TY - JOUR
T1 - Diatomaceous sedimentation in the Tertiary Lampang Basin, Northern Thailand
AU - Owen, R B.
AU - Utha-aroon, C.
N1 - Funding Information:
This study was funded by a Faculty Research Grant (FRG/95-96/I-01) of the Hong Kong Baptist University. Field and logistic support was provided by the Economic Geology Division, Department of Mineral Resources in Thailand, which at the time was under the direction of Mr. Boonmai Inthuputi. We would like to thank Khun Preecha Nupairoj, our driver and field aide, for his excellent support. Thin sections of the rambutan nodules were prepared by Khun Pramuanpong Sindhusen of the Department of Land development in Bangkok.
PY - 1999/7
Y1 - 1999/7
N2 - The Lampang Basin is the second largest Tertiary graben in northern Thailand and was formed in response to the Himalayan orogeny. Deposition started with Miocene sandstone, lignite, mudstone, shale and oil shale of the Mae Sot Formation, which gave way to Pliocene diatomite, diatomaceous clay and silty clay of the Ko Kha Formation, with coarse clastics being restricted to the basin margins. Secondary iron-staining and iron-rich nodules are also common in the latter formation. Diatoms only occur in the Ko Kha Formation, where they are abundant and well-preserved. Five assemblages, indicative of fresh to moderately alkaline water, are present. These floras are variously dominated by Aulacoseira granulata, A. granulata var. valida, A. agassizi, A goetzeana, A. ambigua, A. italica var. bacilligera and A. italica var. tenuissima. Pennate species are present, but infrequent. During the Pliocene, in the Ban Pa Muang area, non-diatomaceous lacustrine sediments were initially laid down. These gave way to the deposition of diatomaceous clays and diatomites dominated by A. granulata and A. agassizi, which flourished in the deeper and shallower sectors (respectively) of a fresh water body. The palaeolake then became mildly alkaline, with a flora dominated by A. granulata var. valida. Shallow, fresh conditions followed, characterised by varied Aulacoseira diatoms, before the lake again became deeper. This latter phase may be related to increased river recharge.
AB - The Lampang Basin is the second largest Tertiary graben in northern Thailand and was formed in response to the Himalayan orogeny. Deposition started with Miocene sandstone, lignite, mudstone, shale and oil shale of the Mae Sot Formation, which gave way to Pliocene diatomite, diatomaceous clay and silty clay of the Ko Kha Formation, with coarse clastics being restricted to the basin margins. Secondary iron-staining and iron-rich nodules are also common in the latter formation. Diatoms only occur in the Ko Kha Formation, where they are abundant and well-preserved. Five assemblages, indicative of fresh to moderately alkaline water, are present. These floras are variously dominated by Aulacoseira granulata, A. granulata var. valida, A. agassizi, A goetzeana, A. ambigua, A. italica var. bacilligera and A. italica var. tenuissima. Pennate species are present, but infrequent. During the Pliocene, in the Ban Pa Muang area, non-diatomaceous lacustrine sediments were initially laid down. These gave way to the deposition of diatomaceous clays and diatomites dominated by A. granulata and A. agassizi, which flourished in the deeper and shallower sectors (respectively) of a fresh water body. The palaeolake then became mildly alkaline, with a flora dominated by A. granulata var. valida. Shallow, fresh conditions followed, characterised by varied Aulacoseira diatoms, before the lake again became deeper. This latter phase may be related to increased river recharge.
KW - Aulacoseira
KW - diatomite
KW - Tiertiary
KW - Thailand
KW - palaeogeography
KW - lakes
UR - http://www.scopus.com/inward/record.url?scp=0032804005&partnerID=8YFLogxK
U2 - 10.1023/A:1008033813344
DO - 10.1023/A:1008033813344
M3 - Journal article
AN - SCOPUS:0032804005
SN - 0921-2728
VL - 22
SP - 81
EP - 95
JO - Journal of Paleolimnology
JF - Journal of Paleolimnology
IS - 1
ER -