Provenance analysis of sediments in SE Aegean during Upper Quaternary: A composite approach based on bulk and clay mineralogy and geochemistry

During the Miocene-Pleistocene, generally sub-tropical to tropical warm and humid paleoclimate prevailed in Southeast Asia with a gradual cooling trend. The Truc Thon clay (TTC) mine presents interesting outcrops for sedimentological and provenance analysis. The present study uses results of geological investigation in 16 outcrops and wells at the clay mine Truc Thon. The TTC has lens-shaped geometry, filled with two clay bodies, including grey-white clay and multicolor clay. Bulk mineralogy indicates the predominance of quartz and a relatively high amount of pyrophyllite. Clay mineralogy shows the presence of main kaolinite, followed by illite and mixed-layer illite-smectite. These may interpret a warm, humid paleoclimatic condition in the source areas. Illite may be inherited from basement rocks. The bulk rock geochemistry supports intense chemical weathering with the Chemical Index of Alteration (CIA) in the TTC ranged ca. 80.6-98 (average = 90.4). In combination with the geochemical proxies and the mineralogical composition of the TTC, the chemical weathering intensity indicated warm/hot, semi-humid/humid tropical paleoclimate in the source area. A combination of mineralogical and geochemical analyses with regional geological features show that the Hon Gai Triassic rocks are the main source for the TTC. Source materials are originally related to silicic rocks of granitic-granodioritic composition. Paleoclimatic conditions favored intense chemical weathering of the Hon Gai Triassic rocks and surrounding rocks, creating a ceramic mine of great industrial value.

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Implications for Provenance since the Last Glaciations in Southeastern Andaman Sea Sediments by Clay Mineralogy

Journal of Environmental Management and Tourism ◽

10.14505//jemt.10.1(33).14 ◽

2019 ◽

Vol 10 (1) ◽

pp. 140

Author(s):

Suratta BUNSOMBOONSAKUL ◽

Penjai SOMPONGCHAIYAKUL ◽

Zhifei LIU ◽

Akkaneewut CHABANGBORN ◽

Anond SNIDVONGS

Keyword(s):

Sea Level ◽

Clay Minerals ◽

Clay Mineral ◽

Clay Mineralogy ◽

Andaman Sea ◽

Interglacial Period ◽

Provenance Analysis ◽

Geological Time ◽

Core Mass ◽

Fine Grained

This study presents high-resolution clay mineralogy of Core MASS-III-10, located in the southeastern Andaman Sea. The study aimed to investigate terrigenous sedimentary input from various potential provenances throughout different periods of geological time. The clay mineral assemblages of MASS-III-10 reveal a high amount of smectite at 73% (65-79%), a moderate kaolinite at 12% (10-17%), and a low illite and chlorite content(<15%) over the last 45 ka. Provenance analysis suggests the most fine-grained terrigenous sediments originated from the Irrawaddy Delta Shelf (IDS), with minor sediments deriving from the Andaman Islands, the East Continental Shelf (ECS), and Sumatra provenance. The results show that IDS were predominantly smectite (~44%) while the ECS largely produced kaolinite (47%). The provenance interpretation based on the smectite content revealed that over time there has been no change in the main source of sediment in the Andaman Sea, despite changes in the volume of sedimentary input. Since the last glaciation, the Myanmar provenance (including IDS) has always contributed clay minerals, while other sources made up only minor contributions to the Andaman Sea. The clay minerals from the Myanmar provenance increased when the sea level was at a low stand (MIS 2), potentially due to shoreline retreat which enabled easier transportation of sediment from other sources. During the interglacial period (MIS 1 and 3), the study found a decrease in Myanmar-sourced clay minerals, which may be because the higher sea level made clay mineral deposition more difficult.

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