the identified sand column from Chhatrapur Mineral Sand Deposit along the coastal tract of Odisha to infer the environment of deposition of heavy mineral bearing sand and their heavy mineral content variation. Standard procedure of sampling, data analysis and interpretation techniques were adopted. Result shows that, sands from frontal and rear dune are characterized by distinct bi-modal distribution, medium to fine, moderately to well sorted with good positive skewness, whereas, sand from Inter-dunal region shows dominant unimodal, medium to coarse grain, moderately poorly sorted nature and slightly positive skewness. The better heavy mineral concentration (10 to 25 % grade) in frontal and rear dunes is attributed to prevalence of aeolian dune deposition accompanied by good sorting. In contrast, the low concentration of heavy mineral (3 to 6 %) in inter dune region is due to occasional fluvial regime and poor sorting of sediments. Thus, grain size analysis can be an effective tool to decipher local prevailing depositional environment, which has a bearing on heavy mineral concentration as well.


2020 ◽  
Vol 12 (1) ◽  
pp. 1512-1532
Author(s):  
Temitope Love Baiyegunhi ◽  
Kuiwu Liu ◽  
Oswald Gwavava ◽  
Christopher Baiyegunhi

AbstractA total of 92 representative sandstone samples of the Bredasdorp Basin in boreholes E-AH1, E-AJ1, E-BA1, E-BB1 and E-D3 have been investigated for their grain size characteristics. Grain size textural parameters and their cross plots, linear discriminate functions (LDFs), C–M (C = first percentile and M = median) diagram and log–probability plots were calculated and interpreted to understand the mode of transportation and hydrodynamic conditions and also to unravel the depositional environments of the sediments. The grain size textural parameters revealed that the Bredasdorp sandstones are unimodal, predominantly fine-grained, moderately well-sorted, mesokurtic and near symmetrical. The bivariate plots of grain size textural parameters indicate that the depositional environments had been influenced mainly by river/beach/coastal dune conditions. The LDF plots show that the sediments are turbidity current deposits in a shallow marine environment. The C–M diagram revealed that the studied sandstones were mainly deposited by traction currents and beach process. In addition, the grain size log–probability curves and C–M diagram show the predominance of suspension and saltation modes of sediment transportation. Based on the inter-relationship of the various statistical parameters, it is deduced that the Bredasdorp Basin are mainly shallow marine deposits with signature of beach and coastal river processes.


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