Spiti, Lahaul and Zanskar; Nv Himalaya) : Sedimentary Evolution During Rift/Drift Transition and Initial Opening of Neo-Tethys

Rivista Italiana di Paieontologia e Stratigrafia volume t uz numero 2 tavola I pagrne r/f-zuu Agosto 1996

THE PERMIAN KULING GROUP (SPITI, LAHAUL AND ZANSKAR; NV HIMALAYA) : SEDIMENTARY EVOLUTION DURING RIFT/DRIFT TRANSITION AND INITIAL OPENING OF NEO-TETHYS

EDUARDO GARZANTI, LUCIA ANGIOLINI & DARIO SCIUNNACH

Key-raords: Tethys Himalaya, Permian, Brachiopods, Strati- Syncline), marks the end of rifting, followed by initial opening of graphy, Sandstone petrography, Transgressive arenites, Continental Neo-Tethys and thermal subsidence of the newly-formed Indian pas- break-up. sive margin. The Kuling Group in Spiti consists of glaucony-rich pebbly Riassunto. La fine della glaciazione gondwaniana fu segnata in arenites yielding brachiopods of Late Sakmarian age at the base and tutto il Tethys Himalaya dalla deposizione, in ambienti da paralici a Midian,/Early Djulfian age at the top (Gechang Formation), overlain marini poco profondi a partire dal Sakmariano superiore, di arenarie by black phosphatic shales rich in brachiopods of Djulfian age (Gun- conglomeratiche intercalate ad areniti ibride trasgressive a brachiopo- gri Formation). The much thicker Zanskar succession consists of di e briozoi. Nella regione di Spiti, questi sedimenti costituiscono la glaucony-rich arenites containing brachiopods of Late Sakmarian age, base del Gruppo di Kuling, che riposano in discordanza erosrva su mudrocks and microconglomerates (Churnik Formation), overlain by formazioni più antiche, da Siiuriane e Devoniane nella Valle del Para- the Panjal Trap basaltic lavas and in turn by glaucony-rich arenites hio, a Carbonifere inferiori nella Vaile del Pin, fino a ricoprire 1e yielding brachiopods of Midian/Early Djulfian age, equivalent to the diamictiti di età Permiana basale nella Valle dello Spiti. Tale discor- top of the Gechang Fomation in Spiti. The overlying black shales of danza, presente anche in Zanska,r e Lahaul dove la serie Paleozoica the Gungri Formation, deposited on àn open shelf in warm climates, viene progressivamente a mancare sia verso ovest (Zanskar occidenta- seal the Paleozoic succession in all studied areas, and thus document le) che verso sud (Sinciinale di Tandi), chiude la fase di rifting e segna the final submergence of rift shoulders following the opening of I'inizio dell'apenura della Neotetide tra il Gondwana e i blocchi Peri- Neo-Tethys. Gondwaniani. I1 Gruppo di fuling a Spiti è costituito da arenarie glauconiose, conglomeratiche o contenenti brachiopodi di età Sakmariana superiore alla base e Midiana/D|uJ,fiana inferiore al tetto (Formazione di Gechang), seguite da argilliti nere fosfatiche e ricche di brachiopodi Introduction. di età Djulfiana (Formazione di Gungri). In Zanskar la successione è assai più potente: areniti glauconiose con brachiopodi di età Sakma- Spectacular Paleozoic and Mesozoic successions riana superiore, peliti e microconglomerati (Formazione di Chumik) crop out in the classic Spiti region of the Tethys Hima- sono seguiti dai basalti dei Panjal Traps e quindi da areniti glauconio- laya (Fig. 1). During our summer t992 expedition, we se con brachiopodi di età Midiana/Djulfiana inferiore, corrispondenti studied detail the well-exposed Permian sediments alla sommità della Formazione di Gechang in Spiti. Le sovrastanti in argilliti nere della Formazione di Gungri, deposte su una piattaforma capping the thick Carboniferouslowermost Permian apena in condizioni climatiche calde verso la fine de1 Permiano, sutu- succession exposed along the Spiti Valley from Losar to rano ovunque la successione Paleozoica, testimoniando la definitiva Lingti (described in the companion paper by Garzanri sommersione delle spalle del rift in seguito ali'awen.uta oceanizzazio- ne della Neotetide. et aI., 1996) or resting unconformably on I-ower Carbo- niferous, Devonian or even Silurian units in the upper Abstract. All along the Tethys Himalaya, sandstones and con- Pin and Parahio Valleys. In the whole Zanskar-Spiti glomerrtes interbedded with transgressive arenites rich in bryozoans and brachiopods were deposited ìn estuarine to shallow-marine envi- Synclinorium, the Permian is followed with sharp para- rorunents since the Late Sakmarian, at the end of the Gondwana gla- conformity by the pelagic carbonates of the Tamba Kur- ciation. These clastics, representing the base of the Kuling Group in kur Fm. (for a complete description of the Triassic suc- Spiti, disconformably overlie arenaceous to carbonate sedimentary cession see other companion paper et units of various age, from Silurian and Devonian in the Parahio Val- the by Garzantí ley to Lower Carboniferous in the Pin Valley, whereas they paracon- a1.,1.995a). {ormably follow lowermost Permian diamictites in the Spiti Valley. Five complete stratigraphic sections and several This major unconformity, which can be traced to the ad.iacent logs were measured; 40 samples were collected for petro- Zanskar and Lahaul regions where the Paleozoic succession is eroded more and more towards the west (western Zanskar) and south (Tandi graphic analysis.

- Dipartimento di Scienze della Terra dell' Università degli Studi di Milano, via Mangiagalli 34,20133 Milano, Italy. t76 E. Garzanti, L. Angiolíni & D, Sciunnach

N A 0 25km

STUDIED SECTIONS 1 Muth 2 Gechang 3 Guling 4 Lingti 5 Losar 6 Baralacha La 7 Rape 8 Chumik Marpo 9 Jinchen 1 O Tanze 1 1 Phugtal 1 2 Thongde 13 Nyimaling 14 Markha Valley

Fio I Location map (eft) and geological sketch map of the study area (right; compiled after Fuchs, 7987; Suxz,1988; Bagati, 1990; Spring, 1993; Ya.nnay, 7993).

The purposes of the present paper are: a) to pro- rnents) are after Dickinson (1970,1985); the L pole includes carbonate extrabasinal grains (CE ofZuÍfa,1985) and chen. Study of intrabasinal vide stratigraphic, paleontologic and petrographic data grains (CI : carbonate; NCI : non-carbonate) followed criteria outlined region, adding from the Permian succession of the Spiti by Zuffa (1980, 1985) and Garzanti (1991). Grain size was determined new information to previous works (Srikantia, 1981; according to semiquantitative method described in Garzanti (1986a). Fuchs, 1982; Rao et al., 1982; Bagati, 1990); b) to compare the Spiti succession with that of the adjacent Tanskar (Gaetani et t990^; Lucchini, 1991; ZeIioIi, The Kuling Group in Spiti ^1., 1992) and Lahaul (Baralacha La and Tandi; Vannay, 1993) regions, in order to establish a firm stratigraphic The term "Kuling shales" was first introduced by framework for the whole Zanskar-Spiti Synclinorium; c) Stoliczka (1866) for the fossiliferous black shales expo- to shed new light on sedimentary and paleogeographic sed at Guling (Pin Valley), where they overlie an inter- evolution of the northwestern Himalaya during initial val of locally bioclastic sandstones with a basal conglo- opening of Neo-Tethys between Northern Gondwana merate. The name was revived by Hayden (1908) and and the Peri-Gondwanian blocks (Baud et a1.,1993). more recently by Srikantia (1981), who subdivided the "Kuling Formation" into a lower arenaceous Gechang Member and an upper shaly Gungri Member, with Methods. type-localities in the Parahio and Pin Valleys of Spiti Sandstones were quantitatively ana'lyzed (300 points on each of respectively. The type-section of the Kuling Formation the 33 rnalyzed sections) .according r.o the Gazzi-Dickinson point- has been described also by Fuchs (1982). method (Ingersoll ei a1., 1984), modified to take into full counting The Gechang Member (mid-Permian "calcareous account the coarse-grained rock fragment population. Mineralogical sandstone" Hayden, 1904) and Gungri Member (Up- and textural classification of sandstones is after Folk (1980). Petro- of graphic parameters (Q:quanz; F:feldspars; L:aPhanitic lithic frag- per Permian "Productus shales" of Hayden, 1904) are Kulíng Group, Spiti, India 177

NW SE LOSAR GULING GECHANG MUTH

INDUAN KURKUB FORMATION

.HS89

upper è s mem ber !

. HSl72

éA A HSS, 111 ì1 ^ Vay':Hs85. 156 . HS&3, 1 10, 155 lower 't-1s154 LIPAK FM memoer

ì U !a. ustzt \!r s N: U ! != v\ HS392 U ^VAi ' : v-:u-G V- v l:177 l?l lX ,* ," GANMACHIDAM DIAMICTITE LIPAK FM. [.' PIN FM.\ MUTH OTZARN l é1 breccia f7l conglo-"rate A brachiopod E sandstone wave nPPle é large concrelron V bryozoan f-'l shale C herringbone x lam a phosphate nodule / gastropod -i--l marl megaripple x lam. o glaucony, iron ooid O coral -l 63r[6p61s scoured base mudclast tl \ bioturbation

Fig.2 - Stratigraphic columns and sedimentary features of the Kuling Group in Spiti.

here formally elevated to formation rank, according to Gechang Formation. the "strong recommendation" by \Taterhouse (1985, p. 7I) and recent views expressed in Singh et al. (in prepa- Parahio Valley (Gechang). fact, black shales the Gungri Forma- ration). In the of In the Parahio Valley type-area above Gechang, (50 1OO are easily mappable tion to m-thick in Spiti) thickness is minimum (increasing laterally within about The much throughout the Spiti-Zanskar Synclinorium. 150 m from 0.4 m to 2.L m and then decreasing again to clastics the Gechang Forma- coarser-grained hybrid of L.4 m; Fig. a). The Gechang Fm. disconformably over- tion (reaching a thickness of 35 m at Losar) are niappa- lies the Silurian Pin Fm. or fills pockets up to 20 cm ble all along the Spiti Valley and in the lower Pin Val- deep into the Devonian Muth Quartzarenite; it also reduced feather-edge ley, whereas its thickness is to a seals a system of paleofaults oriented roughly NE-S\í upper and (few metres or even decimetres) in the Pin and offsetting the underlying miC-Paleozoic units. Parahio Valleys. As a consequence, the Kuling is elevated Two lithozones can be distinguished. to group rank (Fig. 2). Complete reference stratigraphic sections of the Basal Jèruginous conglomerate, These microconglomerates to Kuling Group were measured both in the Pin and Para- pebbly sandstones (0.2 to 1.3 m; HS 176,178,179,180,183) contain both intraformational panicles (glaucony, iron ooids, dark to limonitic hio Valleys (60.6 m-thick at Muth, 94.0 m at Gechang, soil fragments; NCI grains of Garzanti, 1991) and extraclasts derived 95.2 m at Guling) and in the Spiti Valley (about 93 m ar from the underlying substratum (quanzarenite to hybrid arenite and Lingti, 8/.1 m at Losar; Fig. 3). limestone fragments up to 20 cm in size). t78 E. Garzanti, L. Angiolini & D. Sciunnacb

F;. ì Kuling Group ar Losar (A): GE:Gechang Frn. (bc:basal conglomerate; lfa:lower ferrlginous rrenite; ms:middle sandstone: ubb:upper brachiopod-rich bed$; GU:Gungri Fm. (lm:silty lower member; u-:clay"y upper member); black arrows show para- conformable boundary with Triassic Tamba Kurkur F^. (T). B) Unconformable basal boundary (white arrow) with the Ganmachi- dam Diamictite (GD). C) Sharp boundary (white arrow) between Gechang Fm. and Gungri Fm. (F. Berra for scale). D) Gungri Fm., with abrupt boundary $lack arrow) between lower and upper member.

Tópmost ferruginous arenite. These fine-grained and strongly burrowed green sandstones (0.2 to 0.8 m; HS 177,18L,184) contaln glaucony and dark mudclasts; subangular quanzarenite to chen pebbles up to 7 cm in size still occur.

Upper Pin Valley (Muth).

Above Muth, a major disconformity is marked by a sharp-based lenticular breccia (up to 2.4 m; HS 154), cutting at low-angle into the I-ower Carboniferous Li- pak Fm. (about 1 m in 100 m; less than 1'). The breccia, supported by a dark shale matrix and containing clasts and broken beds up to 1.6 m in length from the P underlying Lipak carbonates, pinches out rÀ/ithin 300 m ..?o l': aiong strike. The overlying arenites can be subdivided into four lithozones; since the first three, making a distinct resi- The Gechang Fm. (GE) at Gechang is reduced to a thrc- stant horizon up to 3.2 m-thick, are replaced laterally kness of only 0.4 m; the unit rests disconformably (ar- by 0.5 m-thick hybrid ferruginous arenites (HS11O), ove- rows) on the Silurian Pin Fm. and is sharply overlain by rall thickness of the formation (exciuding the breccia) the Gungri Fm. (GU; A. Nicora for scale). From the distance of just ten metres, crossed a pre-Sakma- varies within 300 m along strike from 1.2 m to 4.1 m. rian paleofault, to the opposite side of the Parahio Valley (Fig. 138), the Kuling Group rests disconformably on the Basal ferruginous conglomerate. This lithozone (up to 0.1 m; HS 83,155) contains brachiopods, subordinate gastropods, black mud- Devonian Muth Quartzarenrte. Kuling Group, Spiti, India 179

clasts and angular carbonate extraclasts up to 10 cm in size, eroded from the Lipak carbonates. Midd.le sandstone. These medium-grained quartzose sandstones (up to 2.9 m) display truncated wave-ripples and lenticular lags enriched in brachiopod shells (HS 84). Large-scale, high-angle crosslamina- tion in the upper part indicates NE-ward paleocurrents (50" to 70"lrl). Upper bracbiopod-ricb beds. These coarse-grained arenites rich in spiriferids (0.2 to 0.4 m; HS 85,156) contain extraclasts up to 2 cm in size. 1óprnost ferruginoils drenite. This bmchiopod-bearing ironstone (0.7 to 0.9 m; HS 86,111) displays sharp base and top.

Lower Pin Valley (Guling) and Spiti Valley (Lingti, Losar). To the north of the confluence between the Pin and Parahio rivers, the Gechang Fm. increases in thickness. At Guling (17.5 m; Fig. 5), the unit disconformably overlies the I-ower Carboniferous carbonates of the Lipak Fm., whereas at Lingti (19 m at least) and Losar Qa.9 m) it unconformably follows the ìowermost Per- mian Ganmachidam Diamictite. In these sections, the Gechang Fm. can be subdivided into four lithozones. At Lingti, the first two are replaced by a 40 cm-thick conglomerate bed containing quartzarenite to carbonate extraclasts up to 30 cm in size and abundant bryozoans, echinoderms and brachio- ': .,i pods (HS 190). .,.'*

Basal conglomerare. This lithozone (2.5 m at Guling, HS 165'

166; 7 .8 m at I-osar, HS 392, 391, 390) displays strongly erosional base and contains common quanzarenite extraclasts, as well as mudclasts and reddened to yellowish soil fragments. Maximum extraclast size decreases from Guling (15 cm) to Losar (3 cm), where channelized con- glomeratic lenses interbedded with pebbly sandstones to shales display N\W-ward dipping crossJamination. The upper 1.2 m (Guling) to 2.7 m (Losar; HS 389) consist of finer-grained sandstones interbedded with siltstones. Loaer fetugìnous arenite. These grey-greenish hybrid arenites (2.7 m er Guling, HS 767,168;3.5 m at Losar, HS 388, 38/) contain shell lags (bryozoans, brachiopods, echinoderms) and abundant glaucony and other NCI grains, including silicate ooids and peloids; bioclasts are commonly glauconìzed or silicified. The lithozone dìsplays sharp burro*ed base at I-osar and comprises microconglomerates in the lower prn et Guling (extreclasts up to 3 cm). Mi.ddle sandstone. These amalgamated NCI-bearing ferruginous arenites with sparse brachiopods and reddish to greenish or black alte- Fig. 5 Gechang Fm. rt Guling (A; acronyms as in Fig. 3). B) Di- (arrows) Fm. ration surfaces (10.7 m at Guling, HS 169,i70;23.1 at Losar, HS 386) sconformable basal boundary with the Lipak are up to fine-grained and burrowed at Losar, where siltstones occur (L). C) Sharp base and top of the upper brachiopod-ricb only at the very base and beds are 5 to 10 cm-thick. Sandstones in 10 beds. to 50 crn-thick beds are locally microconglomeratic (clasts up to 3 cm) at Guling, where low-angle stratification to locally E-!7 bipolar cross- rate: 89+5 F3t5 L8+5, n:7, HS 83, 110, 176, 178,179, 180, 183; lamination occurs. Dip of cross-laminae indicates NE-ward (70'lrf pa- Q boroL ìonglomerate: Fl!2 L6+6, n-5, HS 765, 1.66, 392, 39r, leocurrents at the top, Q93+6 390, 389; lotuer arenite: F1+1 L7+9, n:5, HS 167, Upper bracbiopod-rich beds. These quartzose arenites (I.6 m at ferruginous Q93t9 168, 190, 388, 387; Tab. 1), containing a variety of terrigenous (shale Guling, HS 171; 0.5 m at Losar, HS 385) contain abundant moulds of to quartzarenite;1.5ok of framework), chen (1.3ol") and a few carbona- spiriferid brachiopods up to 15 cm in width. The base is sharp and grains (CE O.5t1ol", vanishing upsection) (Fig, 6A). Volcanic rock mantled by she1l lags (I-osar) or microconglomeratic arenites with te include some felsitic vitric grains, locally showing em- black flat mudclasts up to 3 cm in size (Guling). The topmost surface fragments to is also very sharp and displays extensive Sholitbos-r.ype venical bur' bayed quartz phenocrysts or pumiceous textures, and abundant pseu- Igneous metarnor- rows both at Guling and Lingti. domatrix (V/L about 30olo; Dickinson, 1970). and phic rock fragments are subordinate. Pseudomorphs and altered grains occur (7+7oQ. Cr-rich chromian spinel [Cr,/(Cr+Al) 0.79+0.09] was Arenite petrography. found at Losar (HS 387). Mudclasts, illite to glaucony peloids, pho- The base of the Gechang Fm. consists of mainly medium to sphate clasts, ferricrete grains and iron (chamositic?) ooids are wide- up 10 cm in size, occur at the base at very coarse-grained pebbly sublitharenites (basal ferruginous conglome- spread; soil clasts, angular and to i80 E. Garzanti, L. AngioLini G D. Sciunnach

Fig. 6 - Petrography of the Gechang Fm. in Spiti. A) Arenaceous (a) and chen (c) rock fragments (basaL congLomerate; Losar, HS 391; 20x, 2lrì). B) Bryozoans ft), echinoderms (e) and rounded quartz (q; basalferuginous congLomerate; Lingti, HS 190; 18x,21.0.C) Tilloidal arenaceous grarn (t; middle sandstone; Guling, HS 169; 31x,2lrì). D) Subarkose (middle sandstone; Muth, HS 84,45x,2N). E) Iron ooids upper bracbiopod-rich beds; Guling, HS 171; 31x, 2l$. F) Silicate peloid (white aruows; topnlost @lack ^rrowsi ferruginous arenitetMrrh, HS 1111 40x, 2N.

Guling (NCI 9+87o). Common bioclasts (CI 7+160/o; absent at Ge- mework; phosphate, glaucony and silicate peloids may be abundant chang) include bryozoans (zoecia commonly filled by phosphate or (NICI 12+10o/o). Commonly silicified brachiopods occur (CI 2+3olo). glaucony), brachiopod valves and spines, echinoderm plates (Fig. eB). The upper bracbiopod-rich beds and topmost feruginous arenite The mid.dle sandstone of the Pin and Spiti Valleys consists of also consist of fine to coarse-grained hybrid sublitharenites (Q91+5 fine to coarse-grained hybrid sublitharenites to subarkoses (Q90t10 F3t3 L6+4, n:8, HS 177,781,184, 85,86, 111, 171,385). Terrige- F5t9 L5t9, n:4, HS 84, 169, 170,386; Fig. 6D); siightly greater feld- nous grains (i.67o) prevail over chen (0.3ol") and rare carbonate rock spar/rock fragment ratio may be accounted for by finer grain size of fragments (HS 85). Y/L ratio averages 40olo; pseudomatrix is 15+12olo. analyzed samples with respect to the underlying lithozones. Altered Glaucony to silicate peloids, phosphate clasts, mudclasts, iron (chamo- volcanic grains were locally recorded; sedimentary rock {ragments are siiic?) ooids and a few graphite particles are widespread Q\Cl 22+12'k; rare (chen, tilloid clasts; Fig. 6C). Pseudomatrix is 8+10% of fra- Fig. 6E,F); brachiopods and bryozoans occur (CI< 17o). Kuling Group, Spita India 181

111 a.o 5.3 6.7 2.3 1.0 - 37.7 - 0_3 2.3 1m_0 gM I .12 .n 0 s rFA 9.0 1.7 5.3 1.3 1.7 0.3 - r. É.o 27.o o_7 2.3 1m.0 95W 6 .17 .4 .18 UAB 4.3 2.7 9.3 1.3 r. - 50 19.3 1.3 1m_0 g 2.7 13.0 É5m s .17-0 fts 4.3 - 3.7 5.0 50 1.3 !. 3.3 0.3 0.7 2.3 15.7 19.3 1m.0 1SW 81 .m .€ s EC 4.3 0.3 1.3 3.3 1.3 0.7 - 6.7 57 1.3 0.7 2.7 s.0 1m_0 &P 87 .B.BO 110 u.7 2.3 5.3 2.3 1.7 0.3 0.3 0.3 10.7 6.0 12.3 2.3 19.0 1m.0 415 W a7 .12 .S 0 CH'

1g TFA 4.3 3.7 4.7 0.3 - 14.7 - 4.3 5.7 1_7 3.7 1m.0 &w 81 18 .15 - .S 181 fFA s.3 3.7 8.0 0.3 0.3 - 14.0 - 3.0 5.7 5.7 0.7 1S.0 {5W v 7 .12 - .60 171 TFA 15.7 1.7 1.1 2-7 0.7 1.0 0.3 17.7 11_3 10.3 2.0 1m.0 1DW I 3.6.671 18 EC 9.7 1.7 5.7 r. - 5.0 - 9.7 5.3 8.0 16.3 1m.0 sm & m .12 - .71 1& trc 35.7 - 1 1.3 - 7_O - 1.0 1.0 6.0 9.0 1m.0 165 P 13 .21 - _25 1n FC 51_7 - 9.7 - 2.7 1.3 15.0 18.0 1m.0 MM 97 3 .16 - .60 174 *c 4.7 0.3 12.3 1.0 - 1.0 - 5.3 1.7 22.7 1.3 1m_0 11S W s 10 .22 - _59 176 EC €.0 1.0 5.7 r. t. 12-A - 8.0 10.3 7.7 3_3 1m.0 1SP a .11 - .20

171 UB 9.7 - 12.0 0.7 - 1_3 22-7 4_3 1m_0 s5P 92 8.18-.4 170 ts 4_3 0.3 5.0 1.3 3.7 11.0 3.0 27_3 4_0 1m.0 323 W s o .10 169 trS t.0 4.0 7.o 1.3 3.7 9.0 5.3 1m.0 MP & 17.10-1 168 lFt 4.0 0.7 5.3 4.3 r.3 6_0 0.3 24_7 6.0 1m.0 a5M s 10.10-1 1Sr 61_0 - 41 5.3 - 0.3 4.3 223 0.7 1m.0 5Mtr 91 2 .O7

lW ffC 0.3 37.0 . r. 1.7 0.7 S.0 [email protected] 1T& W 18.11-0

HS385 UAA 45_0 - 5.7 0.3 17.0 3.0 10.3 18.7 [email protected] 165 XN 1@ 0 .11 HS3S MS 42.7 , 8.0 0.7 0.3 ù. 15_3 - 0.3 8.0 14.0 10 3 [email protected] 1SW 97 1.16-0 HS3a7 tFl 4.7 r. 3.3 0.7 [- 18.0 l7 2.7 15.0 2.3 7.7 [email protected] 35P s 0 .07 rc3$ tFI f_0 0.3 4.7 1.7 5.7 5.0 - 3.3 27.3 1m.0 s5w 1m 0 .08 rc3$ & @.3 - 6.0 , 0.3 t. 6.3 25.7 0.3 [email protected] ffM $ 2 .09 HS390 10.3 & 4-3 - - 1.7 2.1 7.0 20.7 - [email protected] 1110 P s 11 .17 - _32 HS391 ff $_7 - 12-O - 2.7 1.0 16.3 4.0 [email protected] 1mP a5 15 .18 - .08 HS392 & s_0,4.7-r. 0.7 7.7 - 0.3 15.7 14.3 1.0 lm.o I 1 ,08

24.7 0.7 2.3 7.7 r. r. 51.7 A.7 4.7 1m.0 13M re 1S 2 .O7 1 31.0 - 2.O 1.A - 49.0 2.0 9.7 [email protected] 105 M s105.061 s.3 - 5.0 r. - - 3.0 12.7 17.7 [email protected] 315 Mru s04.08-.s 22.3 0.3 6.0 14.3 4.3 10.3 21.O 9.3 9.3 [email protected] 125 P @39 1.m.n u2 0? 6? .08

Tab. 1 - Detrital modes for the Kuling Group in Spiti and Lahaul. C:Chumik Fm.; other acronyms as in Fig.3. Q:quanz (Qs:single; Qsb-embayed; Qp, C:polycrystalline); F:feldspars (Pl, P:plagioclase; AF-alkali feldspars including chessboard-albite); L:fine- -'"i"'l ""-L"i'ic" Ìithics. RF:fine- to coarse-grained rock fragments (P:plutonic to hypabissal; V:volcanic; M=metamorphic; T:terrigenous), E and I:extra- and intra-basinal grains (C:carbonate; NC:non-carbonate). HM:heavy minerals and mrcas. p5sui:pseudomatrix; Mat:matrix and epimatrix; Cem:"compatible" syntaxial cemenrs; Aut:authigenic minerals and carbonate replacements. Tot:tota1. GSZ:grain size (in pm); SRT:sorting (\l:good; M:moderate; P:poor).

Fossils and age. very low average accumulation rates. In the Pin Valley type-area, abort 25 Ma (according ro îhe Harland et al., Basal conglornerdte and louer ferruginous arenite. 1989 time scale) are documented by as little as 0.4 m. The spiriferid Tiigononeta cf. orientensis Singh & The mid-Permian seems to be largely represented by the Archbold, 1993 and Ingelareliidae were one collected at less fossiliferous middle sandstone, but significanr gaps Muth (P1. 1), suggesting a Late Sakmarian (Sterlitama- are at least locally present. kian) age and cool climatic conditions (Singh & Archbold, 1993). Depositional Trepostomata bryozoaîs (similar to Parnirella; environments. S.Sakagami, writ. comm., 1996) are widespread, from In the upper Pin and Parahio Valleys, rhe unit Muth and Guling to Lingti and Losar, where also was largely deposited in high-energy shoreface setrings. Pseudoabatostomella sp. occurs (det. by S. Sakagami, Sedimentation of condensed hybrid arenires took place 1995; Fig. 7A,B). Correlation vzith the mid-Lower during successive transgressive stages, of Late Sakmarian Permian "Ritung Bioturbated Mudstone" of the Nepal (basal ferruginous conglomerate) to Midian/Early Djul- Lesser Himaiaya is thus indicated (Sakagami & Sakai, {ian (topmost ferruginous arenite) age. 1,ee1). To the north and west (Guling, Lingti, Losar), the Upper bracbiopod-rich beds. The spiriferid Cleiotlty- basal conglomerate was sedimented in estuarine channels. ridina gerardl (Diener, 1899) constitutes a monospecific A major transgression is testified by the louer ferrugi- assemblage found at the base of the lithozone at Muth, nous arenite. The middle sandstone upper bracbiopod- ^nd reflecting unfavourable sandy substrates; a Late Permian rich beds were deposited in estuary mouth to shoreface (Midian/Early Djulfian) age is indicated (Thomas, 1969; environments during renewed transgression. Final drow- Archbold et a1., 1993). The top of the lithozone at Gu- ning of the Neo-Tethyan shelf is documented by the ling contains abundant large spiriferids of Late Permian topmos t ferru gin o us a ren ite. age Weospirifer sp; Fusispirifer sp.; A. Tintori, pers. Coarser grain size throughout the unit at Guling comm. 1994) and yielded the bryozoan Rhombopora sp. documents more proximal environments with respect to at Muth (det. by S. Sakagami, 1995). Losar. Northward dispersal of detritus is also suggested The Gechang Fm. 'was thus deposited from the by paleocurrent indicators, directed both towards the Late Sakmarian to the Midian or even Early Djuifian, at NE and N\L r82 E. Garzanti, L. Angiolini & D. Sciunnach

PLATE 1

Permian brachiopods from the Kuling Group in Spiti (GechangFm.: basalferruginous conglomerate at Muth, HS 155; upper bracbiopod-rich beds at Muth, HS 156. Gungri Formation: lower member at Muth, HS 87). All photos 1x.

Fig. 1,2 - "Lamnimargus"hitnaLayensk(Diener),ventralvalves:i) specimenMPUMT9A2i2) specimenMPUMT903. Fig.3,4 - Cleiotlryridinagerardi (Diener): 3) dorsal valve, specimen MPUM ZSOZ; 4) ventral va1ve, specimen MPUM 7908. Fig.5 - Trigonotreta cf. orientensis Singh 6c Archbold, ventral valve, specimen MPUM 7911. Ftg.6,7 - TintorieLlarajah(Salter),ventralvalvein:6) ventralview,specirnenMPUMT912;7) posteriorview,specimenMPUMT9t2, Fig.8-13 - Tintoriella rajah (Salter), serial sections of ventral talve (specimen MPUM 79131 all 1.3x) at: 8) 2.5 mm; 9) 3.1 mm; 10) 5.5 mm; 1 l) 6.1 mm; 12) 6.7 mm: 13) 7 .7 mm from the umbo. Kuling Group, Spiti, India 183

Permian bryozoans from the Kuling Group in Spiti and Zanskar (a1l determinations by S. Sakagami, 1995). Gechang Fm. in Spiti (basal ferruginous conglomerate at Lingti, HS 190; lcruer ferruginous armite at Irsat HS 387): A) TiEostotndtd gen. et sp. indet. (HS 190; 50x, 7tn);B) Pseudoabatostornella sp. (HS 387; 50x, 1N). Gechang Fm. in Zanskar (upper lìthozone at Jinchen): C) Discrytella sp. (HZ a7;25x, llrl); D) Rhombopora sp. (HZ 47;50x, llÍ);E) PoLypora? sp. (ZZ 6; 62x,2lrì); F) Sulcoretepora sp. (HZ 47;40x, 1Nf.

Provenance. Although the unit unconformably overlies various carbonare to terrigenous Paleozoic formations, relative abundance of rock frag- The Gechang Fm. mostly consists of quartzose sub- ment types is not significantly controlled by lithology of substratum, litharenites derived from sedimentary successions uplif- suggesting homogeneous detritus dispersal during widespread tran- ted during rifting. Subordinate contribution from sgression onto the newly-forrned passive continental margin. Feldspars however are more common at Muth, sources. igneous and metamorphic sources indicates that uplift possibly reflecting local Terrigenous and chen rock fragments, along with Cr-rich and erosion of rift shoulders only locally were intense chromian spinels, characterize the basal conglomerate and loaer ferrugi enough to exhume basement rocks beneath the thick nous arenite (average detrital modes: Q91 F2 LZ), as other Upper pre-rift sedimentary cover. Sakmarian to Aninskian sandstones of the Tethys Himalaya from 184 E. Garzanti, L. Angiolini G D. Sciunnach

Fig. 8 Upper member of the Gungri Fm. (GLf at Lingti. A) Black shales with large concretions (arrow; F. Berra for scale). B) Zooplrycos- tvoe burrows.

Zanskar (Chumik Fm., Member A: Q9O Ftr. L1O; base of Member B: Ammonoids of Djulfian age (Cyclolobus walleeri Q97 Ftr. L3; Gaetani et al., 99Aa) to Manang (Puchenpra Frn., Mem- Diener) are reported to occur up to 1.3 m below the top ber A: Q92 Fl L7; Garzanti et al,, 1994). of the unit at Lingti, where the Dorashamian seems to Detrital modes from the ntiddle sandstone (Q90 F5 L5) to the be largely missing (Bhatt upper bracbiopod-ricb beds and upper fenuginous arenite (Q91 F3 L6) et a1., 1980) also compare with those of coeval lithozones from Zanskar (Gechang The Gungri Fm. is therefore Djulfian in age. Fm.: Q88 F2 L10) to Dolpo (Puchenpra Fm., Costiferina arenites to base of glauco-phospborites md black shales: Fl L2 ro F2 L5; Q97 Q93 Depositional environments. Sciunnach & Garzanti, 1996) and Manang (Puchenpra Fm., Mernber B to lower-middle Member C: Q95 F2 L3 to Q96 F1 L3). The unit accumulated in offshore shelf environments only episodically disturbed by major (louer mem- Gungri Formation. be.r) to exceptional (upper rnembe?.) storm events. During the Late Permian, water depth thus increased from a few This pelitic unit (56.5 m at Muth; 93.6 m at Ge- to many tens of metres, due to thermal subsidence of chang; 77.7 m at Guling; about 74 m at Lingti; 52.2 m the newly-formed passive continental margin (Gaetani at Losar) can be subdivided into a loaer mernber, charac- k Garzanti, 7991; Yannay, 1993). Abundance of pho- terized by two relatively resistant bands of brachiopod- sphates is ascribed to strong upwelling of nutrient-rich rich phosphatic siltstones, and an upper me?nber, m de waters in the E-W trending narrow Neo-Tethyan ocea- by black fissile shales with sparse large concretions (Fig. nic seaway (Cook Er McElhinny, 1979). 8A). The lmer menber (27.5 m ar Muth, HS 87,88; 40.2 m at Ge- chrng, HS 185;33 rn rt Guling, HS 172; about 34 m at Lingti;28 m The Kuling Group in Zanskar, Ladakh and Lahaul at Losat HS 384) begins with black shales (10 m), followed by micaceous phosphatic siltstones rich in productid and subordinately spirife- The stratigraphic framework suggested in previous rid brachiopods (2.3 to 1.0.6 m). Next, black shales with brachiopods (5.2 to 10 m) are capped by a second resistànt band contaìning bra- papers by European teams (e.g., Baud et al., i984; Nico- chiopods and burrowed phosphatic siltstones in up to 20 cm-thick ra et al., 1984; Gaetani et a1., 1986, l99Oa; Spring, 1993; beds at Muth (4.5 to 12 m); phosphate nodules reach 30 cm in size. Vannay, 1993) was based on extensive field work carried The upper nember (29 m at Muth; 53.4 m at Gechang; 44.7 m out in Zanskar and Lahaul but not in Spiti: the area at Guling; about 40 m at Lingti; 24.2 m at Losar, HS 383) consists of black shales wìth rare intercalations of thin micaceous siltstones. Pho- where the Kuiing Formation was originally defined sphate nodules and large concretions (up to 120 cm in size at Lingti) (Stoliczka, 1866; Hayden, 1908; Srikantia, 1981) was occur. Brachiopods and corals are locally found (Muth, HS 89); specta- then closed to foreigners for political reasons. Only in crlar Zooplrycos-type burrows (Fig. 88; Bhargava et al., 1985) charac- the 1992 expedition we have been able to study the Ku- terize the lower pan at Lingri. ling Group in Spiti, and to realíze that its base contains Late Sakmarian fossils and is thus significantly older Fossils and age. than previously thought (major paleogeographic and pa- Spiriferid lTintoriella rajah (Saker,1865)l and pro- leogeodynamic implications of this discovery will be di- ductid l"l-amn imargus" h imalayensis (Diener, 1 899)l bra- scussed below). chiopods, collected in the first phosphatic band of the Therefore, stratigraphic sketches tentatively propo- loaer member (11 m above the base of the unit at Muth), sed a few years ago (e.g., Gaetani et al., L990^, fig. 6; Van- indicate warm water conditions during the Early Djulfian. nay, 1993, fig.23) need substantial revision. In particular: Kuling Group, Spiti, India 185

SPITI LAHAUL ZANSKAR LADAKH

Muth Losar Tandi Baralacha La Chumik Marpo Phugtal Nyimaling Gèchang Guling Jinchen Tanze Thongde

56 : 94 52 + 78 =22 15 + SO ?1 + 33 s1T s2OO

GU N GR I F OR MA T I O N K DJULFIAN fem4inous U arenites upper arenaceous limestone 0.2 + 0.9 L =5 5+5.5 0.6+ 2 <40 0 + 0.4 0.5 + 1.6 I =5 7+10 2.5;10 E brachiopo+ich beds low er c a I c a reou s sandsf N a one MIDIAN Fig. 9 - Stratigraphic framework for H the Kuling Group in the GECHANG FORMATION Zanskar-Spiti Synclinorium. A Q + 2.9 10.7+23j N Thickness for each unit is in- 1l middle sandstone 0+30 30+15O =3O0 dicated in merres. Due in- Mrr PANJAL TRAPS ro Mb. tense tectonic deformation, \t Member B 10; 15 >3 the Lower Permian succession F R fenuginous arenites MemberA 5 + 20 in the Nyimeling is fr. region 0.1 * 1.3 2.7 + 3.s = 10 10 + 15 upper lithozone still poorly understood z.J + t.ó U = 8 30 + 50 middle lithozone (Stutz, 1988; Fuchs 8c Linner, basal conglomerate 20 15 + 20 lower lithozone P = Late 1995). See text for full expla- J CHUMIK FORMATION SAKMARìAN nation. breccia

1) the Kuling Formation as originaily defined in Spiti, and comprises the Chumik Formarion, the Panjal Spiti is equivalent not only to the sediments overlying Trap basalts (up to 300 m+hick) and the overlying sedi- the Panjal Traps, but also with the lithologically similar ments ("Kuling Fm." of Srikantia et al., 1980; Baud et Chumik Formation underlying the traps; aI., 1984; Gaetani er al., 1,990a), including hybrid areni- 2) the Chumik Formation does nor occupy rhe tes at the base (Gechang Fm.) and black shales in the same stratigraphic position as - and is by no means equi- uPper part (Gungri Fm.; Fig. 9). valent to - the Ganmachidam Diamictite, which is di- stinctly older and separated from it by a first-order un- Chumik Formation. conformity (as seen locally also in easrern Zanskar; Gar- The Chumik Fm. unconformably overlies mid- zaîî.i ef aI., 1996, p. 88). Carboniferous quartzarenites of the Po Group; the As a consequence: lowermost Permian diamictites are only locally repre- 1) the usage "Kuling Formation" of to desribe sented (Garzanti et al., 1996). oniy the Upper Permian sediments overlying rhe Panjal The unit, 65 to 85 m in the east (Chumik Marpo Traps in Zanskar must be abandoned; area; Chumik Unit) and reduced ro abour 20 m or less 2) the terms "Ganmachidam" and "Chumik" desi- westward (Tanze; Zangla Unit), is subdivided inro two gnate two distinct formations which differ notably in members (Gaetani et al., 1.990a; Lucchini, 1991). lithology, sedimentary features and fossil conrenr. Mo- reover, their contrast in paleogeographic and paleotecro- Member A begins with burrowed phosphatic subarkosic silt- nic significance is apparent: the Ganmachidam Diamicti- stones yielding brachiopods, pelecypods, echinoderms, gastropods, bryozoans and conulariids, followed by quanzose hybrid arenites con- te, originally defined in the Losar area of Spiti by Sri- taining glaucony peloids and iron ooids (louer litbozone, 15 to 20 m; kantia (1981) and comprising uppermosr Carboniferous ZB 2, ZG 45, 46, LZ 85, 54, 37). The overlying dark-green glaucony- to lowermost Permian pebbly glaciomarine sediments, rich sublitharenites (middle lithozone,30 to 50 mi ZG 47,48,49,50, was accumulated during the climax of rifting (Garzanti LZ 86a, 87,74,75, 52, 41, 42, 3I, 32, 38,9) are up to coarse-grained and contain a variety of NCI peloids (Garzanti, 1991) (Fig. 1OA). In- er al., 1.996); the Chumik Formation, originally defined terbedded placers are strongly enriched in higher-density heary mine- in eastern Zanskar by Gaetani et al. (1990a) and mostly rals such as rutile and chromian spinels [yellow-brown Al-rich to dark- consisting of marine arenites and mudrocks similar to red Cr-rich picotites, with Cr,/(Cr+Al) ratio from 0.62 to 0.94f; zir- con, tourmaline, monazire also occur (Fig. 108). The those contained in the lower part of the Gechang Fm. upper lithozone (up to 15 m) is pelitic and poorly exposed. in Spiti, was instead deposited during rransgression at Member B consists of cross-bedded quartzose microconglome- the end of the rifting stage (see discussion below). rates with sharp erosive base, containing chen, felsite and arenaceous rock fragments (10 to 15 m; ZG 51, 52, 53, 54, LZ 1O), passing upward to greenish tuffaceous rocks (ZG 55, 56) directly overlain by Zanskar. the Panjal Trap lavas.

In Zanskar, the mid-I-ower Permian to Upper Per- Member A, yielding a varied cold-water fauna of mian sedimentary succession is much thicker than in Late Sakmarian age (Archbold & Gaetani, 1993), is 186 E. Garzanti, L. Angiolini G D. Sciunnach

r &

Fig. 10 - Petrography of the Kuling Group in Ztnskar. A, B) Glaucony-rich (g) greensands (Chumik Fm., Member A; Chumik Marpo) (A: ZG 50;63x, 1lrì), locally strongly enriched in heavy minerals with density between 4.5 and 5 g/cm'(rutile, monazite, chromirn .-;..1 ^-.^"""\ (B: LZ 86; 45x, llrl). C) Glauconizedbryozoan (b) and lathwork volcanic grain (v; Gechang Fm., lower lithozone; Thongde, H 134; 40x, 2ND. D) Glauco-phosphorite with bryozoans (b) and siliceous spicules (s; Gechang Fm., upper lithozone; Jinchen, HZ 47 ; 16x, 219. time-equivalent with the base of the Gechang Fm. in The name "Testha Member" used by \íaterhouse Spiti (e.g., basal ferruginous conglomerate). Abundance of (1985) for the same unit is a younger synonym. Moreo- glaucony suggests deposition in shoreface to shelfal envi- ver, the term should be abandoned for poor original de- ronments during major transgression at the end of the scription and synonymy with the mid-Cambrian Teta Gondwana glaciation (Gaetani et al., 1990a; Garzanfi, (another spelling of the same village, located about 8 1991). Such condensed arenites can be traced in fact km NW of Tanze) Member of the Karsha Fm. (Gaetani along the Tethys Himalaya to as far as Nepal (Garzantì et a1., 1986; Garzanti et a1., 1986; Stutz, 1988; Spring, ef a1.,1.994, fig. 5). 1993; Vannay, 1993). Member B documents a major regression shortly The GechanB Fm., 1.2 to 75 m in the east [in- before the emplacement of continentai flood basalts chen-Tanze area) and reduced to only 3 m westward (Fig. 11A). Coarse siliciclastics with similar composition (Thongde), consists of two lithozones ("lower calcareous are found at the base of the Gechang Fm. in Spiti and sandstone" and "upper arenaceous limestone" of Joshi in Nepal (Member A of the Puchenpra Fm.; Garzanti et & Arora, 1976; Iithozones a and b of Gaetani et ai., al., 1994). 1990a; ZeIioIi, 1992).

In the Jìnchen-Tanze area, r.he loaer Lithozone (7 to 70 m) con- Gechang Formation. sists of a basal horizon of fine-grained sublitharenites with a few green peloids or ferruginous ooids (3 to 5.8 m; ZZ 1,2,3, I, HZ 534); The Gechang Member of Srikantia et al. (1980) brachiopods, echinoderms or bryozoans occur locally at the base (HZ and Gaetani et a|. (1990a), designating the arenaceous 533) and commonly in the upper pan (ZZ 4, HZ 46). The overlying unit overlying the Panjal Traps (Fig. 11B) and yielding very fine-grained burrowed sublitharenites are sparsely bioclastic and contain phosphatic matrix and glaucony peloids (3.5 to 4.7 m;77 5, spiriferid brachiopods of Late Permian age, is here eleva- 9, 10, 14). The upper lithozone (5 to 5.5 m) consists of burrowed and ted to formation rank. phosphatic, very fine-grained hybrid arenttes (ZZ 11,12,15,47b, HZ Kuling Group, Spiti, India t87

sp., Protonodosari.a sp., Lingulonodosdria sp., Frondicula- ria af[. orndta Mikhluko-Maclay, 1954, E aff. dilemma Gerke, !962, Dentalina aff. orientd Sosnina, 1965, n.gen. aff. Austrocolomia, n. gen. aff. Caloezina, Gerbeina (?) sp., Geinitzina (?) sp.; det. by D. Vachard, 19951 and

bryozoan (Dyscritella sp., Rb ombopora sp., S ulcoretepora sp.; Polypora sp.; det. by S. Sakagami, t995; Fig. ZC, D, E, F) assemblages oI Late Permian age. The very top of the Gechang Fm. is dominated by "Lamnimdrgus" bimalayensis (Diener, 1899), Tinto- riella mjab (Saiter, 1865) and Cleiotlryridina subexpansa (lWaagen, 1883), indicating the Early Djulfian (Gaetani et al.,l99Oa). The unit, Midian to Early Djulfian in age, was deposited in shoreface to rapidly deepening shelfal environments after the end of rift-related magmatic activity. Up to coarse-grained fossiliferous glauco-phosphorites are roughly coeval s/ith similar NCI-rich arenires in Ne- paI (Garzanti et al., 1994, fig.9), documenting a m jor regional transgression. The Gechang Fm. in Zanskar is time-equivalent only with the topmost part of the Gechang Fm. in Spiti (i.e., wpper brachiopod-rich beds, toprnost ferrwginous arenite). The Panjal Traps in Zanskar are thus roughly time-equivalent rÀiith the main part of the Gechang Fm. in Spiti (middle sandstone) and can be constrained pa- Fig. 11 - Base and top of the Panjal Trap basalts (PT) rn Zanskar. leontologically as post-sakmarian and pre-Midian. This A) Abrupt basal boundary (black arrow$ with arenaceous is consistent with the late Early Permian age ascribed to Member B of the Chumik Fm. (Cb) east of Phugtal (pho- the Panjal Traps in Kashmir (Nakazawa et al., 1975; Sri- to by counesy of M. Gaetani). B) Disconformable upper kantia & Bhargava, 1983), but is at odds the latest boundary (white arrows) with channelized breccias with with angular basaltic clasts (base of Gechang Fm. at Thongde; Permian (Tatarian) age recently given by Veevers Ec Te- \rEl, wari (1995).

538), commonly capped by up to coarse-grained condensed glauco- Gungri Formation. phosphorites QZ 6, 18,HZ a7); these layers contain comonly glauconized bryozoans, brachiopod shells and spines, echinoderm remains, The unit ('Waterhouse, 1985; Gaetani et al., 1990a) siliceous sponge spicules, benthic foraminifers, greenish phyllosilicate consists of black shales rich in brachiopods and pho- to cheny peloids, silty to arenaceous lithoclasts and pyrite (Tig. 10D). sphatic nodules; burrowed phosphatic and chloritic silt- At Phugtal the formation is largely represented by poorly fossiliferous and crosslaminakd coarse-grained calcareous siltstones (about stones or silty micrites with sponge spicules and cri- 10 m; H 171,172), capped by a bioclastic horizon. Thickness is grea- noids are intercalated. Thickness is 21 to 33 m in the ter east of Phugtal (Baud et al., 1984; Nicora et al., 1984). Jinchen-Tanze area and 12 m east of Phugtal (Baud et At Thongde, the loaer lithozone (2.5 m) includes up to 0.3 m- al., 1984); to the northwest (Phugtal, Thongde) it is tec- thick basa1 lenses of channelized bioclastic breccia with angular voica- tonically reduced to only a few m. nic pebbles and glauconized bryozoans (Fig. 10C; H 134, 135), overlain by fine-grained, crosslaminated greenish sublitharenites with Megasteges nEalensis and Aulosteges dalhousii índi- green peloids, enriched in echinoderms and panially silicified brachio- cate the Late Djulfian (Gaetani et a1., 1990a). The Do- pods in the upper part (H 136, 137, L38, 139, 140, 141, HZ 287, 288). rashamian has never been documented and is oossiblv The upper lithozone (Q.6 ro 2 m; H 139, HZ 288b, 289) consists of missing. sandy biocalcarenites with echinoderms and silicified brachìopods (Garzanti, 1986b). Ladakh (Nyimaling). Abundant Neospirifer and subordinate productids occur in the lower-middie part of the Gechang Fm.; Wa- In the Nyimaling region, the Kuling Group un- terhouse (19 85) report ed Cleiotlryridina gerardi (Diener, conformably overlies a reduced Carboniferous section, 1899) 4 to 6 m above the base. consisting of recrystallized carbonates (Lipak Fm.) local- The upper lithozone contains rich foraminiferal ly followed by quartzites (Po Group; Stutz, 1988, p. 41) lNodosaria (?) lagenocamerata Sosni.rra, !978, Nodosaria oi even diamictites (Fuchs & Linner, 1995, p. 670). 188 E. Garzanti, L. Angiolini & D. Sciunnacb

t*l *4 d

:-ri&-

Fio l2 Petrography of the Kuling Group in Lahaul. A) Quanzose (Q and dolomitic (d) rock fragments (Rape conglomerate; Rxpe, V 256A; i6x, 2lrl), B) Chitinous periderm of conulariid (Chumik Fm., Member A; Chandra Valley, L 78;25x,2N). These cold-water schypho- zoans typically occur in the Chumik Fm, C) Vell-soned calcitic (c) quartzarenite (Gechang Fm.; Baralacha La,Y !71; aOx,2N). D) Very fine-grained micaceous subarkose with plagioclase (p; Gungri Fm.; Baralacha La,Y 172;45x,2lrt).

The basal crinoidal marbles, up to 40 m-thick, The occurrence of a bryozoan assemblage of Ar- contain at the top phosphate nodules, corals and bra- tinskian age, found in a block of phosphatic ferruginous chiopods of Djulfian age (Tintoriella cf. rajah; Stutz, packstone further to the north close to the Tethyan su- 1988); these layers thus correlate with the Gechang For- ture (Stutz, 1988, p. 69), is consistent with opening of a mation. rifted seaway in the late Early Permian. The upper part, up to 200 m-thick and still strongly deformed, mainly consists of pyritic to calcareous Lahaul. black shales; it thus corresponds to the Gungri Forma- tion. Late Permian brachiopods (Fusispirifer cf. nitiensi), Baralacha La. benthic foraminifers (Hemigordius ssp.) and bryozoans (Frondina sp.) are locally found; an up to 10 m-thick In the Baralacha La area (uppermost Chandra Val- interval of crossJaminated dolomitic quartzose sandsto- ley), the Kuling Group (80 to 90 m) paraconformably nes capped by crinoidal carbonates is intercalated (Stutz, overlies the Ganmachidam Diamictite (Yannay, 1993). 1e88). Stratigraphic information and samples kindly provided In the Markha Valley further to the northeast, by J.-C.Vannay document several similarities with the thin-bedded grey quartzose schists (Lutchungse Fm.), Permian succession of eastern Zanskar and allowed us to over LOO m-thick and intercalated with greenschists or recognize the occurrence of the Chumik Fm., sharply locally associated with serpentinite lenses, have been overlying the Ganmachidam Diamictite and followed by tentatively interpreted as Permian turbidites deposited at the Gechang Formation. \le could thus extend to north- the oceanward edge of the newly-formed indian margin ern Lahaul the stratigraphic scheme proposed by Gaeta- (Stutz, 1988, fig. 15). Their Permian age, however, is di- ni et al. (1990a) and make direct correlations with the sputed (Fuchs & Linner, 1995, p. 660). nearby l-osar section of western Spiti. Kuling Group, Spíti, India r89

The Chumik Formation (40 m overall) consists of 6c Raj, 1990; Fuchs & Linner, 1995) unconformably on- grey-brown siltstones and phosphatic hybrid arenires Iap the Upper Precambrian-Cambrian Phe Fm. (Vannay, with chonetid brachiopods Qower lithozone of Member 1993, p. 55). We have no personal experience with this A; about 20 m), followed by grey-green sandstones (mid- area; the following considerations srem from study of dle lithozone; 8 m) and next by burrowed siltstones (zp- samples and stratigraphic information kindly provided per lithozone; 10 m). Dark green, glaucony- and pho- by J.-C.Vannay. sphate-bearing arkoses rich in the cold-water scyphozo- The Rape Member begins with lenticular (up to a an Paraconwlaria sp. also occur (Fig. 12B). few m-thick) and subangular pebble conglomerares con- The cold Gondwanian fauna reported from the taining abundant quartzarenitic and dolomitic rock frag- base of the Kuiing Group by Srikantia et al. (1928) pro- ments (maximum clast size 15 cm; Fig. 12A); rare tour- bably comes instead from the underlying diamictites maline-bearing NCI grains occur. Next, some metres of (see Rao et al.,1982). interbedded quartzose sandstones and impure dolostones pass rapidly upward to an about 10 m-thick interval of The Chumik Fm. includes fine-grained burrowed quartzose strongly recrystallized sandstones containing abundant cherty to phyllosilicate peloids and hybrid dolomitic limestones yiel- pseudomatrix (up to 37o/o of framework; V 338) and hybrid arkoses (Q ding brachiopod valves and echinoderm plates. The up- 60 F 39 L 1; L 78) yielding microlitic volcanic rock fragments, conula- per half of the unit (about 22 m), consisring of calca- rids and echinoderm remains 18"/"). OfCI reous siltstones and black shales with spiriferid remains, The Panjal Trap basalts are absent in the Baralacha is directly followed by Triassic cephalopod-bearing car- La area, but are 20 to 30 m-thick in the Chandra Valley bonates; it can be thus correlated with the Gungri For- to the east (above Likhim Yongma: Vannay, 1993, fíg. mation. 44;Yannay & Spring, 1993). A similar section is described from the Mt. Mul- The Gechang Formation (25 m overall) consists of kila Syncline (about half-way between Tandi and Barala- cross-laminated quartzose sandstones (15 m), followed by cha La), where Late Permian? sediments unconformably hybrid arenites (about 10 m) rich in brachiopods of Ear- overlie the Ordovician Thaple Fm. (Vannay, 1993). ly Djulfian age (Tintoriella ra1ah, "Lamnirnargus" hima- layensi), becoming more calcareous, intensely burrowed and rich in phosphate nodules in the upper half ("upper Sedimentary evolution during opening of Neo-Tethys arenaceous iimestone" of Joshi 6t Arora, 7976;lithozone b of Gaetani et al., 1990a). The unit is time-equivalent with the middle-upper part of the Gechang Fm. in Spiti The break-up unconformity. (i.e., middle sandstone, upper bracbiopod-rich beds, topmost The base of the Kuling Group is invariably mar- ferruginous arenite). ked by a m jor unconformity (Hayden, 1904; Fuchs, The base of the Gechang Fm. includes medium-grained and 1982), which is overlain by Upper Sakmarian strata well-soned calcitic (Q quanzarenites 96 F 0 L 4,Y 171 Fig. i2C). from Spiti ftase of the Gechang Fm.) rc Zanskar (Mem- ber A of the Chumik Fm.) and can be traced all along The Gungri Formation consists of burrowed car- the Himalayan Range. bonaceous siltstones Qouter member) gradually passing In the Spiti Valley (Losar, Lingti) ro northern La- upward to burrowed calcareous siltstones and black sha- haul (BaralachaLa area), the unconformity is underlain les with phosphatic nodules deposited on an offshore by lowermost Permian diamictites, and the associated shelf (upper mernber; Kanwar 6c Ahluwalia, 1979; Yan- time-gap is minimum (Fig. 3). In other localities, the naft 1993); overall thickness decreases towards the gap includes large parts the Carboniferous, as in easrern northwest from 40 + 50 m to only 15 m. Zanskar and Pin Valley of Spiti (Fig. 58, 13A). Permian Intercalated at the base of the Gungri Fm. are very fine- to units directly overlie the Devonian Muth Quartzarenite fine-grained subarkoses (Q 82J4 F 1516 L 3!2; B 44, Y 172; Fig. or the Silurian Pin Fm. in the Parahio Valley (Fig. 4, 12D); NCI particles are lacking, but for common graphite grains. De- 13B), the Ordovician Thaple Fm. in the Mt. Mulkila trital modes compare with the feldspar-enriched top of the Puchenpra area and the Upper Precambrian-Cambrian Phe Frn. in Dolpo (ower-central par. oI glauco-pbosporites and. black sbales: Fm. in Q81 F1Z L2; Sciunnach & Garzanti, 1996). the Tandi syncline (Vannay, 1993). The complete Ordo- vician to lowermost Permian succession was eroded also ìn Zanskar west of Phugtal (Srikantia et al., L980; Gae- Tandi and Mulkila Synclines. tani et al., 1986). In the Tandi Syncline (owermost Chandra Val- To the east, the Kuiing Group is reported to un- ley), about 40 m-thick and strongly deformed transgres- conformably overlie the Devonian Muth Quartzarenite sive marine sediments of Permian? age (Rape Member both in Kinnaur (Bassi et al., 1983; Bassi, 1989) and Ku- of the Kukti Fm.; Srikantia & Bhargava, 1979; Prashn maon ft{eim 6c Gansser, 1939; Sinha, 1989). Further to 190 E. Garzanti, L. Angiolini & D. Sciunnacb

Fig. 13 - Basal unconformity (black arrow) in the Pin Valley (Muth; A) and Parahio Valley (Gechang; B), where the Gechang Frn. (GE) is reduced to a few m and unconformably onlaps the earliest Carboniferous Lipak Fm. (I-) or the Devonian Muth Quanzarenites (M) respectively. $lhite arrows indicate the two phosphatic siltstone bands in the lower member of the Gungri Fm. (GLD. the east, the time-equivalent Puchenpra Fm. of Nepal Manang. Thickness becomes much greater only in Sout- unconformably overlies Devonian dolomites in western hern Tibet (up to 570 m) and in the northwestern FIi- Dolpo (Fuchs, 1.977, fig. 22), mid-Carboniferous malaya, where the Panjal Traps are present (reaching quartzarenites in central Dolpo (Garzantr et a1., \992) about 300 m in Zanskar - where the basaltic unit itself and lowermost Permian diamictites in Manang (Colchen is tabular and its thickness increases gradually towards et al., 1986; Garzanti et al., 1994).In west Southern Ti- the northwest - but much more in Kashmir). bet, diamictites are unconformably followed by Iower Moreover, the major mid-Sakmarian unconformi- Permian tholeiites, locally with intervening transgressive ty seals paleofaults in the Parahio Valley (Fig. a; Fuchs, black mudrocks and debris flow deposits (Garzanti et 1.982, p. 344), and is mantled by veneers of transgressive al., in preparation). arenites enriched in Cr-rich chromian spinels from In the central Nepal Lesser Fl.imalaya, the lower- Zanskar to Spiti and Dolpo (Sciunnach & Garzanti, most Permian Sisne diamictites are transgressed by the 1996). Since it marks a major change both in tectonic "Ritung Bioturbated Mudstone" (Sakai, 1991), which is style and magmatic character (Spring et al., 1993; Yan- correlatable with the Kuling Group. Even within several nay &. Spring, 1993; Caironi et a1., 1996), it is interpre- basins in Peninsular India, lowermost Permian continen- ted here as the break-up unconformity. tal diamictites (i.e., Talchir Boulder Beds) are separated Dating of Upper Sakmarian fossiliferous strata from the overlying coal-bearing paralic to marine sedi- transgressing the rift shoulder in Spiti (Fig 2) thus al- ments by the Umaria lJnconformity (Frakes et al., lows us to revise previous interpretations, made when 1.e7s). the Spiti region was still closed to foreigners (Baud et The Visean to Low'er Sakmarian succession below al., 1984; Gaetani et al., 1990a, fíg. 6; Gaetani Ec Gar- the unconformity is absent in several regions (western z nfí, 1991., fig. 7; Stampfli et a1., 1991, fig. 5). Recent Zanskar; Nyimaling; Mulkila and Tandi synclines; Pin studies have shown in fact that Neo-Tethys opened .western and Parahio Valleys; Kinnaur; Kumaon; Dolpo), north of India in the Early Permian (Garzanti et a1., while in others it varies rapidly in thickness from less 1994), notably earlier than previously expected. than 100 m (central Dolpo) or only a few hundred me- The break-up unconformity caps the rift sequen- tres (eastern Zanskar to Baralacha La), to as much as ce, which in many areas (e.g., eastern Zanskar, Dolpo) is 750+1000 m (Losar, Manang) or even 1000+1500 m reduced to bits of Carboniferous units bounded by un- (Southern Tibet). conformities; even where it is most complete (e.g., Lo- The Permian succession above the mid-Sakmarian sar, Manang, Southern Tibet; Garzanti ei 1994, ^I., unconformity (Kuling Group) is instead present every- 1,995b, 1996), the Upper Carboniferous is very poorly where; thickness varies lirtle and gradually, from a mini- represented, suggesting widespread thermal uplift during mum of 40 m (Tandi) to 60+95 m (Baralacha La to Spi the climax of rifting (Vannay, 1993, p.72). ti). Similar thickness (about 50 m, locally up to 100 m) In large parts of the Himalaya, the rift sequence rs is reported from Kinnaur, Kumaon and western Dolpo entirely missing, and the break-up unconformity coinci- (Heim & Gansser, 1.939; Fuchs, 7977;Bassi et al., 1983); des with the post-Tournaisian rift unconformity (Gar- further to the east, the time-equivalent Puchenpra Fm. zanti Er Sciunnach, 1996; Sciunnach & Garzanti, 1996). varies from 745+170 m in central Dolpo to 60+1.25 m in At several places (i.e., 'western Zanskar, Tandi, Parahio Kuling Group, Spiti, India 191

SUBSTRATE OF THE KULING GROUP SPITI Gechang Fm. N (BC & LFA) A ZANSKAR li Chumik Fm. 0 25km TANDI Rape Mb.

to?^- 0.5 ""1 " e o0.5 %

LEGEND A f l G.nr."hidam Fm. (Assetian) fiI,rlfrl po group lvisean- Moscovia nl

ÉÈEEH Lipak Fm. lTournaisianl SPITI F Thaple, Pin & Muth Fms. Gechang Fm. lOrdovician to (UBB & TFAI Karsha & Kurgiakh Fms fmPhe, ZANSKAR Gechang Fm. LEGEND B to E TANDI Sandstone --ga.- l.'.1 Rape Mb. t== fol L_- Black mudrock Conglomerate È loo C a;1 t"J Hybrid arenite Basalt lr) ]-,.1 tack of sediments s lo9 of crystalline rocks 5 thickness in m

Fig. 14 - Facies and thickness maps for the Kuling Group in the studied Spitilahaul-Zanskar area. Acronyms as in Fig. 3.

Valley), even pre-rift units of Precambrian to earliest northern India lay at middle-high southern latitudes Carboniferous age were uplifted, exhumed and deeply (Scotese 8c Mc Kerrow, 1990). eroded during rifting (Fig, 1aA). At this stage, the Panjal Trap basaltic lavas and similar subalkalic tholeiites fed by MORB-type magmas were emplaced all along the Tethys Himalaya (Fig. 14C; Paleogeographic scenario. Garzanti et al., in preparation), suggesting increasing The Gondwanian glaciation came to an end in the amounts of partial melting of the rising astenosphere mid-Sakmarian, when melting of continental ice indu- during initial opening of Neo-Tethys (Coffin & El- ced rapid sealevel rise and widespread marine transgres- dholm, 1992; Vhíte, 1.992). sion onto the newly-formed Himalayan and Karakorum In mid-Permian times, when the crust remained margins of Neo-Tethys (Gaetani et a1., I990a, 1995; Fig. hot and subsidence was negligible (pelagic sediments 148). were deposited only in eastern Manang; Garzanti et al., As indicated by cool-water faunas contained in 1994), sedimentation occurred in high-energy nearshore condensed sediments at the base of the drift sequence, environments, with veneers of NCI-rich hybrid arenites cold-temperate climates persisted until the end of the documenting starvation during peak transgressive stages Early Permian at least (Garzanti et al., 1994), when (Fig. 1aD). From the Zanskar-Spiti Synclinorium to 192 E. Garzanti, L. Angiolini & D. Sciunnach

central Nepal, deepening took place mosrly ar Djuifian pelagic limestones of the Triassic Tamba-Kurkur Fm. times, when the widespread black shales of the Gungri (early highstand tract). All along the Tethys Himalaya Fm. eventually sealed the topography created by rift tec- maximum water depth was reached in the Olenekian tonism and associated magmatism (Fig. 1aE). (Garzanti et al., 1995a; 1995c). Brachiopod faunas indicate rapid warming at the Interpreting the gap ar the Permian,/Triassic close of the Paleozoic, when climates turned to semiarid boundary as associated with long-term maximum floo- (Dutta & Suttner, 1986; Sciunnach &. Gananti, 1996) as ding is clearly at odds with the commonly held views the Tethys Himalaya was being rapidly displaced that it marks instead a major eustaric fall all over rhe northward towards the Southern Tropic (Scotese & world (e.g., Duval et aI., 1992) and in the Himalayas as McKerrow; 1990; Baud et aL, 1.993). well (e.g. Bhatt et al., 1980; Atudorei et al., 1995). How- ever, not only in Spiti (Fig. 2, 3, 4,5) but also in Nepal and Tibet (Garzanti et a1., 1992, 1994, 1995b), the Stratigraphic model. Sakmarian to Induan succession unquestionably docu- Passive margin sedimentary successions consist of ments a second-order transgressive trend, interrupted nested sets of aggrading, backstepping and forestepping only by third-order downward shifts of coastal onlap sequences at various scales, controlled by the interplay (Garzanti 6c Sciunnach , 1996). of eustasy and tectonism (Hubbard et al., 1985; Boote & This shows once more that regional subsidence Kirk, 1989; Bosellini, 1989; Gaetani &, Garzanrí, 1997; patterns have to be carefully investigated before almi- Mitchum & Van \fagoner, 1991; Premoli Silva et al., ghty sea-level is invoked: eustasy may well be just a 1992; Garzanfí, 1993). higher-frequency modulation of the long-term rectonic The Kuling Group, as the correlative Puchenpra signal! Fm. of Nepal, is made by a stack of third-order depositional sequences, which are easier to distinguish in the thicker successions of central Dolpo and Southern Tibet Geodynamic model. (Garzanti et al., 1995b; Sciunnach k Garzanri, 1996).In The Permian sedimentary evolution of the Hima- Spiti, due to much lower subsidence rates, they are redu- layan margin of Neo-Tethys facing Karakorum (Gaetani ced to a series of transgressive horizons, which only sel- et al., 1990b; Gaetani k Garzanti, 1991) can be inter- dom can be resolved with paleontologic or petrographic preted according to models of asymmetric rifting domi- tools. The Zanskar succession is thicker, but complica- nated by simple shear (e.g., \Wernicke, 1985). In this fra- ted by processes related to the emplacemenr of the Pan- mework, the northwestern Flimalaya represents an "up- jal Trap basalts, Therefore, recognition of third-order per plate margin", characterized by intense volcanism "Vail-type" depositional sequences and systems tracts in and slow gradual subsidence with absence of block faul- Permian the of the northwestern Himalaya is by no ting (Stampfli et aI., t991). means straightforward, and will not be attempted here. Time elapsed from the beginning of rifting to If the stratigraphic model of Van Wagoner et al. oceanisation was however as long as 80 Ma (i.e., one (1988) can be applied at the scale of second-order se- order of magnitude more than observed in the North quences, the lower part of the Upper Sakmarian/lower- Atlantic; e.g., Eldholm et al., 1987). This may be ascri- most Norian supersequence (Gaetani &. Garzantt, 1991; bed to a complex tectonic evolution, occurring at slow Garzanti er al., 1995a) may be subdivided into second- strain rates and possibly fostered by a Late Paleozoic order systems tracts punctuated by major flooding surfa- "superplume" event (Larson, 199!; Garzanti, 1993). ces, The break-up unconformity, separating the rift se- Rift stage (from transtension to shoulder uplift). quence from the drift sequence, is overlain by transgressive hybrid arenites gradually thickening oceanward and The first stages of intense extensional activity, asso- deposited during long-term relative sealevel rise (Ge- ciated with sporadic mafic magmatism, dare from the chang Fm. in Spiti; Chumik and Gechang Fms., with close of the Tournaisian (Garzanti, 1986b, pp. 69-70; the intervening Panjal Trap basalts, in Zanskar). These Vannalr, 1993; Garzanti & Sciunnach, 1996), even rhough aggrading ("keep-up') Upper Sakmarian to lowermost transtensional (l) movements might have begun as eady Djulfian units (owstand tract) are followed by the back- as the Lare Devonian (Garzanti et al., 1992, 1996). stepping ("give-up') black shales of the Djuifian Gungri The major thermal uplift event, associated with ii- Fm. (transgressive tract) (Fig. 3, 4, 5). mited but widespread production of alkalic magmas with In this framework and at this scale, final drow- bimodal basaltic,/granitic composition (Spring er al., ning of the Indian shelf occurred at the end of the Per- 1993;Yannay & Spring, 1993; Caironi et al., 1996), took mian, followed from Zanskar to Southern Tibet by the place in the Late Carboniferous to earliest Permian. Kuling Group, Spiti, India 193

The shoulder of the rift was located in the south- Sakmarian to Midian/Early Djulfian age (Gechang ernmost part of the study area, as documented by the Fm.), overlain by shelfal black shales of Djulfian age deeply-eroded Paleozoic successions of Parahio Valley (Gungri Fm.). and Lahaul (Vannay, 1.993, fig. 23, 24) but also of we- The Kuling Group is capped by the Gungri shales stern Zanskar, Kinnaur, Kumaon and Dolpo. These gla- also in Zanskar, where the underlying succession is thic- ciated reliefs extended roughly parallel to the future ker and includes subalkalic MORB-type tholeiites (Pan- Tethyan margin, and separated the rift basins of the jal Traps), sandwiched between condensed transgressive Tethys Himalaya to the north, from the rim basins of arenites of Late Sakmarian (Chumik Fm.) and Mi- the Lesser Himalaya (e.g., Chamba and Kashmir basins; dian/Early Djulfian age (Gechang Fm.). Jain et al., 1980; Bhat, 1.982; Guntli, 1.993) and northern The Kuling Group was deposited at the end of Pakistan (e.g., Salt Range, Potwar and Peshawar basins; the Gondwanian glaciation, and recorded progressively Stampfli et aL, 1.991.; Pogue et aI., 1992; \flardlaw & Po- warming climates from cold periglacial to temperate- gue, 1.994) to the south. cool in the Early Permian, and finally to tropical-arid at This model explains why Paleozoic strata are l^r- the end of the Late Permian. gely missing in the Lesser Flimalaya (Gansser, 1964; All along the Spiti-Zanskar Synclinorium, the Ge- Brookfield, 1993), and rectifies the old idea of a ridge chang Fm. onlapped and the Gungri Fm. eventually bu- rising in the course of the Paleozoic to separate Lesser ried rift-related reliefs during a long-term relative seale- Himalayan basins to the south from Tethyan basins in vel rise, documenting onset of thermal subsidence of the north (e.g., Fuchs, '1,976; Srikantia & Bhargava, the newly-formed Neo-Tethyan margin. 1979; Jain et al., 1980). It also accounts, in a radically The major pre-Upper Sakmarian unconformity, different geodynamic framework, for extensive Late Pa- which seals paleofaults and marks the end of continen- Ieozoíc uplift in the Himalayas, ascribed instead by seve- tal rifting and associated aikalic magmatism, is thus in- ral authors to an "Flercynian" orogenic event (e.g., terpreted as the break-up unconformity, followed by ini- Kanwar & Bhandarí, 1976; Srikantia, 1981; Fuchs, tial opening of the Neo-Tethys Ocean. 1,e82).

Drift stage (from oceanisation to thermal subsidence). The rift stage ended in the mid-Sakmarian, when major transgression also marked the end of the Gond- wanian glaciation. Sea-level rise is thus seemingly largely glacio-eustatic in nature, even though we cannot exclude that opening of a rifted seaway could have been at least in part responsible the climatic amelioration which for Achnoaledgments. brought about the end of giaciation. Maurizio Gaetani, Jean-Claude Vannay, Gianmarco Lucchini, Nearby tholeiitic magmatism heated the Indian Laurent Spring and Andrea Zelioli kindly provided many samples, crust, and subsidence in Spiti remained negligible for various personal material and precious unpublished stratigraphical information on Zanskar and Lahaul. Alda some 25 Ma (Late Sakmarian to Midian; "juvenile ocean Nicora and Fabrizio Berra gave fundamental help measuring sections and collecting samples in stage" Von 1,992). of Rad & Bralower, Shortly after the field. lle heanily thank Sumio Sakagami (Tokyo) and Daniel break-up, subsidence was faster only in areas burdened Vachard (Lille) for determination of Permian bryozoa and by thick piles of lava or close to magmatic centres (e.g., foraminifera respectively. Views on the Pin Valley ourcrops were exchanged with Trilochan Singh (Dehra Dun), eastern Manang, 's/est Southern Tibet). who also kindly provided copy of p.rpers in preprrlrion. Rapid thermal subsidence began everywhere in Thanks also to Giovanni Chiodi, Curzio Malinverno, Magda the Himalayas at Midian/Early Djulfian times (Gaetani Minoli and Agostino Rizzi for carefully-made photographs, thin & Garzanri, 799I, fig. 14; Vannay, 1993, fig. 25,26) and sectìons, drawings and SEM-EDS analyses of chromian spinels. The manuscript has benefitted from the valuable advice of Maurizìo after less than 10 Ma the newly-formed passive margin Gàetani and careful reviews by Dr. T.N. Bagati, Aymon Baud and was buried beneath pelagic sediments ("mature ocean Jean-Claude Vannay. stage'). EG is responsible for field work, stratigraphic framework and paleogeographic interpretation; LA studied brachiopod associations; DS quantitatively,---/ analysed sandstone mineralogy. The expedition, Conclusions panly supponed by Ev-K'-CNR, was carried to full success by our guide Rahoul, driver Balwinder Singh and Dawa sherpa. Printing expenses panly covered by Progetto Coordinato CNR "Ritmi ed The Kuling Group in Spiti consists of transgressi- Eventi in Biostratigrafia" (Coord. Prof. A. Farinacci) - Sottoprogetto ve basal conslomerates and NCI-rich arenites of Late "Microfossili ed Eventi Paleozoici" (Resp. Sc. Prof. M. Tongiorgi). 1,94 E. Garzanti, L. Anpiolini & D. Sciunnach

APPENDIX

Systematic descriptions Order Athyri dida Dagys, 197 4 L. Angiolini Suborder Athyrididina Boucot, Johnson & Staton, 1964 Superfamily A t h y r i d a c e a Mc Coy, L844 Family A t h y r i d i d a e McCoy, 1.844 Productida Sarycheva L959 Order & Sokolskaya, Genus Cleiothyridina Buckman, 1906

Suborder Productidina \laagen, 1883 Type-species : Atryp a p e c t in ifera S owerby, 1 8 40 Superfamily P r o d u c t a c e a Gray, 7840

Family Marginif eridae Stehli, 1954 Cleiothyridina gerardi (Diener, 1899) Genus Lamnimargus'Waterhouse, 1975 PI. 1, fig. 3,4

Type-species : Ret im argin ife r a p e rfo rat a S7ate rhouse, 1 970 1899 Atlryris gerardiDiener, p. 56, pl. 6, fig. 12-14. 19A3 Atlryris gerardi - Diener, p. 110, pl. 5, fig. 10, 11. "Lamnimargus" himalayensis (Diener, 1899) 1985 Himailryris gerardi - S7aterhouse, pp. 70 72.

PL 1., Íig. 1.,2 Material and locality. 13 ventral valves (MPUM 79A8, 7909) and 3 dorsal valves (lr4PUM 7907,791,0) from the Gechang Fm. (up- 1899 Marginifera bimalayensis Diener, p. 39, pI. 2, Íig. l-7; pl. 6, fig. per brachiopod-rich bed$ at Muth (sample HS.156). t,2. 19a3 Marginifera hirnalayensis - Diener, p. 104, pl. 5, fig.5,6,27. Comments. The available specimens clearly belong 1975 Marginifera hinalayensis - Diener, p.79, pl.8, fig, 9. to Cleiotbyridina gerardl (Diener) by the large dimen- 1941 Marginifera himalayensis - Muir-rVood 6c Oakley, p. 19, pl. 1, fig. 1-3. sions and the flat ventral valve with a poorly defined 1975 Larnnimargas bimalayensis - rVaterhouse, p. 10. sulcus. The species gerdrdi has been recorded as Hima- L978 - Lamnimargus himalayensìs ìlaterhouse, p. 31, pl. 2, ftg. U,-1,5. tlryris gerardl by \X/aterhouse (1985) from the Testha 7979 Lamnimargus birnalayensis - Gupta & lVaterhouse, pp. 8, 15, pl. Sandstone Member r, rrg. J-òi pl. J, llg. b. of the Gungri Fm. (: Kuling Fm.) 1985 Lamnimargus himalayensis - $Taterhouse, pp.7A-72. in South Zanskar. According ro Branson (1948) and to 1990 a Larnnirnargus himalayensis - Gaetani et al., p, 156. Grunt (1986) the species gerardi is here included in the genus Cleiotlryridina. Material and locality. 1 complete specimen 04PUM 7906), 3 A large species of Cleiotlryridina, very similar to ventral valves 04PUM 7902,79A3,79A4) and 1 dorsal valve (MPUM C. gerardi, has been described as Cleiotlryridina sp. n. cf.. /905) frorn the Gungri Fn. (lower member) at Muth (sample HS 37). C. gerardi by Thomas (1969) from the Hardman Fm. of Canning Basin. age Comments. We did not observe the two or rhree The of this formation is Midian-Ear- ly Djulfian, according (1969) trails arising from the marginal ridges in both valves, to Thomas and Archbold et al. (1993). which seem to characterize the genus Lamnitnargus described by Waterhouse (7975, p. 10) with rype-species Superfamily S i e Marginifera bimalayensis Diener. Furrhermore, the de- p i r f r a c e a King, 1846 scription and illustrations of Diener do not show the Family Spiriferidae King, 1846 multiple trails described - but never illustrated - by Wa- Subfamily T r i g o n o t r e t i n ae Schuchert, 1893 terhouse (1975, 1978). FIowever, we retain Diener spe- Genus Tiigonotreta Koenig, 1825 cies in the genus Lamnimargus, due to the exiguity of Type-sp ecies : 7i igo n ot re t d st o k e s i Ko enig, 18 25 the material at hand. L. himalayensls characterizes the Late Permian of Trigonotreta cf. Himaiaya, occurring in Nepal (Waterhouse, 1978), Spiti orientensis Singh & Archbold, 1993 Pl. 1, fig. s (Gupta Ec Waterhouse, 1,979), Zanskar (Gaetani et a1., 1990a) and of Kashmir, where it has been found in the Material and locality. One ventral valve (\4PUM 7971) from Zesvan Fm. Mb. B2 Q.{akazawa et a1.,7975). \flaterhouse the Gechang Fm. (basal ferruginous conglomerate) at Muth (sample (1978, 1985) correlates the L. himalayensis zoîe with the HS lss). Kalabagh member and the lower to middle Chhidru Fm. of Salt Range (Gupta & Waterhouse, 1979;'Water- Comments. The transverse venrral valve of the house, 1985), suggesting an Early Djulfian age (Pakista- available specimen of Tiigonotreta is characrerized by niJapanese Research Group, 1985). small and pointed umbo, "V" shaped ventral sulcus, 4 Kuling Group, Spiti, India 195

plications on the lateral flanks and fascicles anteriorly l9l5 Spirifer rajah - Drener, p. 86, pl. 9, Írg.5, 6. 1941 SpirifereLla rajah - Mut-\lood & Oakley, p. 36, pl. 2, frg. 2, 3, consisting of 3-4 costae. 9-tl. The species from Spiti seems to belong to the spe- 1966 Spiriferella rajab - Ylarerhouse, p. 48, pl. 1, fig. 5; pr. J, rlg. z; cies Tiigonotreta orientensls Singh & Archbold, 1993 b. pl. 7, fig. 1, 2, 4; pl. Il, fig. 2; pl. 12, frg. 2. 70, fig. 10 A-), described as early Sterlitamakian (Late 1978 Spiriferella rajah - Ylarcrhouse, pp. 38, 88, 123, p1. 4, fig. l-7; pL 14, fig. 1-13; pl.2a, ftg. 2. Sakmarian) from the Garu Fm. of the Eastern Himalaya 1979 Spìriferella mjah - Gnpt: 6c Vaterhouse, p. 11, pl. 1, fig. 10-14; (Singh & Archbold, 1993). p!.2,[ig. l-10; pI.3. fig. l. 7985 Spiriferella rajab - Varcrhouse, pp.70-72. 799Q Spiriferella rajab - Gaetani et a1., p. 156. Subfamily S p i r i e r e I I i n ae'Waterhouse, 1968 f 1994 Spiriferella rajab - Garzanri et al., p. 171, pl. 1, fig. 5.

Material and locality. 1 complete specimen (MPUM 7974) and Tintoriella gen. n. 2 ventral valves (\4PUM 7912, 7913) from the Gungri Fm. (ower Type-species: Spirifera rajab SÀter, t865 member) at Muth (sample HS 87).

Derivatio nominis. Tintoriella from the name of Dr. Andrea Description. Large, biconvex shell with elongated Tintori. oval outline. Hinge iine rather wide, less than mxximum width which is anteriorly. Cardinal extremities obtuse. Diagnosis. Large, strongly plicate, biconvex Spiri- Anterior commissure uniplicate, with rather high fold. ferellinae. Hinge line rather wide, but iess than maxi- Ventrai valve strongly convex, with high recurved mum width. Ventral umbo recurved; ventral interarea umbo. Interarea high and concave, orizontaily striated high, with open delthyrium. Ornamentation of strong with large open delthyrium. Median sulcus moderately fascicles of 3-6 costae each. Interior of ventral valve with deep, "V" shaped, widening anteriorly and producing in very long dental plates and adminicula and a tubercular a tongue towards the dorsal valve. myogliphe. Dorsal valve less convex than the ventral one. Fa- Discussion. The new genus is characterized by its stigium low, with acute section and with a narrow me- open delthyrium, strongly fasciculate ornamentation dian groove. and very long and high dental piates and adminicula. Ornamentation of ventral valve of six strong pli- Tintoriella gen. n. differs from Spiriferella Tscher- cations forming fascicles of 4-5 rounded costae on each nyschew, 1902 by means of the open delthyrium, longer flank. The plications bounding the sulcus are larger dental plates and adminicula which are not embedded in than the lateral ones. The ventral sulcus is ornamented the apical callus; from Elioina Fredericks, 1924 by by simple ribs, as is the dorsal fastigium. Concentric means of the strongiy fasciculate ornamentation and the growth lamellae are developed anteriorly. parallel dental plates; from Hunzina Angiolini, 1995 by Interior of ventral valve (Pl. 1, fig. 8 to 13) with means of the ornamentation and of the very long dental long, subparallel dental plates and adminicula prolon- plates and adminicula. ging anteriorly up to 7 mm from the umbo. They are apically embedded in the umbonal filling. A tubercular Tintoriella rajah (Salter, 1865) myogliphe is present at about 5-6 mm from the umbo.

Pl. 1, fig. 6 - 13 Muscle field deeply impressed and diamond shaped. Comments. T rajab (Salter) is common in the 1865 Spirfera rajah Safter & Blanford, pp. 59, 11 1. "Lamnimargus" bímalayensis zoîe, but it may occur also 1.866 Spirifer rajab - Davidson, p. 40, pl. 2, fig. 3. higher (\ùTaterhouse, 1928). According to this author 7 1.899 Spiriferrajab -Diener, p.68, pl. 4,{ig. l-7; pI.5, fig. 1. rajah (Salter) ranges from Djulfian to Dorashamian. 1.9A3 Spirifer rajab - Diener, pp. 105, 137, 186, pl. 4, fig. 3-5.

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