(Ostracoda) from the upper Miocene Tambo River Forma

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May 30, 2011 - Miocene Cheltenhamian and younger marine strata of the Bass Strait ... Key words: Ostracoda, Tambo River Formation, late Miocene, ...
Record of the deep marine Clinocythereis australis Ayress and Swanson, 1991 (Ostracoda) from the upper Miocene Tambo River Formation, Gippsland Basin, Australia: Palaeooceanographic and biostratigraphic implications MARK T. WARNE WARNE, M.T., June 2012. Record of the deep marine Clinocythereis australis Ayress and Swanson, 1991 (Ostracoda) from the upper Miocene Tambo River Formation, Gippsland Basin, Australia: Palaeo-oceanographic and biostratigraphic implications. Alcheringa, 151–156. ISSN 0311-5518. Fossils of the deep marine ostracod, Clinocythereis australis Ayress & Swanson, 1991 occur within the Tambo River Formation, Gippsland Basin, southeastern Australia and record an approximately 6 Ma phase of late Miocene coastal ocean upwelling within this region. The presence of deep marine faunal elements within late Miocene Mitchellian strata is in contrast to the absence of such faunal elements in latest Miocene Cheltenhamian and younger marine strata of the Bass Strait hinterland. The absence of deep marine faunal elements in postMitchellian onshore strata is due to the Kosciusko Uplift, which transformed Bass Strait into a wholly shallow seaway placing adjacent coastal regions beyond the reach of ocean upwelling influences. Mark T. Warne [[email protected]], School of Life and Environmental Sciences, Deakin University (Burwood Campus), 221 Burwood Highway, Burwood, Victoria, 3125, Australia. Received 26.3.2011; revised 20.5.2011; accepted 30.5.2011. Key words: Ostracoda, Tambo River Formation, late Miocene, Kosciusko Uplift, Gippsland Basin, upwelling.

THE TAMBO RIVER FORMATION of the Gippsland Basin is an upper Miocene ferruginous, glauconitic marl well exposed in cliffs along the Mitchell and Tambo rivers in the Bairnsdale and Swan Reach districts of southeastern Victoria (Thomas & Baragwanath 1949, Carter 1964). Two broad facies types have been identified. The first is a heavily ferruginized glauconitic marl containing a dominantly pectinid– echinoid–brachiopod–bryozoan macrofauna, and the second a less ferruginized and less glauconitic sand containing a more diverse bivalve and gastropod macrofauna (Hocking et al. 1976, Darragh 1985). A diverse normal marine ostracod fauna has been recorded from the Tambo River Formation (Crespin 1943, McKenzie 1974). In equivalent aged strata to the Tambo River Formation from the subsurface of the nearby Lakes Entrance district, Li & McGowran (1994, 2000) recorded foraminiferal faunas characteristic of upwelling on a narrow late Miocene continental shelf. At Swan Reach (Fig. 1A), an unconformity separates the Tambo River Formation from the overlying fluvial Haunted Hills Gravel (Gallagher & Holdgate 1996). ISSN 0311-5518 (print)/ISSN 1752-0754 (online) Ó 2011 Association of Australasian Palaeontologists http://dx.doi.org/10.1080/03115518.2011.593123

The Tambo River Formation is the last phase of marine deposition that occurred in the Bairnsdale– Lakes Entrance region of the Gippsland Basin prior to the major tectonic movements of the late Cenozoic ‘Kosciusko Uplift’ (Andrews 1910, Hill et al. 1995). The initial phase of this southeast Australian uplift ‘event’ caused the formation of a widespread erosion surface across the northern Bass Strait hinterland, which manifests in the stratigraphic record as a major latest Miocene unconformitiy (Fig. 1B; Bolger 1991, Dickinson et al. 2002). Prior to this tectonic event, Miocene sedimentation within the Bairnsdale—Lakes Entrance region extended from shallow to deep neritic environments in relatively close proximity to offshore bathyal realms (see palaeogeographic maps: fig. 8.26d of Hocking et al. 1976 and fig. 12 of Bernecker et al. 1997). After this tectonic event, Pliocene sedimentation within the Bairnsdale—Lakes Entrance region occurred in fluvial and shallow neritic environments, the latter being relatively distant from offshore bathyal realms (see palaeogeograhpic map: fig. 13 of Bernecker et al. 1997).

Materials Around 1990, the late Dr Ken McKenzie passed on to me a slide of ostracod specimens he collected from

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the type section of the Tambo River Formation near Swan Reach in Gippsland, eastern Victoria (Fig. 1; Lat. 37.833338S, Long. 147.86678E). The stratigraphy and palaeontology of the type section have been discussed by Dennant & Clarke (1898), Boutakoff (1955), Wilkins (1963), Carter (1964), Hocking et al. (1976) and Gallagher & Holdgate (1996). Ferruginized and glauconitic marl is the predominant facies type of the Tambo River Formation exposed at Swan Reach (Gallagher & Holdgate 1996). The exact stratigraphic horizon at the type location from which McKenzie collected his ostracods is not known. The collection includes 183 specimens of individual valves and carapaces plus fragmented specimens. Most

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specimens display a faint, dull, reddish brown iron oxide staining. Illustrated specimens of C. australis (Fig. 2) are housed within the palaeontological collections of Museum Victoria under registration numbers P316467–P316469.

Results Within the collection are 12 specimens (mainly carapaces) of the deep marine ostracod Clinocythereis australis Ayress & Swanson, 1991. Other abundant ostracod taxa within this collection (10 specimens) are Cytheropteron sp. 1, Cytheropteron sp. 2, Kangarina sp. and Callistocythere sp. Other common taxa

Fig. 1. Locality and stratigraphic details. A, Locality map: Swan Reach, Gippsland, Victoria, Australia. B, Upper Cenozoic stratigraphy of the onshore Gippsland Basin. C, Palaeogeographic features of the eastern Bass Strait during the late Cenozoic. Large black arrows indicate migration paths (schematic) for late Miocene upwelling Ostracoda.

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Fig. 2. Clinocythereis australis Ayress & Swanson, 1991. All figs are lateral views; A, carapace, adult female, external LV view, P316467. B, Carapace, adult male, external RV view, P316468. C, LV adult female(?), internal, P316469. D, LV adult female(?), internal enlargement anterior hinge elements, P316469. Scale bar for A, B, C ¼ 100 mm, D ¼ 33.3 mm.

(5 specimens) are Rotundracythere sp., Hemicytherura sp., Semicytherura sp. and Loxoconcha sp. Rarer ostracod faunal elements (55 specimens) are Bradleya sp., Trachyleberis sp., Microcytherura sp. 1, Microcytherura sp. 2, Munseyella punctata Yassini & Jones, 1995, Munseyella (s.l.) sp., Heinia sp., Occulocytheropteron sp., Cletocythereis caudispinosa (Chapman & Crespin, 1928), Neonesidea australis (Chapman, 1914), Ponticocythereis militaris (Brady, 1866), Argilloecia sp., Paijenborchella sp., Uroleberis (s.l.) sp., Cytherella sp. 1, Cytherella sp. 2 (lata group), Xestoleberis sp., Eucytherura sp. and Indeterminate spp. 1–4. Examinations of sediment samples housed in Museum Victoria originally collected from the less glauconitic sand facies of the Tambo River Formation exposed at Rose Hill on the Mitchell River near Bairnsdale (Carter 1964, fig. 5) failed to yield any specimens of Clinocythereis australis, although these samples contain a rich normal shallow marine fossil ostracod fauna (Warne, unpublished data).

Palaeo-oceanographic significance The type unit for Clinocythereis australis is the lower Miocene (Altonian) Rifle Butts Formation at All Day Bay, North Otago on the South Island of New Zealand, and the species has a recorded stratigraphic range of late Eocene to Holocene (Ayress & Swanson 1991). The type unit for C. australis at All Day Bay is

an outer shelf to upper slope sedimentary deposit indicating a deep marine habitat for this species (Fordyce et al. 1985, Beu & Maxwell 1990, Ayress & Swanson 1991). Ayress & Swanson (1991) also recorded the species from Holocene sediments off the coast of Westland, New Zealand, over a depth range of 621 to 769 m, and along New Zealand’s eastern shelf over a depth range of 123 to 1130 m. This species has also been recorded from Neogene and Quaternary deep sea sites in the Tasman Sea (SW Pacific Ocean) extending from 1066 to 1088 m in depth (Ayress & Swanson 1991); from a Pleistocene DSDP site with a modern depth of 4696 m within the Indian Ocean adjacent to the Western Australian continental slope (Ayress & Swanson 1991); from Holocene sediments of the Campbell Plateau (Southern Ocean) between 562 and 630 m (Jellinek & Swanson, 2003); and from Holocene sediments of the Challenger Plateau (Tasman Sea) at 695 m (Jellinek & Swanson 2003). Ayress & Swanson (1991) summarized the modern water depth range for this species as being from 123 to 1130 m, but being rare above 500 m. The record of this species in the Tambo River Formation, therefore, indicates that the fossil fauna of this formation has a deep marine aspect. Molluscan and benthic foraminiferal faunas from the Tambo River Formation have generally been considered to be shallow marine in origin (Carter 1964, Beu & Darragh 2001), although Gallagher &

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Holdgate (1996) proposed a cold outer shelf environment for exposures at Swan Reach on the basis of lithology and various fossil foraminiferal occurrences. The discovery of the deep marine ostracod species Clinocythereis australis in association with fossils of extant shallow marine ostracod species, such as Ponticocythereis militaris (Brady, 1866), indicates a mixing of deep and shallow marine taxa suggesting the influence of intense late Miocene coastal upwelling processes/events. A modern analogue of this type of faunal association occurs in SubAntarctic waters of the southern Magellan Strait (South Atlantic Ocean)—a region also subject to strong upwelling influences (Whatley et al. 1996).

Biostratigraphic implications Foraminiferal evidence of late Miocene coastal upwelling has been recorded from similar aged strata within the nearby Lakes Entrance Oil Shaft by McGowran & Li (1997) and Li & McGowran (1994, 2000). However, these authors indicated that their late Miocene upwelling event (Event 4) apparent within the Lakes Entrance Oil Shaft occurs at approximately 8.5 Ma—prior to the FAD of the planktonic foraminifera Globorotalia conomiozea (see figs 7 & 17 of Li & McGowran, 2000). The planktonic foraminifera fauna within the Tambo River Formation at Swan Reach includes Globorotalia conomiozea (Mallett 1977, Gallagher & Holdgate 1996). One implication that can be drawn from this foraminiferal data, and the upwelling-related occurrence of Clinocythereis australis within the Tambo River Formation at Swan Reach, is that late Miocene sequences of the onshore Gippsland Basin may record two upwelling events—one during the early Mitchellian (ca late Tortonian) and one during the late Mitchellian (ca early Messinian). Significantly, Li & McGowran (1994) discussed planktonic faunal evidence from DSDP Site 214 within the Indian Ocean (presented by Gupta & Srinivasan 1992) of windinduced upwelling for the two periods 8.5–7.2 Ma and 6–5 Ma. Li & McGowran (1994) suggested that their upwelling Event 4 of the Lakes Entrance Oil Shaft correlates with the earlier of these Indian Ocean upwelling episodes. Li & McGowran further suggested that the 8.5–7.2 Ma event recorded at DSDP site 214 and within the Lakes Entrance Oil Shaft, might be manifestations of a global oceanic event. One might, therefore, also infer that the occurrence of Clinocythereis australis within the Tambo River Formation at Swan Reach correlates with the 6–5 Ma event of Gupta & Srinivasan (1992). Such an interpretation is consistent with the FAD of Globor-

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otalia conomiozea, which was placed at 6.9 Ma by Berggren et al. (1995), and with strontium isotope dates on shell materials from the Tambo River Formation at Swan Reach (ca 5.58 and ca 6.18 Ma) recorded by Wallace et al. (2005). The Tambo River Formation at Swan Reach rests below the major regional late Miocene unconformity (Bolger 1991), which is broadly present across the northern Bass Strait hinterland (coastal plain). At some locations across this region, such as in coastal cliffs at Beaumaris within the Port Phillip district, similarly ferruginized argillaceous marine sediments (Black Rock Sandstone ¼ lower Sandringham Sands) occur immediately above this regional unconformity (Carter 1985). Shell strontium isotope ages for lower beds of the Black Rock Sandstone exposed near the base of the cliffs at Beaumaris were recorded as ca 5.67 Ma by Dickinson et al. (2002) and ca 5.84 Ma by Wallace et al. (2005). Age differentiation between the Tambo River Formation and lower beds of the Black Rock Sandstone exposed at Beaumaris (type section for Cheltenhamian Stage) has historically relied on the stratigraphic position of these formations relative to the regional latest Miocene unconformity surface (e.g. Carter 1985), and on the difference in fossil faunal assemblages (e.g. Darragh 1985). To the later can now be added the presence or absence of deep sea ostracod species. Deep marine taxa are sporadically present within Mitchellian strata such as the Tambo River Formation of the Gippsland Basin, but are absent from onshore Cheltenhamian and younger strata such as the Black Rock Sandstone and Wannaeue Formation of the Port Phillip Basin (for relevant fossil data pertaining to Cheltenhamian and younger strata, see Warne 2005). The presence of deep marine ostracod species within the Tambo River Formation and absence of deep marine ostracod species in younger strata of the Bass Strait hinterland relates to the initial latest Miocene phase of the Kosciusko Uplift. Based on the distribution of ostracod biofacies, Warne et al. (2003) suggested that this tectonic event caused a broad-scale shallowing of the Bass Strait seaway. Palaeogeographic reconstructions by Bernecker et al. (1997) similarly indicate a transition from a relatively narrow continental shelf to a broad continental shelf within the Gippsland Basin during the late Cenozoic. As a consequence, marine sedimentation across the northern Bass Strait hinterland prior to latest Miocene uplift (i.e., in the onshore regions of the eastern Otway, Port Phillip and Gippsland basins) occurred in relatively close proximity to the continental shelf-slope break

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and was, therefore, susceptible to the influence of cold oceanic upwelling waters. Accordingly, preuplift (Mitchellian) marine sediments of the region contain fossil evidence for the migration of deep sea taxa into continental shelf realms (Fig. 1C). After latest Miocene uplift, the continental shelfslope break shifted further offshore, and shallow neritic sedimentation across the northern Bass Strait hinterland became distant from upwellinginfluenced shelf-slope break regions (Fig.1). A consequence of the later is that deep sea ostracods are not known from latest Miocene and Pliocene (Cheltenhamian and Kalimnan) marine sediments deposited in onshore regions of southeast Australian sedimentary basins (Warne 2005).

Conclusions The occurrence of the deep sea ostracod Clinocythereis australis within the Tambo River Formation of the Gippsland Basin reflects the influence of late Miocene oceanic upwelling along a narrow continental shelf. The intial latest Miocene phase of the Kosciusko Uplift of southeastern Australia transformed the Bass Strait region into a broad shallow marine seaway shifting the influence of ocean upwelling further seaward and beyond the onshore regions of the Gippsland Basin.

Acknowledgements The late Dr K.G. McKenzie provided ostracod materials from the type section of the Tambo River Formation at Swan Reach, Gippsland. Museum Victoria is thanked for access to sediment samples of the Tambo River Formation exposed at Rose Hill along the Mitchell River, near Bairnsdale, Gippsland. This work was undertaken with support from the Environmental Sustainability Faculty of Science and Technology Research Cluster (FRC) at Deakin University.

References ANDREWS, E.C., 1910. Geographical unity of eastern Australia in the late and post Tertiary time. Journal and Proceedings of the Royal Society of New South Wales 67, 251–350. AYRESS, M.A. & SWANSON, K.M., 1991. New fossil and recent genera and species of cytheracean ostracods (Crustacea) from South Island, New Zealand. New Zealand Natural Sciences 18, 1–18. BERGGREN, W.A., KENT, D.V., SWISHER, C.C. III & AUBRY, M.-P., 1995. A revised Cenozoic geochronology and chronostratigraphy. In Time Scales and Global Stratigraphic Correlations, W.A. BERGGREN, D.V. KENT & J. HARDENBOL, eds, SEPM Special Publication 54, 129–212.

MIOCENE UPWELLING, GIPPSLAND BASIN

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BERNECKER, T., PARTRIDGE, A.D. & WEBB, J.A., 1997. Mid-Tertiary deep-water temperate carbonate deposition, offshore Gippsland Basin, southeastern Australia. In Cool Water Carbonates, N.P. JAMES & J.A.D. CLARKE, eds, SEPM Special Publication 56, 221–235. BEU, A.G. & DARRAGH, T.A., 2001. Revision of southern Australian Cenozoic fossil Pectinidae (Mollusca: Bivalvia). Proceedings of the Royal Society of Victoria 113, 1–205. BEU, A.G. & MAXWELL, P.A., 1990. Cenozoic Mollusca of New Zealand. New Zealand Geological Survey Palaeontological Bulletin 58, 1–518. BOLGER, P.F., 1991. Lithofacies variations as a consequence of Late Cainozoic tectonic and palaeoclimatic events in the onshore Gippsland Basin. In The Cainozoic in Australia: a Re-appraisal of the Evidence, M.A.J. WILLIAMS, P. DE DECKKER & A.P. KERSHAW, eds, Special Publication of the Geological Society of Australia 18, 158–180. BOUTAKOFF, N., 1955. A new approach to the petroleum geology and oil possibilities in Gippsland. Mining and Geological Journal 5(4/5), 39–56. BRADY, G.S., 1866. On new or imperfectly known species of marine Ostracoda. Transactions of the Zoological Society of London 5, 359–393. CARTER, A.N., 1964. Tertiary Foraminifera from Gippsland, Victoria and their stratigraphical significance. Geological Survey of Victoria Memoir 23, 1–154. CARTER, A.N., 1985. A model for depositional sequences in the Late Tertiary of southeastern Australia. Special Publication of the South Australian Department of Mines and Energy 5, 13–27. CHAPMAN, F., 1914. Description of new and rare fossils obtained by deep boring in the Mallee. Part 3. Ostracoda to Fishes. With a complete list found in the borings. Proceedings of the Royal Society of Victoria, New Series 27, 28–71. CHAPMAN, F. & CRESPIN, I., 1928. III.—Description of new and rare species. In CHAPMAN, F., CRESPIN, I. & KEBLE, A., The Sorrento Bore, Mornington Peninsula, with a description of new or little-known fossils. Records of the Geological Survey of Victoria 5(1), 1–195, pl. I–XII. CRESPIN, I., 1943. The stratigraphy of the Tertiary marine rocks in Gippsland, Victoria. Palaeontological Bulletin 4, Department of Supply and Shipping, Commonwealth of Australia, 1–101. DARRAGH, T.A., 1985. Molluscan biogeography and biostratigraphy of the Tertiary of southeastern Australia. Alcheringa 9, 83–116. DENNANT, J. & CLARKE, D., 1898. The Miocene strata of the Gippsland Lakes area. Proceedings of the Royal Society of Victoria 10(2), 129–139. DICKINSON, J.A., WALLACE, M.W., HOLDGATE, G.R., GALLAGHER, S.J. & THOMAS, L., 2002. Origin and timing of the Miocene– Pliocene unconformity in southeast Australia: Journal of Sedimentary Research 72, 288–303. FORDYCE, R.E., HORNIBROOK, N. DE B. & MAXWELL, P.A., 1985. Field Trip Guide to Cenozoic Geology of North Otago and South Canterbury. Geological Society of New Zealand, Miscellaneous Publication 33B, 1–50. GALLAGHER, S. & HOLDGATE, G.R., 1996. Sequence Stratigraphy and Biostratigraphy of the Onshore Gippsland Basin, S.E. Australia. Australasian Sedimentologists Group Field Guide Series No. 11, Geological Society of Australia, Sydney, 70 pp. GUPTA, A.K. & SRINIVASAN, M.S., 1992. Uvigerina proboscidea abundances and paleoceanography of northern Indian Ocean DSDP Site 214 during the Late Neogene. Marine Micropaleontology 19, 355–367. HILL, K.C., HILL, K.A., COOPER, G.A., O’SULLIVAN, A.J., O’SULLIVAN, P.B. & RICHARDSON, M.J., 1995. Inversion around the Bass Basin, SE Australia. In Basin Inversion, J.G. BUCHANAN & P.G. BUCHANAN, eds, Geological Society Special Publication 88, 525–547.

156

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HOCKING, J.B., GLOE, C.S. & THREDFALL, W.F., 1976. Gippsland Basin In Geology of Victoria (1st Edition), J.F. DOUGLAS, & J.A. FERGUSON, eds, Special Publication of the Geological Society of Australia 5, Geological Society of Australia (Victorian Division), Melbourne, 248–273. JELLINEK, T. & SWANSON, K.M., 2003. Report on the taxonomy, biogeography and phylogeny of mostly living benthic Ostracoda (Crustacea) from deep-sea samples (Intermediate Water depths) from the Challenger Plateau (Tasman Sea) and Campbell Plateau (Southern Ocean), New Zealand. Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft 558, 1–329. LI, Q. & MCGOWRAN, B., 1994. Miocene upwelling events: Neritic foraminiferal evidence from southern Australia. Australian Journal of Earth Sciences 41, 593–603. LI, Q. & MCGOWRAN, B., 2000. Miocene foraminifera from Lakes Entrance Oil Shaft, Gippsland, southeastern Australia. Memoirs of the Association of Australasian Palaeontologists 22, 1–142. MALLETT, C.W., 1977. Studies in Victorian Tertiary Foraminifera; Neogene Planktic Faunas. PhD thesis, University of Melbourne, 265 pp. MCGOWRAN, B. & LI, Q., 1997. Miocene climatic oscillation recorded in the Lakes Entrance oil shaft, southern Australia: reappraisal of the planktonic foraminiferal record. Micropaleontology 43, 129–148. MCKENZIE, K.G., 1974. Cenozoic Ostracoda of southeastern Australia with the description of Hanaiceratina new genus. Geoscience and Man 6, 153–182. THOMAS, D.E. & BARAGWANATH, W., 1949. The geology of the brown coals in Victoria. Mining and Geological Journal 3(6), 28–55.

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WALLACE, M.W., DICKINSON, J.A., MOORE, D.H. & SANDIFORD, M., 2005. Late Neogene strandlines of southern Victoria: a unique record of eustasy and tectonics in southeast Australia. Australian Journal of Earth Sciences 52, 277–295. WARNE, M.T., 2005. The global Mio-Pliocene climatic equability and coastal ostracod faunas of Southeast Australia. Palaeogeography, Palaeoclimatology, Palaeoecology 225, 248–265. WARNE, M.T., ARCHBOLD, N., BOCK, P., DARRAGH, T., DETTMANN, M., DOUGLAS, J., GRATSIANOVA, R., GROVER, M., HOLLOWAY, D., HOLMES, F., IRWIN, P., JELL, P., LONG, J., MAWSON, R., PARTRIDGE, A., PICKETT, J., RICH, T., RICHARDSON, J., SIMPSON, A., TALENT, J. & VANDENBERG, A., 2003. Chapter 24: Palaeontology: The biogeohistory of Victoria. In The Geology of Victoria (3rd Edition), B.W. BIRCH, ed., Geological Society of Australia Special Publication 23; Geological Society of Australia (Victorian Division), Melbourne, 605–652. WHATLEY, R.C., STAUNTON, M., KAESLER, R.L., MOGUILEVSKY, A., 1996. The taxonomy of Recent Ostracoda from the southern part of the Strait of Magellan. Revista Espan˜ola de Micropaleontologia 28, 51–76. WILKINS, R.W.T., 1963. Relationships between the Mitchellian, Cheltenhamian and Kalimnan stages in the Australian Tertiary. Proceedings of the Royal Society of Victoria 76, 39– 59. YASSINI, I. & JONES, B.G., 1995. Foraminiferida and Ostracoda from Estuarine and Shelf Environments of Southeastern Coast of Australia. University of Wollongong Press, Wollongong, Australia, 484 pp.