Lower Permian glacially influenced deposits in Phuket and ... · Themotic Article Lower Permian...

Themotic ArticleLower Permian glacially influenced deposits in Phuket and adjacent

islands, peninsular Thailand

TIANPAN AMPAIWAN,1,* KEN-ICHIRO HISADA2 AND PUNYA CHARUSIRI3

1Chevron Thailand Exploration and Production, SCB Park East Building, 19, Chatuchak, Bangkok 10900,Thailand (email: [email protected]), 2Graduate School of Life and Environmental Sciences, University ofTsukuba, Ibaraki 305-8572 Japan, and 3Research Unit for Earthquake and Tectonic Geology, Department of

Geology, Chulalongkorn University, Bangkok 10330, Thailand

Abstract It has previously been proposed that the Sibumasu block of Southeast Asia,which contains glaciomarine deposits, became detached from the Gondwana margin duringthe Early Permian. A combination of facies analysis and the identification of dropstonesand dump structures from a Lower Permian diamictite-bearing sequence at Phuket, Thai-land, and adjacent islands suggests that the sediments originated as glaciomarine anddebris-flow deposits. The Lower Permian diamictite-bearing sequence in the study areacorresponds to the Ko Sire and Ko He Formations, both of which consist of three principallithofacies: diamictite, sandstone, and fine-grained facies. The low-lying Ko Sire Formationis up to 400 m thick and is characterized by laminated mudstone; the presence of drop-stones and dump structures associated with Cruziana ichnofacies indicates ice-raftedsedimentation in a glacially influenced offshore area. The Ko Sire Formation is overlain bya diamictite sequence of the Ko He Formation (up to 400 m thick). Poorly and well-stratifieddiamictites with tabular and lensoidal geometries, in combination with resedimentationtextures, indicate that the diamictites within the Ko He Formation are debris-flow deposits.The similar lithology of clasts in the diamictites and dropstones possibly suggests that thedebris-flow diamictite was presumably remobilized from pre-existing glacial deposits. Theevidence of a glacially influenced offshore environment supports a previously proposedpaleogeographic interpretation in which the Sibumasu block was most likely located at theNorthwest Australian margin of Gondwana.

Key words: dropstone structure, dump structure, Early Permian, glaciomarine, Gondwana,Sibumasu block.

INTRODUCTION

The Permo–Carboniferous glaciation across Gond-wana was the longest-lived of the multiple glacia-tions that occurred during the Phanerozoic(Veevers & Powell 1987). The event was recordedin Permo–Carboniferous sedimentary sequencesof both glacioterrestial and glaciomarine deposits(Eyles 1993). The climatic conditions of this periodsaw the emergence of both distinctive terrestrialflora and cold-water fauna (Veevers & Powell 1987;

Wopfner 1996; Wang et al. 2001). The glacialdeposits and Gondwana-affinity flora and fauna aredistinguishing features of this period.

Metcalfe (1999) proposed that the Sibumasublock, the Shan–Thai microcontinent of Bunopas(1982), of Southeast Asia, which includes the ShanState of Myanmar, western Thailand, peninsularMyanmar and Thailand, western Malaysia, andSumatra (Indonesia), was originally located at theNorthwest Australian margin of northeast Gond-wana, and rifted and drifted away from this sitein the Early Permian. This interpretation of theorigin of the Sibumasu block is well supported byextensive paleobiogeographical data (Burrett &

*Correspondence.

Received 5 June 2007; accepted for publication 21 August 2008.

Island Arc (2009) 18, 52–68

© 2009 The AuthorsJournal compilation © 2009 Blackwell Publishing Asia Pty Ltd

doi:10.1111/j.1440-1738.2008.00653.x

mailto:[email protected]

Stait 1985; Burrett et al. 1990; Shi & Archbold1995).

‘Diamictite’ is a non-genetic term used todescribe unsorted sedimentary rocks that com-prise a lithified mixture of gravel, sand, and mud(Flint et al. 1960). A possible glaciomarine originfor the Permo–Carboniferous diamictite-bearingsequence within the Sibumasu block in Malaysiaand Thailand (Fig. 1) was first proposed byStauffer and Mantajit (1981), followed by similarinterpretations by Tantiwanit et al. (1983),Stauffer and Lee (1986) and Raksaskulwong andWongwanich (1993); however, previous interpreta-tions of the sequence favored an origin as slopedeposits associated with subaqueous debris flows(Mitchell et al. 1970; Piyasin 1975; Altermann1986).

To verify the glaciomarine origin of thesequence, it is necessary to clearly identify sedi-mentary structures related to glaciomarine sedi-mentation (Eyles 1988; Eyles et al. 1998; Martin1999; Condon et al. 2002). Dropstones and dumpstructures provide important diagnostic evidencefor the deposition of debris from melting icebergs(Thomas & Connell 1985). A dropstone structureforms when a stone drops from a melting iceberg,thereby deforming, penetrating, and rupturinglaminae within the seafloor sediments. A dumpstructure is formed when a large amount of debrisis released by the break-up of icebergs (Miller1996). Essential additional criteria in the inter-pretation of such rocks for a glaciomarine originare the sedimentary facies and the stratigraphicsequence (Eyles et al. 1983, 1985; Hambrey 1994;Martin 1999).

The main aims of the present study are to sys-tematically examine lithofacies of the diamictite-bearing sequence in Phuket and adjacent islands,interpret the depositional environments of thesequence, and reconstruct the paleogeography ofthe Sibumasu block. Field observations focused onthree outcrops along coastal zones of Ko Sire, KoYao Noi, and Ko Phi Phi Don (‘Ko’ is Thai for‘island’) (Figs 2,3). The facies codes used in thepresent study are taken from Miall (1977), Eyleset al. (1983), Martin (1999), and Eyles and Eyles(2000).

STRATIGRAPHIC OUTLINE

The Paleozoic stratigraphy of the Sibumasu blockin western and peninsular Thailand comprises ashallow-shelf siliciclastic sequence of the Cam-

brian Tarutao Group, a tidal to deep-marine car-bonate sequence of the Ordovician Thung SongGroup, a clastic and carbonate shelf sequence ofthe Siluro–Devonian Thong Pha Phum Group,a diamictite-bearing sequence of the Permo–Carboniferous Kaeng Krachan Group, and a car-bonate shelf sequence of the Permian RatburiGroup (Bunopas 1994; Wongwanich et al. 2002). In

Fig. 1 Distribution of the Permo–Carboniferous diamictite-bearingsequences on Southeast Asia (modified from Raksaskulwong & Wong-wanich 1993; Charusiri et al. 2002; Jin 2002).

Glacially influenced deposits, Thailand 53


some areas in western and peninsular Thailand,the Thong Pha Phum Group extends up to EarlyPermian in age. The Cambrian and Ordoviciansequences are generally affected by low-grademetamorphism, especially in western Thailand(Wongwanich et al. 2002). Paleontological evidencewithin the Ordovician and Siluro–Devonian se-quences suggests that the Sibumasu block waspart of Gondwana (Burrett et al. 1990). Thesequence is overlain by the Permo–Carboniferousdiamictite-bearing sequence.

Paleomagnetic and paleontological data indicatethat the Sibumasu block rifted from Gondwana inthe Early Permian (Metcalfe 1999), drifting north-ward across the Paleotethys from the mid-latitudeGondwana margin toward a low-latitude tropical

belt where the Middle Permian Ratburi Group wasdeposited (Ueno 2003). The Paleotethys was closedcompletely during the Triassic following multipleepisodes of collision and the amalgamation oftectonic blocks such as the Sibumasu (Shan–Thai), Lampang–Chiang Rai, Nakhon Thai, andIndochina blocks (Charusiri et al. 2002). Theseevents led to the formation of the majority of main-land Southeast Asia.

The Permo–Carboniferous diamictite-bearingsequence of the Kaeng Krachan Group, Thailand,was first proposed by Piyasin (1975) and laterrevised by Raksaskulwong and Wongwanich (1993),who divided the group into the following four for-mations (in ascending stratigraphic order): KhaoWang Kradat, Spillway, Ko He, and Khao Phra. The

Fig. 2 Geological map of Phuket andadjacent islands (after Mantajit and Hin-thong 1999).

54 T. Ampaiwan et al.


Fig. 3 Geological maps of (a) Ko Sire, Phuket, (b) southern Ko Yao Noi, and (c) northern Ko Phi Phi Don.



diamictite is a distinctive component of the KaengKrachan Group, and occurs only in the Spillway andKo He Formations (Raksaskulwong & Wongwanich1993). The Spillway Formation was establishedbased on rocks exposed along the spillway of theKaeng Krachan dam; however, the rules of strati-graphic nomenclature dictate that a lithostrati-graphic unit should be named from an appropriateplace name shown on a topographical map. Accord-ingly, in the present study we use the Ko SireFormation rather than the Spillway Formation.

KO SIRE FORMATION

The Ko Sire Formation is characterized by lami-nated mudstone and siltstone along with localdropstones and dump structures. The coastlinesalong Laem Mai Phai and Laem Phap Pha (‘Laem’is Thai for ‘cape’) upon Ko Sire, eastern Phuket(Figs 2,3a), were chosen for the type section of theformation because of extensive exposures thatcontain well-preserved dropstones and dumpstructures. The Ko Sire Formation is conformablyoverlain by the Ko He Formation, but the lowerboundary of the Ko Sire Formation is not exposedat the type section. In the measured section at KoPhi Phi Don (Fig. 3c), the Ko Sire Formation over-lies an unnamed quartzitic sandstone sequenceand is conformably overlain by the Ko He Forma-tion. The brachiopod fauna found within calcareousnodules and lenses in the Ko Sire Formation at KoPhi Phi Don were identified by Waterhouse (1982).The age of the brachiopod assemblage is mostlikely to be Late Asselian to Early Sakmarian (Shi& Archbold 1998). The thickness of the formationvaries from approximately 100 to 400 m.

FACIES DESCRIPTION OF KO SIRE FORMATION

Three principal lithofacies are identified within theKo Sire Formation: diamictite, sandstone, andfine-grained facies that locally contain dropstonesand dump structures. The fine-grained facies is therepresentative lithofacies of the Ko Sire Forma-tion, while the others are subordinate lithofacies(Fig. 4).

Diamictite facies

A diamictite facies is defined as a very poorlysorted sedimentary rock consisting of a randomdistribution of gravel and sand within a mudmatrix (Flint et al. 1960). The diamictite facies

within the Ko Sire Formation, which makes upapproximately 10% of the formation (Fig. 4),can be divided into two types: massive matrix-supported diamictite and graded matrix-supported diamictite. The clasts in the diamictiteare made up of quartzite, mudstone/shale, carbon-ates, and vein quartz (Fig. 5). The density of clastsvaries from 75 to 120 clasts per m2 (for countedclasts larger than granule size). The roundness ofthe clasts, as measured using the visual compari-son charts of Powers (1953) and Krumbein (1941),varies from rounded (0.7) to sub-rounded (0.4);both the statistical mode and mean of roundnessfall into the category of rounded. The largest clastsfound in this facies are 10-cm cobbles. The diamic-tite beds usually contain faint laminations, andare interbedded with laminated mudstone alongsharp contacts (Fig. 6a). Some of the diamictitebeds contain broken fragments of solitary rugosecorals.

Sandstone facies

The sandstone facies is a relatively minor constitu-ent of the Ko Sire Formation, and usually occurs asalternating layers within the fine-grained facies(Fig. 6b). The sandstone is a very fine- to medium-grained, moderately- to well-sorted quartz arenite,with beds ranging from 1 to 10 cm in thickness.The sandstone facies is characterized by low-anglecross-bedding, ripple cross-laminations, andplanar stratifications.

The low-angle cross-bedding is usually associ-ated with the ripple cross-laminations; however,at Ko Phi Phi Don the low-angle cross-beddedsandstone overlies the diamictite along a sharpcontact and is conformably overlain by laminatedmudstone. The layer of low-angle cross-beddingis approximately 10 to 20 cm thick. The ripplesare asymmetrical and have small amplitudes ofapproximately 2 cm (Fig. 6b). The planar stratifiedsandstone is commonly in sharp contact with alter-nating laminated mudstone, and commonly showsgraded bedding from fine to very fine-grainedsandstone, and finally ripple cross-laminated, veryfine-grained sandstone and siltstone on top. Con-volution structures are observed in some of thesandstone beds.

Fine-grained facies

The facies consists of laminated mudstone and silt-stone, deformed laminated mudstone and silt-stone, and massive mudstone. The facies is



generally alternated with either the diamictite orsandstone facies (Fig. 6a,b). Laminations withinthe facies are parallel and laterally continuous.The light-colored siltstone layers are composedmainly of fine sand- to silt-sized quartz in calcare-ous cement. In some cases, the siltstone layershows fine-scale normal grading that can beobserved under the microscope (Fig. 6c). Themudstone layers are gray to dark gray in color andcontain abundant organic matter. Several horizonsof the laminated mudstone and siltstone are bio-turbated. The Ko Sire Formation contains trace

fossils such as Planolites sp., Teichichnus sp., andChondrites sp. At Ko Yao Noi and Ko Phi Phi Don,the fine-grained facies commonly contains calcar-eous nodules and lenses that yield rare brachio-pods and nautiloids. The long axes of the lenses areapproximately parallel to the surrounding beddingplanes.

The deformed laminated mudstone and siltstoneis characterized by soft-sediment deformation,including simple and complex recumbent folds(Fig. 6d); these structures are especially commonat Ko Sire. Rounded quartzite clasts are sparsely

Fig. 4 Stratigraphic columns from the measured sections in (a) Ko Sire (Laem Phap Pha, Laem Mai Phai) and (b) northern area of Laem Mai Phai, KoYao Noi, and Ko Phi Phi Don. The gray area shows the equivalent to the Ko He Formation. D, S and F as the first part of the facies codes represent diamict,sand, and fines (silt and clay), respectively. One or two letters as the second part of each facies code describe the common internal feature of the lithofacies.



distributed within dark gray to gray massive mud-stone. Under the microscope, sand-sized quartzgrains are commonly observed in the mudstonematrix.

DROPSTONE STRUCTURES

Well-preserved dropstone structures areobserved in the Ko Sire Formation at Ko Sire.Evidence of dropstone structures includes thedistortion of laminations immediately below agranite boulder that is 70 cm in diameter (Fig. 7a)

and the occurrence of a quartzite boulder (50 cmin diameter) within well-laminated mudstone. Anumber of cobble-size dropstones were also foundat the same locations. The laminations immedi-ately below the dropstones are either penetrated(Fig. 7a,b) or down-warped (Fig. 7c). In contrast,the laminations above the dropstones either onlapthe dropstones (Fig. 7a,b) or are gently curved(Fig. 7c). The degree of distortion of the lamina-tions varies according to the size and shape ofthe clasts, as described by Thomas and Connell(1985).

Fig. 4 Continued



Lithologically, the dropstones are one of quartz-ite, granite/gneiss, carbonate, or slate (Fig. 8).They show flattened surfaces along the long axis(Fig. 7b,c) and rounded edges (Fig. 7c). Striationsare not observed on the surfaces of the dropstones.The proportion of striated clasts within glaciogenicsediments has been estimated to be approximately10% for carbonate clasts, and lesser proportionsfor quartz, quartzite, sandstone, and granite clasts(Wentworth 1936; Dowdeswell et al. 1985). In thecase of the Ko Sire Formation, the lithology of thedropstones appears to be unfavorable in terms ofthe development of striations on their surfaces.

In some outcrops of the Ko Sire Formation, lens-shaped diamictite clasts are surrounded by lami-nated mudstone. The diamictite lenses are concavedownward and slightly convex upward (Fig. 7d).A significant feature of this structure is the dis-turbance of laminations along the basal contact(Fig. 7d). It seems that the diamictite clasts pen-etrated the underlying laminations and were sub-sequently flattened and deformed during laterloading, and became lens-shaped. They are inter-preted to be dropstones of semi-consolidateddiamictite.

Small-scale sand injections into the laminatedmudstone are commonly observed. These struc-tures are similar to those described by Gustavson(1975) from recent glacial lake sediments in Alaskaand Scotland and those reported by Thomas andConnell (1985) from Pleistocene glacial lake sedi-ments in Scotland. Ovenshine (1970) describedsimilar but much smaller (2–3 mm) structuresfrom recent ice-rafted debris in Alaska, which theauthor termed ‘till pellets’.

DUMP STRUCTURES

Within the Ko Sire Formation at Ko Sire, diamic-tites with lens-shaped enveloping surfaces areinterpreted as dump structures. Dump structuresare considered to develop with the melting ofa debris-laden iceberg (Miller 1996). The diamic-tites at Ko Sire are massive and homogeneous.The lower surfaces of the lens-shaped bodies ofdiamictite are non-erosive, and the laminae im-mediately below the lenses are down-warped(Fig. 9a,b). Some outcrops also show penetrativedeformation beneath the lower surfaces of largeclasts (Fig. 9c). The combined sedimentologicalevidence provided by these outcrops indicates thatthe diamictite lenses represent debris that fell ver-tically from melting icebergs rather than deposi-tion associated with lateral transport.

Dump structures have previously been observedin Pleistocene glacial–lacustrine sediments inScotland (Thomas & Connell 1985) and Neoprot-erozoic glacial sediments in Ireland (Condon et al.2002). Link et al. (1994) described similar struc-tures from Neoproterozoic glacial marine facies inthe western USA, referring to them as isolatedsediment pods. Both dump structures and isolatedsediment pods provide evidence for the depositionof ice-rafted debris (Thomas & Connell 1985; Linket al. 1994; Condon et al. 2002). Dump structuresare well exposed at Laem Phap Pha, Ko Sire,Phuket.

DEPOSITIONAL SETTING OF KO SIRE FORMATION

The association of lithofacies within the Ko SireFormation at Ko Sire is somewhat different fromthat at Ko Yao Noi and Ko Phi Phi Don. The litho-facies of the Ko Sire Formation include fine-grained diamictite and sandstone facies; thesections at Ko Sire also contain dropstones anddump structures. In contrast, the lithofacies withinthe Ko Sire Formation at Ko Yao Noi and Ko PhiPhi Don include laminated mudstone and siltstone,diamictite, and low-angle cross-bedded sandstone;no evidence is seen of typical soft-sediment defor-mation. Neither dropstones nor dump structuresare found at Ko Yao Noi and Ko Phi Phi Don,although rounded pebbles are found in the lami-nated mudstone and siltstone.

The presence of dropstones and dump struc-tures in the Ko Sire Formation at Ko Sire indi-cates the deposition of ice-rafted debris in anoffshore depositional setting. Laminated mud-stones, a common facies in glacially influencedmarine settings, are interpreted to have been

Fig. 5 Percentage of lithology of clasts in diamictite in the Ko SireFormation, n = 288.



deposited by suspended sediment plumes of melt-water discharge (Eyles 1993), indicating deposi-tion at or below the maximum storm-wave base(Eyles et al. 1998). In addition, bioturbation byPlanolites sp., Teichichnus sp., and Chondritessp. is indicative of the trace fossils of an offshoreCruziana ichnofacies assemblage (Pembertonet al. 1992; Eyles & Eyles 2000), and soft-sediment recumbent folds within laminated faciesindicate the occurrence of paleoslides (RicciLucchi 1995). The occurrence of diamictite alter-nating with laminated mudstone across sharpbedding contacts is commonly regarded as evi-dence of a debris-flow diamictite (Kurtz & Ander-son 1979). In addition, the grading observed insome diamictite beds represents the turbulentflow of poorly sorted sediments (Eyles et al.2001). The alternating diamictite and laminatedmudstone probably records the repeated deposi-tion of sediment gravity flows and fine-grainedsediments from suspension. The lens-shapeddiamictite with erosional contacts is interpretedto represent the resedimentation of rainout sedi-ment within debris flows.

Within a distal glaciomarine environment, directglacial influence is restricted to the deposition ofsuspended sediment and ice-rafted debris; otherrelated sedimentation is generated by sedimentgravity flows (Eyles et al. 1985). For these reasons,the depositional setting of the Ko Sire Formationat Ko Sire is interpreted to be a distal glaciomarine

environment in which ice-rafted debris was depos-ited within an offshore environment.

At Ko Yao Noi and Ko Phi Phi Don, the lami-nated mudstone and siltstone, which yieldshallow-marine ichnofossils such as Teichichnussp. and Planolites sp., indicates a mud-dominatedoffshore depositional environment under low-energy conditions (Eyles et al. 1998; Eyles &Eyles 2000). The fact that the graded diamictitefacies overlies the fine-grained laminated faciesalong erosional contacts suggests that the diam-ictite originated as a debris flow (Eyles 1988,1990; Eyles et al. 2001).

Lithological correlations (Fig. 4) indicate thatthe Ko Sire Formation at Ko Yao Noi and Ko PhiPhi Don corresponds to the distal glaciomarinesequence at Ko Sire. In other words, there is alateral facies change between the sequence at KoSire and that at Ko Yao Noi and Ko Phi Phi Don.The outer limit of distal glaciomarine deposits isdefined by the farthest distribution of ice-rafteddebris (Eyles et al. 1985). The absence of obviousdropstone structures at Ko Yao Noi and Ko Phi PhiDon leads us to the conclusion that the islandswere not part of a glaciomarine environmentduring the Asselian. Although both islands werelocated beyond the outer limit of the distal glaci-omarine environment, a cold-water environmentis supported by the Asselian Gondwana-type bra-chiopod assemblage found at Ko Phi Phi Don(Waterhouse 1982). The combined lines of evidence

Fig. 6 Ko Sire Formation. (a) Massivematrix-supported diamictite interbeddedwith laminated mudstone with sharpcontact, (b) rippled sandstone showingrippled crossed lamination, (c) photo-micrograph of laminated mudstoneshowing normal grading of sediments,(d) complex recumbent fold of soft-sediment deformation in laminatedmudstone.



suggest that the depositional setting of the Ko SireFormation at Ko Yao Noi and Ko Phi Phi Don wasa coldwater offshore environment affected by raredebris flows that possibly remobilized pre-existingglacial deposits.

KO HE FORMATION

The Ko He Formation, characterized by diamictite,was first defined by Raksaskulwong and Wong-wanich (1993). In the study area, the diamictite

Fig. 7 Dropstone structure in the Ko Sire Formation. (a) Ellipsoidal granite boulder penetrated in laminated mudstone, Laem Phap Pha, Ko Sire, (b)quartzite cobble penetrated in laminated mudstone with onlap of the top contact, Laem Mai Phai, Ko Sire, (c) rounded quartzite pebble embedded inlaminated mudstone with bending of the top and bottom contacts, Laem Phap Pha, Ko Sire, and (d) diamictite clast penetrated in laminated mudstone, LaemPhap Pha, Ko Sire.



sequence of the Ko He Formation conformablyoverlies laminated mudstone of the Ko Sire For-mation (Fig. 3). At Ko Phi Phi Don, the brachiopodassemblage in the Ko Sire and Ko He Formationsindicates an Early Asselian to Early Sakmarianage (Shi & Archbold 1998). Furthermore, the KoHe Formation at Ko Yao Noi is conformably over-lain by the Ko Yao Noi Formation (Fig. 3b), whichyields a Late (Upper) Sakmarian brachiopodassemblage (Shi & Archbold 1998). The total thick-ness of the formation varies remarkably from 20 to400 m; Raksaskulwong and Wongwanich (1993)also commented on the marked variation in thethickness of this unit.

FACIES DESCRIPTION OF KO HE FORMATION

The Ko He Formation contains two main litho-facies: a dominant diamictite (which makes upmore than 90% of the formation) and subordinatefine-grained facies (Fig. 4).

Diamictite facies

The diamictite facies consists of sparsely distrib-uted clasts within a sandy mudstone matrix. Thefacies is a massive matrix-supported diamictitethat also contains stratified matrix-supporteddiamictite with tabular or lensoidal geometries.Individual beds range in thickness from 15 cm togreater than 5 m. Clasts within the diamictite varyin size (Fig. 10a): the largest observed clast is agneiss boulder of 40 cm in diameter found in thenorthwestern part of Laem Phan Wa, but mostclasts are smaller than cobble size, commonly

around 2 cm. The density of clasts varies from 175to 300 clasts per m2 (for counted clasts larger thangranule size). Most of the large clasts are quartzite(orthoquartzite, metaquartzite), with 77% of thelarge clasts recorded from the six counting locali-ties being this lithology, along with lesser quartz,mudstone/shale, carbonate, and granite/gneiss(Fig. 11). The roundness of the clasts varies fromwell-rounded (0.8) to sub-angular (0.3), as deter-mined from the visual comparison charts of Krum-bein (1941) and Powers (1953). The statistical modeand mean of clast roundness both fall in the cat-egory of rounded. Under the microscope, the pet-rographic characteristics of the diamictite matrixcorrespond to a quartz-wacke (Fig. 10b); 70–90%of matrix sand grains are quartz. Reworkedclasts of laminated mudstone are also observed(Fig. 10c). Locally, clasts within the diamictiteshow a preferred orientation (Fig. 10d) parallelto bedding. The diamictite beds are in sharpcontact with underlying and overlying laminatedmudstones.

Fine-grained facies

The fine-grained facies is subordinate within theKo He Formation, and is restricted to the lowerpart of the formation. The facies consists ofmassive mudstone and laminated mudstone andsiltstone. The massive mudstone is usually amixture of clay, silt, and sand particles. The lami-nated mudstone and siltstone contain well-developed laminations that are parallel andcontinuous. Graded bedding within the laminationis sometimes observed under the microscope. Anumber of localities show a gradational verticalchange from diamictite to massive mudstone.

DEPOSITIONAL SETTING OF KO HE FORMATION

The massive diamictite within the Ko He Forma-tion is characteristic of a debris-flow deposit (Miall1983; Eyles 1990; Visser 1994; Martin 1999). Theorigin of poorly- and well-stratified diamictiteswith tabular and lensoidal geometries is also gen-erally ascribed to debris flows (Eyles 1990; Zhenget al. 1994; Eyles et al. 2001). The preferred orien-tation of clasts in the diamictite is interpreted tohave resulted from shearing within the basal zonesof the debris flows (Middleton & Hampton 1973),while clasts of laminated mudstone in the diamic-tite (Fig. 10c) indicate erosion and resedimenta-tion of the laminated fine-grained facies by debrisflows; this is thought to be a common process at

Fig. 8 Percentage of lithology of dropstones in the Ko Sire Formation,n = 30.



glaciomarine continental margins (Kurtz & Ander-son 1979; Wright & Anderson 1982; Visser 1983;Eyles 1993; Benn & Evans 1998).

The dominance of quartzite clasts within thediamictite indicates that the sediment was derivedfrom a quartzite terrain; quartzite is also the domi-nant lithology of dropstones in the Ko Sire Forma-tion. The lithological similarity between clasts inthe diamictite and the dropstones, and the occur-rence of reworked laminated mudstone clasts indiamictite suggest that the debris-flow diamictite

probably represents the reworking of the Ko SireFormation.

IMPLICATIONS FOR PALEOGEOGRAPHY ANDREGIONAL TECTONICS

During the Asselian to Early Sakmarian, the off-shore environment of the Ko Sire Formation sawthe accumulation of ice-rafted debris and debris-flow sediments. The common occurrence of drop-

Fig. 9 Dump structures in the Ko SireFormation at Laem Phap Pha, Ko Sire.(a) Diamictite lens embedded in lami-nated mudstone, (b) diamictite lens con-formably overlies laminated mudstonewithout erosional feature at the base ofthe lens, and (c) diamictite lens withdropstone structure at the base of thelens (in circle).



stone structures at Ko Sire suggests that this areawas closer to the ice sheet margin than Ko Yao Noiand Ko Phi Phi Don during the Asselian to EarlySakmarian (Fig. 12a). In terms of the present-daygeographical configuration, it appears that the icesheet was located to the west, with icebergsmoving eastward to Ko Sire during the Asselian toEarly Sakmarian; subsequently, most of the studyarea was covered by debris-flow sediments, asseen in the Ko He Formation. Without firm evi-dence, it is difficult to interpret the presence ofglaciers during the deposition of the Ko He

Formation. However, considering the observationthat subaqueous fans in the proximal glaciomarineenvironment are usually subject to downslopegravity flows (Eyles et al. 1983; Benn & Evans1998), the generation of debris-flow sediments isconsidered to be a common process upon glaciallyinfluenced continental shelves (Wright & Ander-son 1982). In the present study, the debris-flowsediments of the Ko He Formation were presum-ably remobilized from proximal glaciomarinedeposits at the margin of the ice sheet (Fig. 12b).

The presence of Early Permian distal glacioma-rine sediments at Ko Sire, Phuket, which is locatedin the Sibumasu block, strongly suggests that awide shelf environment existed between the Sibu-masu block and northeast Gondwana. The North-west Australian margin, which corresponds tonortheast Gondwana, is the most likely area for theoriginal location of the Sibumasu block (Metcalfe1999). This proposal is supported by several linesof evidence: the similarity in Asselian brachiopodassemblages of the Sibumasu block and NorthwestAustralia (Archbold 1983; Shi & Archbold 1998),the similarity in Ordovician fauna of the Sibumasublock and Australia (Burrett & Stait 1985), theoccurrence of passive glacially influenced marginsalong both the Sibumasu block and West andNorthwest Australia (Eyles 1993), and the compa-rable ages of Early Permian diamictite sequenceswithin the Sibumasu block and the Canning andCarnarvon basins in Australia (Eyles & Eyles

Fig. 10 Ko He Formation. (a)Massive matrix-supported diamictitecut by quartz veins, (b) photomicrographof diamictite showing angular to sub-rounded grains of quartz (Q) and feldspar(F), (c) reworked clast of laminated mud-stone in diamictites, and (d) diamictiteshowing preferred orientation of clastscaused by shearing at the basal part ofdebris flow.

Fig. 11 Percentage of lithology of clasts in diamictite in the Ko HeFormation, n = 1505.



2000; Eyles et al. 2003). According to the interpre-tation of iceberg rafting, the icebergs calved andfloated northward from Northwest Australia,which was marked by extensive Early Permianglaciations (Fig. 13a).

The debris flows recognized within the Sibu-masu block formed during the Early Permian,roughly contemporaneous with rifting-related sub-aqueous mass flows in the Canning and Carnarvonintracratonic rift basins of Northwest Australia(Eyles & Eyles 2000; Eyles et al. 2003). Accordingto paleogeographic interpretations, the Sibumasublock was located near the Canning and Carnar-von basins (Bunopas 1982; Burrett & Stait 1985).

Based on the combined results of the presentstudy and the paleobiogeographical data of Shi andArchbold (1995), it can be reasonably assumed thatthe debris-flow diamictite sediments analyzed inthe present study represent the sedimentaryrecord of the initial rifting of the Sibumasu block(Fig. 13b). The Asselian to Early Sakmarian bra-chiopod assemblage in the Sibumasu block has aGondwana affinity (Shi & Archbold 1995), and theEarly Sakmarian debris-flow sediments are con-formably overlain by Late Sakmarian brachiopodbeds that yield a mixed Gondwana and Cathaysianbrachiopod assemblage (Shi & Archbold 1995).The fact that the timing of the debris-flow

Fig. 12 Illustrations for depositionalmodels of (a) the Asselian Ko Sire For-mation, and (b) the Early Sakmarian KoHe Formation with a presumably pre-existing glacial deposits.

Fig. 13 Illustrations for paleogeogra-phy of the Sibumasu block in (a) theAsselian, and (b) the Early Sakmarian.Bs, Baoshan; L, Lhasa; Qi, South Qiang-tang; Sb, Sibumasu; Tc, Tengchong; Wb,Western Burma; Wc, Western CimmerianContinent. Positions of the tectonicblocks compiled from Shi and Archbold(1998) and Metcalfe (1999).



sediments approximately coincides with the exten-sional tectonics of intracratonic rift basins inNorthwest Australia and a change in Gondwana totransitional brachiopod assemblages suggestsrifting of the Sibumasu block during the EarlySakmarian and drifting of the block to lower paleo-latitudes in the Late Sakmarian.

CONCLUSIONS

We correlated the diamictite-bearing stratigraphicsections at Phuket and adjacent islands based onkey lithologies within the thick diamictite se-quence. The Ko Sire and Ko He Formations areconsidered to be Asselian and Early Sakmarian inage, respectively. Well-preserved dropstones anddump structures at Ko Sire provide clear evidenceof ice-rafted sedimentation. Facies analysis of theKo Sire Formation reveals a distal glacial offshoreenvironment associated with debris flows; in con-trast, the absence of dropstones and dump struc-tures at Ko Yao Noi and Ko Phi Phi Don suggeststhat during the Asselian these areas were locatedfurther from the margin of the ice sheet than KoSire. Subsequently, the Ko He Formation formedin the Early Sakmarian by the resedimentation ofexisting glacial deposits as debris-flow processes.The presence of dropstones and dump structuresclearly suggests that the Sibumasu block was partof Gondwana and was probably originally locatedalong the Northwest Australian margin.

ACKNOWLEDGEMENT

Funding for the two-year M. Sc. study undertakenby T. Ampaiwan was provided by the Jinnai Inter-national Student Scholarship administered bythe Association of International Education, Japan(AIEJ).

REFERENCES

ALTERMANN W. 1986. The Upper Paleozoic pebbly mud-stone facies of Peninsular Thailand and WesternMalaysia–continental margin deposit of Paleoeur-asia. Geologische rundschav, Stuttgart 75, 78–89.

ARCHBOLD N. W. 1983. Permian marine invertebrateprovinces of the Gondwana realm. Alcheringa 7,59–73.

BENN D. I. & EVANS D. 1998. Glaciers and GlaciationArnold, London.

BUNOPAS S. 1982. Palaeogeographic history of westernThailand and adjacent parts of S.E. Asia: A platetectonic interpretation. Geological Survey Paper 5,1–810.

BUNOPAS S. 1994. Regional stratigraphy, paleogeo-graphic and tectonic events of Thailand and continen-tal Southeast Asia. In Angsuwathana P., WongwanichT., Tansathien W., Wongsomsak S., Tulyatid J.(eds.) Proceedings of the International Symposiumon Stratigraphic Correlation of Southeast Asia,pp. 2–24, Department of Mineral Resources,Bangkok.

BURRETT C. & STAIT B. 1985. South East Asia as a partof an Ordovician Gondwanaland – A palaeobiogeo-graphic test of a tectonic hypothesis. Earth andPlanetary Science Letters, 75, 184–90.

BURRETT C., LONG J. & STAIT B. 1990. Early-MiddlePalaeozoic biogeography of Asian terranes derivedfrom Gondwana. In Mckerrow W. S. & Scotese C. R.(eds.) Palaeozoic Palaeogeography and Biogeogra-phy, Geological Society Memoir, vol. 12, pp. 163–74,The Geological Society, London.

CHARUSIRI P., DAORERK V., ARCHIBALD D., HISADA K.& AMPAIWAN T. 2002. Geotectonic evolution of Thai-land: A new synthesis. Journal of the GeologicalSociety of Thailand 1, 1–20.

CONDON D. J., PRAVE A. S. & BENN D. I. 2002. Neopro-terozoic glacial-rainout interval: Observations andimplications. Geology 30, 35–8.

DOWDESWELL J. A., HAMBREY M. J. & WU R. 1985. Acomparison of clast fabric and shape in Late Precam-brian and modern glacigenic sediments. Journal ofSedimentary Petrology 55, 691–704.

EYLES C. H. 1988. Glacially and tidally-influencedshallow marine sedimentation of the Late Precam-brian Port Askaig Formation, Scotland. Palaeogeog-raphy Palaeoclimatology Palaeoecology 68, 1–25.

EYLES N. 1990. Marine debris flows: Late Precambrian‘tillites’ of the Avalonian – Cadomian orogenic belt.Palaeogeography Palaeoclimatology Palaeoecology79, 73–98.

EYLES N. 1993. Earth’s glacial record and its tectonicsetting. Earth Science Review 35, 1–248.

EYLES C. H. & EYLES N. 2000. Subaqueous mass floworigin for Lower Permian diamictites and associatedfacies of the Grant Group, Barbwire Terrace,Canning Basin, Western Australia. Sedimentology47, 343–56.

EYLES C. H., EYLES N. & MIALL A. D. 1985. Modelsof glaciomarine deposition and their implication toancient glacial sequence. Palaeogeography Palaeo-climatology Palaeoecology 51, 15–84.

EYLES C. H., EYLES N. & GOSTIN V. A. 1998. Facies andallostratigraphy of high-latitude, glacially-influencedmarine strata of the Early Permian southern SydneyBasin, Australia. Sedimentology 45, 121–61.

EYLES N., EYLES C. H. & MIALL A. D. 1983. Lithofaciestypes and vertical profile models; an alternative



approach to the description and environmental inter-pretation of glacial diamict and diamictite sequences.Sedimentology 30, 393–410.

EYLES N., DANIELS J., OSTERMAN L. E. & JANUSZZAK

N. 2001. Ocean Drilling Program Leg 178 (AntarcticPeninsula): Sedimentology of glacially influencedcontinental margin topsets and foresets. MarineGeology 178, 135–56.

EYLES C. H., MORY A. J. & EYLES N. 2003.Carboniferous-Permian facies and tectono-stratigraphic successions of the glacially influencedand rifted Carnarvon Basin, Western Australia.Sedimentary Geology 155, 63–86.

FLINT R. F., SANDERS J. E. & RODGERS J. 1960. Diam-ictite: A substitute term for symmictite. GeologicalSociety of America Bulletin 71, 1809–10.

GUSTAVSON G. B. 1975. Bathymetry and sediment dis-tribution in proglacial Malaspina Lake, Alaska.Journal of Sedimentary Petrology 45, 450–61.

HAMBREY M. 1994. Glacial Environments. UniversityCollege London Press, London.

JIN X. 2002. Permo-Carboniferous sequences of Gond-wana affinity in northwest China and their paleo-geographic implications. Journal of Asian EarthSciences 20, 633–46.

KRUMBEIN W. C. 1941. Measurement and geological sig-nificance of shape and roundness of sedimentary par-ticles. Journal of Sedimentary Petrology 11, 64–72.

KURTZ D. D. & ANDERSON J. B. 1979. Recognition andsedimentologic description of recent debris flowdeposits from the Ross and Weddell seas, Antarctica.Journal of Sedimentary Petrology 49, 1159–70.

LINK P. K., MILLER J. M. G. & CHRISTIE-BLICK N.1994. Glacial-marine facies in a continental rift envi-ronment: Neoproterozoic rocks of the westernUnited States Cordillera. In Deynoux M., Miller J.M. G., Domack E. W., Eyles N., Fairchild I. J. &Young G. M. (eds.) Earth’s Glacial Record, pp. 29–46,Cambridge University Press, Cambridge.

MANTAJIT N. & HINTHONG C. 1999. Geological Mapof Thailand, 1:1 000 000. Department of MineralResources, Bangkok.

MARTIN D. M. 1999. Depositional setting and implica-tions of Paleoproterozoic glaciomarine sedimentationin the Hamersley Province, Western Australia. Geo-logical Society of America Bulletin 111, 189–203.

METCALFE I. 1999. Gondwana dispersion and Asianaccretion: An overview. In Metcalfe I. (ed.) Gond-wana Dispersion and Asian Accretion, pp. 9–28, A.A. Balkema, Rotterdam.

MIALL A. D. 1977. A review of the braided river depo-sitional environment. Earth Science Review 13, 1–62.

MIALL A. D. 1983. Glaciomarine sedimentation in theGowganda Formations (Huronian) northern Ontario.Journal of Sedimentary Petrology 53, 477–92.

MIDDLETON G. V. & HAMPTON M. 1973. Sedimentgravity flows: Mechanics of flow and deposition. In

Middleton G. V. & Bouma A. H. (eds.) Turbidites andDeep Water Sedimentation, pp. 1–38, SEPM ShortCourse Notes, SEPM, Oklahoma.

MILLER J. M. G. 1996. Glacial sediments. In ReadingH. G. (ed.) Sedimentary Processes; Stratigraphy,Facies and Environment, pp. 454–83, BlackwellScience, Cambridge.

MITCHELL A. H. G., YOUNG B. & JANTARANIPA W. 1970.The Phuket Group, peninsular Thailand: A Paleozoicgeosynclinal deposit. Geological Magazine 107, 411–28.

OVENSHINE A. T. 1970. Observations on ice berg raftingin Glacier Bay, Alaska, and the identification of ice-rafted deposits. Geological Society of America Bul-letin 81, 891–4.

PEMBERTON S. G., MACEACHEN J. A. & FREY R. W.1992. Trace fossil facies models: Environmental andallostratigraphic significance. In Walker R. G. &James N. P. (eds.) Facies Model: Response to SeaLevel Change, pp. 47–72, Geological Association ofCanada, St. John’s, NF.

PIYASIN S. 1975. Stratigraphy and Sedimentology ofthe Kaeng Krachan Group (Carboniferous), In StokeR. B. & Tantisukrit C. (eds.) Proceedings of the Con-ference on Geology of Thailand, pp. 25–36, Depart-ment of Geological Sciences, Chiang Mai University,Chiang Mai.

POWERS M. C. 1953. A new roundness scale for sedi-mentary particle. Journal of Sedimentary Petrology23, 117–9.

RAKSASKULWONG L. & WONGWANICH T. 1993. Stratig-raphy of the Kaeng Krachan Group, Peninsular &Western Thailand. Geological Survey Division,Department of Mineral Resources, Thailand. (inThai).

RICCI LUCCHI F. 1995. Sedimentographica: A Photo-graphic Atlas of Sedimentary Structures, 2nd edn,255, Columbia University Press, New York.

SHI G. R. & ARCHBOLD N. W. 1995. Permian brachiopodfaunal sequence of the Shan-Thai terrane: Bio-stratigraphy, palaeobiogeographical affinities andplate tectonic/palaeoclimatic implication. Journal ofSE Asian Earth Sciences 11, 177–87.

SHI G. R. & ARCHBOLD N. W. 1998. Permian marinebiogeography of Asia. In Hall R. & Holloway J. D.(eds.) Biogeography and Geological Evolution of SEAsia, pp. 57–72. Backhuys, Leiden.

STAUFFER P. H. & LEE C. P. 1986. Late Palaeozoicglacial marine facies in Southeast Asia and its impli-cation. Geological Society of Malaysia Bulletin, 20,363–97.

STAUFFER P. H. & MANTAJIT N. 1981. Late Paleozoictilloids of Malaysia, Thailand and Burma. InHambrey M. J. & Harland W. B. (eds.) Earth’s pre-Pleistocene Glacial Record, pp. 331–5, CambridgeUniversity Press, Cambridge.

TANTIWANIT W., RAKSASKULWONG L. & MANTAJIT N.1983. The Upper Paleozoic Pebbly rocks in Southern



Thailand. In Nutalaya P., Thanasuthipitak T., Thira-mongkol N. et al. (eds.) Proceedings of the Workshopon Stratigraphic Correlation of Thailand andMalaysia, 1, 96–104, Geological Society of Thailand,Bangkok.

THOMAS G. S. P. & CONNELL R. J. 1985. Iceberg drop,dump and grounding structures from Pleistoceneglacio-lacustrine sediments, Scotland. Journal ofSedimentary Petrology 55, 243–9.

UENO K. 2003. The Permian fusulinoidean faunas of theSibumasu and Baoshan blocks: their implicationsfor the paleogeographic and paleoclimatologic recon-struction of the Cimmerian Continent. Palaeogeog-raphy Palaeoclimatology Palaeoecology 193, 1–24.

VEEVERS J. J. & POWELL C. M. 1987. Late Paleozoicglacial episodes in Gondwanaland reflected intransgressive-regressive depositional sequences inEuramerica. Geological Society of America Bulletin98, 475–87.

VISSER J. N. J. 1983. Submarine debris flow depositsfrom the Upper Carboniferous Dwyka Tillite Forma-tion in the Kalahari Basin, South Africa. Sedimentol-ogy 30, 511–23.

VISSER J. N. J. 1994. The interpretation of massiverain-out and debris flow diamictites from the glacialmarine environment. In Deynoux M., Miller J. M. G.,Domack E. W., Eyles N., Fairchild I. J. & Young G.M. (eds.) Earth’s Glacial Record, pp. 83–94, Cam-bridge University Press, Cambridge.

WANG X. D., UENO K., MIZUNO Y. & SUGIYAMA T. 2001.Late Paleozoic faunal, climatic, and geographic

changes in the Baoshan Block as a Gondwana-derived continental fragment in Southwest China.Palaeogeography Palaeoclimatology Palaeoecology170, 197–218.

WATERHOUSE J. B. 1982. An Early Permian cool-waterfauna from pebbly mudstones in Southern Thailand.Geological Magazine 109, 337–54.

WENTWORTH C. K. 1936. An analysis of the shapes ofglacial cobbles. Journal of Sedimentary Petrology 6,85–96.

WONGWANICH W., TANSATHIEN W., LEEVONGCHAROEN

S. et al. 2002. The Lower Paleozoic Rocks of Thai-land. In Mantajit N. (ed.) Proceedings of the Sympo-sium on Geology of Thailand, pp. 16–21, Departmentof Mineral Resources, Bangkok.

WOPFNER H. 1996. Gondwana origin of the Baoshan andTengchong terranes of West Yunnan. In Hall R. &Blundell D. (eds.) Tectonic Evolution of SoutheastAsia, Geological Society Special Publication 106, pp.539–47, Geological Society of America, Boulder, CO.

WRIGHT R. & ANDERSON J. B. 1982. The importanceof sediment gravity flow to sediment transport andsorting in a glacial marine environment: EasternWeddell Sea. Antarctica. Geological Society ofAmerica Bulletin 93, 951–63.

ZHENG Z., LI Y., LI Z. & LI H. 1994. Lithology, Sedi-mentology and genesis of the Zhaengmuguan For-mation of Ningxia, China. In Deynoux M., Miller J.M. G., Domack E. W., Eyles N., Fairchild I. J. &Young G. M. (eds.) Earth’s Glacial Record, pp. 101–8,Cambridge University Press, Cambridge.



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