Table Of ContentNAT. HIST. BULL. SIAM Soc. 53(1): 17-32，20 05
TERTIARY BASIN EVOLUTION INN ORTHERN THAILAND:
A PALYNOLOGICAL POINT OFV IEW
Wickanet Songtham1，Be njavun Ratanasthie~， Manas Watanasa ，eT
ι ，
Dallas MildenhalfSampan Singharajwarapan2 and Wittaya Kandharosa
ABSτ"RACf
Tertiぽyb鎚加s泊northernThailand developed in Oligocene to Middle Miocene tirne. At
出eb巴g泊凶ngof developrnent白巴regionwas in aw ann ternperate clirnate. The飽町'ainwas
occupied by forest types cornparable to血巴presentrnid-latitude forests of the nor世間mhemi-
sphere.百leseforests consisted of co凶fercommunities composed of Dac.ηIdium，Po docarpus
(Podocarpaceae)，Pi cea，Pi nus，Ts uga (Pinaceae)，Se quoia and Taxodium (Tax吋iaceae).Broad-
leaf deciduous mesotherma1 taxa were a1so present，in cluding Acer (Acerace鎚，)Alnω，Betula，
Carpinus，C oηIlus (Beωlaceae)，Ca rya，Ju glans，Pt erocarya (Juglandaceae)，Fa gus，Q uercus
(Fagaceae)，Il ex (Aquifoliaceae)，Li quidambar (Hamamelidaceae)，an d Ulmus (Ulma<閃ae)wi由
ferns ∞mmon，e specia1ly Polypodiaceae and Pteris (Pteridaceae). In the Early Miocene the
climate changed and became wanner until in the la旬EarlyMiocene it w錨 comple除ly位。pic，1a
persisting until the end of血eMiddle Miocene. At血istime conifers and mesothermal taxa
declined and were replaced by evergreen megathermal taxa. These included Alangium
(AI加 giaceae)，Ammannia，L agerstroemia (L:同国印刷，Anogeissus (Combre版印刷，Bursera
(Burseraceae)，C aesa伊inia(Leguminosae-Caesalpinoideae)，C alophyllum (Guttiferae)，
Combretaceae，D ipterocarpaceae，D ipterocarpus，H opea (Diptero問中抑制，Homonoia
(Euphorbiaceae)，Il ex (Aquifoliaceae)，L e伊m泊osae・Mimosoideae，Myrtaceae，O ro.巧Ilum，
Radermachera (Bignoniaceae)，P andanus (P danaceae)，Sonneratiaceae，a nd Spondias
飢
(Anacardiaceae) with abundant spores from Lygodium (Schiazaeaceae)，P olypodiaceae，
Cya出.eaceae，and Pteris (Pteridaceae)泊somehorizons. These two pa1ynologica1 assemblages
came from different stratigraphic positions strongly suggesting that血ereare two m司jor
s回.tigraphiczones on the basis of pa伽lologyand there was am 旬。r<climatic change from a
wann temperate to a回 pica1condition across血eperiod of Oligocene to Middle Miocene.
Genera1ly，co a1s針。mOligocene to early Early Miocene foロnationsare sub-bituminous in rank
while coa1sf rom late Early Miocene to Middle Miocene formations are lignites. Since the
older，su b-bituminous coa1sa 1l conta泊 W釘rntemperate pa1aeofloras and血eyounger，le ss
deeply b町iedlignitic coa1sa1 l conta泊位。pica1pa1aeofloras. Dis甘ibutionpattern of the wann
temperate組 d甘opica1formation expos町民 in出isregion caused by mountain building and
cordilleran erosion is proposed.
町τ'RODUCTION
Northem Thailand ranges in latitude from about 16・to200 north and in longitude from
・
about 980 to 101 eastand is predom加antlyin the tropical zone (Fig. 1).百leregion is
IBu ofGeologica1 Survey，D epartment of Minera1 Resources，B angkok，T hailand
印刷
2Depar回entof Geologica1 Sciences，Fa culty of Science，C hiang Mai University，T hailand
3Faculty of Environment and Resource Studies，M ahidol Univer冨ity，Nakhornpathom，T hailand
4Institute of Geological and Nuclear Sciences，L ower Hutt，N ew Zea1and
Received 24 February 2004; a<∞epted 4M arch 2005.
17
18 甲山CKANETSONGTHAM ET AL
98 99 日JO 101
20
1. Fang BωIn
2.Po ng Bosln
19 3.C hlong Muan Bosln
4.N aH ong Bosln
5.C hlong MaiB asln
6.l ampong Bosln
7.M aeM oh Bosin
8.M aeT eep Basln
18 9.Ph rae Bosln
10. Mae5 01 Basln
11. MaeLo 円、aoBasln
12.P hltωnulok Bosln
13.N ong Ya Plong Basln
17
16
。
NokαnSawon
15
ld -1 N \ o Konchono以JIr
BANGKOK
100 km.
13 -1
Figure 1. Map of north巴rnand cenlralT hailand showing provincesa nd Tertiary basin localiti巴smentioned in
thisp aper
τ'ERTIARY BASIN EVOLUTION IN NORTHERN THAILAND 19
dominated by mountainous紅easwith some lowlands along four main回hutariesof the
Chao Phraya River，n amely the Ping，W ang，Y om，a nd Nan rivers.百emountain ranges
generally住endnortlトsouth，controlled by the main geological s住uct町'es.百lehighest peak
is Doi Intanon at 2，565 m above mean sea leve .lThere emany lower peaks of
紅
approximately similar heights such as Doi Pha Hom Pok，D oi Chiang Dao，D oi Phu Soi
Dao，加dDoi Lang Kha.百lelowland areas arちgenerally300 to 500 m above me佃 sea
level and contain the main rivers and some tributaries.
官leclimate of northem 百lailandis strongly seasonal and as is characteristic of a
monsoonal climate consists of altemate wet叩 ddry seasons each year.τ'hew 釘m，wet
season is between May and October with an annual rainfall vyingfrom 1，100 to 1，500
紅
mm.百le世yseason consists of ac ool dry and ah ot dry period of time.官官 cooldry
season，wi nter，is between November and February. December，Ja nuary，a nd February e
訂
virtually without rain.百lehot dry season，s ummer，is from March to May.
Vegetation in the region is a甘opicalforest nat町'allyvaried by two main factors，
moisture and altitude. Altitude differences result in two major forest types namely tropical
lowland forests and佐opicalmontane forests. Tropical lowland forests are at elevation
below 1，000 m above mean sea level and are regarded as typical tropical plant communities.
On the other hand，th e tropical montane between 1，000 and 2，565 m above mean sea level
are mainly occupied by typical w mtemperate plant communities.
創
Mountainous landforms with scattered isolated intermontane basins are the most obvious
topographic features of northem Thailand. Theb asins釘'ebound by pre-Tertiary rocks wi白
ages from Precambrian，P aleozoic，t o Mesozoic. Precambrian rocks 'eexposed d
釘 組
distributed over the westem s凶Pof the region extending north to south from Mae Hong
Son，C hiang Mai，to Tak prov泊ces.Precambrian rock types are metamorphic，i ncluding
gneiss，sc hist，a mphibolite-schist，q u紅白ite，calc-silicate，m arble，a nd biotite marble. The
central s凶pof the region is dominated by younger marine Paleozoic rocks，i ncluding
shale，sa ndstone，ph yllite，q utziticphyllite，li mestone，me talimestone，an d chert. Mesozoic
紅
rocks cover出eeastem p制 of出eregion and are dominated by non-metamorphic clastic
rocks. Marine Triassic rocks of the Lampang Group釘'econfined to血ecentral and eastem
boundary. Terrestrial red-bed clastic Jurassic rocks occur along the eastemmost strip with
some scattered marine Jurassic deposits加 thesouthwest of the region. Jurassic red-bed
formations in出.eareas of Chiang Muan District of Phayao Province have yielded dinosaur
bones which are now being studied by the Department of Mineral Resources.
Cenozoic deposits，i ncluding Tertiary and Quatemary sediments，o ccur in isolated
fault-bound graben and half graben intermontane basins. TheT ertiary deposits vary from
unconsolidated to consolidated sediments，n nelysand，c lay，c onglomerate，s andstone，
創
claystone，m udstone，oi l shale，d iatomite，a nd coal with crude oil sources泊 Fangand
Phitsanulok basins. Thes tratigraphic succession within each basin is different m紘ing出e
stratigraphy difficult to correlate in view of the differing depositional environments，t he
isolation of the basins and their differences in age and rock types (GIBLING &
RATANASTHlEN，1 980). Palaeontologically，v arious macrofossil旬xahave been reported
from Mae Moh，Li， Mae Teep，L amp g，Chiang Mai，C hiang Muan，M ae Sot，a nd Pong
佃
basins. Thef ossils include related forms of elephant，rh inoceros，pi g，ro dents，bi rd，d eer，
barking deer，ot ter，a nd primates，w ith common crocodile，tu rtle，fi sh，a nd molluscs. The
oldest known mantmal fossils in no叶lemThailand紅eStegolophodon remains from Na
Sai coal field in血eLi basin suggesting Lower Miocene or MN3 (TASSY ETA L.，1 992).
20 WICKANET SONGTHAM EfA L.
Normal and reverse magnetic po加itypa悦 rns合omthe Chiang Muan and Mae Mohb 出泊S
indicate al ate Middle Miocene age (BENAM閲 EfAL.，2 002; CHAIMANEE EfA L.，2 003).
Some basins，su ch as Na Hong，M ae Tun，M ae Lamao，N ong Ya Plong，an d Ban PU
and Ban Pa Khac oalfields泊 theLi basins，yi elded no indicative macrofossils to enable
establishment of bo血 ameaningful stratigraphy and the paleoenvironmenta1 and climatic
conditions during deposition.官邸paperrepo巾 onthe results of palynological research泊
both macrofossil-bearing and macrofossil-barren formations undertak:en to checkぜ白ey
contain different palynological assemblages.百usstudy also provides some ideas expla白血g
basin evolution in no油 ern百lailand泊 palynologicalterms.
MAτ'ERIALS ANDM ETHODS
Tertiary sedimentary samples were collected from in加montaneCenozoic basins and
processed for fossil sporomo中hs.Each sample w邸 initiallycleaned to get an inner
uncontaminated portion and was broken up into smaller pieces阻 dput泊toa2 50-ml
polypropylene beak:er. Diluted hydrochloric acid (10% HCl) was applied and left until air
bubbles disappeared at which time all carbonates were removed. Subsequently，hy drofluoric
acid (48% HF) was added for aw eek under room temperature to remove silicates and
followed up with 10% HCl to prevent formation of calcium fluoride.百leresidues were
then oxidised by concentrated nitric acid (1町03)for 3t o 5m inutes and washed with
diluted potassium hydroxide (5% KOH).官leresidues were washed with disti11ed water
and出encentrifuged，u p to白reetimes，ev ery time the chemicals were changed. F泊ally，
the residues were sieved by nylon net to obtain the 11 to 133 micron仕actionswhich were
kept in as mall vial with dilute polyvinyl alcohol solution (PVA ).官levial was labelled
with the sample number and date of preparation.
A few drops of the polyvinyl alcohol solution containing suspended sporomo甲hswere
smeared onto ac over slip that was placed on ah eated hotplate.百usDUXture would
dispersed evenly over the cover slip surface and adhere as af ilm to the cover slip after it
dried.τ'hec over slip would then be sealed to as lide glass by one or two drops of Eukitt
mounting medium solution and allowed to命yat room tempera加reovernight. Each slide
was labelled with the snplenumber and some important identification information. This
釘
slide was examined under al ight microscope.
A small drop of polyvinyl alcohol solution with suspended sporomorphs was also
applied to aw m l-cm diameter rounded cover slip，w hich was equal in size to the
創
.sc anning electron DUcroscope (SEM) stub being used.官lIsmixture dispersed even1yo ver
the cover slip surface and adhered as af ilm to the cover slip when it合ied.百lecover slip
was then placed on the SEM stub with as mall piece of carbon sticky tape. Then the
sporomorphs were coated with gold under av acuum. This coating needed to be as血inas
possible and yet effective for SEM. A 15 to 30・nanometrecoat泊gsatisfied血isneed.百le
stub was stored in ad esiccator to keep血especimens dry at all times prior to use in SEM
work.
Microscopic work was done with bo白 alight microscope and aS EM.τbe light
microscope was used for sporomo甲hobservation and statistical counting.τ'heS EM was
used for detail study of features observed under the light microscope. Sporomorphs were
described and photographed with both light dSEM.
組
百 RTIARYBASIN EVOLUTION町 NORTHERNTHAILAND 21
百lesporomorphs were studied using aZ eiss light microscope，Ax iolab，w hich was
usually connected to digital equipment and ac omputer.τ'hea nalogue image f旨omthe
microscope was transferred to digital form by special computer hardware and出endisplayed
on ac omputer monitor by sp配 ificKS・200software，ve rsion 2.00.百出 operationmade
statistical counting easier. This work was done at白eDepar加lentof Mineral Resources in
Bangkok.
A Jeol JSM 5410 model w出 usedas the scanning electron microscope sys飽m.百lis
equipment is at the National Science and Technology Development Agency (NSTDA)泊
Pathumthani.
PALYNOLOGY
Fossil sporomorphs identified here are generally named using form generic
nomenclature. Some features of fossil sporomorphs are well compableto those of reent
紅 氾
forms，pa rticularly at白egeneric佃 dfamily levels. Therefore，s ome fossil sporomorphs
were named using Linnaean nomenclature where they were deemed identical to the recent
forms，e specially with respect to tropical pollen. Linnaean names are used (Table 1) as
their botanical affmities where the palaeophytogeographic setting is described.
Fossil sporomo中hsfrom this study are classified into two main groups. One group
contains pollen with morphologies close to recent w mtemperate pollen，an d the other
紅
group is tropical. Warm temperate and佐opicalpollen are clearly distinguishable by
differences in their general morphology. Pollen classification using the Linnean system is
the best way to group pollen assemblages when reconstructing palaeophytogeographic
settings at the time of sedimentation組 dto comp紅efossil with modem vegetation.τ'hus
fossil pollen c beused as indicative of as imilar ecological tolerance to its modem form
釦
when its mo甲hologyis comparable to血atform. However，m 組 yfossil sporomorphs，
including some pollen，s pores，a nd microscopic algae，c annot be placed into血ewarm
temperate or tropical group. Some of these are used as supplementary evidence in白e
elucidation of depositional environments. Some pollen and spores like Cyperaceaepollis
neogenicus，S porotrapoidites medius and Striatriletes susannae，a s well as the algae
Actinastrum，Bo tη ，Cl osterium，an d Pediastrum，'efreshwater elements suggesting
IOCOCCUS 紅
sedimentation加 alacustrine environment.
Some elements of the warm temperate and tropical fossil pollen assemblages e
釘
illustrated on Plates 1，II ，a nd III.
Warm Temperate Pollen Assemblages
百leseassemblages were derived from five sedimentary formations namely NaH ong，
Mae Tun，a nd Mae Lamao basins and Ban pu and Ban Pa Khac oalfields in出，eLi basin.
τ'hese formations yielded exclusively w mtemperate pollen without the presence of any
創
distinctive tropical pollen. Pollen compositions of the five formations 'esomewhat similar.
釘
They comprise conifer pollen Dacrydiumites florinii，P odocarpidites ellipticus，
Tsugaepollenites igniculus，l naperturopollenites dubius，P inuspollenites，a nd
Piceaepollenites.' Angiosperm pollen consists of Aceripollis，A lnipollenites verus，
Caryapollenites simplex，F aguspollenites，ll expollenites iliacus，Ju glanspollenites verus，
22
WICKANET SONGTHAM ETA L
Table 1. Lists of fossil sporomorphs recovered from the Terti創ysediments of northem
τ
'hailand with their botanical affinities.
ー。
白a回凶a u占E
Sporomorph/Basin 民由皆孟凶由晶国帽同 ー。e帽 ド田園 z知。国 ~ -明国同 同。。Ea主 邑 Botanical affinity
Z帽 筒国国 凶司国 E帽E 冨司副 国園 E帽EZ 帽 冨司 2帽副2民 E包国S
Gymnosperms
Araucariacites a/IJtralis X IX Araucaria (Araucariaceae)
Dacrydiumites florinii x xI Da crydium (Pod paαae)
侃訂
lnaperturopol/enites dubi，ω X IX X IX X IX IX Taxodium，Se quoia
Piceaepollenites X IX X IX X IX x Picea (Pinaceae)
Pin/IJpol/enites X IX X IX X IX IX X IX Pinus (Pinac儲e)
Podocarpidites ellipticus X IX X IX X IX X IX Podocarpus (Podoc訂paceae)
Tsugaepollenites ignicul/IJ X IX X IX X IX IX Tsuga (Pinaceae)
Angiosperms
Ace.r伊ollis x x X IX Acer (Aceraceae)
Alnipol/enites verω X IX X IX X IX IX X IX Alnus (Betulaωae)
Cary沼Ipollenitessimplex X IX X IX X IX X IX Carya (Juglandaceae)
Fag/IJpol/enites X IX X IX x X IX Fag/IJ (Fagac凶e)
llexpol/enites iliac附 X IX X IX X IX X IX llex (Aquifoliac倒的
Jugla.n伊ol/enites即rus x X IX x Juglan.s (Jugl叩da悶 e)
Liquidambarpollenites stigmos/IJ X IX X IX X IX L句uidambar
Momipites coryloides X IX X IX X IX x Coηlω(Be知lac伺e)
Polyporopollenites carpinoides x Carpinus (Be加laceae)
Pterocary百Ipollenitesstellat/IJ X IX IX x Pterocarya (Juglandaceae)
Quercoidites X IX IX X IX X IX Quercus (Fagaωae)
Retit附 C。伊ites x x Oleaceae
Salixpol/enites discoloripites x x x Salicaceae
Trivestibulopollenites betuloides x X X IX x Betula (Betulac儲e)
Ulmipol/enites x Ulmus (Ulmaceae))
Ammania x x Ammania (Ly伽閥的
Bombacacidites x Bombaca民活E
Bursera x x Bursera (Burserace)
悶
Calophyllum Calophyllum (Guttiferae)
Cardamine x Cardamine (Cruciferae)
Cephalomappa Cephalomappa (Euphorbiaceae)
Combretaceae Combretaceae
Dipter，∞訂pac侃E X IX Dipterocarpaceae
Dipterocarpus x X IX Dipterocarpus (Dipterocarpaceae)
Flo rschuetzia X Sonneratiaceae
Homonoia X IX IX Homonoia (Euphorbiaceae)
Hopea E x Hopea (Dipteroc唱rpaceae)
Lagerstroemia x X IX E Lagerstroemia (Ly由問問e)
Margocolporites vanwijhei x X IX Caesa炉inia(Leguminosae・Caesalpinoideae)
Myrtaceidites mesonesus x x Myrtaceae
Oro.勾lum x Oroxylum (Bignoniac伺e)
Pandaniidites texus x Pandanus (Pandanaceae)
Peヴ'otricolpitesdigitatus x Merremia (Convolvulaceae)
τ'ERTIARY BASIN EVOLUTION IN NORTHERN THAILAND 23
Table 1. (continued)
。。
= -Egha 'EhubE・司 4
凶」帽
Sporomorph/Basin 国ag ao 白E岡 自司司 2ド E初 国 2」-2=- 帽国圃 zま 邑 Botanical affinity
Z司 箇国司 簡書:帽zE帽E 2帽2Z 帽 Z帽曲E ~司副 Ba帽Eh ao
Radermachera x Radermachera (Bignoniaωae)
Spondias x Spondias (Anacardiaceae)
Striatricゆitescatatumbus Crudia (Leguminosae-Caesalpinoideae)
Monoporopo/lenites gramineoides x X IX IX x Grarnineae
Cyperaceaepo/lis neogenicω X x Cyperaceae
Sporotrapoidites附'diω X X IX Trapaσrapaceae)
Ferns
8aculatisporites primarii旧 x x H卯lenophyllaceae
Crassoretitriletes vanraadshoovenii x Lygodium (Schizaeaceae)
Cy官thiditesminor E x 匂a曲eaceae
Fove otriletes margaritae X IX Lycop叫laceae
Laevigatosporites haardtii X IX X IX X IX x X IX Polypodiaceae
Polypodiaceoisporites retirugatus x X IX x X IPt eris (Pteridaceae)
Polypodiisporites alienus x x X IX Polypodiaceae
Polypodiisporites inangahuensis x x Polypodiaceae
Polypodiispor附 minimus x x x Nephrolepis (Davalliaceae)
Polypodiisporites pohangensis x X IX Polypodiaceae
Polypodiisporites radiatus x X IX x Polypodiaceae
Polypodiisporites usmensis Polypodiaceae
Rugulati平，oritesquint凶 x Polypodiaceae
Striatriletes susannae x X IX X IX Ceratopte.，is thalictoides (Pteridaceae)
Undulatisporites undu/irad.iω x Fem
Algae
Actinastrum X IX Actinastrum
8otryococcus c .f8braunii x x x 8otryococcus c .f8braunii
， ，
Closterium x x Closterium
Pediastrum boryanum x x X IX x X IX Pediastrum boryanum
Pediastrum duplex x Pediastrum duplιr
Pediastrum simplex x x X IX E X IX Ped iastrum simplex
24
WICKANET SONGTHAME TA L
Plat巴1 1: Pilluspolleniles - Ban Pa Kha; 2: Piceaepolleniles - Ban Pa Kha; 3:In aperlllropolleniles dubias
- Ban Pa Kha; 4: TSlIgaepolleniles igniclllus- Ban PaK ha; 5: PodocGljJidiles - Ban Pa Kha;
6:C aryapolleniles sil1lpl.eλ一-Na Hong;7 -8: Alnipolleniles \lemsーー BanPa Kha; 9: lIexpolleniles
iliacus - Ban Pa Kha; 10: Juglanspolleniles \lerus - Ban Pa Kha; 11:P lerocaryapolleniles SlellalUS
Ban Pa Kha; 12:L iqllidal1lbarpolleniles sligl1loSIISーー BanPa Kha.A IIscal巴barsare 10 microns
TERTIARY sASIN EVOLUTION IN NORTHERN THAILAND 25
PlmeI l.1 :M omipites coryloides - sanP aK ha; 2:R eli/rescolpi/es - Naトlong3-4:Sporo/rapoidi/es medills
‘
一-Na Hong; 5: Calophyllllll1 - Na Sa :i6:!- Iol1lolloia - Ma巴Long;7:!- Iopea - Chiang Muan:
8-9: Lagers/roerl1iaー ChiangMuan. A IIscaleb arsa I巴 10micronse xcept whereo th巴rwisestated.
26 WICKANETS ONGTHAM ET AL
Plate日1.1:c f. Oroxylum一MaeMoh; 2:Sr riarricolpires cararumblls- Na Sai;3: Allogeissus - Chiang Muan;
4: Alangiopollis - Ban Pa Kha; 5: BorryococclIs- Na Sai; 6:P ediasrrum simplex - Ban Pa Kha;
7:P ediasrrtlm simplex - Ban Pa Kha; 8:P ediastrtlm borya1/ul1l - Ban PaK ha; 9: Pediastrlll17 duplex
BanP a Kha. A IIscal巴bars加e10 microns exceptw h巴reotherwise stated
