Stratigraphy and palaeoceanography o f a top og ra p h y-co n tro lle d con tou rite d rift system in the Pen Duick area, Southern G ulf o f Cadiz V a ndorpe T h o m a s ', D avid Van R o o ij', H enk De Haas2 and Francisco Javier H e rn a n d e z -M o lin a 3 1 Renard C entre o f M arine G eology, D e p a rtm e n t o f G e o lo g y and Soil Science, G h e n t U n ive rsity, K rijg sla a n 281 S8, B-9000 Gent, B elgium E-mail: T h o m a s.va n d o rp e @ u q e n t.b e 2 D e p a rtm e n t o f M arine G eology, NIOZ Royal N e th e rla n d s In s titu te fo r Sea Research, D e p a rtm e n t o f M arine G eology, PO Box 59, 1790 AB Den Burg, th e N e th e rla n d s 3 D e p a rtm e n t o f Earth Science, Royal H o llo w a y U n iv e rs ity L ondon, Egham, S urrey TW 20 OEX, U nited K in g d o m The n o rth e rn p a rt o f th e G u lf o f C adiz has and s till is re ce ivin g a lo t o f a tte n tio n fro m th e s c ie n tific c o m m u n ity due to (a m o n g s t o th e rs ) th e re ce n t IODP E x p e d itio n 3 3 9 (N o ve m b e r 2 0 1 2 - January 20 1 3 ). On th e c o n tra ry , th e s o u th e rn p a rt o f th e G u lf received fa r less a tte n tio n , a lth o u g h m ud volcanoes, d ia p iric rid g e s and c o ld -w a te r co ra ls are p re se n t in th is re g io n (Van R ensbergen e t al., 2 0 0 5 ; W ie n b e rg e t al., 2 0 0 9 ). The El A rra ic h e m ud vo lca n o fie ld is c h a ra c te riz e d by a co m p re ssive re gim e (op p o se d to th e e x te n sive re g im e in m o s t o f th e G ulf), c re a tin g several rid g e s and a id in g the m ig ra tio n o f h y d ro c a rb o n s to w a rd s th e surface. T h is s tu d y p re se n ts se ism ic and m u ltib e a m evidence fo r th e e x iste n ce o f a c o n to u rite d r ift a t w a te r d e p th s betw een 550 and 6 5 0 m e te rs along th e so u th w e s te rn fla n k s o f th e Pen D u ick e s c a rp m e n t (PDE) and G em ini m ud vo lc a n o (GMV), w ith in th e El A rra ic h e m ud vo lca n o fie ld . From th e o n s e t o f th e Q u a te rn a ry, w hen th e e s c a rp m e n t sta rte d to lift and th e m ud vo lca n o o rig in a te d , c o n to u ritic d e p o s itio n was in itia te d a t th e fo o t o f both to p o g ra p h ie s . In itia lly , fa irly low -speed b o tto m c u rre n ts gave rise to sheeted d r ift d e p o s its , a ffe c te d by th e u p lift o f th e PDE o r e x tru s io n o f m ud fro m th e GMV. From th e M id-P leistocene on w a rd s, separated m o u n d e d d r ift d e p o s its fo rm e d due to in te n s ifie d b o tto m c u rre n ts . The m o u n d e d nature o f th e d e p o s its increases u p w a rd , in d ic a tin g an in cre a sin g b o tto m c u rre n t speed. A re ce n t AAIW in flu e n ce fo r th e d r ift is p ro p o se d based on CTD d a ta and its in flu e n c e d u rin g g la c ia l p e rio d s is also like ly. H ow ever, as th e n o rth e rn e x te n t o f g la cia l AAIW is n o t y e t c o n s tra in e d , g la c ia l n o rth A tla n tic in te rm e d ia te w a te r m ig h t also p lay a role in th e fo rm a tio n o f th e d rift. The in flu e n c e o f the M ed ite rra n e a n O u tflo w W ater (MOW) is n o t obse rve d at p re s e n t and th e changes re co rd e d w ith in th is c o n to u rite d r ift d iffe r fro m th e M O W -dom inated c o n to u rite d e p o s itio n a l syste m in th e n o rth e rn G u lf o f C adiz and th e Le D anois area (Van Rooij e t al., 2 0 1 0 ; B ra cke n rid g e e t al., 2 0 1 3 ). D rift d e p o s its in th e Pen D u ick area o n ly o c c u r as e a rly as th e base o f th e Q u a te rn a ry (co m p a re d to the Early-Pliocene fo r th e n o rth ) and m o u n d e d d r ift d e p o s its o n ly o c c u r fro m th e M id d le -P le isto ce ne o n w a rd s (co m p a re d to th e Early-Pleistocene). A ll o f th e se in d ic a tio n s rule o u t a M O W -influence on th e d r ift system . C o ld -w a te r co ra l m o u n d s have been fo u n d w ith in and on to p o f th e s e d im e n ta ry sequence a t th e fo o t o f th e PDE. T h is im p lie s th a t e n v iro n m e n ta l c o n d itio n s in w h ic h c o ld -w a te r corals th riv e w ere p re s e n t in th e past at th e fo o t o f th e PDE and n o t o n ly on to p . References B rackenridge R.E., F.J. H e rn á n d e z-M o lin a , D.A.V. S tow and E. Llave. 2 0 1 3 . A Pliocene m ixe d c o n to u r ite - tu r b id ity system o ffs h o re th e A lg a rve M argin, G u lf o f C adiz: Seism ic response, m a rg in e v o lu tio n and re s e rv o ir im p lic a tio n s . M arine and P e tro le u m G e o lo g y 4 6 :3 6 -5 0 . Van R ensbergen P., D. D e p re ite r, B. Pannem ans, G. M o e rke rke , D. Van Rooij, B. M arsset, G. A k h m a n o v , V. Blinova, M. Ivanov, M. R achidi, V. M agalhaes, L. P inheiro, M. C unha, J.-P. H enriet. 2 0 0 5 . The El A rra ic h e m ud v o lca n o fie ld at th e M oroccan A tla n tic slope, G u lf o f Cadiz. M arine G e o lo g y 21 9:1 -1 7. Van Rooij D .,J. Iglesias, F.J. H e rn á n d e z -M o lin a , G. Ercilla, M. G o m e z-B a lle ste ro s, D. Casas, E. Llave, A. De H auwere, S. G arcia-G il, J. A co sta , J.-P. H e n rie t. 2 0 1 0 . The Le D anois C o n to u rite D e p o s itio n a l System: In te ra c tio n s betw een th e M e d ite rra n e a n O u tflo w W a te r and th e u p p e r C a n ta b ria n slope (N o rth Iberian m a rg in ). M arine G e o lo g y 2 7 4 :1 -2 0 . W ienbe rg C., d. H ebbeln, H.G. Fink, F. M ienis, B. D orschel, A. V e rtin o , M.L. C o rre a and A. Freiwald. 2 0 0 9 . S cle ra ctin ia n c o ld -w a te r co ra ls in th e G u lf o f C á d iz — First clues a b o u t th e ir s p a tia l and te m p o ra l d is trib u tio n . D eep Sea Research Part I: O c e a n o g ra p h ic Research Papers 5 6 :1 8 7 3 -1 8 9 3 . - 119-