The Geology of Southern Zanskar (Ladakh) - Evidence for the Autochthony of the Tethys Zone of the Himalaya 465 ©Geol

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Zeitschrift/Journal: Jahrbuch der Geologischen Bundesanstalt

Jahr/Year: 1987

Band/Volume: 130

Autor(en)/Author(s): Fuchs Gerhard

Artikel/Article: The Geology of Southern Zanskar (Ladakh) - Evidence for the Autochthony of the Tethys Zone of the Himalaya 465 ©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at

Jb. Geol. B.-A. ISSN 0016-7800 Band 130 S.465-491 Wien, Dezember 1987

The Geology of Southern Zanskar (Ladakh) - Evidence for the Autochthony of the Tethys Zone of the Himalaya

By GERHARD FUCHS.)

With 14 Figures und 3 Plates

Himalaya Zanskar Geological Mapping Stratigraphy Tectonics

Contents

Zusammenfassung 465 Abstract 466 1. Introduction 466 2. Stratigraphy 466 2. 1. The Central Crystalline 467 2. 2. The Phe Formation and Intrusive Granitoids 468 2. 3. The Karsha Formation 471 2. 4. The Kurgiakh Formation 472 2. 5. The Thaple Formation 472 2. 6. The Muth Quartzite 473 2. 7. The Lipak Formation 473 2. 8. The Po Formation 474 2. 9. The Panjal Trap 474 2.10. The Kuling Formation 475 2.11. The Triassic Formations 475 2.12. The Quartzite Series 477 2.13. The Kioto Limestone 477 2.14. The ~erruginous Oolite 478 2.15. The Spiti Shales 478 2.16. The Giumal Sandstone 478 2.17. The Chikkim Limestone and Shillakong Formation 478 2.18. The Upper Cretaceous Parts of the Lamayuru Formation 480 2.19. The Stratigraphic Evolution of the Tethys Zone of Zanskar 481 3. Tectonics 482 3.1. The Axial Depression of Lahoul 482 3.2. The Relation between the Central Crystalline and the Sedimentaries of the Tibetan Zone 483 3.3. The Structure of the Tibetan Zone in SE-Zanskar 483 4. Conclu~ons 487 Acknowledgements 489 References 490

Zusammenfassung E p i ro gen e Bewegungen an der Karbon/Perm-Grenze Die Arbeit ergänzt die bereits von anderer Seite vorliegen- führen zu teilweiser Erosion der paläozoischen Formationen den stratigraphischen und paläontologischen Veröffentlichun- und transgressivem Übergreifen des Perm. Diese Diskordanz gen durch die Geologische Karte von SE-Zanskar und beglei- sowie der begleitende Panjal-Vulkanismus werden mit dem tende Profilserien. Öffnen der Neotethys in Zusammenhang gebracht. Das im Hinsichtlich der stratigraphischen Entwicklung wird Perm sich bildende F Iach m e er bestand im wesentlichen betont, daß der mächtige schiefrig-sandige Basiskomplex der durch das ganze Mesozoikum. Mit der Mit tel k rei d e dif- Tibet-Zone eine typische flyschoide Beckenfazies dar- ferenziert sich die Fazies in couches rouges pelagischer stellt. Die reichliche, rasche und rhythmische Sedimentschüt- Rücken und Plateaus, dunkle pelagische Kalke tieferen Was- tung erfolgt in einem instabilen Senkungsraum. Ein 0 r 0 ge- sers, euxinische siltige Beckenfazies und sandig-tonige ne s Ereignis, das zeitmäßig mit den k a led 0 n i s c hen Fal- Flyschschüttungen. Die vielfältigen Veränderungen der Fazies- tungsphasen korreliert wird, bringt einen scharfen Wechsel in verteilung in der Oberkreide zeigen Unruhe, und daß der N- der Sedimentation: In epikontinentalem Milieu werden Rand des Indischen Kontinents bereits nahe der Indus-Sutur Transgressions-Konglomerate, reife Quarzarenite, Seichtwas- war. Der orogene Umbruch begann in Zanskar erst im ser-Karbonate und lokal sogar Evaporite gebildet. Eozän. Te k ton i k: Es wird gezeigt, daß das Zen t r a 1- K r ist a II i n und die Basisserien der Tethys-Zone eine Einheit bil- den, die jedoch lokal wie im Raume von Padam gestört sein *) Author's address: Univ.-Doz. Dr. GERHARDFUCHS, Geologi- kann. Durch eine Achsendepression in Lahoul ist das Zentral- sche Bundesanstalt, Rasumofskygasse 23, A-1031 Wien. Kristallin dort abgetaucht, Tibet-Zone und Chamba-

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Synclinorium sind in Verbindung. Einzelne Granitstöcke in den Thus there is no evidence for thrusts over large horizontal Sedimentserien von Lahoul stammen wohl aus dem darunter- distances in the Tibetan Zone. Also in respect to the underly- liegenden Kristallin, sind aber mit diesem nicht identisch. ing Central Crystalline the Tibetan Zone is autochthonous. Die von BAUDet al. (1982a,b, 1983, 1984) und GAETANIet al. (1985) vorgeschlagene Gliederung der Tibet-Zone in einen Stapel von Decken wird mit folgenden Argumenten abgelehnt: 1) Im Sti'rnbereich der "Decken" kann an den angenommenen Überschiebungen in einigen Fällen der un g est ö rt e 1. Introduction Primärverband nachgewiesen werden. 2) Der "Deckenstapel" in S-Zanskar entspricht der nor ma- The complicated tectonic belt along the Indus - Yar- len stratigraphischen Abfolge vom Präkambrium lung - Tsangpo was difficult to access for many de- bis ins Unter-Eozän. Lokal gestörte Formationsgrenzen cades. So, when India opened Ladakh for tourism, sind kein Beleg für Deckenbau. there began a rush of geological parties from many 3) Zahlreiche Gä nge von Pan j a I T rap in den paläozoi- countries to this region. The investigations concen- schen Formationen im Liegenden der Panjal Laven zeigen, daß es sich um den pr i m ä ren Untergrund und nicht um trated on the flysch- and molasse zones, ophiolite belts, fremde tektonische Einheiten handelt. and the melanges. I was particularly interested in the 4) Viele der angenommenen Deckengrenzen erweisen sich relations of the named zones to the Tibetan (Tethys) bei seitlicher Verfolgung als lokal gestörte Gesteins- Zone with the aim to reconstruct the original facies pat- grenzen, durchscherte Faltenschenkel oder Schuppungen. tern along the margin of the Indian Continent. 1976 on Für tektonischen Ferntransport fehlt somit jeglicher Beleg, und die Tibetische Zone ist in Bezug auf ihren Kristallin-Unter- my first traverse of western Zanskar I discovered the grund sowie ihren Innenbau als autochthon zu betrachten. Spongtang Klippe (FUCHS,1977b) at a place where LVDEKKER(1883) has indicated the occurrence of traps Abstract amid of the Mesozoic sedimentaries. 1980 I mapped The paper presents the Geological Map and Sections of SE- western Zanskar and came to the conclusion that in the Zanskar, a supplement to the stratigraphical and palaeontolo- Spongtang area thrust sheets deriVed from the Indus gical work done by other authors. Zone rest on the autochthonous to parautochthonous Regarding the stratigraphical development it is series of the Tibetan Zone. French geologists (BAS- stressed that the thick monotonous argillaceous-arenaceous SOULLETet aI., 1978, 1980, 1983) active in the same re- complex forming the base of the Tibetan Zone ist typical fly s c h 0 id bas i n fa eie s. There was rich supply of sedi- gion accepted the northern carbonate belt of Zanskar ment and rapid, rhythmic deposition in an unstable, subsiding as a higher nappe ("Zanskar-Shillakong Nappe"). After trough. An 0 r 0 gen ic event, which is correlated in age with further studies there is agreement now that the area in the Caledonian revolution, causes an abrupt change in question forms a fan-shaped anticlinorium as suggested sedimentation: In e pic 0 ntin e nta I environment transgres- by me (1977b, 1979, 1982b). sion conglomerates, mature quartz arenites, shelf carbonates, and locally even evaporites were deposited. BAUDet al. (1982a,b; 1983, 1984) started work in Ep i r 0 gen e tic movements at the Carboniferous/ Permian eastern and southern Zanskar and arrived at the sensa- boundary cause partial erosion of the Palaeozoic formations tional result that the whole of the Tibetan Zone repre- and transgression of the Permian. This unconformity and the sents a pile of nappes. As this allochthony concept was associated Panjal Volcanism are related to rifting and the in contradiction to all my experience from northern opening of the Neo t e thy s. The shelf formed in the Permian Nepal, Spiti, and Kashmir, I visited the Markha-Nimal- persisted throughout the Mesozoic. In the Mid die C re t ace- o u s the facies becomes diversified: Couches rouges form on ing area in 1983. To my surprise I found that facies pelagic ridges and plateaus, dark pelagic limestones in deeper belts bordering along tectonic planes in western Ladakh water, euxinic silty shales in basins, and sandy to shaly flysch (Lamayuru Unit - Zanskar Carbonates) are still con- in troughs rich in terrigenous detritus supply. The changes in nected in eastern Ladakh. Thus the original transitions Upper Cretaceous facies distribution indicate instability and of faciesfrom the shelf to the basin and to the subduc- that the northern margin of the Indian Continent was already close to the Indus subduction zone. In Zanskar the orogeny tion Zone in the N are still recognizable there. The began in the Eocene. partly metamorphic sedimentary series overlying the Tee ton i es: The Central Crystalline and the basal complex Tso Morari Crystalline in the Nimaling Dome represent of the Tibetan Zone belong to the same unit, although their the sequence of the Tibetan Zone ranging from the Pre- primary connection may be disturbed, such as in the Padam cambrian to the Paleocene (FUCHS,1984a,b; 1986). All area. In the Lahoul axial depression the Central Crystalline is covered by the sedimentaries, which are in connection from that contradicts BAUDet aI., who assumed a series of the Tibetan Zone via Lahoul to the Chamba Synclinorium. nappes there. STUTZ& STECK(1986) observed strong There are several granitoid intrusions in the sedimentary deformation and shearing in the Nimaling sequence and series of Lahoul; their source may be in the underlying crystal- therefore follow BAUD assuming the existence of a line complex, but they are not identical with the Central Crys- Langtang Nappe. Certainly the sequence is disturbed, talline. The suggestion that the Tibetan Zone represents a pile of but in my view it is the chronological succession and nappes (BAUDet aI., 1982a,b, 1983, 1984; GAETANIet aI., not a pile of tectonic units. 1985) is rejected: Admittedly there may be some ambiguity to discern 1) In the frontal portions of the "nappes" several of the whether a disturbed sequence is stratigraphic or tec- "nappe boundaries" show undisturbed primary contacts. tonic, because nappes can show similarities and close 2) The assumed pile of nappes in southern Zanskar corres- relations near their root zone (e. g. parautochthonous ponds to the normal stratigraphic Precambrian-Lower Eocene sequence. Locally disturbed formation boundaries Helveticum and Helvetic Nappes in the Alps). are not evidence for nappe structure. In their frontal portions, however, nappes should be 3) The numerous dikes of Panjal Trap, which penetrate the distinct from each other and from their autochthonous Palaeozoic formations underlying the Panjal flows, prove base. Therefore in 1985 I went to southern Zanskar, that these series represent the primary substratum of the where BAUDand his co-workers describe the front of volcanics - they are not another tectonic unit. 4) Many of the assumed nappe boundaries turn out to be just their nappes. There it should be possible to clarify the locally disturbed formation contacts, sheared fold limbs, or problem whether the Tibetan Zone was allochthonous wedge structures, if traced along the strike. or not.

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After the first reconnaissance work by STOLlCZKA E of Ichar, however, the original transitional contact (1865) and LVDEKKER(1883) geological research in Crystalline/sedimentaries is still preserved: E of the vil- southern Zanskar was not taken up again before the lage coarse-grained two-micaschists (:tgarnet and seventies of this century. A series of reports were pre- kyanite) become predominating, the gneisses gradually sented by Indian parties (NANDA& SINGH,1976; NANDA disappear. Then further E the micaschists pass into et aI., 1978; RAINA& BHATTACHARVVA,1977; KANWAR& phyllitic micaschists and dark phyllites intercalated with AHLUWALIA,1979; KANWAR& BHANDARI,1979; JOSHI & dark grey to violet quartzitic beds. SE of the impressive ARORA, 1979; SRIKANTIAet aI., 1980). GUPTAdescribes Syncline of the Karsha Formation near Abnop the phyl- many fossil finds from this area (GUPTA& RAVI KAUL, litic series grades into phyllitic slates with beds of 1975; GUPTA & WEBSTER, 1980; GUPTA & JANVIER, metasiltstone and metasandstone, and SW of Purni fi- 1981; GUPTA& MICHALIK,1981; GUPTA& SHAW, 1981, nally the metamorphism dies away. Thus there is a pas- 1985; THAKUR& GUPTA,1983; WEBSTER& GUPTA,1984; sage from the Crystalline to the sedimentaries of the GUPTA,1981, 1986). The Italian geologists team, partly Tibetan Zone, which from my experience from other reworking together with BAUD, presented a series of de- gions of the Himalaya may be called a rule (compare tailed accounts on the stratigraphy of southern Zanskar also GRIESBACH,1891, p. 209; HAVDEN,1904, p. 9-10; (GAETANIet aI., 1980, 1983, 1985, 1986; BAUD et aI., HEIM & GANSSER,1939; GANSSER,1964, 1983, p.33; 1984; NICORAet aI., 1984; JADOULet aI., 1984; CASNEDI SRIKANTlA,1981; BORDETet aI., 1971, 1975; HONEGGER et aI., 1985). et aI., 1982). Unfortunately they had no geological map as a basis It is of great interest that further E in the traverses for their measured stratigraphic sections, only the from Lahoul towards the N over the Bara Lacha La re- generalized tectonic sketch map of Zanskar by BAUD.In spectively Shingo La typical Central Crystalline, which respect to the general geology of Zanskar the stratig- can be traced continuously from the NEFA-Himalaya in raphers followed the views of BAUD (BAUD et aI., the E of the Rohtang Pass area in the W, forming the 1982a,b; 1983, 1984; GAETANIet aI., 1986). According backbone of the Himalaya, is interrupted in Lahoul. to this concept the observed sequence of formations There the Rohtang Crystalline plunges towards the NW ranging from the Precambrian up to the Paleocene is and the Crystalline of the Brahman-Zanskar Range seen as a pile of "nappes". The fact that these "struc- plunges axially SE. This fact already known to LVDEK- tural units" are found in the original stratigraphic order KER(1883, see his map) is shown by alilater geological is explained by the assumption of decollements. maps (e. g. GANSSER,1964; FUCHS,1982c). In the axial Thus the present situation is the following: There depression of Lahoul the sedimentary series of Spiti - exists a lot of new stratigraphic information, but no Zanskar are connected with those of the Chamba- adequate geological map - only the sketch map by Kashmir Synclinoria. Therefore along the road from the NANDA& SINGH(1976). Therefore I understand my work Chandra Valley to Darcha and the Bara Lacha La re- as complementary: spectively the Shingo La most of the country rock be- 1) The geological map (PI. 1) and the geological sec- longs to the Phe Formation. This thick argillo-arenace- tions (PI. 2) presented in this paper give the frame ous complex shows varying grades of metamorphism, for the stratigraphic knowledge already existing. generally not exceeding greenschist facies. Alteration 2) Careful examination of the critical parts of the sec- commonly increases near granitoid intrusions (e. g. tions, where BAUDet al. assume their nappe bound- Jaspa Granite, Gumboranjan). Sedimentaries younger aries, shall clarify the problem of tectonics, which is than the Phe Formation occur in synclines around Bara a principal one concerning the entire Tethyan Zone Lacha La and at Tandi in the Chandra Valley. The of the Himalaya. rocks of the latter syncline are altered like the underly- 3) Investigation of the facies development in the Cre- ing series (POWELL& CONAGHAN,1973). taceous of southern Zanskar may help to complete our knowledge of the palaeogeography just before NANDA& SINGH(1976) termed the Central Crystalline the beginning of the Himalayan orogenesis. of the Zanskar Range "Suru Formation" and distinguish four members. The uppermost, the Darcha Member actually belongs to the Phe Formation, which is intruded by discordant granites. The Crystalline is separated from the overlying sedimentary series not by a sharp 2. Stratigraphy boundary, but by a passage zone. A good portion of the 2.1. The Central Crystalline Crystalline consists of altered sedimentaries and the basal parts of the sedimentary succession have suf- On our 1985 expedition the Central Crystalline was fered slight metamorphism. From place to place the marginally touched in the Tsarap Valley between Ichar front of metamorphism reached into various levels of and Padam. There it consists of two-mica augengra- the sedimentary column. In Lahoul and eastern Zanskar nite-gneisses, nebulitic migmatites, grey and dark the alteration dies away in the Early Palaeozoics, paragneisses (coarse-to fine-grained) containing garnet whereas in the Rangdum area of western Zanskar it and sillimanite. This migmatite complex is frequently reaches up high into the Mesozoic series. In view of penetrated by aplite and pegmatite bearing tourmaline. this, it is meaningless to subdivide the Central Crystal- Between Ichar and Padam the highly metamorphosed line into stratigraphic units, and as said above, it is migmatitic gneisses are overlain by slightly altered ar- doubtful where to draw a boundary between Crystalline gillites and siltites of the Phe Formation. There is a and sedimentaries. In this paper the high-grade great contrast in metamorphism and it is clear that the metamorphics and the transitional zone are dealt in the two rock units are separated by a tectonic plane, as al- chapter Central Crystalline, the slightly altered ready stressed by BAUDet al. (1982 a) and GAETANIet sedimentaries and intrusive bodies are described in the al. (1985). next chapter.

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2.2. The Phs Formation and Intrusive Granitoids

As the name Phe Formation (NANDA& SINGH, 1976) is in common use, I keep to it, though no doubt the formation is identical with the Haimanta Formation of Spiti (HAYDEN,1904). The monotonous argillaceous-arenaceous succession attains thickness of at least 2000 m. It consists of thick-bedded green to grey, massive-unstratified or laminated sandstoneand siltstones alternating with green to dark grey, finely laminated silty slates and slates occasionally being carbonaceous. The sandstones are predominantly fine-grained, but there are also medium-grained, micaceous sandstones, fine- conglomeratic layers, and clay gall' breccias. Petro- graphically the sand- and siltstones are immature, Fig.3. micaceous subarkoses (CASNEDI et aI., 1985). The Graded and current bedded metasandstone (light) and metasiltite (dark) ca. thick-bedded arenaceous rocks disintegrate to coarse 10 km S of Shingo La. Note flame structures in the central part of the photo. irregular blocks. Characteristic are the laminated rocks with fining up units, current ripple cross laminations, lenticular, irregular, flasery and cross stratifications (fig. 1, 2). Flame structures at sandstone-slate inter-

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<~"/' :' '~~ _\}\'li;'. " .~}J f \.: / ~ ',~ ~\ }:' ./

Fig.4. , f l~~-~"Bulbous load convolutions in Phe Formation N of Purni. -- 1, Fig.1. Lamination and graded bedding in block of the Phe Formation. Note the transversal schistosity in the dark pelitic laminae. N of the Shingo La (cover of photo lens gives the scale).

Fig.5. Load casts in fine-grained sandstones of Phe to Karsha Formation. N of Kurgiakh (lens cover for scale). L.~'~~~' Fig.2. faces are not rare (fig. 3). Load convolutions ball- and- Metasandstone to Metasiltstone showing lenticular flaser- and slight cross pillow structures, and beds disturbed by slumping are bedding. Units fining towards the top (near lens cover). frequent (fig. 4, 5). Also scour and fill structures are ob- Phe Formation, lower part of the valley leading from Kado Topko Valley to served. On the s-planes of the sandstones various Shingo La. types of flute casts, rill moulds, groove moulds, burrows

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and linguoid ripples are found (figs. 6-10). The ripples, which were also reported by BAUD et al. (1984) and CASNEDIet al. (1985), are of a type quite different from shallow-water oscillation ripple marks. Considering the sedimentary structures, lithology, great thickness and the vast areal extent of this type of formations throughout the Himalaya, deposition in a basin with flyschoid conditions is suggested (SRIKANTIA, 1981; FUCHS,1982a,b, 1985). Thus I do not agree with BAUDet al. (1984), CASNEDIet al. (1985) and GAETANI et al. (1986), who assume a tidal flat environment with estuarine deposits. This assumption is inconsistent with the large thickness. There was sufficient supply of sediment, which was deposited in a rapidly subsiding instable trough. The areal extent exceeds by far a tidal flat. There are clear indications of activity of turbidity currents in a flysch environment, though these conditions Fig.8. did not persist necessarily throughout the formation (in Flute casts in Phe Formation S of Purni. time and space). The mudcracks and ripples cited as shallow-water indicators (CASNEDIet aI., 1985) may be explained as pseudo-mudcracks (DZULYNSKI& WALTON, /f) 1965, p. 167) respectively ripples or sinuous anas- Ai tomosing pattern of rill moulds (op. cit., p. 59, fig. 43) in a flysch environment.

Fig.9. Flute casts in the Phe Formation between the villages Yal and Telha.

~. .. '~'.' , Fig.6. Flute casts in flysch sandstone. )1: Block from upper Phe to Karsha Formation, N of Kurgiakh (lens cover for scale).

Fig.10. Linguoid ripple marks not inconsistent with a flysch environment. The author finds these ripples reminiscent of the "sinuous, anastomosing pattern of rill moulds", fig. 43 in DZULINSKY & WALTON (1965). Phe Formation between the villages Yal and Tetha.

Tectonics frequently caused small-scale folding or transversal schistosity in the laminated rocks (fig. 1). Fig.7. The grade of metamorphism shows local variation. Bulbous load cast and small flute casts. Epimetamorphic rocks predominate: Phyllitic slates, Phe Formation S of Char. phyllites, metasandstones and -siltstones. Even if the

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grade of greenschist facies is exceeded the sedimen- are close to the Phe/Karsha Formations contact. Thus tary structures are still preserved. the granite intruded in a high level of the Phe Forma- The increase of metamorphism is easily recognized tion. on the descent from the Shingo La to Langkang, which From Darcha walking up the Kado Tokpo VaI- apparently was caused by the Gumboranjan Granite. At ley in direction to the Shingo La after ca. 2 km one en- the northern foot of the pass the phyllitic rocks pass ters a huge g ran it 0 i din t r us ion. It appears that it into phyllitic micaschists. Porphyroblasts of biotite (up represents the direct continuation of the Jas p a G ra- to 5 mm thick) grow partly across the s. They are often nit e, which was dated by FRANK et al. (1976) amoeboid and filled with quartz grains showing internal 495:t16 m. a. s, which was partly rotated. Metamorphic minerals are With intrusive contact coarse-grained, massive light brown biotite, sericite, clinozoisite and tourmaline. leu cog ran i te, bearing muscovite and tourmaline, The sedimentary lamination is still preserved. There are borders the only slightly metamorphic Phe Formation, also a few layers of amphibolite consisting of coarse- which builds up all the region of Darcha. This marginal grained, green hornblende, some biotite porphyro- facies is followed by coarse-grained two-mica granite blasts, quartz, plagioclase, clinozoisite, apatite and ore; containing sporadic, idiomorphic phenocrysts of potas- chlorite and sphene are of secondary origin. sium feldspar (up to 5 cm lenght). There are also ir- E of the Langkang encamping ground, already very regular dark patches rich in biotite. These patches close to the Gumboranjan intrusion, the grade of altera- reach sizes of several cm and seem to indicate con- tamination. Under the microscope the granite exhibits tion increases. Coarse-grained tw 0 - m i cas chi st s contain numerous grains of staurolite (up to 5 mm), hypidiomorphic structure. The rocks are almost free of which enclose quartz and ore; chlorite is secondary foliation, but may be cataclastic. Perthitic mi c roc Ii n e after biotite and staurolite. The micaschists bearing shows idiomorphic phenocrysts with Karlsbad twinning small quantities of oligoclase may pass into two - m i c a and oriented inclusions of plagioclase. PIag i 0 c Iase paragneiss (:tgarnet). Both are interbedded with (oligoclase) partly automorphic and zonary, encloses numerous flakes of sericite and patches of carbonate. light gneisses of 0 rtho type. It appears that the gneiss-micaschist alternation reflects the sedimentary Quartz frequently is undulaceous. Biotite is brown sandstone-siltstone-slate layering of the Phe Formation. and contains sagenite and zircon. Muscovite and The orthogneisses have granitic compositon: Microc- se r i ci t e are rather frequent. Accessory minerals are line, somewhat perthitic, oligoclase, quartz, biotite, z i rcon, a pat i te, and i Imen it e with leucoxen rims. muscovite, subordinate apatite, garnet, zircon, ore and Such porphyric and slightly hybrid granites build up secondary chlorite. Also in the described micaschist- the area around the place Razik. Further upstream to gneiss series there are some rather rare amphibolitic the tributary coming from Shingo La granitic and layers. granodioritic types are cropping out. In the latter the p Iag i 0 c Iase predominates the mi c roc Ii n e. It is The Gumboranjan Granite occurs as a small zonary oligoclase to andesine, partly idiomorphic, and boss in the centre of a domal structure. It is full of in- contains sericite and clinozoisite. Brown bio tit e with clusions of the country rock and does not form a some sagenite; asccessories: zircon apatite; sec- homogeneous intrusion rather a network of dikes and on d a ry minerals: chlorite, clinozoisite, and sericite. sills. First a generation of sills penetrated the country The structure is hypidiomorphic. rocks subparallel to their s planes, thus following the The granitoid rocks along the Kado Tokpo Valley are domal structure. Then a more or less homogeneous rather massive, only occasionally they are foliated. mass of leucogranite intruded into the centre of the Higher up in the orographically left slopes of the valley dome and swarms of dikes cut the country rock and the light-coloured granitoids are seen intertonguing with older sills in all directions. There are quartz-tourmaline the overlying dark Phe Formation. There are inclusions veins, and predominating aplites and pegmatites bear- of the metasiltites in the magmatites measuring dm to ing tourmaline, muscovite, garnet, traces of secondary several hundred meters, and there are numerous dikes copper minerals and occasional beryl crystals of up to penetrating the sedimentaries (fig. 11). There can be no 5 cm length. Frequently the dikes are composite showing banding parallel to the margins. The boundary to the country rock is mostly sharp, in some cases, however, where impregnations occurred, it is not very distinct. The granite in the centre of the intrusion is a fine to medium-grained, light granite to aplite-granite poor in mica. Impregnations with tourmaline are common. A detailed study of the intrusion would reveal several gener- ations of veins and an interesting intru~ive history. As to the age of the Gumboranjan Granite SRIKANTIA et al. (1980) suggested an Early Palaeozoic, whereas GAETANIet al. (1985) prefer a Late Himalayan age judg- ing from the lack of foliation and the composition of the granite. To me these arguments seem very reasonable and I too think that the intrusion belongs to the group of Miocene leucogranites widespread in the Himalayas. According to GAETANIet al. (1985) the Gumboranjan Granite is faulted along its northern contact, which I did Fig.11. not observe. After crossing the intrusive body the Granite of the Kado Topko Valley containing enclosure of metasiltite of the metamorphism dies away, the sills become rare and we Phe Formation.

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doubt the contact being intrusive. Besides inclusions of The lower boundary of the Karsha Formation is not slates and metasiltites also gabbroic and dioritic rocks sharply defined. I draw it with the first appearance of are found in the granitoids. They are probably rocks carbonate beds. The deposition of flyschoid dark grey from the first stages of differentiation of the magmatic to green slates, siltstones, and subarkoses persisted body. There are also fine- and coarse-grained from the Phe into the Karsha Formation. The first car- granitoids penetrating each other. bonate intercalations are thin (up to a few meters) and The trail leading up the tributary towards Shingo La sporadic, but become abundant in the higher part of the crosses the boundary between the granitoids and the formation. There we find algal reefs up to 200 m thick. succeeding sedimentaries. In the orographically left The carbonates weathering in bright ochreous colour slope the contact is interlocking in decametric dimen- are predominantly light to medium grey, rarely green- sions, on the right side elongate decametric bodies of grey dolomite. These very fine-grained to dense rocks the magmatites can be seen amidst the metasiltite are mostly massive and unstratified. However, locally series. It is evident there that the contact is intrusive also cm alternation of dolomite and shale was ob- and not tectonic as interpreted by GAETANIet al. (1985). served; in these cases the carbonate bands were fre- These authors mention that the lithology of the quently distorted to small scale boudins. The dolomites, sedimentaries "may suggest an affinity with the Phe particularly the riff complexes, disintegrate to huge ir- Formation". However, I should like to stress that it is regular blocks. Stromatolites are not rare and figs. 12 the Phe Formation, which is continuous there and 13, photographs from the top of the formation, from Zanskar via Lahoul to Chamba. The Tethyan Zone show algal colonies resembling bread loaves. is connected from Zanskar-Spiti to Chamba, thus we are in 0 n e tectonic unit not in serveral units making up the "High Himalayan Crystalline" tectonically separated from the Tibetan Zone in the N. The granitoids form discordant intrusions in this vast sediementary complex and do not represent the Central Crystalline (s. s). In the terrain built up by the Phe Formation metadiabases and metagabbros are occasionally found. These form dikes, up to decamteric dimensions, penetrating the Phe rocks unconformably. They seem to be related with the extrusion of the Panjal Trap (see chapter 1.9.). Finally the age of the Phe Formation should be dis- cussed. The formation is practically devoid of fossils. NANDA& SINGH(1976, p. 372) refer the finding of trilobites from the upper part of the formation, from their Thonde Member; from this member the authors also mention the occurrence of grey carbonate rocks, thus I infer that the Upper Cambrian fossils are from the Karsha Formation. The Karsha Formation, no doubt, corresponds with the Middle- to Upper Cambrian Parahio Formation of Spiti (HAYDEN,1904). The underlying Phe Formation correlates to the Haimantas. The Haimantas pass into the Parahio Formation by alternation, as does the Phe Formation into the Karsha Forma- tion. Therefore the Haimanta - Phe complex comprises the Cambrian up to its middle portion and most probably also Up per Pre c a m b ria n. THAKUR and GUPTA (1983) regard the Phe Formation Cambrian - Lower Ordovician. In my view this is too young because in Spiti the Ordovician conglomerate transgresses on the Haimantas and Parahio Formation with angular unconformity (HAYDEN,1904; FUCHS,1982a).

Fig.12. Top of the Karsha Formation showing algal colonies resembling bread loaves 2.3. The Karsha Formation (rucksack for scale). ESE of Tanze on the trail to Sinchan. The name was introduced by NANDA& SINGH(1976) for the thick alternation of argillo-arenaceous and carbonate rocks succeeding on the Phe Formation. These The flyschoid series interbedded with these shallow- authors assumed Ordovician age, which from the above water dolomites consist of green to dark grey and black said is very unlikely. THAKUR & GUPTA (1983) and slates and phyllites, laminated, green, silty slates, GUPTA & SHAW (1985) report on ill-preserved trilobite siltstones, and fine to medium-grained micaceous and brachiopod faunas and suggest Upper Ordovician sandstones. The latter are partly thick-bedded, partly to Lower Silurian age. Like BAUDet al. (1984) I prefer a platey. Sedimentary' structures observed are bulbous Mid die to Up per Ca mb ria n age from analogy with load casts, burrows, but also ripple marks. CASNEDIet SpitL al. (1985) and GAETANIet al. (1986) additionally record

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Fe-hydroxyds. The gangue is composed frequently of quartz (cataclastic and mainly recrystallized) and ba- ryte (particularly associated with tetrahedrite). Pyrite occurs in xenomorphous to idiomorphous grains, which are often cataclastic and replaced by Fe-hyd- roxyd. The idiomorphous pyrite grains are mostly observed in tetrahedrite. The latter contains small quantities of Fe, Zn and As. In the above samples the tetrahedrite and chalcopyrite fills interspaces, joints up to 0,2 mm, and the intergranularies of the gangue minerals.

2.4. The Kurgiakh Formation

CASNEDIet al. (1985) and GAETANIet al. (1986) use the term Kurgiakh Formation for a flysch sequence, at Fig.13. least 300 m thick, following on the Karsha Formation. Close-up photo of stromatolites of fig. 12 (lens cover for scale). They describe dark bioturbated pelites with layers of nodular dolomite and basaltic tuffs in the lower part. The upper part is a "thickening - coarsening upward cross-bedding, . mudcracks, bioturbation, patch reefs megasequence of thin-bedded greenish siltstones and peritidal structures. These authors found cycles of characterized by Tb-d Bouma sequences passing up- shale, sandstone and dolomite and infer an environ- wards to thick-bedded, very fine-grained subarkoses. ment of tidal flat to coastal sands and peritidal carbo- The Kurgiakh Formation records the transition from nates. In my view the basin in which the Phe Formation shelf and slope sedimentation in poorly oxygenated was deposited, was finally filled up. This is shown by waters to non-channelized distal turbidites. The the increasing frequency and thickness of the shallow sedimentary evolution thus testifies active tectonic sub- water carbonates. In the uppermost portion of the for- sidence which largely exceeded sedimentation rates" mation, gradual increase of water depth is indicated (GAETANIet aI., 1986, 447-448). It is symptomatic that (GAETANIet aI., 1986). this geologist's group has mistaken the above flysch The thickness of the Karsha Formation is estimated series in the type area for the Phe Formation (BAUDet about 800 m by GAETANIet al. (1986), whereas I think aI., 1984, fig. 8), though these authors deny the flysch- that it may exceed 1000 m. There is uncertainty about oid nature of the Phe Formation. the primary thickness because of tectonic disturbance. The Kurgiakh Formation can be traced through- The rigid reefal dolomite bodies within the ductile ar- out the Tanze-Chumik-Marpo area as a greenish ban.d gillo-arenaceous rocks led to much shearing along the on top of the brown dolomite cliffs of the Karsha Forma- dolomite boundaries. tion. The rocks of the Kurgiakh Formation are less re- At Phuktal the top of the Karsha Formation consists sistant than the surrounding formations, thus they form of slates, siltstones, light grey sandstones and thick- soft terrain frequently covered by talus. I observed bedded, fine-grained light quartzites. Such quartzites green to dark grey, very fine slates and needle shales, are not very characteristic of the Karsha Formation, and frequently laminated, alternating with green to light seem to be confined to the Phuktal area. grey, micaceous sandstones, mainly fine-grained; load In connection with the Karsha Formation it is neces- casts, rill marks, tool marks etc. are frequent. sary to mention the occurrence of veins containing ore. This basin facies indicates a renewed subsidence In the Surichun Chu thick-bedded dolomite of the after the shallow-water carbonates of the Karsha For- Karsha Formation forms the core of a secondary anti- mation. GAETANIet al. (1986, p. 447) report Middle cline (pI. 1, 2 [16, 17]). These dolomites are discor- Cambrian trilobites from the lower part of the formation, dantly penetrated by serveral veins, up to 1 m thick. which shows that this subsidence occurred still in the Prof. Dr. W. SIEGL (Montan. Univ. Leoben, Austria) Cambrian. There is disagreement with GUPTA, who kindly has made preparates of my samples and deter- suggests for each formation of the Lower Palaeozoic a mined the main ore minerals: chalcopyrite, pyrite, and considerably younger age (THAKKUR& GUPTA,1983). tetrahedrite. By courtesy of Dr. O. SCHERMANN,Dr. H. NEINAVAIE (VOEST-Alpine AG, Eisenerz) kindly examined my samples also by microprobe. His results 2.5. The Thaple Formation of two typical samples are presented: 85/11/5: The ore consists predominantly of tetrahedrite, chal- NANDA& SINGH(1976) introduced this name for a copyrite and subordinate cobalt glance. Pyrite occurs varicoloured, mainly red and brown formation, a marker sporadically. Malachite, azurite and Fe-hydroxyds are horizon from the Kurgiakh area of Zanskar to SpitL The secondary. The groundmass of the vein is composed Thaple Formation (some tens to 200 m thick, attaining of prevailing dolomite and some quartz. The cobalt glance occurs in xenomorphous to 300 m in the Chumik Marpo area) is composed of con- idiomorphous grains, with random distribution in the glomerates, quartzites, sandstones, carbonate sand- matrix and as fine inclosures in tetrahedrite; it is also stones, slates and thin lenses of dolomite. The red, found intergrown with chalcopyrite. Cobalt glance al- purple and brown con g 10mera te s prevail in the ways contains traces of Fe, Cu, and Sb as revealed lower part of the formation. They are unstratified to by microprobe analysis. 85/11/7: The ore consists predominantly of tetrahedrite and thick-bedded, ill-sorted and contain moderately to well- pyrite, sporadic chalcopyrite, bornite, and covellite. rounded components up to 30 cm sizes; the latter are Secondary ore minerals are azurite, malachite and varicoloured sandstones, quartzites and slates of the

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same formation, and dolomites, limestones, phyllites, ing of my views, because I never assumed a connec- quartz, greenstone etc. from the beds underlying. The tion between the Himalaya and the North-European ochreous weathering matrix is arenaceous-calcareous. orogene but correlated in tim e. The granites clustering The conglomerates pass into conglomeratic sand- about 500 m. a. and the Ordovician conglomerates in stones, red coarse to medium-grained sandstones, Spiti-Zanskar mark an initial phase, because in other quartzites, carbonate-sandstones and quartzites. parts of the Himalaya (Nepal-Kumaun, Kashmir) the Cross-bedding and claygall breccias are very common. basin facies persisted through the Ordovician and the in these rocks, rarely ripple marks were observed. Ac- significant facies change took place in the Silurian. The cording to GAETANIet al. (1986) the arenaceous rocks epicontinental Muth Quartzite (Devonian) signals the are predominantly Iitharenites. There are also' impure end of the Caledonian cycle. argillites and thin discontinuous cream dolomites. In the orographically left slopes of Chumik Marpo dark haematitic quartzites crop out in the neighbourhood of 2.6. The Muth Quartzite the Muth Quartzite. As the rocks are vertical along a (STOLlCZKA, 1865) fault there is some ambiguity whether the rocks belong to the Muth Quartzite or represent Thaple Formation - The massive to thick-bedded, white Muth Quarzite is I favour the last possibility. The hard, thick-bedded a marker horizon from Kumaun to Kashmir. In the area quartzites are ill-sorted, moderately to poorly rounded investigated its thickness .varies between 0 and 20 m, quartzarenites rich in calcareous algae. The latter are occasionally reaching a maximum of 50 m. The primary frequently replaced by haematite. thickness seems to have been reduced, and by defor- In the Kenlung area (Yunan Valley) the Thaple For- mation the band of the Muth Quartzite was frequently mation has lost the bright red colour due to metamorph- squeezed.and distorted to lenticular bodies (e. g. near ism (greenschist facies). Tanze). From the lithofacies and fining-up cycles GAETANIet The rocks are white to light grey, very hard al. infer a subaerial, alluvial environment of alluvial fan quartzites, massive or thick-bedded. They disintegrate to braid-plain (1986, p. 449). The Thaple Formation to large irregular blocks, weathered surfaces being marks a break in the sedimentary development: Aft~r a cream coloured. Cross-bedding and oscillation ripple long period of flyschoid basin deposition (Phe Forma- marks are common; burrows were also observed. For tion) a phase of shallowing caused by retarded subsi- petrographic details I refer to GAETANIet al. (1986, dence (Karsha Formation) and renewed flysch p.449). sedimentation (Kurgiakh Formation) the conglomeratic, In the Chumik Marpo area sporadic beds of ochreous mainly terrigeneous beds of the Thaple Formation weathering dolomite were found in the Muth Quartzite. transgress after a gap. In Spiti a marked angular un- Such carbonates accompany the quartzites in Spiti conformity is found at the base of these conglomerates (FUCHS,1982a), Kumaun (HEIM& GANSSER,1939) and (HAYDEN,1904; FUCHS,1982a). There the purple con- western Nepal (FUCHS,1977a). glomerates and quartzites pass upwards into a mixed The Muth Quartzite was deposited in a stable envi- argillo-arenaceous carbonate series, which has yielded ronment with a low rate of subsidence allowing re- Caradocian to Wenlockian faunas (HAYDEN, 1904; peated recycling, which led to the superstable composi- REED,1912). Thus the age of the conglomerates is de- tion and high grade of maturity. termined as Ordovician in SpitL The orogenic phase in- Generally the Muth Quartzite is poor in fossils. On dicated by the unconformity is further documented by the basis of plants and faunas found in different parts an invasion of granites in the Himalaya dated by FRANK of the Himalaya GUPTA(1973) and THAKUR& GUPTA et al. (1976), MEHTA(1977), HONEGGERet al. (1982) (1983) assigned a Middle to Upper Devonian age. and LE FORTet al. (1986). In Zanskar the fossiliferous Ordovician-Silurian sequence of Spiti overlying the conglomerates is missing, however THAKUR& GUPTA 2.7. The Lipak Formation (1983) report on crinoids and trilobites from the Thaple (HAYDEN, 1908) Formation (their Tanze Formation). On the basis of these fossils they suggest an Upper Silurian-Lower In the investigated area the Lipak Formation consists Devonian age. Similar young age is proposed by GUPTA of grey, dark bluish grey and black limestones, dolo- & SHAW(1985). In my view the break in sedimentation mitic limestones, sandy siliceous limestones and marls occurred at the same time in Spiti and Zanskar: at the and light-coloured evaporitic series in the upper part. Cambrian/Ordovician boundary. GUPTA'Sfossils, how- The thickness varies between 25 and 250 m, probably ever, may indicate that the conglomeratic facies per- due to the mobility of the evaporitic rocks. The carbo- sisted for a longer period in Zanskar than in SpitL Thus nate sequence is always well-bedded-platey to thick- the Thaple Formation would represent the Ordovician bedded with even or nodular s-planes. The individual conglomerates and Quartzites as well as the fossilifer- beds often show fine lamination, slightly lenticular ous Ordovician to Silurian sequence of SpitL stratification and intraformational breccias. Crinoidal The orogenic event documented by the Thaple For- limestones and shell beds are very common. The latter mation is related with the Pan-African orogeny accord- contain brachiopods and bivalves. ing to BAUDet al. (1984), CASNEDIet al. (1985) and The rich fossil content of the Lipak Formation is refer- GAETANIet al. (1986). The 550-500 m.a. event in the red by THAKUR& GUPTA(1983) and most recent finds Himalaya is interpreted by these authors as the last are recorded by WEBSTER& GUPTA(1984) and GUPTA pulse of the Pan-African Orogeny. Thus they disagree (1986). A Lower Carboniferous age of the Lipak with my concept of a Caledonian orogeny (FUCHS, Formation is well-established. In the lowermost carbo- 1967) "on chronological and spatial grounds" (BAUDet nates following immediatelyon the Muth Quartzite how- aI., 1984, p. 184). There is apparently misunderstand- ever, GUPTA(1986) discovered an upper Upper Devo-

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nian (Fammenian) conodont fauna. Thus the change Lipak Formation and the transgressing Panjal Trap. The from arenaceous to carbonate deposition took place in conglomeratic quartzites and black slates immediately the uppermost Devonian, similarly to Spiti (HAYDEN, below the panjal Trap, however, are excluded from the 1904; FUCHS,1982a, p. 338). Po Formation and belong to the transgressing Permian Regarding facies of the carbonates GAETANIet al. series. This is shown by the fact that the conglomeratic (1986) infer a "shallow subtidal environment, possibly quartzite accompanies the trap irrespectively what for- an open to restricted carbonate shelf" (p. 451). mation is underlying. The gyp sum fa ci e s in the upper Lipak Formation The age of the Po Formation is Middle and Upper is of much interest: It commences with ca. 10m of Carboniferous on the basis of the fossil content referred blackish limestones alternating with red shales, pink in literature. limestones and brown to cream shaly marls. The carbonates are micritic-detrital, pelletal or sandy limestones showing numerous shells of ostracods. GAETANIet al. 2.9. The Panjal Trap (1986) record ostracods, crinoids, brachiopods, (RalakungFormation,NANDA & SINGH, 1976) bivalves, and gastropods from this lower part; one of these fossils Tomiproductus ranges in age from Middle The dark band of the Panjal Trap is a conspicuous Tournaisian to Early Visean. marker horizon in the landscape of southern Zanskar Then follow basic volcanic rocks and the first gypsum and can be traced also on satellite imagery. The Panjal layers. The volcanics are concordantly interbedded, Trap rests with an angular unconformity on various old- green-grey, schistose rocks. The fabric is fine-grained er Formations (Karsha to Po Formation). This conspi- ophitic with numerous patches of carbonate, which are cuous unconformity was rightly recognized as stratigra- partly enclosures of the syngenetic carbonates partly phic by NANDA& SINGH(1976), but recently misinter- amygdales filled with carbonate. Around these carbo- preted as nappe boundary (BAUDet aI., 1982a,b, 1984). nate patches the plagioclase laths are arranged parallel The base of the Panjal Trap is formed by a 8 to 10m to the boundary. The components of the metavolcanics band of thick-bedded quartzite with partings of black - lavas to tuffs - are idiomorphic plagioclase, chlorite, silty argillite. The very hard quartzite is white, green, carbonate, ore, and small quantity of quartz. or grey, fine- to coarse-grained with conglomerate to Above these volcanics the main mass of white, breccia layers. The components of the latter reach 3 cm coarse-grained gypsum follows, several tens of m thick. sizes and show rounded to angular shapes. They con- Interbedded with the gypsum we find pink limestone. sist of white quartz and dark grey to black quartzite and These carbonates are micritic-detrital, pelletal, showing slate in light quartzitic matrix. The quartzite shows strong bioturbation. Crinoidal and algal remains are fre- under the microscope angular grains of quartz, fine- quent. grained quartzite, tourmaline, zircon, ore and flakes of Above the evaporitic series we find well-bedded car- white mica in a predominantly siliceous groundmass, bonates like the lower part of the Lipak Formation. which is generally subordinate. The quartzite is mode- There may be a repetition by folding or the facies re- rately to well-sorted, frequently cross-bedded and turned from evaporitic to carbonate shelf conditions shows fining up units. The interlayered argillite is black, near the top of the formation. silty-micaceous shale. At the top just beneath the Pan- jal Trap the uppermost dms of the sediments are darker and hardened under the influence of the magmatic con- 2.8. The Po Formation tact. In thin-section it can be observed that the groundmass has recrystallized with growth of chlorite, HAYDEN(1904) introduced this name for the thick sericite, and sphene. In the section NNW of Tanze, shale-quartzite series overlying the Lipak carbonates in where I met the above beds for the first time, the litho- Spiti.' In the investigated area of southern Zanskar the logy is not so much different from the underlying Po Po Formation is 200-300 m thick, locally it may attain Formation. But I observed that this quartzite band over- even 400 m. The formation is a thick-bedded alternation lapped different beds of the underlying formation. Then of quartzites, sandstones, siltstones, slates, and impure I found the conglomeratic quartzites at the base of the limestones. The hard quartzites are white, grey, green Panjal Trap at Phuktal and in blocks in the Thongde and break into large irregular blocks. The green, grey, area, where the Po Formation is missing. Thus it is evi- and brown sandstones and subarkoses show current dent that the quartzite band marks the Permian trans- bedding and uneven s-planes. They may contain gression so widespread in the Himalayas (W-Nepal, sporadic mud-supported well-rounded pebbles and cob- FUCHS,1967, 1977a; Kumaun, HEIM& GANSSER,1939; bles. Greenish siltstones pass over silty shales into Spiti, HAYDEN,1904; FUCHS,1982a). It should be stres- black slates, often disintegrating as "needle shales". sed that the lower contact of the quartzite to the Po The dark argillites exhibit bleachig on weathered sur- Formation is a stratigraphic one, the upper to the flows faces. The grey to blue limestones are mostly impure of the Panjal Trap is a magmatic contact, both bound- by silt or sand content. Brachiopods, crinoids, and gas- aries being undisturbed by tectonics. BAUDet al. (1984, tropods are sometimes observed. Burrows and other fig. 2, 10) assumed a thrust separating their Pughtal- biohieroglyphs are not rare. GAETANIet al. (1986) and Zangla Units at the base of the panjal Trap. suggest a shallow epicontinental shelf environment for GAETANIet al. (1986, fig. 5) draw this nappe boundary the lower part of the formation, more proximal deltaic lower down within the Po Formation or at its base. Ac- deposition for the upper portions. tually none of these envisaged thrusts does exist. Different stratigraphic subdivisions of the Carbonifer- The Pan j a I T rap consists of green basaltic rocks ous are used by SRIKANTIAet al. (1980) and THAKUR& weathering into sharp-edged blocks. According to HON- GUPTA(1983). In the present paper the term Po Forma- EGGERet al. (1982) the traps are mainly silica-saturated tion assigns the clastic series between the underlying or nepheline normative basalts of the tholeiitic or al-

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... ~ for instance N of Phuktal, shows the connection of the mafic dikes with the Panjal volcanism. GAETANI et aL (1986, 454-455) studied some samples of the mafic dikes and found them to compare well with the Panjal Traps. It is surprising that inspite of these facts BAUD et al. (1984) and GAETANI et al. (1986) think the Panjal Trap as belonging to their "Zangla Nappe" separated by a thrust from the underlying formations ("Phuktal Nappe"), which are cut by the mafic dikes. In my view the observations only allow the conclusion that, when the flows of the trap extruded, the underlying formations were penetrated by numerous dikes from the same magmatic source. Besides the undisturbed contacts this is another evidence that the Panjal Trap forms 0 n est rat i g rap h i c succession with the underlying Palaeozoic formations.

2.10. The Kuling Formation (STOLlCZKA, 1865)

The formation varying in thickness betwen 20 and 50 m is composed of quartzite, sandstone, impure limestone, and silty shales. Thick-bedded white, grey and brown, coarse-grained quartzites dominate in the basal part of the formation. They also contain breccia layers. Associated with the quartzites we find green- grey impure micaceous sandstones. These rocks are succeeded by brown weathering, green-grey, medium- grained carbonate sandstones, -quartzites, grey arenaceous limestones and blue-grey marly limestones and shales. The upper portions of the formation consist Fig.14. of dark silty, micaceous argillites with sporadic black Ropy flow structures in block of Panjal Trap, E of Thongde Gompa. nodules, a series well-known in the Tethys Zone under the name Kuling Shales. NICORA et al. (1984) give a more detailed description of the Kuling Formation, to kaline series. There are thick-bedded series of flows which I refer. showing very fine-grained chilled margins and being The Kuling Formation is very rich !n fossils and they medium- to coarse-grained in the central portions of the are found throughout the formation. Brachiopods, bryo- flow. Pillow structures are sometimes to be found. Vesi- zoans, corals, gastropods, bivalves, and echinoderms cular rocks are common, the amygdales filled by chlo- are found. Near the top the first ammonoids occur. The rite, epidote, quartz, calcite etc. Further cm-wide gas Kuling Formation following the panjal Trap seems to be pipes are found perpendicular to the margins of the mainly Middle and Upper Permian (SINGH et aI., 1982) flow. Structures due to lava flow, such as ropy lava, are whereas in the E, where the Volcanics are missing, the not rare (fig. 14). Agglomerates and other pyroclastic formation comprises the whole of the Permian (JOSHI & rocks are generally multicoloured - red, green, and ARORA, 1979; THAKUR & GUPTA, 1983, 15-16). There purple. The components reach dm sizes. Interlayered, GUPTA uses the local term Sarchu Series. and particularly at the top, purple and green tuffaceous The environment of the Kuling Formation was shal- slates are associated with the traps. For details of pe- low-water. It is a transgressive series like the basal trography and geochemistry I refer to SINGH et al. beds of the Panjal Trap Formation. These effusions (1982) who studied the Panjal Trap of Zanskar particu- seem to be related with rifting, which led to the opening larly. of the Neotethys (ANDREWS-SPEED& BROOKFIELD,1982; The thickness of the Panjal Trap in Zanskar - ap- HONEGGERet aI., 1982). The transgressive sequence of proximately 300 m - is small compared to the the Permian reflects this break up and the following thousands of meters in Kashmir. In the Lingti Valley the subsidence (BAUD et aL, 1984; GAETANI et aI., 1986). Panjal Trap pinches out towards the E. NANDA & SINGH (1976) and SINGH et aL (1982) report on fossiliferous limestones interstratified with the trap. On the basis of the fossils a Lower to Middle Permian 2.11. The Triassic Formations age is proved for the Panjal Trap of Zanskar (THAKUR& GUPTA, 1983). In western and northern Zanskar the Triassic is re- All the older formations underlying the Panjal Trap presented by an approximately 1000 m thick sequence are penetrated by swarms of basic dikes. Their thick- of limestone, dolomite, and shale. This succession is ness varies from one to tens of meters. Increased fre- rather uniform and does not show distinct litho-units quency of the dikes near the Panjal Trap, as observed suitable for subdivision. It is difficult even to separate

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the Kioto Limestone from the underlying Triassic beds, 2.11.3. The Daonella Limestone if the Quartzite Beds are missing. Additional difficulty to Above the geomorphologically soft terrain of the subdivide arises from the tight folding of the sequence. Daonella Shales the well-bedded Daonella Limestone Thus on a reconnaissance survey I used the term Trias- forms cliffs several tens of meters high. It consists of sic-Jurassic Carbonates (FUCHS, 1982b) or Zanskar- dark grey, blue, and black limestone partly nodular, and Carbonates (1986) for this series. subordinate black marls and shales. The name-giving InSE-Zanskar, however, the litho-units known from lamellibranchs are rather frequent (e. g. on the trail Spiti are more and more recognizable. The subunits are from Sinchan to Phirtse La). indicated in the map (pI. 1) and sections (pI. 2) in In Spiti the Ladinic/Carnic boundary is assumed traverses along the Shingri- and Tsarap Chu. within this limestone series (HAYDEN,1904). In Zanskar, In recent papers the old term "Lilang" has come in however, BAUDet al. (1984) and GAETANIet al. (1986) common use again. BAUDet al. (1984) and GAETANIet report Late Ladinic ammonite faunas from the upper al. (1986) use the name Lilang Group in the sense of part of their member 2 of the Hanse Formation, which HAYDEN(1908) for the Triassic sequence from the base corresponds to the Grey Beds of SpitL Only the lower up till the Kioto Limestone. SRIKANTIAet al. (1980) in- part of member 2 correlates to the Daonella Limestone. clude also the Kioto Limestone. The latter seems pre- Thus there is ambiguity whether the age of the Grey ferable to me, because on satellite imagery or by Beds in Spitl. should be revised to be Late Ladinic or a binocular observation from afar the carbonate belt can change in lithofacies should be assumed. be traced only as a whole.

2.11.1. The Tamba Kurkur Formation 2.11.4. The Grey Beds SRIKANTIAet al. (1980) introduced this name for a Above the Daonelle Limestone marly and argilla- very distinct Iithounit traceable from Nepal to Zanskar. ceous rocks become predominant. Like the two underly- It is relatively thin, generally less than 50 m - W of the ing formations the sediments are of dark colour and are Zanskar River it reaches 100 m according to NICDRAet bleaching light grey if weathered. The sequence of thin- al. (1984) and GAETANIet al. (1986). Composed pre- bedded shales, marls, and limestones is much de- dominantly of well-bedded limestone the Tamba Kurkur formed. The thickness of the Grey Beds - less than Formation can be followed as a thin resistant band in 100 m - is much smaller than in SpitL The Grey Beds the scenery. are regarded as Carnic in Spiti (HAYDEN,1904; DIENER, The formation starts with a thin-bedded alternation of 1912). The lithologically corresponding series in Zanskar has yielded a Late Ladinian fauna (BAUDet aI., grey, dense limestone and grey shale. Some limestone 1984; Gi~TANI et aI., 1986). beds abound in ammonites, which are commonly much deformed. The central parts of the formation are thick- The argillaceous-calcareous sequence succeeding the Tamba Kurkur Formation is deposited on pelagic bedded to massive forming escarpments. They consist of grey to bluish, frequently nodular limestone, rather outer shelf (GAETANIet aI., 1986). The uppermost part of the Hanse Formation (member 3) of these authors in- barren in macrofossils. The upper part of the Tamba dicates transition to shallow water carbonate environ- Kurkur Formation is composed of thick-bedded, dark ment. This member 3 corresponds to the lower portions grey to blue nodular limestones with some shale partings. They are rich in Anisian ammonites. BAUDet al. of the Tropites Limestone, which f9110wSon top of the Grey Beds. GAETANIet aI., suppose their member 3 to (1984), NICDRAet al. (1985) and GAETANIet al. (1986) reach into the Carnic, which fits well with the above show by means of conodont faunas that the Scythian/ correlation. Anisian boundary is in the upper part of the central member. The Tamba Kurkur Formation comprises the Scythian and Anisian in Zanskar, in Spiti it reaches into the Lower Ladinian accordig to DIENER(1912, p. 71) 2.11.5. The Tropites Limestone and KRYSTYN(FUCHS,1982a). In Spiti a 250-300 m carbonate succession forms a As to the environment GAET~NIet al. (1986) suggest marked cliff above the soft Grey Beds. HAYDEN(1904) "pelagic sedimentation in upp~r bathyal condition with named the series Tropites Beds and I used the term low sedimentation rate" (p. 457), which agrees very Tropites Limestone (FUCHS,1982a) for this very distinct well with my views (FUCHS,1967). litho-unit. Like in Spiti the Tropites Limestone shows tripartition in eastern Zanskar (Tsarap Valley N of Phuktal): 1) The lowest member consists of dark thick-bedded 2.11.2. The Daonella Shales limestones and dolomites. At the top the limestones of the Tamba Kurkur For- 2) The middle member is distinctly sandy and weathers mation become marly and are increasingly interbedded in brownish colour. It is composed by a thick-bedded with shale. Thus there is a passage into the succeeding alternation of grey sandy limestones and dolomites, Daonella Shales (ca. 40 m). These consist of soft calcareous and dolomitic sandstones, and fine- earthy-coloured shales, marls and dark mudstones, grained light sandstones and quartzites. Cross-bed- which are generally much contorted and covered by ding, intraformational breccias, scour and fill struc- talus. HAYDEN(1904), DIENER(1912) and GUPTA(1975) tures, oolites, crinoid and shell layers suggest shal- assign Ladinian age to the sporadic fossils. The low-water deposition. Fine-lamination, partly graded, Daonella Shales correlate to member 1 of the Hanse is common; burrows were observed. Formation of GAETANIet al. (1986). The fossils found by 3) The upper member consists of thick-bedded dolo- the named authors (p. 459) fit well with this correlation. mites and limestones.

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The Tropites Lim~stone is approximately 300 m thick confusion in nomenclature arising from the above use and rather poor in fossils. On the basis of the fossils of the term "Quartzite Series". found HAYDEN (1904) and DIENER (1912) regard the Regarding environment there is a marked increase in Tropites Limestone as Carnic. In the nomenclature of terrigenous influx in the Noric, which may be traced BAUD et al. (1984) and GAETANIet al. (1986) member 3 throughout the Tibetan Zone. GAETANlet al. (1986, of their Hanse Formation and 'their Zozar Formation p. 463) infer "deltaic systems in an inner shelf becom- seem to correlate to the Tropites Limestone. GAETANIet ing more diversified upwards (channels, bars)". al. found a fauna of megalodontids at the top of their Along the strike the facies of the Noric beds changes Zosar Formation, which according to them may suggest from flyschoid basin conditions in Nepal to shallow Noric age. It should be noted, however, that water in the western Himalaya. megalodontids occur already in .the Carnic. GAETANI et al. (1986) regard the series as regressive, a transition from subtidal inner shelf to interior platform/tidal flat (p. 461). 2.12. The Quartzite Series

2.11.6. The Juvavltes and Monotis Shales Between the underlying shaly-silty-arenaceous-cal- From Nepal to Kumaun, Spiti, and Zanskar the Noric careous alternation and the Kioto Limestone thick-bed- is characterized by shaly-silty-arenaceous beds being ded quartzites form a marker horizon throughout the predominant or alternating with limestone: Tarap Tethys Himalaya. In Zanskar, however, the ..Quartzite Shales, Kuti Shales, Juvavites-Monotis Shales etc. Series is not as well-developed as in other regions. It is From the E towards the W the carbonate content in- a few tens of meters thick only or may be missing at all creases and in western Zanskar and Kashmir finally the in some sections. Characteristic are the thick-bedded Noric is calcareous-dolomitic. In the region of the upper quartzites of white, grey, brown, or green colour alter- Zanskar River the Noric seems to lose its distinct nating with brown-weathering carbonate quartzites, character towards the NW. In parts of Spiti the Noric is blue limestones of Kioto Limestone type and a few divisible into the lower Juvavites Shales and the upper shaly beds. The limestone beds may contain large Monotis Shales by a marker horizon - the Coral Lime- shells of Megalodon and Dicerocardium. Intraformational stone (HAYDEN, 1904). Where the latter is missing the breccias and current-bedding are frequent in these lower and upper shale series are difficult to separate. A shallow-water beds, marking a general regression in similar situation is in Zanskar: the Himalaya. Towards the top the sand content de- The Tropites Limestone issucceeded by a creases and the Quartzite Series passes into the Kioto 100-200 m alternation of nodular, partly thiqk-bedded Limestone. blue limestone, green, grey to plack, silty slates, The age of the Quartzite Series is generally accepted siltstone, and impure, fine-grained sandstone. Flasery, to be Upper Noric to Rhaetic. lenticular stratification, and cross-bedding are common. As to the fossil content I refer to HAYDEN (1904), DIENER (1912), GUPTA (1975), and GAETANI et al. (1986). BAUD et al. (1984) and GAETANI et al. (1986) desig- 2.13. The Kioto Limestone nate only one formation - the "Quartzite Series" - be- (HAYDEN, 1908) tween their Zosar Formation (Tropites Lms.) and the Kioto Limestone. Though BAUD et al. (1984, p. 181) From the Quartzite Series a 500-600 m thick carbo- refer to HAYDEN (1904) in using the term '~Quartzite nate sequence develops, forming conspicuous cliffs and Series", it is clear from their description that the series rock faces. The Kioto Limestone is a thick-bedded suc- comprises both the Monotis-Juvavites Shales (HAYDEN, cession of grey, blue, and black, partly nodular lime- 1904) and the Quartzite Series (HAYDEN, 1904). stones, grey dolomites, subordinate marls and a few GAETANIet al. (1986) discern two litho-zones and it is of arenaceous layers in the lower part. Many of the dolo- great interest that on the top of the lower one they re- mites are the product of dolomitization. Oolithic, oncoi- cognized a coral horizon (lithofacies d). It is very dal layers, fossil debris, current bedding large scale rip- suggestive to correlate these "small coral boundstones, ples and intraformational breccias indicate deposition in occasionally reaching plurimetric size" (p. 462) to the shallow water. From their facies studies GAETANI et al. Coral Limestone of Spiti. Thus their lithozone A seems (1986) infer a "transgressive-regressive sequence start- to correspond with the Juvavites Shales, lithozone B ing with medium to high energy inner shelf environment with the Monotis Shales. In these series the arenace- characterized by bars, channels and small patch reefs. ous beds are mostly fine-grained subarkoses. The Low to medium energy subtidal inner shelf conditions Quartzite Series in the sense of HAYDEN start with the with poor but differentiated fauna and extensive biotur- "medium grained quartzarenites::with subrounded but bation follow. In the middle part of the unit low energy, moderately sorted grains" below the boundary with the interior platform conditions are documented. The upper Kioto Limestone (p. 462). To the same horizon BAUD et Kioto Limestone is interpreted as medium energy inner al. (1984, p. 181) refer by noting quartzarenites "con- shelf with terrigenous supply possibly connected to fined to the top of the unit and to the base of the over- short term base level fluctuations" (p. 464-465). lying Kioto Limestone". Thus their "Quartzite Series", The fossils are mainly algae, benthic foraminifers, being ca. 300 m thick, represents HAYDEN'S Monotis- corals, bryozoa, brachiopods, gastropods, bivalves, and and Juvavites Shales and only the uppermost crinoids. Typical are shell beds of Megalodon, Dicerocar- quartzarenites may be correlated to HAYDEN'S Quartzite dium, and Lithiotis. The age is accepted Rhaetic to Early Series. This discussion was necessary to remove the Dogger.

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2.14. The Ferruginous Oolite prevailing dark argillites. The lower part rich in sandstone is approximately 200 m thick in the Namtse Throughout the Tethys Himalaya a thin ochreous La section, 120 m at Zangla; the upper more shaly por- weathering band follows the Kioto Limestone and un- tion is 80 m in the first, 180 m in the second area. The derlies the dark Spiti Shales. This marker horizon of sandstones and quartzitic sandstones are fine to Upper Dogger age was studied in much detail by medium-grained and show grey-green colours. S- JADOULet al. (1985) and GAETANIet al. (1986) in south- planes are often uneven and burrowed and the rocks ern Zanskar: disintegrate to large irregular blocks. There are also A) The lowest Iithozone (0.5-10 m) an 001 it hie beds of white, green, grey, and black fine-to medium- i r 0 ns ton e rich in fossils follows on the Kioto grained quartzite. The arenites are interbedded with Limestone after a gap, which was larger in the E. black shales and silty shales, which are often found as B) Varicoloured shales with scattered belemnites, clay fragment breccias in the sandstone. In the Oma ammonites, and ferruginous ooids (2-20 m). Chu-Zangla area the uppermost sandstone bed fre- C) Cross-bedded bioclastic quartzarenites «20 m) quently shows dark blackish colour. As I suspected a D) Fossiliferous oolitic arenites (2-5 m) correspondence with the phosphoritic beds at the top of The Spiti Shales follow with sharp contact. the Giumal Sandstone in other parts of Ladakh de- The time gap between the Kioto Limestone and the scribed by FUCHS(1979), BAUDet al. (1982b, p.355) Ferruginous Ooolite (Early resp. Middle Callovian to and GAETANIet al. (1986, p. 468), I gave a sample for Late Callovian) spans at least 10m. a. (JADOULet aI., chemical examination. Dr. P. KLEIN,Geol. B.-A., kindly 1985). During this time deposition continued in other informed me that there was a P20S content of only parts of the Tibetan Zone. In Nepal, for instance, the 0.6 %, Mn 0.06 %, but Fe 23.8 %. Thus the dark sedi- Kioto Limestone grades into the Lumachelle Formation, ment colour is obviously caused by iron compounds. which in turn is succeeded by a ferruginous impure GAETANIet al. (1986) on the basis of detailed studies limestone bed of Callovian age (EGELERet aI., 1964; subdivided the Giumal Sandstone into three parts: the FUCHS,1967; BORDETet aI., 1971). In Kumaun the Lap- lower one (160-200 m) consists of dark grey tal Series corresponds with the Lumachelle Formation, sandstones and pelites, the latter becoming prominent and in the Shalshal Cliff the beds between the Kioto towards the E (Tantak). A forams find points to Late Limestone and the Sulcacutus Beds (DIENER,1912, Aptian, possibly Albian age. The middle part p. 101, fig. 9). In these regions there may be a slight (110-130 m) is composed of dark grey shales and thin- gap at the base of the Callovian ferruginous bed, in the bedded laminated sandstones. The upper portion western Himalaya, however, its time span is obviously (90-100 m) commences with very coarse-grained larger. cross-bedded quartzarenites, followed by pelites, volcanic arenites and biocalciruditic layers with belemnites. Then come black glauconitic sandstones several 2.15. The Spiti Shales m thick. As the arenaceous bodies are fining if traced to the E, the middle and upper Giumal are difficult to (STOLlCZKA, 1865) separate in the Zangla area. The formation consists of soft, green-grey to black, The terrigenous debris comes from the SW from a silty shales with sporadic thin layers of dark impure continental source. It was deposited in deltaic systems, limestone or siltstone. Dark concretions are not rare. which pass laterally into offshore pelites towards the Ammonites and belemnites are frequently found but NE (BAUDet aI., 1984; GAETANIet aI., 1986; FUCHS, poorly preserved. GAETANIet al. (1986) observed a 1986, p. 426). The basic volcanic influence recognized layer of fine-grained sandstone and graded calcirudite by GAETANIet al. is a problem. Should we accept a rich in belemnites and ammonite fragments at the base local source from basaltic intercalations in the Spiti- of the formation. In the same position a belemnite bed Shales recorded by KANWAR& BHANDARI(1979)? Was it is recorded from Spiti (FUCHS,1982a, p. 351). The Spiti basaltic volcanism related to the initial rifting between Shales are ca. 20 m thick in western Zanskar, ca. India and Australia as envisaged by GAETANIet al. 100 m in the lower Oma Chu, and attain 100 to 150 m (1986, p. 469)? Or should we assume that the northern in the lower Niri Valley. Due to the soft rocks the Spiti margin of India was already in a distance from the Shales are frequently covered by float and good expo- Indus suture to be influenced by the volcanic arc (Dras) sures are rare. already active then? The formation was deposited in deeper water, (outer The age of the Giumal Sandstone is Upper Neoco- shelf) under euxinic conditions as indicated by the dark mian to Late Cenomanian. The upper boundary has be- sediment colours. come younger by recent ammonite finds (GAETANIet aI., The age of the Spiti Shales is generally accepted as 1986, p. 468). Upper Oxfordian to Lower Neocomian.

2.17. The Chikkim Limestone 2.16. The Giumal Sandstone and (STOLlCZKA, 1865) Shillakong Formation The Giumal Sandstone shows brown ferruginous The dark coloured terrain built by the Giumal weathering colours, by which the formation can be Sandstone is overtowered by light-weathering carbo- easily traced on satellite imagery. In the region of the nate formations of distinct pelagic character. They are Zanskar Valley the Giumal Sandstone consists in its either grey or blue - the Chikkim Limestone named by lower part of a thick-bedded sandstone sequence with STOLlCZKA(1865) - or consist of a varicoloured alter- subordinate pelites interbedded, and an upper part with nation of limestone, marl, and pelites - a couches

rouges facies - termed Shillakong Formation by FUCHS follow. Sample 85/38 immediately above the base (1982b; synonym Fatu La Formation). In western yielded (all determinations kindly by Dr. R. Zanskar the Chikkim Limestone is confined to the OSERHAUSER,Geol. B.-A., Vienna"): Strongly recrystal- south-western portions of the Tibetan Zone. Towards lized forams, from their shape highly probable the N it thins out from 50 m to a few m only. The Shil- Ce nom ani a n (to Lower Tu r 0 n i an) . lakong Formation, on the contrary, is missing in the SW Sample 85/36 from the basal blue-grey limestones and attains several hundred m thickness in the N. Thus yielded: Rotall{Jora and Diearinella of an association in the N the multicoloured facies replaces the grey one. suggesting U ppe rmost Cenom an i an: In the transitional zone the Chikkiim Limestone always R. ex gr. eushmanni underlies the Shillakong Formation. This facies change R. ex gr. deeekei is more abrupt in western Zanskar because the north- Praeglobotruneana ex gr. algeriana-imbrieata ern parts (N. Z. U.) border the southern parts of the Tibetan Zone along a thrust of a few km displacement Approximately 20 m above the base of the carbo- (FUCHS, 1982b). E of the Zanskar River this tectonic nates they become multicoloured. Sample 85/39 taken plane has died away and the northern and southern in these beds contains: facies belts are connected. It was my aim to study the Globotruneang ex gr. sigali-sehneegansi facies intertonguing and the way of mutual replacement Age: Turonian (or younger) of the Mid and Upper Cretaceous formations. The basal grey-blue beds correspond in facies with The Chikkim Limestone is a well-bedded se- the Chikkim Limestone the overlying multicoloured quence of grey, rarely blue, partly nodular dense lime- limestones are Shillakong facies. Both facies together stone with extensive bioturbation. The rocks are free of are 50 -100 m thick. At the top the Shillakong Forma- terrigenous detritus and full of foraminifera, however ill- tion is succeeded by dark grey to black marly and silty preserved. Shale partings are subordinate. The forams slates, a ca. 1000 m thick series assigned to the determined by R. OSERHAUSER in my samples Lamayuru Formation by FUCHS(1982b). Sample 85/40 suggested Cenomanian to Campanian age (FUCHS, from their lower part yielded: well-preserved Globotrun- 1982b, p. 9). GAETANIet al. (1986, p. 469) were able to canas. define the age of the base as Early Turonian, the top as G. area uppermost Santonian. From their description it is not G. ex gr. stuarti evident, why these authors assume a hiatus between Age:U pp e r Ca m pan i a n (Maestrichtian can not the Chikkim Limestone and the Kangi La Formation. be excluded) Contrary I found passage beds yielding a Campanian The next section was studied along the ascent to fauna (FUCHS, 1982b, p.9). Namtse La from the S: The Giumal Sandstone is suc- The Chikkim Limestone was deposited in upper ceeded with sharp boundary by blue-grey, thick bedded bathyal pelagic environment poor in oxygen and with limestone. Sample 85/32 from the base of the carbo- low rate sedimentation (GAETANIet aI., 1986). nates yielded: abundant small Thalmanninella, Praeglobo- The Shillakong Formation (FUCHS,1982b) con- truneana, and Globigerina proving Up per A Ib i a nage. sists of an alternation of cream, red, green, grey, and This is the only sample free of recrystallization. blue limestones and red, purple, green slates and 8 m above the base the carbonates become multi- marls. This series is banded in dm to decametric coloured. The red and green marly limestones exhibit rhythms. Frequently the rocks show fine recrystalliza- bioturbation. Sample 85/33 contains a poorly preserved tion, phyllitic alteration, and transversal cleavage. fauna, which allows only the identification as Upper The abundant foraminifera are recognized by the un- Cretaceous. aided eye, but difficult to determine due to recrystalliza- Sample 85/34 ca. 15 m above the base, rather tion. In the following I shall describe a series of strati- sheared, yielded Globotruneana cf. eoronata BOLLI. The graphic sections in the region investigated. In southern fauna suggests Upper Turonian to Coniacian Zanskar the Shillakong Formation has its westernmost age. outcrops in the lower Oma Chu, further W it is replaced In the Namtse La section the Chikkim facies is by the Chikkim Limestone and Kangi La Flysch. 8-12 m, the Shillakong facies about 40 m thick. The Our westernmost section was measured along the carbonates are overlain by a several hundred meters ascent from the 0 maC h u to the Ha lu maL a (trail to thick complex of black slates. A sample 85/35 from the Lingshet): The boundary between the Giumal lowest portion of these slates yielded small Globotrun- Sandstone and the succeeding pelagic limestones is canas, G. ex gr. area, suggesting Up per Ca m pan i an. sharp, but tectonically disturbed. In the orographically left slope a wedge of the carbonates is pushed into the Further E the next section was studied in the gorge N upper portion of the Giumal Sandstone. KELEMEN& of Z a n g Ia: the dark silty slates and siltstones of the SONNENFELD(1983, p. 272) seem to interprete this situ- upper Giumal Sandstone are followed with distinct ation as facies intertonguing between the Shillakong boundary by thick-bedded, grey to dark blue limestones Formation and Giumal Sandstone. But without doubt with black shale partings. Sample 85/26 taken from the this is a local tectonic reduplication. lowest limestone bed yielded abundant, but iII-preserved Rotaliporas and Praeglobotruncanas. The uppermost bed of Giumal Sandstone is almost black, fine- to medium grained sandstone with some cross bedding. In thin section it can be seen that the groundmass as well as part of the quartz grains have *) Dr. R. OSERHAUSER notes that most of the foraminifera tests (all of them planktonic forms of Middle to Upper Cretaceous been replaced by black to dark brown iron compounds age) are strongly recrystallized. Therefore the examinations (analyt. kindly by Dr. P. KLEIN, Geol. B.-A., Vienna). often had to be based on outer shape and the size, naturally With sharp boundary well-bedded, blue-grey limestones limiting the possibilities of determination.

R. ex gr. appenmmca (very frequent) the Albian. Cenomanian faunas are reported by BAUDet R. cf. cushmanni (very frequent) aL (1982b), who found the change from couches R. reicheli (rare) rouges to black shale facies already in the Upper Pr. stephani (frequent) Cenomanian (Chirche Valley). Very likely these Turo- Age: middle part of Cenomanian nian black shales join up with the black slates replacing part of the Turonian pelagic limestones and marls in the Sample 85/27 ca. 12 m above the base contains ill- Khurnak area (FUCHS,1984a, 1986). There Turonian as preserved planktonic forams. As Praeglobotruncanas well as Santonian to Maestrichtian Shillakong Forma- are associated with the first double-carinated forms, the tion are documented. GAETANIet aL (1986) find the for- sample is from the Ce no ma n i a n - Tu ro n i an bound- mation bracketed between Turonian and Early Campa- ary. About 40 m above the base the varicoloured carbo- nian in the region W of the Zanskar River. In the north- nates (85/28) yielded: poorly preserved one keeled and ern parts of Zanskar from the Khurnak area mentioned flat double-keeled tests, such as Globotruncana coronata. above towards the W (Fatu La) the Shillakong Forma- Age: Upper Middle to Upper Turonian (Lower tion reaches up into the Upper Campanian (BASSOULLET Coniacian can not be excluded). et aL, 19780; FUCHS,1986) and attains its greatest Sample 85/29 is derived from the core of the thickness. syncline: In the schistose rock flat double-keeled forms As to the environment it is characteristic that the Shil- are just recognizable. The age is probably Up per lakong Formation and the Chikkim Limestone are free Tu ron i an - Con iacian. of terrigenous debris, consisting mainly of planktic Sample 85/30 was taken from the lowest multi- foraminiferal remains and pelitic-calcareous muds. The coloured beds just above the Chikkim facies of the bright colours of the Shillakong formation indicate bet- northern limb of the syncline. It yielded undeterminable ter oxygenation than the Chikkim Limestone (GAETANI Globotruncanids. et aL, 1986, p. 470). The first appears to be deposited From the upper Chirche Valley NE of Zangla on sills, pelagic plateaus or seamounts (FUCHS,1982b; BAUDet aL (1982b, p. 535) describe a section across GAETANIet aL, 1983), whereas, the latter points to the Cretaceous rocks of a syncline NE of the one de- deeper less aerated conditions. Both formations are scribed above: succeeded by thick clastic formations. The Campanian The uppermost bed of the Giumal Sandstone - a to Lower Maestrichtian Kangi La Flysch follows on the sandstone with black phosphate nodules - yielded an Chikkim Limestone. Its areno-argillaceous material was A Ib i a n microfauna. Varicoloured marly limestones derived from the S from the Indian Craton. N of this ter- showing bioturbation follow (Shillakong Formation). rigenous basin the pelagic sedimentation persisted on a From the lowest bed BAUDet aL recovered an Up per swell, unaffected by detrital influx. The pelagic facies A I bi a n microfauna. Higher up Ce nom ani a n faunas interfingers with euxinic basin facies (Lamayuru) bor- were found in the Shillakong Formation. The change dering mainly in the N. With the Maestrichtian the dark from multicoloured pelagic carbonates to black shale silty-pelitic series transgresses the subsiding swell, put- facies occurred in the Up per Ce nom ani an. The ting an end to the Shillakong facies. dark series yielded Up per Ce nom ani an, Up per Turonian and Turonian-Coniacian faunas. The dark shales pass into monotonous marly limestone of brownish colour tentatively related to the Kangi La 2.18. The Upper Parts Flysch (FUCHS,1979). The SE continuation of the Cretaceous syncline de- of the scribed above was studied near the village S had e. Lamayuru Formation There the Giumal Sandstone, composed mainly of silty In the last chapter it was described that in all sec- shales, is overlain by blue-grey marly limestone suc- tions the multicoloured Shillakong facies is overlain by ceeded by black marly slates. Samples 85/41 and 85/42 black silty argillites. FUCHS(1982b) correlated these are derived from the dark basal limestones: The first - beds to the Lamayuru Formation in the N and explained lower in the sequence - yielded ill-preserved Globo- it as an overlap of the basin facies due to subsidence truncanas. of the pelagic ridge. KELEMEN& SONNENFELD(1983) and Rotalipora cf.reicheli GAETANIet aL (1983, 1986) connected these series with Rotalipora ex gr. cushmanni the Kangi La Flysch of SW-Zanskar. Though both com- Praeglobotruncana stephani plexes are flyschoid I felt it necessary to distinguish Age: Probably lower Middle Cenomanian them for following reasons: 85/42 contains poorly-preserved partly double-keeled o Lit hol 0 g y: At the top of the Shillakong Formation Globotruncanas leaving open Up per Tu ro ni a n to the red and green colours turn into dark grey to Ca m pan i a n age. In the float of the eastern slope of black, but the slates and marls still abound in the hill N of Shade I found sporadic rock fragments of foraminifers, easily recognizable by the naked eye. red colour, but the Shillakong facies seems to be very Though the formation becomes more silty, it can not subordinate or missing in the Shade area. There the compare with the arenaceous Kangi La Flysch. The Chikkim facies appears to pass directly into the black prevailing rocks are dark grey to black, silty slates shale (Lamayuru) facies. The multicoloured (Shillakong) bleaching on weathering. The lithology is so similar facies is only locally interbedded. to the Lamayuru Formation that it is almost impossi- From the above descriptions it is evident, that the ble to discern the overthrust Lamayuru rocks of the Shillakong Formation from place to place is of different Spongtang Outlier form the underlying series in age. question, where the separating Tertiary formations The Shillakong facies seems to start first in the (Lingshet Limestone, Kong Slates) are cut out by Chirche (BAUDet aL, 1982b) and Namtse La areas - in tectonics.

Contrary the Kangi La Flysch shows ochreous The La te Pre c a mb ria n - Ca mb ria n formations weathering and grey, dark grey and green sediment indicate rich supply of detrital material and rapid depos- colours. The rocks are siltstones, silty marls, slates, ition in an unstable subsiding trough. The extension of and thin-bedded sandstones. In the upper portions this depositional site was considerable being repre- of the formation sandstones become prominent. sented in the whole Himalayas. Montonous series were o Age: By increase of silt and sand the Chikkim deposited, thousands of meters thick, partly under Limestone (Upper Santonian) passes into the Kangi flysch conditions. The algal reefs of the Karsha Forma- La Flysch. The passage beds yielded Campanian tion signal a gradual filling up of the basin. The Kur- faunas (FUCHS,1982b; GAETANIet aI., 1986). The giakh Formation documents a recurrency of flysch con- top of the Kangi La Flysch is Maestrichtian (GAETANI ditions after the foregoing shallowing episode. et aI., 1986) and is succeeded by Upper Maestrich- The conglomerates of the 0 r do v i cia n Thaple For- tian - Paleocene shallow-water carbonates (Span- mation mark a significant break in the conditions of both Formation). sedimentation: Long continued basin deposition is fol- The Shillakong Formation spans a wide range of lowed by continental sedimentation. Along with the an- time - from Upper Albian to Upper Campanian. It is gular unconformity in Spiti and the invasion of granites interfingering with the Lamayuru basin facies in the clustering around 500 m. a. an orogenic event is indi- N. In the SE the basin facies starts to overlap the cated. It is the first phase of the Caledonian orogeny, pelagic carbonates in the Upper Cenomanian (BAUD which phase was active particularly in the western et aI., 1982b) respectively Upper Turonian (sample Himalaya. In other parts (Nepal, Kumaun Kashmir) the 85/40), finally putting an end to this facies after the marked change occurs in the Si I u ria n . Upper Campanian. The parautochthonous Lamayuru The De von i a n Muth Quartzite signals conditions of Formation around the Spongtang Klippe yielded only an epicontinental environment. The supermature Maestrichtian foraminifers (FUCHS, 1982b). These quartzarenites indicate a low rate of subsidence and black pelites are succeeded, possibly after a hiatus depositon on a stable platform. These stable conditions by the Paleocene Lingshet Limestone. So the black were brought about by the foregoing Caledonian slates overlying the Shillakong Formation are Upper orogeny. The Lower Carboniferous dark carbo- Cenomanian - Maestrichtian, respectively only nates and gypsum facies suggest deposition on partly Maestrichtian, whereas the Kangi La Flysch is Cam- restricted inner shelf resp. Sabkha environment panian - Lower Maestrichtian. (GAETANIet aI., 1986). . For the above reasons I prefer to discern between The Up per Car bon i fer 0 u s Po Formation shows Kangi La Flysch and the Cretaceous portions of the increased supply of continental debris rapidly deposited Lamayuru Formation. The difference to the views of on the shelf. This indicates a disturbance of the stable KELEMEN& SONNENFELD(1983) and GAETANIet al. conditions prevailing since the Devonian. GAETANIet al. (1983, 1986), however, is not so great. There are trans- (1986) infer from petrographic data penecontemporane- itions between these formations in the Kong-Wakha ous basaltic volcanism in progress, which points to be- area of western Zanskar (FUCHS,1982b) and I do not ginning rifting. doubt that they were originally connected. The Kangi La Thus the Upper Carboniferous sedimentation signals Flysch derived the terrigenous material from the Sand disturbance, which was of epirogenetic type. In Spiti has the character of distal flysch deposited in outer pre-Permian faulting and erosion different from block to shelf to bathyal environment (GAETANIet aI., 1983, block are documented (FUCHS,1982a, p. 344). 1986; BROOKFIELD& ANDREWS-SPEED,1984). The The mapped area is an excellent example for the Up- Lamayuru Formation indicates turbidite deposition on a per Paleozic unconformity found in so many areas of basin plain or possibly the outer part of a deep-sea fan the Tethys Himalaya (HAYDEN,1904; HEIM& GANSSER, (BROOKFIELD& ANDREWS-SPEED,1984, p. 260). I infer 1939; NANDA& SINGH, 1976; FUCHS,1977a, 1982a, that the Kangi La facies was closer to the cratonic a. 0.): The Permian beds transgress over various older source. Its shallowing trend, shown by increase in grain formations, from the Po Formation .down to the Ordovi- size, led to filling up of a basinal depression in the cian. In the area of Tanze the unconformity is an angu- Zanskar Shelf. The ridge with pelagic carbonate lar one. The Palaeozoic succession complete from the sedimentation N of the mentioned depression was fi- Precambrian to the Upper Carboniferous and dipping nally transgressed by basin facies after the Campanian. ENE at medium to steep angles, is transgressed by the In Maestrichtian times after the subsidence of the swell Panjal Trap gently hading NE. Within the short distance the site of Kangi La Flysch was connected with the of approximately 5 km the post-Cambrian formations di- Lamayuru basin in the N. Probably there was a perfect sappear towards the NW and the Panjal Trap rests on passage between the two flysch facies, but the wedge the Karsha Formation (pI. 2, 3). BAUDet al. (1984) and thrusting S of the Spongtang Outlier interrupted this GAETANIet al. (1985, 1986) interpreted the situation as transition: More northern parts - the Lamayuru Forma- tectonic overlap of the "Zangla" over the "Phuktal tion of the N. Z. U. - came in touch with the Kangi La Unit". In the present paper, however, it is shown that Flysch (Tibetan Zone s. s.), thus strengthening facial the contact between the Po Formation and the trans- differences (FUCHS,1982b). gressive conglomeratic quarztite as well as the magma- - tic contact of the laUer with the succeeding Panjal Trap 2.19. The Stratigraphic Evolution are both undisturbed. There is no observation sugge- of the sting the existence of a thrust. NANDA& SINGH(1976) Tethyan Zone of Zanskar have given the right explanation as a stratigraphic unconformity. After the description of the formations occurring in It is suggestive to correlate the Upper Carboniferous the area studied, an outline of the stratigraphic de- - Permian epirogenetic movements to the extrusion of velopment is given. the Panjal Trap. ANDREWS-SPEED& BROOKFIELD(1982),

HONEGGERet al. (1982) a. o. envisage a connection of dicates the subsidence of the northern margin of the In- the Panjal volcanism with continental rifting. dian Continent coming in touch with the suture zone The Per mi a n Kuling Formation like other Permian (FUCHS,1982b). This submergence was only of short series (e. g. Thini Chu Formation) is a shallow-water duration - still in the Maestrichtian the southern transgressive series. The basal arenites followed by the parts of the Zanskar Shelf became very shallow (Span- dark silty Kuling Shales shows the progressive deepen- both Formation), in the Paleocene the northern ing. Important subsidence to bathyal conditions occurs portions of Zanskar followed (Lingshet Lms.). A gap in in the Lower Triassic (Tamba Kurkur Formation). the Lower Paleocene is inferred by GAETANIet al. The subsidence is unbalanced, because of low supply (1983, 1986). in sediment. Influx of pelitic material increases in the The Paleocene shallow-water carbonates are suc- Lad i n i an. The environment was pelagic outer shelf ceeded by multicolour~d fresh-water beds - the with anoxygenic muddy bottom conditions (GAETANIet C h u Iu ng LaS Iate s in southern Zanskar, respec- aI., 1986). The Carnian Tropites Limestone was tively Lower Eocene marine beds, the K0 ng S Iate s deposited in a regressive phase under shallowing con- in central Zanskar. These are the youngest sediments ditions (subtidal inner shelf to tidal flat). The Nor i c is of Zanskar. After their deposition thrust masses slid characterized by subsidence (inner shelf, GAETANIet from the Indus Suture Zone onto the Zanskar Shelf and aI., 1986) and -increased supply in terrigenous material. folding began. These features are found from Nepal to Zanskar. In the In the area mapped the Upper Maestrichtian latter area, however, the deeper facies influenced by Eocene shallow- water series are not exposed. terrigenous debris passes into the carbonate platform of western Zanskar - Kashmir, where the Noric is not very much distinct. The Qua rt zit e Se ri e s marks a regression in the Upper Noric- Rhaetic, which af- 3. Tectonics fected the entire Tibetan- Tethyan Zone. The following The investigated region of south-eastern Zanskar Ki 0 t 0 Li mest 0 n e (Rhaetic- Lower Dogger) was deposited in rather shallow-waters of a carbonate plat- comprises the marginal parts of the Central Crystalline and the adjoining Tibetan Zone. The latter forms the form. After a gap the Callovian Ferruginous 001- it e transgresses the Kioto Limestone. The formation in- wide Spiti-Zanskar Synclinorium and we are dealing dicates deposition in shallow water high energy envi- here with its SW-limb. The relation of the Central Crys- ronment with influx of terrigenous material. talline to the overlying sedimentaries and the problem, whether the sequence of sedimentary formations is The Up per J u ras sic to Neo com i anS pit i stratigraphic or tectonic, were of central interest in this S h a Ie s are sediments of deeper water in an euxinic research. environment pointing to a transgressive phase. The Neo com i a n to La t e Ce nom ani an G i u m a I San d s ton e shows a marked change in sedimenta- 3.1. The Axial Depression of Lahoul tion: There was rich supply of terrigenous detritus from the craton in the SW. The coarser material was depo- It is a peculiarity of this part of the Himalaya that the sited in a deltaic environment (SW-Zanskar). Fining in northern sedimentary belt (Tibetan-Tethys Zone) ex- the NE direction indicates the deepening of the shelf. posed in Spiti and Zanskar is connected with the Phosphates and glauconite are derived from shallow sedimentaries of the Chamba-Kashmir Synclinoria. water by multiple reworking. The deposition of the ill- This is brought about by an axial depression in Lahoul. sorted immature rocks was not in a high energy coastal The Central Crystalline of the Brahman-Zanskar environment (BROOKFIELD& ANDREWS-SPEED,1984). In Range plunges towards the SE and reappears in the my view the Giumal Sandstone is the first signal of the Rohtang area and the Great Himalayan Range of Himalayan orogenesis. southern SpitL The sedimentaries covering the Central When the supply of terrigenous material ceased in Crystalline in Lahoul are mainly the Phe-Haimanta com- the Upper Albian respectively Upper Cenomanian, plex. Only locally younger formations are exposed such pelagic limestones were deposited on the Zanskar as in the Tandi Syncline of the Chandra Valley. The al- Shelf. The Chikkim Limestone (Turonian - top of teration of the sedimentariesis mainly greenschist, loc- Santonian) formed in deeper less aerated waters, ally lower grade of amphibolite facies, and the rocks whereas the multicoloured S hill a k 0 ng For mat ion are still recognizable by the sedimentary features pre- (Upper Albian - Upper Campanian) indicates deposi- served. tion on ridges, pelagic plateaus etc. These submarine Like in the Kulu-Rohtang area there are discordant heights remained undisturbed by terrigenous detritus granitoid intrusions also in northern Lahoul (e. g. Jas- when the Chikkim Limestone became burried under the par Granite, 495::!:16 m. a., FRANKet aI., 1976). The Kangi La Flysch (Campanian-Lower Maestrich- named granite seems to be connected with the large in- tian). Like the Giumal Sandstone the Kangi La Flysch trusion of the Kado Tokpo Valley. Large tongues and derived the terrigenous debris from the SW. The clastic smaller inclusions of the sedimentaries in the granite sedimentation was triggered by epirogenetic move- and apophyses of the latter document the magmatic ments in the Indian Craton probably related to first dis- contacts. There is no observation supporting the in- turbances along the Indus Suture Zone. The dark silty terpretation as a tectonic contact (GAETANIet aI., 1985). slates (Upper Cenomanian to Maestrichtian) progres- On the traverses from the Bhaga Valley in Lahoul to sively overlapping the multicoloured pelagic limestones Zanskar via Bara Lacha La or Shingo La it is evident are either distal parts of the Ka ngi La Fly s chor that the silty-phyllitic series of Lahoul are coherent with Lam a y u ruF 0 r mat ion. With the Mae stri c ht i a n the Phe Formation of Zanskar. GAETANIet al. (1985) the last pelagic swell areas submerged in the silty, note the "affinity with the Phe Formation" but expect muddy, euxinic basin facies (Lamayuru). This event in- more than one structural unit in the Shingo La section.

In 'their fig. 1 they draw a thru'st plane between the the Tsarap Valley between the villages Purni and Ichar phyllitic series around Darcha and those of the Bara the metamorphism increases gradually and the transi- Lacha La and the upper Kurgiakh Valley. Thus they did tion from the sedimentary series to the Crystalline is al- not realize that the Phe Formation of the latter areas most perfect. Similar passages can be observed in and those of Lahoul ("phyllites") form one unit, continu- Kashmir, Chamba (FUCHS, 1975), Spiti (GRIESBACH, ous even with Chamba. 1891; HAYDEN,1904), Kumaun (HEIM& GANSSER,1939) This connection is a strong argument against the and Nepal (FUCHS,1967, 1977a; BORDETet aI., 1971, hypothesis of a "Phuktal Nappe" (BAUDet aI., 1982a, 1975; PECHER& LE FORT,1986). The fact that the Tibe- 1984; GAETANIet aI., 1985, 1986). The existence of this tan Zone is linked with the underlying Central Crystal- nappe would imply allochthony of the Chamba sedirnen- line in so many places is a strong argument against its taries in respect to the underlying Crystalline. However allochthony. In its frontal parts a nappe can not become these units are structurally inseparable as shown by coherent with the underlying units when followed for FUCHS(1975) and FRANKet al. (1976). some distance along the strike. It is easier to explain GAETANIet al. (1985) recognized the intrusive nature the observed tectonic contacts as local disturbances. In of the Gumboranjan Granite with the metapelitic wall- my view there was generally a transition from the rocks, its northern contacts, however, they interprete as sedimentaries to the Crystalline, which was disturbed tectonic. In their fig. 1 the named granite belongs struc- by shearing in certain regions. I envisage a mechanism turally to the "phyllites" of Darcha, the rocks adjoining of gravity gliding during the Himalayan uplift similar to the granite in the N are designated to the "Phuktal the "failles soustractives" reported from the Tibet! Nappe". Contrary I found no indication of a thrust. The Nepal border by BURG (1983). When the Great Gumboranjan Granite intrudes the upper portions of the Himalayan Range was rising, the sedimentary cover Phe Formation, which shows domal structure with the was locally decoupled from the crystallines, remained leucogranite in the core. The sills and dikes are also behind, or slumped down along NE-dipping shearing found in the northern limb of this dome, but there the planes. Gravity tectonics are also accepted by PECHER Phe Formation soon passes into the overlying Karsha & LE FORT(1986). Formation. In their 1983 paper BAUDet al. speak of a "Ring- Thus the region Shingo La - Bara Lacha La - dom-Phuktal Unit", which consists of a crystalline Lahoul is composed of the Phe- Haimanta complex in- basement (Tibetan slab), Palaeozoic metasediments truded by various granitoid bodies. The sedimentaries and the Late Palaeozoic Panjal Trap (p. 139). Thus are slightly metamorphosed and represent a transitional BAUDet al. seem to give up the hypothesis of a tectonic series between the Tibetan Zone and the Central Crys- separation of the Central Crystalline from the Tibetan talline, which is so often observed in the Himalaya. The sedimentaries. extraordinary wide extent is a consequence of the Lahoul axial depression. There the Central Crystalline is covered by the weakly altered basal sedimentary 3.3. The Structure series of the Tibetan Zone. The Central Crystalline of the Tibetan Zone pl~nges towards the SE somewhere W of Shingo La. in SE-Zanskar This is the reason why the migmatite complex of the' Padam area is lacking towards the SE. The gneisses The investigated area lies in the south-western parts disappear because ofaxial plunge beneath the metape- of the Tibetan Zone. We are here in the marginal por- lites and not due to overlapping of the "Phuktal Nappe" tions of the Zanskar Synclinorium, where the sequence (GAETANIet aI., 1985). from the crystallines up to the Upper Cretaceous is exposed in the SW-limb of this synclinorium. The sedimentary succession, however, is complicated by 3.2. The Relation between folding, imbrication and faulting. In my description I the Central Crystalline shall start in the NW in the Zanskar-Oma Chu area and the Sedimentaries going towards the SE to the Bara Lacha La. of the Tibetan Zone W of the wide Zanskar Valley at Pad a m the Central Crystalline dips NE at medium angles and is succeeded In the mapped area the Central Crystalline is found by the Phe Formation with tectonic contact (pI. 1, pI. 2 only in the W - in the area Padam-Ichar. From Muni [3-5]). The beds of the Phe Formation dip conform with to Padam and W thereof the Crystalline consisting of this structural plane, but higher up they show gentle dip migmatites of high metamorphic grade (sillimanite towards the NE and even slightly SW hading s-planes. zone) is overlain by epizonal Phe Formation. The con- W of Kar s h a the dip becomes steeper and near the tact certainly is tectonic, as found by BAUD et al. monastery we find steep folding in the rocks of the (1982a,b, 1984) and GAETANIet al. (1985). According to Karsha Formation. The folded series is followed by them the 'dip of this structural plane, which is shallow in gently NE-dipping Panjal Trap (pI. 3). The dark band of the Bardan-Padam area, becomes steeper W of the trap cutting the steeply folded Karsha Formation Padam. The named authors explain the sedimentaries was taken as the base of their "Zangla Nappe" by BAUD as a nappe formed by decollements. I doubt that the et al. (1982a,b, 1984, p.192) and GAETANIet al. epizonal sediments came in contact with the crystal- (1985). In my view it represents an excellent instance lines by thrusting from the N over large distances as of the Upper Palaeozoic angular unconformity. envisaged by the named authors: Near Rangdum and in N of Karsha the Panjal Trap is affected by imbrica- the Suru-Kashmir area it is evident that the Palaeo- tion. The competent and rigid band is broken into three Mesozoic series of the Tibetan Zone pass into the high slabs pushed towards the SW into the incompetent Ku- grade crystallines - a thrust contact is impossible there ling and Lower to Mid Triassic formations. The scale (FUCHS,1977b, 1979, 1982b; HONEGGER,1983). Also in structure is of the order of a few hundred meters only

and has nothing to do with nappe tectonics. A little the lineament is no more discernible - the series Nand further N - opposite of Thongde - the Panjal Trap is S of it form one coherent stratigraphic succession af- steeply folded with the Permo-Triassic series (pI. 2 [5]). fected only by isoclinal N-directed folding. Like in other parts of the Tibetan Zone the folding of Thus the northern limb. of the Zangla Syncline is tec- competent and incompetent formations led locally to the tonically disturbed from N of Namtse La to W of Kangi. formation of wedge structures. But also the southern flank is sheared. From Zazar to Between N Tho ngd e and Zang Ia both sides of the Zanskar - Oma Chu junction the stratigraphic suc- the Zanskar Valley show Triassic-Jurassic carbonates cession is well-preserved, but in the lower 0 maC h u tightly folded. The vergency of the folds varies fre- enormous shearing is observed in the Spiti Shales quently between SW and NE (pI. 1, 2 [2-6]); the axial (pI. 1, 2 [1]). There is intensive folding directed SW and planes are generally steep. the extraordinary thick Spiti Shales are sheared off At Z a ng Ia the Triassic-Jurassic carbonate series from their base. This is evident from the many bands are succeeded by Mid-Jurassic to Upper Cretaceous and lenses of the Ferruginous Oolite within the Spiti formations, which form an important syncline. This syn- Shales. In my view this decollement is the SE-end of cline begins E of Zazar and widens towards the NW to the thrust separating the Tibetan Zone (s. s.) form the a huge synform, in the core of which further W the Northern Zanskar Unit (N. Z. U., FUCHS,1982b,c). Spongtang Klippe is found. At its south-eastern end the The last named unit is a subunit of the Tibetan Zone, Z an g Ia Sy nc Ii ne is marked by vertical Spiti Shales. a wedge, not a nappe. The maximum displacement Towards the Zumlung Chu also the Cretaceous series should be a few km only. This amount is suggested by come in, and in the NE-flank we find a steep subsidiary facies differences Nand S of the thrust: Chikkim lime- syncline (pI. 1, 2[5]). N of Zangla the Upper Cretaceous stone in the S - prevalence of Shillakong Formation in black slates come in as the youngest formation in the the N; Kangi La Flysch in the S - euxinic flysch (La- core of the syncline.. They gain large extention around mayuru) in the N. Spanboth Limestone in the S - Namtse La. N of Zangla it is obviou.s that the Triassic- Lingshet Limestone in the N; Chulung La Slates in the -Jurassic carbonates NE of the syncline re pre sen t S - Kong Slates in the N (see FUCHS,1982b, PI. 2A). the Ii m b 0 fit and do not form a next higher nappe My correlation of the N. Z. U. Thrust with the disturbed ("Zumlung Nappe", BAUDet aI., 1982b, 1983, 1984; GA- zone of the lower Oma Chu is based on the rich deve- ETANIet aI., 1985). At medium angles the carbonates lopment of the multicoloured pelagic limestones (Shilla- bend down beneath the younger formations and then kong Formation) NE of the tectonic line. This is a cha- become vertical (pI. 2 [4]). They form an ant i c Ii n e racteristic of the N. Z. U., whereas this facies is un- between the Zangla Syncline and the syncline of Chir- known SW of the thrust in the upper Oma Chu - Span- che La (BAUDet aI., 1982b, 1983). both - Kangi La region. NW of Na mt s e L a the NE flank of the syncline be- I suppose that the N. Z. U. Thrust like the comes overturned and sheared. The Spiti Shales and Kangi-Naerung Fault is caused by the Spongtang Giumal Sandstone are cut out and Shillakong Forma- Klippe. It develops as a decollement in the lower Oma tion and Kioto Limestone come in touch along the Chu and dies out in highly deformed Triassic carbo- " Ka ngi - Na er un g Fa u It" of KELEMEN& SONNEN- nates of the Phulungma Valley. That gives a regional FELD(1983). This zone of disturbance is the result of extent of 70 to 80 km along the strike, which is about different tectonic acts (see FUCHS,1982b): equal to the length of the Kangi-Naerung Fault. The maximum displacement along the N. Z. U. Thrust 1) When the Spongtang Klippe took its place the Juras- seems to be between Photak La and the Chulung Chu, sic- Tertiary formations were partly sheared off from where even the Dras Unit of the Spongtang Outlier the Triassic-Jurassic carbonates (decollement). comes in contact with the Chulung La Slates of the 2) During later compression the limb between the Tibetan Zone (s. s.) (FUCHS,1982b, PI. 1, 2). Spongtang Synclinorium and the Honupatta Anti- The Spongtang Klippe as a rigid mass seems to be clinorium was overturned and squeezed. responsible for the development of wedge structures 3) The tendency of the Honupatta Anticlinorium to SW and NE of it. These reverse faults date back to the override the Spongtang Synclinorium persisted ap- compression following the emplacement of the outlier. parently until Quaternary times. These complications In this tectonic phase, probably in the Miocene, the around the Spongtang Outlier are no evidence for a Indus Molasse was folded and overthrust from the S, all hypothetical "Shillakong-Zumlung Nappe" (GAETANI the tectonic units of the Indus Zone became over- et aI., 1985). turned, and the carbonate belt of northern Zanskar was The idea of a "Zanskar-Shillakong Nappe" (BAS- tightly folded and became fan-shaped (Honupatta Anti- SOULLETet aI., 1983) is abandoned now by the French clinorium, KELEMEN& SONNENFELD,1983) f'J of the geologists (GILBERT,1986; COLCHEN,personal commu- Spongtang Outlier (see FUCHS,1982b, pI. 2). nication 1986). So my recent mappings in the Zanskar Valley join up Certainly the Kangi-Naerung Fault is a major zone of with the investigations of my 1980 expedition published disturbance but not a nappe boundary. This is evident in 1982b. . by the fact that the lineament dies out in the SE and the Finally it should be noted that besides folding and im- NW. In the Zangla area the shearing of the northern brications there are also ver tic a I fa u Its.~ Near limb of the Zangla Syncline becomes insignificant and it Pidmu along the ascent to the Namtse La the trail fol- is obvious that the carbonates N of the syncline are lows a ENE-WSW trending traverse fault. The north- part of that fold structure. The stratigraphic sequence western block is subsided along this fault for several from Triassic carbonates up to the, Upper Cretaceous tens to a hundred meters. This fault is already recorded black shales is only folded but otherwise undisturbed. by GAETANIet al. (1985). In the same way the lineament loses its importance W Now I shall describe the tectonics from the Z ans kar of Kangi (FUCHS,1982b). In the upper Wakha Valley R i ver towards the SE.

At Ku mi, NE of Padam, the Karsha Formation is Oolite and Spiti Shales come in between the mentioned isoclinally folded with the overlying Panjal Trap. Bands carbonates and the Giumal Sandstone. Though dis- of Kuling- and Tamba-Kurkur Formations in the upper turbed the stratigraphic sequence is more complete parts of the Panjal Trap near Thongde show that the there (PI. 2 [8-10]). Also this shear zone was taken as great thickness of the Trap is caused by internal fold- a nappe boundary, between the "Zumlung-" and the ing. The Triassic formations NE of Thongde are folded succeeding "Khurna Nappe" (GAETANIet aI., 1985, with !'teep axial planes and varying direction, like W of fig. 1). Actually the NE-flank of the syncline was some- the Zanskar Valley (pI. 2 [6]). what reduced by shearing, which may be called a Further SE between the villages Ich a r and Ab n0 p wedge or imbrication, but there is no indication of a there is a conspicuous synform in the Karsha Formation nappe. The Shade- Tsho Tok Phu area shows the N of the Tsarap River. The light colour of the involved syncline consisting of a series of subsidiary folds (pI. 1, dolomites is easily recognized even on satellite imag- 2 [9-12]). The vergency of the folding is SW. ery. The axis of this steep syncline is directed NE-SW On satellite imagery the syncline may be traced across the regional strike. The cross folding may be farther SE by the brown colours of the Giumal related with the axial plunge of the Central Crystalline Sandstone. and the light weathering of the Upper Cre- and the forming of the Lahoul depression (see chapter taceous formations. SW of this syncline brownish 2.1.). patches amidst the Triassic-Jurassic Carbonates indi- SW of Ph ukt a I the dolomites of the Karsha Forma- cate the occurrence of different rock series, which I tion dip at low angles towards the NE. The upper parts would interprete as Palaeozoic formations occurring in of the Karsha Formation are penetrated by numerous an anticlinal zone. However this is speculation. discordant dikes of Panjal Trap. Their thickness and After the description of the tectonics of the Tsarap re- frequency increases towards the top of the formation gion I shall now deal with the Tanze-Kurgiakh (e. g. N of the monastery). It is evident there that the area: In the basal formations of the Tibetan Zone there Karsha Formation represents the original base for the is an interesting structure. Kurgiakh Formation forms flows of the Panjal Trap. Between the Karsha Forma- the core of a syncline, the flanks consist of Karsha For- tion and the trap there are, however, a few meters of mation. The axial strike is roughly N-S and the direc- conglomeratic quartzite indicating the Permian trans- tion of thrust is towards the E. This transverse syncline gression just before the effusions of the trap. The out- was described by BAUDet al. (1984, fig. 8, 10, Sect. III) crops at the new water pipe above the precipices of the as an imbricate structure: An anticline of Phe Formation gompa show that the Panjal Volcanics follow the under- should be thrust onto Karsha Formation. The "Phe For- lying rocks stratigraphically and not as the base of mation" is the Kurgiakh Formation, the southern conti- the "Zangla Nappe" (BAUD et aI., 1982a,b, 1984; nuation of the type section along the Kurgiakh River GAETANIet aI., 1985). There are no observations downstream of Tanze (CASNEDIet aI., 1985). As the na- suggesting a tectonic contact. Contrary the transgres- med formations both exhibit distinct flysch type, they sing beds as well as the many dikes of trap in the un- are easily mistaken. There is no doubt, however, about derlying series document the primary coherence of the the synclinal character of the structure. The Karsha sequence. Apparently BAUDet al. (1983) realized that it rocks of the eastern flank dip W beneath the flysch, and was not possible to place a nappe boundary between so BAUDet al. (1984) who took this as Phe Formation, the Karsha Formation and the panjal Trap and so they assumed a thn.ist. The W-limb dips E at medium to assumed the thrust at the top of the Panjal Trap (fig. 2, steep angles, but is overturned near the southern end 138-139). Actually both nappe boundaries are not of the syncline (in the Lunak Valley NW of Kurgiakh Vil- existing. lage) (pI. 1, 2 [15]). The syncline crosses the Kurgiakh The Tsarap Valley N 0 f Ph ukt a I provides a com- Valley towards the N, becomes isoclinally dipping E plete section from the Permian up to the Kioto lime- and ends E of Kuru. It is suggestive that the described stone. The series are folded with subvertical axial plane syncline is a pre-Ordovician fold element, which is cut and are younging towards the NE. Between the knee of out by the transgressing Thaple Formation (Ordovic- the Tsarap Chu and the Niri Chu there are several ian-Silurian). This, however, is difficult to prove, be- synclines of Spiti Shales in the Kioto Limestone. These cause of the complicated geology of the area: synclines are In the strike of the Zangla Syncline and Besides the unconformity marked by the Ordovician may be regarded as south-eastern continuation of this conglomerate there ist the Upper Palaeozoic angular fold (pI.1, 2 [8-12]). unconformity at the base of the Panjal Trap, along At the j u nc t ion of the T s a rap and NI r i Chu the which the whole succession Kurgiakh Formation to Po "Zangla Nappe" is followed by the "Zumlung Nappe" Formation pinches out NW of Tanze. BAUD et al. according to GAETANIet al. (1985, Fig. 1). There like (1982a,b, 1984) interpreted this discordance as tecto- further up in the Niri Chu there is no support for the as- nic (thrust between the "Phuktal" and "Zangla Units"). sumption of a nappe boundary. One can only observe 1983 BAUDet al. assumed the base of the Zangla Unit the folded succession Kioto Limestone to Giumal at the top of the Panjal Trap; GAETANIet al. (1986, Sandstone. fig. 5) draw the thrust at the base of the Po Formation NE of the zone just mentioned we find a major just above the evaporites of the Lipak Formation. In my syncline, which is the direct continuation of the view nappes and thrusts do not exist in the whole area. syncline of Chirche La described by BAUDet al. In Zanskar like in other parts of the Tibetan Zone strati- (1982b, 1983). From satellite imagery it seems that the graphic boundaries are frequently disturbed. But, if one NE-limb of the syncline is tectonically disturbed: The follows these disturbances along the strike, in most ca- light-weathering Upper Cretaceous sediments are im- ses they are shown to be local. There are also some mediately succeeded by Triassic-Jurassic carbonates wedges and imbrications. which can be followed over (PI. 1, 2 [4-7]). In the Shade-Tantak area the tens of km (e. g. Kangi-Naerung Fault, N. Z. U.- shearing was apparently not so strong: Ferruginous Thrust). Also these shear zones finally end and we find

the undisturbed stratigraphic sequences, which contra- (Yunan Valley). The Triassics are in contact with vari- dicts the assumption of nappes. ous Palaeozoic formations (pI. 1, 2 [20-22)). I think this Returning from these general considerations to the structure to be a "faille soustractive" a late orogenic Tan z e area, I have shown in the stratigraphical part gravity slide like the thrust at the top of the Central that the conglomeratic quartzites at the base of the Crystalline in the Padam area. Panjal Trap mark a transgression. The stratigraphic The above shear zone cuts the structures of the contact of these quartzites to the underlying Po Forma- underlying Palaeozoics unconformably. S of the Sarchu tion as well as the magmatic contact to the succeeding Plain an anticline crosses the Yu n a n Vall e y. This trap are both undisturbed by tectonics. Naturally the fold is directed SW. Further upstream the sequence evaporites in the upper portions of the Lipak Formation Karsha-to Lipak Formation is exposed in both flanks of are disturbed, which is easily explained from the mate- the Yunan Valley. The series are subhorizontal and ap- rial. Imbrication leads to reduplication of the strati- pear little disturbed. On the crest W of the valley, how- graphic sequence in the slopes E of Tanze (pI. 2 [15)). ever, the Lipak Formation is succeeded by Muth Further the thin band of the Muth Quartzite is frequently Quartzite and Thaple Formation showing the existence interrupted by shearing. The rigid quartzites are often of a huge recumbent fold. Near the Ken I u ng camping squeezed between the Thaple and Lipak Formations. ground it can be observed that the recumbent syncline Thus the sedimentary succession is certainly affected closes towards the S and therefore is directed NE. by tectonics, particularly where rocks of rather different BAUDet al. (1984, fig. 7) described the same syncline properties join each other. But the local shearing of as SW-vergent. The closure of the syncline at Kenlung stratigraphic boundaries, imbrications etc. do not docu- proves this interpretation to be wrong. Such NE-di- ment the existence of nappes. Several dikes of Panjal rected megafolds along the south-western margin of the Trap in the underlying formations show that these sedi- Tibetan Zone are not rare. In Nepal a huge NE-vergent mentaries formed the substratum for the volcanic flows, recumbent anticline can be followed from the An- that means that the sequence is s t rat i g rap hie and napurna- to the Dhaulagiri- and Kanjiroba Group not tectonic. (EGELERet aI., 1964; FUCHS,1967, 1977a; BORDETet SE of the village Tanze, in the Surichun La - aI., 1971, 1975). Phirtse La region, besides folds vertical faults deter- S of the overturned fold zone of Kenlung most of the mine the structure. The regional dip is towards the ENE country is built by the thick basement series, mainly the at moderate to medium angles. Deca- to hectometric Karsha Formation. Younger series, the Thaple Forma- folds complicate this simple picture (pI. 2 [16, 17)). tion and Muth Quartzite, are seen only on the tops of Further complication comes from a series of faults the mountains N of Bara Lacha La. They mark the (pI. 1, 2) W of the Sinchan camping ground a N-S cores of synclines. trending fault crosses the valley leading to Phirtse La. Along the tributary leading from Bar a Lac h a L a to The rocks E of the fault are thrown down. Another fault the B hag a Vall e y a fault strikes approximately strikes from SW of Sinchan across the Surichun Valley WNW-ESE (pI. 1, 2 [21, 22)). NANDA& SINGH(1976) and the Surichun La to the Chumik Marpo area. Along show the fault already in their fig. 3. S of this fault the this NW-SE fault the NE block is subsided. Parallel to rocks are thrown down. the mentioned fault another one crosses Phirtse La re- There we find also younger formations up to the Po cognized already by GAETANIet al. (1985, fig. 1). Again Formation. The sequence Karsha- to Po Formation is the NE-side is thrown down. The same is shown by a exposed in a wide syncline. Binocular observation fault crossing the Sinchan Valley near its bend. There suggests that in the mountains S of Bara Lacha La the Upper Palaeozoic formations abut against Triassic limestones of the Lipak Formation follow on top of the carbonates. There is also a E-W striking fault NW of Po Formation. This implies an overturned limb. In my Phirtse La and a small NNE-SSW fault at the village view it is the southern flank overthrown towards the N, Tanze. Generally there is a tendency that the northern which means the existence of another N-directed re- and eastern blocks are subsided along these faults. cumbent syncline (pI. 2 [22)). Probably this is related to the uplift of the Great The peak W of Pat e 0 is formed by Muth Quartzite Himalayan Range and the development of the axial de- marking a small syncline, which may be the continua- pression of Lahoul. Both processes seem to be late tion of the above dealt syncline E of Pateo. orogenic events. All the synclines of the Bhaga-Bara Lacha The reg ion bet wee n C hum i k Mar p 0 and the La- Yunan region are ordinary folds of the Karsha to Po Y una n Vall e y shows similar structure. Gently folded succession. There is no reason to assume a thrust the Palaeozoic formations dip beneath the Triassics N (GAETANIet aI., 1985, fig. 1). The syncline W of Pateo of the Lingti Valley (pI. 1, pI. 2 [18-20)). Also in this is shown by these authors as an outlier of the "Phuktal area there are numerous dikes of Panjal Trap penetrat- Nappe", thus the younger formations are structurally ing the underlying series, thus there can be no doubt separated from the underlying Karsha- and Phe rocks that the latter represent the original underground, on ("Phyllites"). E of Pateo, however, the Karsha Forma- which the lavas flowed. tion is included together with the younger formations in A fault crosses the C hum i k Mar p 0 Vall e y in its the Phuktal Nappe. Actually the Phe ("Phyllite") to Po middle course and may be followed to the lower succession forms a stratigraphic sequence, which was Kamirup Chu and into the slopes S of the Li n gtiC h u . folded but not divided to thrust sheets. Along this lineament the series to the N are subsided. In connection with the tectonics of the Bhaga-Bara In the lower Lingti Valley near the Sarchu Plain Lacha- Yunan area it is necessary to note the varying a peculiar structure is found, which needs more de- grade of met a m0 rphi sm. The Palaeozoic formations tailed work for its clarification. It seems that the Triassic of the orographically right slope of the Lingti Valley carbonates are sheared off from their Palaeozoic base exhibit phyllitic alteration. I first noticed this along a horizontal (in the W) to NNE-dipping plane metamorphism at the junction of the Karnirup Chu and

it seems to increase towards the E. S of the Sa rc h u crystallines and the sedimentaries. In Zanskar also PIa i n I observed dikes of porphyric granite cutting the such passages can be observed between Ichar and phyllitic rocks of the Karsha- or Phe Formation. The alt- Purni or in the Zulidoc-Rangdum area. The named eration also affects the younger formations of the authors were misled to their nappe hypothesis, because Y una n Vall e y. The red sedimentary colour of the the primary coherence is disturbed in the area Thaple Formation disappears and changes to greenish Muni-Padam-Doda Valley. The disturbance, however, or silvery tints (sericitization and chloritization). The is of the nature of an imbrication, probably a gravity carbonates of the Lipak Formation recrystallized to slump of the sedimentaries down from the crystallines, marble. To my surprise the metamorphism fades away when the Great Himalayan Range was uplifted. The li- towards the S, between Kenlung and Bara Lacha mited extent of the tectonic plane - towards the NW La, and the rock series of the Bara Lacha La- Pateo and the SE it dies away and the primary transitions are area are almost free of alteration. S the Bhaga around still preserved - shows that it can not be a nappe Dar c h a a phyllitic metamorphism is recognized again. boundary. In the Tibetan Zone it is a common phenomenon that Similarly I am critical to the concept that the Ti be- the grade of alteration increases towards the Great t a n Z 0 n e consisted of a pile of nappes (BAUDet aI., Himalayan Range in the S, and there are frequent pas- 1982b, 1983, 1984; GAETANIet aI., 1985, 1986). My sages into the Central Crystalline. Therefore I was sur- doubts come from the experience that the tectonics of prised about the metamorphism dying away towards the the Tibetan Zone are characterized by folding and im- S. The particularities of the geology of the region, how- brication with varying vergency, large scale horizontal ever, explain this fact: transport being practically absent. This tectonic style is 1) There is no Central Crystalline to the S of the Tibe- also typical for Zanskar (pI. 2, FUCHS,1982b, pI. 2). It tan Zone. The latter is connected with the Chamba can be recognized also in the section given by BAUDet Synclinorium. The Crystalline plunged beneath this al. (1982b, fig. 4), if we omit their interpretations at Lahoul axial depression. depths not accessible to observation. Formation bound- 2) I expect a granitic intrusive body beneath the aries are sometimes tectonically reactivated - also sedimentaries of the Yunan Valley. An indication are within the assumed nappes - as stated by BAUDet al. the granite dikes S of the Sarchu Plain. Further I ob- and GAETANIet al. (1985). served by binoculars that S of Chumik Marpo and in Overturned limbs of folds may be sheared, but that the upper Kamirup Valley swarms of granitic sills does not indicate the existence of nappes. There is vir- and dikes penetrate the country rocks. Thus in the tually no proof of large scale thrusts by windows or out- eastern continuation of the Gumboranjan Granite liers. more granitic intrusions are to be expected, and There are no tectonic repetitions or old series suc- they probably show a similar aureole of contact ceeding younger ones. Contrary the whole "pile of metamorphism. nappes" is a sequence of formations corresponding to the stratigraphic succession. This fact is explained by the advocates of nappes as decollement thrust sheets. In my view there is not any indication supporting the 4. Conclusions assumption of nappes in the Tibetan Zone (the nappes of the Spongtang Klippe are excepted of course - they In Lahoul the Central Crystalline of the Zanskar are units derived from the Indus Zone and are lying 0 n Range plunges towards the SE and reappears in the the Tibetan Zone). Rohtang area and continues SE in the range bordering The following points suggest the autochthony of the Spiti to the S. In this axial depression the sedimen- Tibetan Zone: taries of the Tibetan Zone are connected with those of the Chamba Synclinorium. Therefore the Central Crys- 1) The sedimentaries of the Tibetan Zone are con- talline crops out only in the western part of the area in- ne c ted with those of Chamba and Kashmir. In all vestigated. In the E exclusively we find the slightly these regions t ran sit ion s into the underlying crys- metamorphosed Tethyan series. They are intruded by tallines are documented. Passages between frontal several g ran i to ids of Lower Palaeozoic (Jaspar Gra- parts of different nappes are difficult to explain. nite) or Alpine (?) age (Gumboranjan Leucogranite). Contrary it is easy to explain local disturbances of These granitoids may have their magmatic source in primarily coherent series. the underlying Central Crystalline, but they do not re- 2) The recumbent folds in the "Phuktal Nappe" present this crystalline. As the magmatites show prim- showing the SW-direction of the nappe tectonics ary contacts with the sedimentaries, they belong to one (BAUDet aI., 1984, fig. 7; GAETANIet aI., 1985) are structural unit. This is in contrast to GAETANIet al. actually directed NE (see pI. 2 [21, 22]). They are (1985) who assumed tectonic contacts and division in probably of young age, however can not be cited as several tectonic subunits. reference for thrusting. A major problem is the relation of the sed i men tar y 3) The proposed nappe boundary between the "Phuk- succession to the Ce nt r a I Cry s t a II i n e. Recently tal-" and "Zangla Units" was studied in detail to BAUDet al. (1982a,b, 1984) and BAUDet al. (1985, prove or disprove the tectonic nature. 1986) proposed the sedimentaries to represent a series BAUD et al. (1982a,b, 1984) and GAETANIet al. of nappes following tectonically on the Central Crystal- (1985) assumed the Panjal Trap to form the base of line. If this was so, the whole of the Tibetan Zone as their Zangla Unit. On the spur NNW of Tanze the Po well as the sedimentary basins of Chamba and Kashmir Formation is t ran s g re sse d by a few meters of would be allochthonous in respect to the underlying conglomeratic quartzite, which in turn is followed by crystallines. This assumption is contradicted by the fact the panjal Trap with mag mat i c con t act. All the that in most areas there is a transition between the contacts are und ist ur bed by tectonics. I suppose

that GAETANIet al. (1986) made the same observa- formations. It is typical bas i n fa c i es: The Phe For- tion and. t.herefore shifted the thrust down to the mation consists of several thousand meters of base of ,the Po Formation. But also there I did not siltstones, very fine-grained subarkoses, and silty find indication of a nappe boundary. slates. This monotonous sequence frequently shows Also abovQ the monastery of Phuktal I observed the rhythmic sedimentation. Lamination, graded bedding, conglomeratic quartzite, here transgressing on ripple cross lamination, flame structures, load convolu- Karsha Formati;Cm. Again the quartzite forms the tions, scour and fills, disturbed bedding, flute casts, prim~ry base of the flows of Panjal Trap and the groove moulds, Iinguoid ripples and burrows give a flys- contacts are not affected by tectonics. Further W in choid character. From the sedimentary features we may the Thongde area again the quartzites are found as- infer that there was rich supply in terrigenous material, sociated with the Panjal Trap. Thus the conglomera- which was rapidly deposited in a subsiding instable tic quartzites and the traps followas transgressive trough. The sedimentation was rhythmic, in part at least Permian series on various older formations, showing controlled by turbidity currents. All this and the large that the unconformity is stratigraphic and not tec- areal extent of these deposits suggets basin sedimenta- tonic. tion instead of a tidal flat assl.Jmed by BAUD et al. 4) Regarding the same thrust it is significant that (1984), CASNEDI et al. (1985), and GAETANI et al. numerous dikes of Panjal Trap penetrate the (1986). underlying formations. That these mafic dikes really The Karsha Formation (Middle to Upper Camb- correspond with the panjal Trap is also rian) indicates filling up of the basin. Algal horizons and strengthened, by petrographic examination (GAETANI reefs are interstratified in the flyschoid series, their fre- et al.; 1986,454-45). If the Panjal Trap really would quency and thickness increases upwards. belong to another structural unit (Zangla Unit) the After this shallow-water episode producing several swarms of veins in the formations of the underlying hundred meters of pelites, siltstones, sandstones, and "Phuktal Unit" would be difficult to explain. In my dolomite, the Kurgiakh Formation was deposited in view it is obvious that the Precambrian-Carbonifer- a renewed flysch environment. ous formations cut by the panjal Trap dikes repre- In Zanskar the Cambrian / Ordovician boundary sent the substratum of the volcanic flows and there- is marked by a b rea k in sedimentary development. fore form one original succession. The basin deposits are followed by the red conglomer- 5) Several folds in the Mesozoic sequence show ates and sandstones of the Thaple Formation, indicat- she are d Ii m b s, which have been interpreted as ing an alluvial fan to braid-plain environment (GAETANI nappe boundaries (BAUD et aI., 1982b, 1983, 1984; et aI., 1986). This change in sedimentation was brought GAETANIet aI., 1985). The fact that they lose their about by the orogenic event documented in Spiti by an importance when followed along the strike shows angular unconformity at the base of the Ordovician con- that they are just wedges. glomerates (HAYDEN, 1904; FUCHS, 1982a). The In the southern flank of the Spongtang Synclinorium orogeny is further proved by an invasion of granitoids a thrust was found to separate a northern wedge - clustering around 500 m. a. (FRANKet aI., 1976; MEHTA, the Northern Zanskar Unit (N. Z. U.) - from 1977; LE FORTet aI., 1986, a.o.). In other regions of the the rest of the Tibetan Zone (FUCHS, 1982b). This Himalaya (Nepal, Kumaun, Kashmir) the sedimentary shear zone dies away in the lowest course of the break occurs later in the Silurian. Considering the Oma Chu. sedimentary development of the whole Himalya I pro- Also the northern limb of the Spongtang posed a Caledonian orogeny already in 1967. Re- Synclinorium is sheared. The lineament between the cently the existence of an Early Palaeozoic orogeny is synform and the Honupatta Anticlinorium was called favoured also by BAUDet al. (1984) and GAETANIet al. the K a n g i - N a er un g Fa u It by KELEMEN& SON- (1986) who accept a Late Precambrian-Cambrian Pan NENFELD(1983). It fades away W of Kangi and N of African orogeny. LE FORT et al. (1986) stress the fact Namtse La, where the normal stratigraphic sequ- that very similar 500 m. a. granites have wide distribu- ences are preserved. tion also in other fragments of former Gondwanaland, The Chirche Syncline (BAUD et aI., 1982b) such as Australia and Antarctica. LE FORTet al. point to seems to be sheared in its NE-Iimb. In the Shade- the importance of the magmatic activity, but consider Tantak area it is obvious that the Triassic-Jurassic the associated effects of metamorphism and deforma- carbonates N of the shear zone belong to the 0 ver- tion to be small. The last holds true for the granites in tu rn e d N Eli m b and not to a next higher nappe the Chail Units of the Lesser Himalaya, but not for the ("Khurna Nappe", GAETANIet al. [1985]). Central Crystalline where surrounded by migmatites the Thus im b r i cat e structures are not rare, but their li- granites formed during regional metamorphism. mited extent contradicts the interpretation as nappe The basin type sedimentation lasted from the Late boundaries. Precambrian to the Upper Cambrian, regionally to the Silurian and a new aera starts with the Devonian Muth Considering all the arguments there is convincing evi- Quartzite. The significant breaks in sedimentation were dence now that the Precambrian-Lower Eocene suc- at the Cambrian/Ordovician boundary (SE-Zanskar, cession exposed in Zanskar represents ast rat i g ra- Spiti), after the Ordovician (Nepal, Kashmir). In my view phi c and not a tectonic sequence. This clarification these were phases of the Caledonian aera, which does was necessary before treating questions of the not imply a connection with the NW-European mountain s t rat i g rap h ice v 0 Iuti 0 nand p a Ia e 0 g e 0 g ra- belt. phy. The Muth Quartzite (Devonian) indicates stable Like in the other regions of the Himalaya the basal conditions in an epicontinental environment with strong Late Precambrian to Early Palaeozoic sedi- terrigenous influence. The Lower Carboniferous Lip a k mentary complex is quite distinct from the succeeding For mat ion was deposited on a shallow carbonate

shelf. The gypsum in the upper portions of the forma- position was below the high-energy zone, because of tion documents evaporitic environment (sabkha). The the poor sorting. Upper Carboniferous Po For mat ion, an alternation With the Middle Cretaceous the facies becomes of conglomerates, arenites, and pelites points to an in- rather diversified on the Zanskar Shelf. Whereas the crease of terrigenous detritus, which was rapidly depo- clastic sedimentation of the Giumal Sandstone may sited in deltas. Thus the shelf became more unstable, reach into the Late Cenomanian (GAETANIet aI., 1986), which is also indicated by contemporaneous basaltic the multicoloured pelagic limestones of the S h i 1- volcanism petrographically documented in the Upper Po lakong Formation may commence already in the Formation (GAETANIet aI., 1986). This stresses the cor- Upper Albian in other places (BAUDet aI., 1982b). This relation with the Agglomeratic Slates of Kashmir and couches rouges facies was deposited on sills or Chamba. oceanic plateaus. It represents a pelagic well-aerated The Pan j a I T rap of the Permian is a marker hori- facies not reached by terrigenous detritus. The Chi k- zon in the NW-Himalaya. According to HONEGGERet al. k i m Li m est 0 ne may start in the Albian or Cenoman- (1982), ANDREWS-SPEED& BROOKFIELD(1982), GAETANI ian- Turonian, it is also a pelagic foraminiferal lime- et al. (1986) a.o. the Panjal volcanism indicates the rift- stone, but deposited in deeper less oxygenated water. ing related to the opening of the Neotethys. Preceding Generally the blue Chikkim Limestone facies appears the volcanism epirogenetic movements caused partial before the Shillakong facies, which replaces it upwards erosion of the Silurian to Upper Carboniferous forma- and towards the N. However there are further euxinic tions. The thin conglomeratic quartzites at the base of silty shales - the Lam a y ur u fa eie s - interfingering the Panjal flows mark the Permian transgression - the with the pelagic limestones. The beginning as well as Upper Palaeozoic unconformity. the end of the different facies vary from place to place. GAETANIet al. (1986) called the long history of Generally the Shillakong facies is better developed in Zanskar from the Permian to the beginning of the the N of Zanskar, where it reaches up into the Upper Himalayan revolution in the Eocene the passive conti- Campanian (BASSOULLETet aI., 1978b). There it is nental margin stage. The Panjal Volcanics are suc- overlapped by the Lamayuru facies in the Maestrich- ceeded by the Ku Ii n g For mat ion of Middle to Upper tian, whereas further S this may happen as early as in Permian age. The sequence, shallow-water arenites at the Turonian. In SW-Zanskar the Shillakong facies is the base leading upwards to dark silty shales, reflects missing at all and the Chikkim facies (Albian, resp. the deepening of the invading sea. This tendency is Cenomanian to Campanian) is directly overlain by the continued in the Triassic. The pelagic limestones and Campanian to Lower Maestrichtian Ka ng i La shales of the Tam b a Kur kur For mat ion Fly s eh. This formation derived its clastic material also (Scytho-Anisian) indicate upper bathyal conditions with from the SW like the Giumal Sandstone. We may infer low rate of sedimentation (GAETANIet aI., 1986). that this flysch sedimentation burried the pelagic Chik- kim Limestone facies in the SW of Zanskar. In the cent- The Da 0 ne II aSh a Ie sand - Li mest 0 ne, and ral and northern parts pelagic sedimentation persisted G re y Bed s are all deposits of deeper poorly aerated on ridges and oceanic uplifts. The latter were sur- water with varying carbonate! clay ratio. After the Ladin- rounded by the Lamayuru basin facies, which was in ian beds shallowing and terrigenous influx are indicated communication with the Kangi La Flysch after the final by the Carnian Tropites Limestone. The terrigen- drowning of the pelagic sills, sea mounts, or plateaus in ous detritus supply still increases with the Noric pro- the Maestrichtian. FUCHS(1982b) took this overlap of ducing the sandy-shaly-calcareous alternation of the the Lamayuru facies as indication that the northern J uv a v it e sand Mon 0 ti s S h a Ies. Traced from the margin of the Indian Continent was already close to the E (Nepal) towards the W (W-Zanskar, Kashmir) the subduction zone. The succeeding Upper Maestrichtian Noric formations s.howpassage from flyschoid series to to Upper Paleocene shallow water carbonates probably monotonous limestone-dolomite beds, which I explain signal the first touch of the Indian Continent with the by accepting a decrease in water depth. Dras Island Arc. After the sedimentation of the Lower The Quartzite-Series (Upper Noric - Rhaetic) Eocene Kong Slates thrust masses slipped from the marks a significant regression traceable throughout the Indus Suture Zone onto the Zanskar Shelf and folding Tethys-Tibetan Zone. The succeeding Ki oto Li m e- began. s ton e (Rhaetic- Lower Dogger) was deposited on a Regarding the sedimentary evolution I agree very very shallow carbonate shelf. well with the stratigraphic work done by the Italian Between the Kioto Limestone and the Fer rug i n 0 u s workers - except in the question of the environment of 001 i te of Callovian age JADOULet al. (1985) found a the Phe Formation and the nomenclature of the gap of several m. a. The detritus of the shallow-water Quartzite Series. The major difference is that the Ita- formation was derived from the craton in the SW. The lians deduced the sedimentary history from a se- Upper Jurassic - Lower Neocomian Spiti Shales quence, which they thought to be a pile of individual were deposited in deeper water in an euxinic environ- tectonic units, whereas for me it is the original stratigra- ment. GAETANIet al. (1986) accept undisturbed mid to phic succession. I hope that I was able to demonstrate outer shelf. in the 1982b., 1986 and this paper that the Tibetan The Upper Neocomian Giumal Sandstone may Zone of Zanskar is an autochthonous fold belt, primarily reach into the Upper Cenomanian according to GAETANI connected with the Central Crystalline. et al. (1986). After long continued carbonate-pelite sedimentation on the Zanskar Shelf this is the first en- tirely sandy-silty formation. The rich clastic supply in Acknowledgements my view was triggered by epirogenetic movements of The "Fonds zur Förderung der wissenschaftlichen For- the Indian Continent. The provenance of the debris is in schung" provided the financial means for this research (Pro- the SW as shown by the fining towards the NE. The de- ject No. 5744), for which I am very much obliged.

The "Bundesministerium für Wissenschaft und Forschung" tral). - Diss. Univ. des Sciences et Techn. Languedoc, granted my leave for the duration of the expedition. The appli- Montpellier 1983. cation for leave was supported by the Director of the Geologi- sche Bundesanstalt, HR Prof. Dr. T. E. GATTINGER.I am very CASNEDI, R., GARZANTI, E. & JADOUL, F.: Lower Paleozoic thankful for all that help. sedimentary evolution in Zanskar (NW Himalaya). - 6. Last not least I want to thank the members of the "Fachab- European Reg. meet. Sedim. I. A. S. L1eida '85, Abstracts, teilung für Kartographie und Reproduktion" of the Geologische 79-82, L1eida 1985. Bundesanstalt for the preparation of the plates and figures. DIENER,C.: The Trias of the Himalayas. - Mem. G. S. I., 36/3, 1-159, Calcutta 1912. DZULVNSKI,S. & WALTON, E. K.: Sedimentary Features of References Flysch and Greywackes. - Developments in Sedimentology, ANDREWS-SPEED,C. P. & BROOKFIELD,M. 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