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Late Jurassic–Early Cretaceous palynostratigraphy of the onshore Mandawa Basin, southeastern Tanzania
Review of Palaeobotany and Palynology 258 (2018) 248–255
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Late Jurassic–Early Cretaceous palynostratigraphy of the onshore Mandawa Basin, southeastern Tanzania Morten Smelror a,⁎, Katrine Fossum b, Henning Dypvik b, Wellington Hudson c, Amina Mweneinda c a b c
Geological Survey of Norway, P.O, Box 6315, Sluppen, No, 7491 Trondheim, Norway Department of Geosciences, University of Oslo, P.O. Box 1047, Blindern, 0316 Oslo, Norway Tanzania Petroleum Development Corporation, P.O. Box 2774, Dar Es Salaam, Tanzania
a r t i c l e
i n f o
Article history: Received 22 November 2017 Received in revised form 24 August 2018 Accepted 1 September 2018 Available online 05 September 2018
a b s t r a c t New palynostratigraphic data are presented for Upper Jurassic and Lower Cretaceous formations of the Mandawa Basin, southeastern Tanzania. A Late Jurassic (Kimmeridgian Tithonian) age is confirmed for the Kipatimu Formation, from which the terrestrial sporomorphs allow a rough correlation to the mid Oxfordian Tithonian Classopollis Araucariacites Shanbeipollenits Assemblage Zone. A dinoflagellate cyst assemblage recorded in the Mitole Formation correlates to the Dingodinium jurassicum–Kilwacysta assemblage as described from the Tithonian Trigonia smeei Bed of the Tendaguru Hill, southeast Tanzania. Dinoflagellate cyst assemblages in the upper Nalwehe Formation contain species typical of the Hauterivian Barremian, while the Kihuluhulu Formation contains marine microfloras of Aptian to Albian ages. The palynological records confirm the presence of sediments related to profound marine transgressions and subsequent sea-level high-stands in the Late Jurassic (Kimmeridgian Tihonian) and in the late Early Cretaceous (Aptian Albian). © 2018 Elsevier B.V. All rights reserved.
1. Introduction The Mandawa Basin of Coastal Tanzania is located onshore, about 80 km west of the giant offshore gas discoveries in Lower Cretaceous to Miocene formations (Mbede, 1991) (Fig. 1). The present study is a supplement to the Mandawa Basin Project, a research and educational project organized between the Universities of Oslo and Dar Es Salaam, the Tanzania Petroleum Development Corporation (TPDC) and Statoil (Tanzania) (Dypvik et al., 2015a,b). The main objective of the project is to study the sedimentological and stratigraphical developments of the Mandawa Basin, along with its structural evolution. The present investigation covers palynological analyses of selected samples from a shallow exploration well (Tanzania drilling program, TDP40A; Mweneinda, 2014) and outcrops in the Mandawa Basin (Fig. 1). The main objective was to identify and document terrestrial and marine microfloras applicable for biostratigraphic age determinations of the studied formations, as a means for correlations among the lithostratigraphic and sequence-stratigraphic units defined in the basin. Schrank (2005, 2010) distinguished four informal dinoflagellate cyst assemblage zones and two informal sporomorph assemblage zones through the Upper Jurassic and Lower Cretaceous (i.e. midOxfordian Hauterivian) succession in southern Tanzania. Where ⁎ Corresponding author at: Geological Survey of Norway, P.O, Box 6315, Sluppen, No, 7491 Trondheim, Norway. E-mail address: [email protected] (M. Smelror).
https://doi.org/10.1016/j.revpalbo.2018.09.001 0034-6667/© 2018 Elsevier B.V. All rights reserved.
possible, the palynological records in the present study are correlated to these zones. Further, the present palynostratigraphic record from well TDP40A is correlated to the foraminiferal assemblages described from this drillhole by Mweneinda (2014). Possible correlations to contemporaneous palynomorph assemblages recovered in the Rovuma Basin (Ruvuma in Tanzania), Northern Mozambique, are also discussed. 2. Sedimentary succession and lithostratigraphy The sedimentary succession of the Mandawa Basin spans Triassic to Neogene formations (Figs. 1, 2) dominated by shallow marine shelf to coastal deposits of evaporitic, siliciclastic and carbonate facies. The sandstones of the Mandawa Basin include fluviatile, tidal and shallow marine formations as well as possible turbiditic beds in younger units. In times and regions with confined clastic input, carbonates were deposited, often with oolitic composition. The basin evolution was mainly controlled by tectonic events related to the breakup of the Gondwana Supercontinent, the opening of the Indian Ocean, and the subsequent development of the East African rift system (Kent et al., 1971; Kent, 1972; Kapilima, 2003; Said et al., 2015). In southern coastal Tanzania, the crystalline basement is overlaid by continental Permo-Carboniferous to Lower Jurassic Karoo deposits (Fig. 2). In the Ruvuma and Mandawa basins, the succession is intercalated with restricted marine deposits, including some marl and evaporites. During the Middle Jurassic shallow marine depositional conditions were established in the basins (Hudson, 2011).
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Fig. 1. Geological map of the Mandawa Basin in southern Tanzania and Rovuma Basin in northern Mosambique, with enlarged map showing the locations of samples and drillhole TDP40A included in the present study.
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The marine transgression continued into Late Jurassic times. During the Oxfordian to Berriasian a series of marine calcareous and sandy sediments (Tendaguru and Mitole formations) were deposited in the southwestern area and the central part of the Mandawa Basin, while fluvial to fluvio-deltaic sediments assigned to the Kipatimu Formation accumulated to the north (Hudson, 2011; Fig. 2). During the Early Cretaceous a regressive phase shed continental sands and fine clastic sediments from the west into the basin, leading to the deposition of the Hauterivian-Barremian Nalwehe Formation and the Aptian-Albian Makonde Formation. To the east marine, calcareous sediments of the Kiturika Formation were deposited, and further eastwards into the more distal part, the basin was filled with shoreface to offshore fine-grained sandstones, siltstones and mudstones of the Kihuluhulu Formation (Hudson, 2011). The Lower Cretaceous succession is capped by an unconformity spanning the Turonian-Conacian time interval. Continued subsidence and a new transgressive phase led to a relative deepening of the ocean in the eastern part of the Mandawa Basin during the Santonian, with deposition of dominantly calcareous sediments throughout the Late Cretaceous and Early Tertiary (Kapilima, 2003; Hudson, 2011). Comparable depositional regimes occurred in the Rovuma Basin in northern Mozambique, where comparable sedimentary sequences were deposited during the Late Jurassic and Cretaceous. The lithostratigraphic framework of the Upper Triassic to Lower Cretaceous of the Mandawa Basin, and correlations between the Mesozoic successions in the Mandawa Basin in Tanzania and the Rovuma Basin in northern Mozambique is presented in Fig. 2. 3. Material and methods The study includes detailed palynological analyses of 22 samples used in the present study (locations on Fig. 1); including 8 samples from the Kipatimu Formation, 2 samples from the Mitole Formation, 3 samples from the Nalwehe Formation, 2 samples from the Makonde Formation, 1 sample from Tendaguru Formation, 6 samples from the Kihuluhulu Formation, and 2 samples tentatively assigned to Mitole Formation. Five of the samples from the Kihuluhulu Formation were collected in exploration well TDP40A, while the rest of the analyzed samples represent various outcrops in the Mandawa Basin (Fig. 1). The samples were processed using standard palynological techniques (Barss and Williams, 1973) at Department of Geosciences, University of Oslo. The palynological slides are housed at the Geological Survey of Norway (NGU). Dinoflagellate cyst systematics follows the recommendations presented by Williams et al. (2017). For pollen and spores the nomenclature is according to the names of species and taxa referred to by Srivastava (1987), Srivastava and Msaky (1999) and Schrank (2010). 4. Palynostratigraphy
Fig. 2. Lithostratigraphic framework of the Upper Triassic to Lower Cretaceous of the Mandawa Basin, with correlations to the Mesozoic successions in Rovuma Basin in northern Mozambique.
Palynostratigraphic information on the Mesozoic succession of the Mandawa Basin and adjacent areas in southern Tanzania has been published by Jarzen (1981), Balduzzi et al. (1992), Srivastava (1994), Msaky (1995, 2007), Schrank (1999, 2005, 2010) and Srivastava and Msaky (1999). In general, the abundance and diversity of palynomorphs vary greatly through the Mesozoic formations. Balduzzi et al. (1992) found that the terrestrial Lower Jurassic Ngerengere Beds are generally poor, yielding only few terrestrial palynomorphs, mostly of limited stratigraphic value. Schrank (1999, 2005) recognized that out of more than 100 analyzed samples from the Tendaguru Beds, only nine samples contained spore-pollen and dinoflagellate cyst assemblages. Similar observations were made further south in the Rovuma Basin in northern Mozambique, where the terrestrial deposits of the Rio Mecole
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Formation yielded very poor assemblages of palynomorphs (Smelror et al., 2008). However, more specific palynological sampling may provide better recoveries, as documented by Schrank (2010). In the present material, the fluvial and fluvio-deltatic sediments of the Kipatimu Formation and the Tendaguru Formation yielded only a few pollen and spores, together with some freshwater algae (Appendix A). Further, the shallow marine (subtidal) sample from the Mitole Formation contained only a few palynomorphs, of which none are of specific value for any detailed age-determinations. However, the marine microfloras found in the deeper marine part of the Mitole Formation offer good means for correlation to the Tithonian Berriasian. The two samples from the Makonde Formation were almost completely barren, yielding only a few specimens of pollen. The nonmarine sample from the sandstone member of the Nalwehe Formation yielded only one specimen of Cyathidites minor, while the sample from the limestone in the same formation contained a somewhat richer assemblage of pollen and spores, along with the marine algae Tasmanites sp. Sample TDP40A-20/2 from the Nalwehe Formation yielded a relatively rich assemblage of dinoflagellate cysts, with foraminifera linings and scolecodonts also present. The marine Kihuluhulu Formation contains moderately rich and diverse assemblages of both terrestrial and marine palynomorphs. These provide good means for the stratigraphic correlations as discussed further. A list of palynomorphs from the Upper Jurassic and Lower Cretaceous of the Mandawa Basin, sample-by-sample within formations is shown in Appendix A. Selected terrestrial palynomorphs and marine
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microplankton taxa recovered in the studied formations are illustrated in Plate I. 4.1. Kipatimu formation The eight samples from the Kipatimu Formation contained a few pollen and spores, together with some fungal remains and rare freshwater (Ovoidites sp.) and marine algae (Tasmanites). The presence of Cyathidites minor in samples K25/5-5-14 and WP92-3-14 points towards a Middle Jurassic or younger Mesozoic age. Araucariacites australis found in several samples from the Kipatimu Formation has a very long stratigraphic range from the Early Jurassic (Sinemurian) to the Miocene. The presence of Contignisporites cooksonii WP92-8-14 limit the age of this sample from Middle Jurassic to Albian (Srivastava, 1987). A presence of cf. Chasmatosporites cf. hians in sample WP92-8-14 may indicate reworking from older Jurassic or Rhaetian strata, as this pteridophytic monolete spore appears to be restricted to the Rhaeto-Jurassic (Srivastava, 1987). The single record of the prasinophycean algae Tasmanites sp. in sample WP92-8-14 may indicate a somewhat restricted circulation marine depositional environment. The present palynostratigraphic records from the Kipatimu Formation are not well-constrained, but the regular occurrence of Araucariacites australis and the common Classopollis spp. in sample WP92-8-14 allow a rough correlation to the mid- Oxfordian Tithonian Classopollis Araucariacites Shanbeipollenits Assemblage Zones as defined by Schrank (2010) in southeast Tanzania.
Plate I.. Marine and terrestrial palynomorphs from the Mandawa Basin. Sample number and England Finder coordinates (in brackets) are given for the illustrated species. 1. Cribroperidinium sp., TDP40A-26/1 (W43/0), 2. Florentinia sp., TDP40A-20/2 (O34/2), 3. Callaiosphaeridum asymmetricum, TDP40A-20/2 (R42/1), 4. Indet., TDP40A-11/3 (029/2), 5. Systematophora sp., TDP40A-20/2 (N40/1), 6. Kaiwaradinium scrutillinum, TDP40A-32/2 (T42/2), 7. Classopollis sp., TDP40A-11/3 (U41/0), 8. Ephedripites jansonii, TDP40–6/2 (S44/0), 9. Canningopsis sp., WP232 (S53/O).
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4.2. Mitole formation Sample NG1-3-13 from subtidal siltstone yielded only one single grain of Araucariacites australis. This species has a very long stratigraphic range from the Early Jurassic (Sinemurian) to the Miocene. In contrast, sample WP232-5-14 consisting of marine siltstone with reworked oolites, yielded a moderately rich and diverse assemblage of terrestrial and marine palynomorphs. Pollen and spores include Araucariacites autralis, Baculatisporites comaumensis, Callialasporites dampieri, Classopollis spp. and Perinopollenites elatoides. The gymnosperm pollen Callialasporites dampieri has a worldwide Middle Jurassic (Bajocian) to Early Cretaceous occurrence (Srivastava, 1987). In his study of the Upper Jurassic Lower Cretaceous Tendaguru Beds in southeastern Tanzania, Schrank (2005) found that all productive samples are dominated by pollen grains from conifers, mainly Classopollis, and to a lesser degree Araucariacites. The marine microflora in WP232-5-14 include Canningopsis sp., common Cribroperidinium spp., Circulodinium distinctum, Dingodinium jurassicum, Scriniodinium cf. inritibile and Systematophora areolata. This dinoflagellate cyst assemblage bears similarities to the Dingodinium jurassicum–Kilwacysta assemblage as described from the Tithonian Trigonia smeei Bed of the Tendaguru Hill in southeast Tanzania by Schrank (2005). Comparable Tithonian dinoflagellate cyst assemblages to the one found in WP232-5-14 are recorded in the lower Pemba Formation in the northern Mozambique Rovuma Basin (Smelror et al., 2008). The two lowermost samples from well TDP40A are here tentatively assigned to the Mitole Formation. Sample TDP40A-32/2 contains a fairly diverse assemblage of dinoflagellate cysts, including Canningia reticulata, Circulodinium distinctum, Kaiwaradinium scrutillinum, Surculosphaeridium sp. and Systematophora spp.. The presence of Systematophora areolata suggests a general Late Jurassic age (Riding & Thomas, 1992), while the recovery of common Canningia reticulata indicates an Early Cretaceous age (Helby et al., 1987). Kaiwaradinium scrutillinum was originally described from the Early Valanginian in the Perth Basin, Western Australia (Backhouse, 1987), but the total stratigraphic range of this species is poorly documented. The presence of Kilwacysta sp. and common Systematophora spp. may suggest a correlation to the Tithonian Dingodinium jurassicum Kilwacysta Assemblage Zone of Schrank (2005). Sample TDP40A-26/1, which is tentatively assigned to the Motole Formation, contains common Classopollis spp. and Cicatricosisporites spp. These findings suggest a rough correlation to the Late Valanginian Hauterivian Classopollis Cicatricosisporites Ruffordiaspora Assemblage Zone as defined by Schrank 2010). However, both taxa have a rather wide stratigraphic range within the latest Jurassic and Early Cretaceous. Sample TDP40A-26/1 also contains Circulodinium disctintum and common Cribroperidinium spp., including Cribroperidinium cf. edwardsii and Cribroperidinum aparsium. The latter species is known from the Berriasian Cassiculosphaeridia delicate Zone on the Exmouth Plateau in Western Australia (Stevens, 1987). 4.3. Tendaguru formation The single sample from the Tendaguru Formation included in the present study (sample TGU 6-14) yielded only Cyathidites minor and freshwater algae Botryococcus. Cyathidites minor has wide stratigraphic range through the Middle Jurassic and Cretaceous. The present palynostratigraphic information does not allow a correlation to the assemblage zones defined in the dinosaur-bearing Tendaguru Beds in southeast Tanzania by Schrank (2005, 2010). 4.4. Nalwehe formation Two of the samples from the Nalwehe Formation yielded sparse palynomorphs, with no specific age-diagnostic species. Sample
WP126-2-14 contained only one single specimen of Cyathidites minor. Sample NQ2-2-14 yielded Classopollis spp., Cyathidites minor, Deltoidospora minor, together with Tasmanites sp. The presence of Classopollis spp. and Cyathidites minor give no further stratigraphic breakdown than indicating a general Middle Jurassic to Cretaceous age, which is in agreement with the Hauterivian Barremian age previously suggested for the formation (Hudson, 2011). The common Florentinia spp. in TDP40A-20/2 may indicate a correlation to the Albian ( Cenomanian) dinoflagellate cyst assemblages recovered in the Luhoi and Kizimbani boreholes in southern Tanzania (Srivastava and Msaky, 1999). Kleithriasphaeridium eoinodes is typically found in the Early Valanginian to Early Albian, but is also known from the Berriasian (Savelieva et al., 2017). Callaiosphaeridium asymmetricum found in TDP40A-20/2 is known from the Hauterivian to the Campanian (Costa and Davey, 1992). The presence of Exochosphaeridium phragmites in this sample further suggests a Hauterivian or younger Cretaceous age (Costa and Davey, 1992). 4.5. Makonde formation The two analyzed samples from the Makonde Formation (MB1-0-13 and MB1-1-13) only yielded single specimens of Inaperturopollenites sp. and Cyathidites minor, respectively. These are in agreement with an Aptian–Albian age of the formation (Hudson, 2011). The Makonde Formation correlates with the Macomia Formation in the northern Mozambique Rovuma Basin. The Aptian Albian Macomia Formation comprises mainly continental conglomerates and sandstones, and passes laterally into the coeval middle and upper parts of the Pemba Formation (Key et al., 2008; Smelror et al., 2008). In the Mandawa Basin, we find a similar depositional setting, with the continental Makonde Formation passing laterally into the marine Kiturika and Kihuluhulu formations (Fig. 2). 4.6. Kihuluhulu formation Productive assemblages of terrestrial and marine palynomorphs were recovered from several of the analyzed samples from the Kihuluhulu Formation. Lowest abundance and diversity were found in the mudstone samples from locations WP92, WP222 and WP232 (Fig. 1), interpreted to represent marine, somewhat restricted depositional environments. The samples from exploration well TDP40A yielded richer and more diverse assemblages of pollen, spores and dinoflagellate cysts. The presence of common Classopollis spp. and Cicatricosisporites spp. in samples TDP40A-11/3 could suggest correlation to the Late Valanginian-Hauterivian Classopollis-Cicatricosisporites-Ruffordiaspora Assemblage Zone (Schrank, 2010), but both taxa have a wide stratigraphic range within the latest Jurassic and Early Cretaceous. Among the palynomorphs recovered in sample WP92-17-14, Callialasporites trilobatus is evidence of an age range between the Middle Jurassic and Early Cretaceous, while Cyathidites minor suggests an age not older than Callovian. The presence of Leiosphaeridia sp. and Tasmanites sp. in WP92-14-17, and Tasmanites sp. in WP222-1-14, may indicate a somewhat restricted marine depositional environment, with reduced bottom water circulation and low toxic conditions. The recovery of the freshwater algae Botryococcus sp. in sample WP92-20-14, a sample which yielded no marine palynomorphs, is also noteworthy. A biostratigraphic breakdown of the Aptian-Cenomanian strata in the wells TDP40A and -40B based on foraminiferal assemblages was established by Mweneinda (2014). She further provided a tentative correlation of the carbon isotope stratigraphy to the isotope records from Ocean Drilling Program Site 1049 in the subtropical Western North Atlantic and Vocontian Basin, southeast France. Her investigations showed that lowermost part of the Albian is missing in TDP Holes 40A and 40B,
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and she argued that this may explain why no organic carbon-rich shales relating to Oceanic Anoxic Event 1b were encountered. More expanded and organic rich successions may exist in the northern part of Tanzania and offshore where the succession thickens (Mweneinda, 2014). Upwards in TDP40A, the recovery of Batioladinium micropodum in sample TDP40A-11/3 suggests an Aptian Albian age at this level in the well. Sample TDP40A-11/3 also contains small amounts of the freshwater algae Botryococcus spp., indicating influx from nearby river systems into the offshore depositional sites. Similar freshwater algae are also found in the Upper Jurassic Lower Cretaceous Pemba Formation in the Rovuma Basin, northern Mozambique (Smelror et al., 2008) (Fig. 2). Sample TDP40A-6/2 from the Kihuluhulu Formation contains relatively abundant and diverse assemblages of marine and freshwater algae, and terrestrial palynomorphs. The recovery of Callialasporites trilobatus restrict the age to not younger than Early Cretaceous, and the presences of Oligosphaeridium cf. asterigerum and Oligosphaeridium complex in the sample support an Early Cretaceous age. The records of the ginkgoopsida Ephedripites jansonii and the fern Crybelosporites pannuceus in TDP40A-6/2 sample points to an age not older than Aptian, although the genus Ephedripites jansonii may first appear in the Barremian (Huges and McDougall, 1987). Comparable ginkoopsida microfloras have been described from the top most core sample in well Kiranjeranje-1 (depth 198–206 ft) by Srivastava (1994), and from the Aptian in the Bahrein-1 well in the Western Desert, Egypt (Lashin, 2007). 5. Discussion The fluvial to shallow marine, nearshore, deposits of the Kipatimu, Mitole, Tendaguru and Makonde formations contain mainly poor sporomorph assemblages, while some of the samples from the offshore, more open marine deposits of the Mitole, Nalwehe and Kihuluhulu formations contain more abundant assemblages of both terrestrial and marine palynomorphs. Even though the palynological record is rather limited, the present data still provide additional insight into the depositional history in the Mandawa Basin. The deposition of the sedimentary formation in southern Tanzania was controlled by regional rifting and local faulting which occurred sporadically along what is now the east coast of Africa during the initial breakup of Gondwana. The local faulting controlled the ingress of seawater into the developing fracture system with marine sedimentation infilling local fault-controlled basins as they opened to the sea. The oldest sedimentary rocks in Coastal Tanzania are Upper Paleozoic to Lower Mesozoic continental Karoo deposits (Kapilima, 2003). The Karoo sequence was succeeded by a marine transgression in the Middle Jurassic, that eventually covered the entire Costal Basin and led to the formation of a carbonate continental shelf in Bajocian times (i.e. the Mtumbei Formation) (Fig. 2). From Middle Jurassic to Early Cretaceous times, a mixed siliciclastic and carbonate depositional environment persisted in the Mandawa Basin leading to deposition of the Mandawa and Mavuij groups (Fig. 2). The data herein confirm the presence of sediments related to profound marine transgressions and subsequent sea-level high-stands in the Late Jurassic and in the late Early Cretaceous. The Late Jurassic transgression appears to have covered most of the Mandwana Basin. While shallow marine sediments of the Tendaguru Formation were deposited to the west and north, fine-grained mudstones accumulated in the low-energy, offshore depositional environments in the central part of the basin. The open marine environment is evident from the relatively diverse marine microfloras found in the lower Mitole Formation. Open marine conditions appear to have prevailed through the Berriasian. During the Valanginian-Middle Aptian, a regression cycle started, followed by deposition of fluvial sediments along the shore-line (Kapilima, 2003; Said et al., 2015), documented by the absence of
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marine palynomorphs in the present samples from the Tendaguru Formation, proximal part of Nalwehe Formation and the overlying Makonde Formation. Subsequent faulting from Early Cretaceous times onwards accompanied continental crust extension, associated with active sea-floor spreading. Hauterivian–Albian ages are confirmed for the marine facies of the Nalwehe and Kihuluhulu formations and for the continental sediments of the Makonde Formation. The data herein indicate both a lateral and a time-transgressive transition from the continental to deltaic and shallow marine Makonde Formation to the distal marine, offshore settings of the Kihuluhulu Formation. These were sourced from a highland area that today is capped by proximal strata on the Makonde Plateau. The highland divided the region into two sub-basins, with deposition of the Makonde, Kiturika and Kikhuluhulu formations in southern Tanzania, and the Macomia Formation and upper Pemba Formation in northern Mozambique (Smelror et al., 2008). A new transgressive cycle in the Aptian Albian (Said et al., 2015) is confined by the dinoflagellate cyst assemblages appearing in the upper Kihuluhulu Formation. This marine transgression is further well-documented by the incoming extensive marine microfloras in the upper Pemba Formation of the Rovuma Basin, northern Mozambique (Hancox et al., 2002; Key et al. 2008; Smelror et al., 2008). 6. Conclusions New palynostratigraphic data are presented for Upper Jurassic and Lower Cretaceous formations in the Mandawa Basin, southeastern Tanzania. The preservation of palynomorphs is generally good, but the abundance and diversity of taxa vary considerably. The fluvial to shallow marine, nearshore, deposits of the Kipatimu, Mitole, Tendaguru and Makonde formations and the sandstone member of the Nalwehe Formation, contain mainly poor assemblages of sporomorphs. The samples from the offshore, open marine, deposits of the Mitole, Nalwehe and Kihuluhulu formations contain more abundant assemblages of terrestrial and marine palynomorphs. A Late Jurassic age (Kimmeridgian-Tithonian age) is confirmed for the Kipatimu Formation, from which the sporomorphs allow a rough correlation to the mid Oxfordian-Tithonian Classopollis-AraucariacitesShanbeipollenits Assemblage Zones as defined by Schrank (2010) in the southeast Tanzania. The dinoflagellate cyst assemblage recorded in the distal part of the Mitole Formation (including samples TDP40A-32/2 and TDP40A-26/1, which tentatively are assigned to this formation) bears similarities to the Dingodinium jurassicum–Kilwacysta assemblage as described from the Tithonian Trigonia smeei Bed of the Tendaguru Hill in southeast Tanzania by Schrank (2005) and to assemblages recorded from the lower Pemba Formation in the northern Mozambique Rovuma Basin (Smelror et al., 2008). Sample TDP40A-26/1, which is tentatively assigned to the Nalwehe Formation, contains terrestrial palynofloras which suggest a rough correlation to the Late Valanginian Hauterivian Classopollis Cicatricosisporites Ruffordiaspora Assemblage Zone as defined by Schrank 2010). Marine microfloras recovered from the more distal, marine part of the Nalwehe Formation confirm Hauterivian to Barremian ages. Marine microfloras recovered in the Kihuluhuhu Formation support previous Aptian Albian age-determinations based on foraminifera (Mweneinda, 2014). Terrestrial floras (i.e. ginkgoopsida Ephedripites jansonii and the fern Crybelosporites pannuceus) in sample TDP40A-6/ 2, further point to an age not older than Aptian. The deposition of the sedimentary formation in southern Tanzania was controlled by regional rifting and local faulting during the breakup of Gondwana. The local faulting controlled the ingress of seawater into the developing fracture system with marine sedimentation infilling local fault-controlled basins as they opened to the sea. The palynological records confirm the presence of sediments related to profound marine
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transgressions and subsequent sea-level high-stands in the Late Jurassic (Kimmeridgian-Tihonian) and in the late Early Cretaceous (Aptian Albian). Acknowledgements Thanks are due to Tanzania Petroleum Development Corporation and Statoil (Tanzania) for supporting the Mandawa Basin Project, the many team members of the Mandawa Basin project, and to Mufak Said Naoroz (UiO) for preparing the palynological slides. Constructive comments on the manuscript by Przemysław Gedl and an anonymous reviewer greatly improved the final paper. Appendix A. List of palynomorphs from the Upper Jurassic and Lower Cretceous of the Mandawa Basin, sample-by-sample within formations Kipatimu formation (Kimmeridgian Tithonian): Sample K25/5–5-14 (Silty mudstone) – Terrestrial palynomorphs: Alisporites similis, Alisporites cf. thomasii, Cyathidites minor. Sample K25/6-1-14 (Mudstone) – Terrestrial palynomorphs: Araucariacites autralis, Cibatiumspora juncta, Todisporites minor. Sample K25/6-4-14 (Mudstone) – Terrestrial palynomorphs: Araucariacites autralis, Araucariacites autralis. Freshwater algae: Botryococcus sp. Sample MN1-1-13 (Mudstone) – Terrestrial palynomorphs: Alisporites similis. Freshwater algae: Ovoidites sp. Sample WP92-3-14 (Mudstone) – Terrestrial palynomorphs: Clavatipollenties sp., Cyathidites minor, fungal remains. Freshwater algae: Ovoidites sp. Sample WP92-8-14 (Mudstone) – Terrestrial palynomorphs: Araucariacites autralis, Baculatisporites sp., Chasmatosporites cf. hians, Classopollis spp., Contignisporites cookonii, Cyathidites minor, Deltoidospora sp., Laevigatisporites mesozoicus. Marine palynomorphs: Tasmanites sp. Sample WP92-9-14 (Silty mudstone) – Terrestrial palynomorphs: Araucariacites autralis. Mitole formation (Kimmeridgian Berriasian): Sample WP232-5-14 (Siltstone with reworked oolites) – Terrestrial palynomorphs: Alisporites spp., Araucariacites autralis, Baculatisporites comaumensis, Callialasporites dampieri, Classopollis spp., Perinopollenites elatoides. Marine palynomorphs: Canningopsis sp., Cleistosphaeridium sp., Cribroperidinium spp., Circulodinium distinctum, Dingodinium jurassicum, Dissilidinium sp., Sentusidinium spp., Scriniodinium cf. inritibile, Systematophora areolata. Sample NG1-3-13 (Siltstone) – Terrestrial palynomorphs: Araucariacites autralis. Tendaguru formation (Tithonian): Sample WP126–2-14 (Muddy siltstone) – Terrestrial palynomorphs: Cyathidites minor. Freshwater algae: Botryococcus sp. Nalwehe formation (Hauterivian Barremian): Sample WP126-2-14 (Very fine sandstone) – Terrestrial palynomorphs: Cyathidites minor. Sample NQ2-2-14 (Silty mudstone with shell fragments) – Terrestrial palynomorphs: Classopollis spp., Cyathidites minor, Deltoidospora minor. Marine palynomorphs: Tasmanites sp. Sample TDP40A-20/2 (Siltstone) – Terrestrial palynomorphs: Cicatricosisporites sp., Classopollis spp., Cyathidites australis, Spheripollenites sp.. Marine palynomorphs: Apteodinium maculatum, Apteodinium sp. A, Callaiosphaeridium asymmetricum, Cassiculosphaeridia reticulata, Circulodinium distinctum, Cleistosphaeridium polypes, Cleistosphaeridium spp., Cribroperidinium cooksoniae, Cribroperidinium? tenuiceras, Cribroperidinium spp., Exochosphaeridium phragmites, Florentinia clavigera, Florentinia mantellii, Florentinia sp., Hapsocysta sp., Kleithriasphaeridium eoinodes, Micrhystridium spp., Surculosphaeridium longifurcatum, Systematophora sp., scolecodonts, foraminiferal linings.
Makonde formation (Aptian Albian): Sample MB1-0-13 (Silty mudstone) – Terrestrial palynomorphs: Inaperturopollenites sp. Sample MB1-1-13 (Very fine silty sandstone) – Terrestrial palynomorphs: Cyathidites australis. Kihuluhulu formation (Aptian Albian): Sample WP222-1-14 (Silty claystone) – Terrestrial palynomorphs: Araucariacites sp.. Marine palynomorphs: Tasmanites sp. Sample WP92-14-14 (Silty mudstone) – Terrestrial palynomorphs: Cyathidites minor. Marine palynomorphs: Leiosphaeridia sp., Tasmanites sp. Sample WP92-17-14 (Silty mudstone) – Terrestrial palynomorphs: Baculatisporites sp., Callialasporites trilobatus, Cyathidites minor. Marine palynomorphs: Indet. species. Sample WP92-20-14 (Silty mudstone with clay clasts) – Terrestrial palynomorphs: Araucariacites autralis. Freshwater algae: Botryococcus spp.. Sample TDP40A-11/3 (Siltstone) – Terrestrial palynomorphs: Alisporites sp., Cicatricosisporites orbiculatus, Classopollis spp., Dictyophyllidites impensus, Ephedripites jansonii, Ephedripites multicostatus, Rugulatisporites sp., Spheripollenites sp., Triporoletes radiatus. Marine palynomorphs: Batioladinium micropodum, Circulodinium distinctum, Micrhystridium sp., Pterospermopsis sp., Spiniferites spp., Tasmanites sp., sp. indet. Sample TDP40A-6/2 (Siltstone) – Terrestrial palynomorphs: Araucariacites australis, Baculatisporites sp., Callialasporites trilobatus, Citricosisporites avnimelechi, Classopollis spp., Contignisporites cooksonii, Crybelosporites pannuceus, Cyathidites minor, Ephedripites jansonii, Ephedripites multicostatus, Perinopollenites elatoides. Freshwater algae: Botryococcus spp.. Marine palynomorphs: Impletosphaeridium sp., Oligosphaeridium cf. asterigerum, Oligosphaeridium complex, Sentusidinium spp., Spiniferites spp., dinocyst indet, foraminiferal linings. Unknown, here assigned to the Mitole Formation (Oxfordian Berriasian): Sample TDP40A-32/2 (Sandy siltstone) – Terrestrial palynomorphs: Araucariacites autralis, Baculatisporites sp., Callialasporites dampieri, Classopollis spp., Inaperturopollenites sp., Verrucosisporites sp.. Marine palynomorphs: Canningia reticulata, Circulodinium disctintum, Cyclonephelium sp., Kaiwaradinium scrutillinum, Kilwacysta sp., Surculosphaeridium sp. I, Systematophora areolata, Systematophora sp. Sample TDP40A-26/1 (Sandy siltstone) – Terrestrial palynomorphs: Alisporites sp., Araucariacites autralis, Baculatisporites sp., Callialasporites trilobatus, Classopollis spp., Verrucosisporites sp. Marine palynomorphs: Circulodinium disctintum, Cleistosphaeridium sp., Cribroperidinium cf. edwardsii, Cribroperidinum cf. aparsium, Cribroperidinium spp., Tasmanites sp. References Backhouse, J., 1987. Microplankton zonation of the lower CretaceousWarnbro Group, Perth Basin, Western Australia. Mem. Ass. Australas. Palaeontol. 4, 205–226. Balduzzi, A., Msaky, E., Trincianti, E., Manum, S.B., 1992. Mesozoic Karoo and post-Karoo Formations in the Kilwa area, southeastern Tanzania – a stratigraphic study based on palynology, micropalaeontology and well log data from the Kizimbani Well. J. Afr. Earth Sci. 15, 405–427. Barss, M.S., Williams, G.L., 1973. Palynology and Nannofossil processing techniques. Geol. Surv. Canada 73, 22 Paper. Costa, L.I., Davey, R.J., 1992. Dinoflagellate cysts of the Cretaceous System. In: Powell, A.J. (Ed.), A Stratigraphic Index of Dinoflagellate Cysts. Chapmann & Hall, London, pp. 99–153. Dypvik, H., Einvik-Heitmann, V., Hudson, W., Fossum, K., Karega, A., Gundersveen, E., Nerbaten, K., Mahmic, O., Hou, G.M.V.D., Andresen, A., Rwechungura, R., Boniface, N., Kaaya, C., Holtar, E., Schomacker, E., 2015a. The Mandawa Basin Project – an interdisciplinary, educational-based research project in costal Tanzania. Abstract, East African Petroleum Conference and Exhibition, 4–6 March, 2015, Kigali, Rwanda. Dypvik, H., Einvik-Heitmann, V., Hudson, W., Fossum, K., Karega, A., Gundersveen, E., Nerbaten, K., Mahmic, O., Hou, G.M.V.D., Andresen, A., Rwechungura, R., Boniface, N., Kaaya, C., Holtar, E., Schomacker, E., 2015b. The Mandawa Basin of Coatal Tanzania and its Reservoir Potential. Abstract, First EAGE Eastern Africa Petroleum Geoscience Forum, 17–19 November 2015, Dar Es Salaam, Tanzania.
M. Smelror et al. / Review of Palaeobotany and Palynology 258 (2018) 248–255 Hancox, P.J., Brandt, B., Edwards, H., 2002. Sequence stratigraphic analysis of the early cretaceous Maconde Formation (Rovuma Basin), northern Mozambique. J. African Earth Sci. 34, 291–297. Helby, R., Morgan, R., Partridge, A.D., 1987. A palynological zonation of the Australian Mesozoic. In: Jell, P.A. (Ed.), Studies in Australian Mesozoic Mesozoic Palynology. 4. Assoc. Australas. Paleontol. Mem., pp. 1–94. Hudson, W., 2011. The Geological Evolution of the Petroleum prospective Mandawa Basin, Southern Coastal Tanzania. PhD thesis. 1. Trinity College, University of Dublin, Theatr. Irel., p. 357. Huges, N.F., McDougall, A.B., 1987. Records of angiospermid pollen entry into the English early cretaceous succession. Rev. Palaeobot. Palynol. 50, 255–272. Jarzen, D.M., 1981. A preliminary report on the palynomorphs recovered from Tendaguru Hill (Tanzania). Pollen Spores 23, 149–163. Kapilima, S., 2003. Tectonic and sedimentary evolution of coastal basin of Tanzania during the Mesozoic times. Tanzanian J. Sci. 29, 1–16. Kent, P.E., 1972. Mesozoic history of the East Coast of Africa. Nature 238, 147–148. Kent, P.E., Hunt, J.A., Johnstone, D.W., 1971. Geology and Geophysics of Coastal Sedimentary Basins of Tanzania. Natural Environment Research Council, Inst. Geol. Sci., Geophys. Res. Paper 6, 1–101. Key, R.M., Smith, R.A., Smelror, M., Sæther, O.M., Thorsnes, T., Njange, F., Powell, J.H., Zandamela, E.B., 2008. Revised lithostratigraphy of the Mesozoic-Cenozoic succession of the onshore Rovuma Basin, northern coastal Mozambique. J. Afr. Earth Sci. 111, 89–108. Lashin, G.M.A., 2007. Palynostratigraphic Studies of the Lower Cretaceous Sediments, Alamein Formation, Bahrein-1 Well in the Northern Part of the Western Desert, Egypt. J. Appl. Sci. 7, 1304–1313. Mbede, E.I., 1991. The sedimentary basins of Tanzania reviewed. J. Afr. Earth Sci. 13, 291–297. Msaky, E., 1995. Palynological biostratigraphy of cretaceous sediments, Rufiji Basin, Tanzania. Tanzania J. Sci. 21, 85–108. Msaky, E.A., 2007. Occurrence of dinoflagellate cyst genera Wanaea and Komewuia in Upper Jurassic strata, coastal Tanzania. Paleontol. Res. 11, 41–58. Mweneinda, A.K., 2014. Mid-Cretaceous stratigraphy and micropaleontology of the Coastal Basins of Tanzania. PhD thesis. University of Leeds, p. 210.
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Riding, J.B., Thomas, J.E., 1992. Dinoflagellate Cysts of the Jurassic System. In: Powell, A.J. (Ed.), A Stratigraphic Index of Dinoflagellate Cysts. Chapmann & Hall, London, pp. 7–97. Said, A., Moder, C., Clark, S., Abdelmalak, M.M., 2015. Sedimentary budgets of the Tanzania coastal basin and implications for uplift history of the East African rift system. J. Afr. Earth Sci. 111, 288–295. Savelieva, Y.N., Shurekova, O.V., Feodorova, A.A., Arkadiev, V.V., Grischenko, V.A., Guzhikov, A.Y., Maniki, A.G., 2017. Microbiostratigraphy of the Berriasian– Valanginian boundary in eastern Crimea: foraminifers, ostracods, organic-walled dinoflagellate cysts. Geol. Carpathica 68, 517–529. Schrank, E., 1999. Palynology of the Dinosaur Beds of Tendaguru (Tanzania) – preliminary results. Mitteilungen aus dem Museum für Naturkunde Berlin, Geowissenschaftliche Rh. 2, 171–183. Schrank, E., 2005. Dinoflagellate cysts and associated aquatic palynomorphs from the Tendaguru Beds (Upper Jurassic–Lower Cretaceous) of southeast Tanzania. Palynology 29, 49–85. Schrank, E., 2010. Pollen and spores from the Tendaguru Beds, Upper Jurassic and Lower Cretaceous of southeast Tanzania: Palynostratigaphical and Paleoecological implications. Palynology 34, 3–42. Smelror, M., Key, R.M., Smith, R.A., Njange, F., 2008. Late Jurassic and Cretaceous palynostratigaphy of the onshore Rovuma Basin, Northern Mozambique. Palynology 32, 63–76. Srivastava, S.K., 1987. Jurassic spore-pollen assemblages from Normandy (France) and Germany. Geobios 20, 5–79. Srivastava, V., 1994. A Middle Cretaceous microflora assemblage from southern coastal Tanzania. J. Palynol. 30, 35–48. Srivastava, V., Msaky, E., 1999. Albian-Cenomanian micro-floral assemblages from coastal Tanzania. Palaeoecology of Africa and the Surrounding Islands. Vol. 26, pp. 31–44 Special edition. Stevens, J., 1987. Some Early Cretaceous dinoflagellates from the Cassiculosphaeridia delicate Zone on the Exmouth Plateau, Western Australia. Mem. Ass. Austr. Palaeontol. 4, 185–197. Williams, G.L., Fensome, R.A., MacRae, R.A., 2017. DINOFLAJ3. American Association of Stratigraphic Palynologists, Data Series no. 2 http://dinoflaj.smu.ca/dinoflaj3.
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Review of Palaeobotany and Palynology journal homepage: www.elsevier.com/locate/revpalbo
Late Jurassic–Early Cretaceous palynostratigraphy of the onshore Mandawa Basin, southeastern Tanzania Morten Smelror a,⁎, Katrine Fossum b, Henning Dypvik b, Wellington Hudson c, Amina Mweneinda c a b c
Geological Survey of Norway, P.O, Box 6315, Sluppen, No, 7491 Trondheim, Norway Department of Geosciences, University of Oslo, P.O. Box 1047, Blindern, 0316 Oslo, Norway Tanzania Petroleum Development Corporation, P.O. Box 2774, Dar Es Salaam, Tanzania
a r t i c l e
i n f o
Article history: Received 22 November 2017 Received in revised form 24 August 2018 Accepted 1 September 2018 Available online 05 September 2018
a b s t r a c t New palynostratigraphic data are presented for Upper Jurassic and Lower Cretaceous formations of the Mandawa Basin, southeastern Tanzania. A Late Jurassic (Kimmeridgian Tithonian) age is confirmed for the Kipatimu Formation, from which the terrestrial sporomorphs allow a rough correlation to the mid Oxfordian Tithonian Classopollis Araucariacites Shanbeipollenits Assemblage Zone. A dinoflagellate cyst assemblage recorded in the Mitole Formation correlates to the Dingodinium jurassicum–Kilwacysta assemblage as described from the Tithonian Trigonia smeei Bed of the Tendaguru Hill, southeast Tanzania. Dinoflagellate cyst assemblages in the upper Nalwehe Formation contain species typical of the Hauterivian Barremian, while the Kihuluhulu Formation contains marine microfloras of Aptian to Albian ages. The palynological records confirm the presence of sediments related to profound marine transgressions and subsequent sea-level high-stands in the Late Jurassic (Kimmeridgian Tihonian) and in the late Early Cretaceous (Aptian Albian). © 2018 Elsevier B.V. All rights reserved.
1. Introduction The Mandawa Basin of Coastal Tanzania is located onshore, about 80 km west of the giant offshore gas discoveries in Lower Cretaceous to Miocene formations (Mbede, 1991) (Fig. 1). The present study is a supplement to the Mandawa Basin Project, a research and educational project organized between the Universities of Oslo and Dar Es Salaam, the Tanzania Petroleum Development Corporation (TPDC) and Statoil (Tanzania) (Dypvik et al., 2015a,b). The main objective of the project is to study the sedimentological and stratigraphical developments of the Mandawa Basin, along with its structural evolution. The present investigation covers palynological analyses of selected samples from a shallow exploration well (Tanzania drilling program, TDP40A; Mweneinda, 2014) and outcrops in the Mandawa Basin (Fig. 1). The main objective was to identify and document terrestrial and marine microfloras applicable for biostratigraphic age determinations of the studied formations, as a means for correlations among the lithostratigraphic and sequence-stratigraphic units defined in the basin. Schrank (2005, 2010) distinguished four informal dinoflagellate cyst assemblage zones and two informal sporomorph assemblage zones through the Upper Jurassic and Lower Cretaceous (i.e. midOxfordian Hauterivian) succession in southern Tanzania. Where ⁎ Corresponding author at: Geological Survey of Norway, P.O, Box 6315, Sluppen, No, 7491 Trondheim, Norway. E-mail address: [email protected] (M. Smelror).
https://doi.org/10.1016/j.revpalbo.2018.09.001 0034-6667/© 2018 Elsevier B.V. All rights reserved.
possible, the palynological records in the present study are correlated to these zones. Further, the present palynostratigraphic record from well TDP40A is correlated to the foraminiferal assemblages described from this drillhole by Mweneinda (2014). Possible correlations to contemporaneous palynomorph assemblages recovered in the Rovuma Basin (Ruvuma in Tanzania), Northern Mozambique, are also discussed. 2. Sedimentary succession and lithostratigraphy The sedimentary succession of the Mandawa Basin spans Triassic to Neogene formations (Figs. 1, 2) dominated by shallow marine shelf to coastal deposits of evaporitic, siliciclastic and carbonate facies. The sandstones of the Mandawa Basin include fluviatile, tidal and shallow marine formations as well as possible turbiditic beds in younger units. In times and regions with confined clastic input, carbonates were deposited, often with oolitic composition. The basin evolution was mainly controlled by tectonic events related to the breakup of the Gondwana Supercontinent, the opening of the Indian Ocean, and the subsequent development of the East African rift system (Kent et al., 1971; Kent, 1972; Kapilima, 2003; Said et al., 2015). In southern coastal Tanzania, the crystalline basement is overlaid by continental Permo-Carboniferous to Lower Jurassic Karoo deposits (Fig. 2). In the Ruvuma and Mandawa basins, the succession is intercalated with restricted marine deposits, including some marl and evaporites. During the Middle Jurassic shallow marine depositional conditions were established in the basins (Hudson, 2011).
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Fig. 1. Geological map of the Mandawa Basin in southern Tanzania and Rovuma Basin in northern Mosambique, with enlarged map showing the locations of samples and drillhole TDP40A included in the present study.
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The marine transgression continued into Late Jurassic times. During the Oxfordian to Berriasian a series of marine calcareous and sandy sediments (Tendaguru and Mitole formations) were deposited in the southwestern area and the central part of the Mandawa Basin, while fluvial to fluvio-deltaic sediments assigned to the Kipatimu Formation accumulated to the north (Hudson, 2011; Fig. 2). During the Early Cretaceous a regressive phase shed continental sands and fine clastic sediments from the west into the basin, leading to the deposition of the Hauterivian-Barremian Nalwehe Formation and the Aptian-Albian Makonde Formation. To the east marine, calcareous sediments of the Kiturika Formation were deposited, and further eastwards into the more distal part, the basin was filled with shoreface to offshore fine-grained sandstones, siltstones and mudstones of the Kihuluhulu Formation (Hudson, 2011). The Lower Cretaceous succession is capped by an unconformity spanning the Turonian-Conacian time interval. Continued subsidence and a new transgressive phase led to a relative deepening of the ocean in the eastern part of the Mandawa Basin during the Santonian, with deposition of dominantly calcareous sediments throughout the Late Cretaceous and Early Tertiary (Kapilima, 2003; Hudson, 2011). Comparable depositional regimes occurred in the Rovuma Basin in northern Mozambique, where comparable sedimentary sequences were deposited during the Late Jurassic and Cretaceous. The lithostratigraphic framework of the Upper Triassic to Lower Cretaceous of the Mandawa Basin, and correlations between the Mesozoic successions in the Mandawa Basin in Tanzania and the Rovuma Basin in northern Mozambique is presented in Fig. 2. 3. Material and methods The study includes detailed palynological analyses of 22 samples used in the present study (locations on Fig. 1); including 8 samples from the Kipatimu Formation, 2 samples from the Mitole Formation, 3 samples from the Nalwehe Formation, 2 samples from the Makonde Formation, 1 sample from Tendaguru Formation, 6 samples from the Kihuluhulu Formation, and 2 samples tentatively assigned to Mitole Formation. Five of the samples from the Kihuluhulu Formation were collected in exploration well TDP40A, while the rest of the analyzed samples represent various outcrops in the Mandawa Basin (Fig. 1). The samples were processed using standard palynological techniques (Barss and Williams, 1973) at Department of Geosciences, University of Oslo. The palynological slides are housed at the Geological Survey of Norway (NGU). Dinoflagellate cyst systematics follows the recommendations presented by Williams et al. (2017). For pollen and spores the nomenclature is according to the names of species and taxa referred to by Srivastava (1987), Srivastava and Msaky (1999) and Schrank (2010). 4. Palynostratigraphy
Fig. 2. Lithostratigraphic framework of the Upper Triassic to Lower Cretaceous of the Mandawa Basin, with correlations to the Mesozoic successions in Rovuma Basin in northern Mozambique.
Palynostratigraphic information on the Mesozoic succession of the Mandawa Basin and adjacent areas in southern Tanzania has been published by Jarzen (1981), Balduzzi et al. (1992), Srivastava (1994), Msaky (1995, 2007), Schrank (1999, 2005, 2010) and Srivastava and Msaky (1999). In general, the abundance and diversity of palynomorphs vary greatly through the Mesozoic formations. Balduzzi et al. (1992) found that the terrestrial Lower Jurassic Ngerengere Beds are generally poor, yielding only few terrestrial palynomorphs, mostly of limited stratigraphic value. Schrank (1999, 2005) recognized that out of more than 100 analyzed samples from the Tendaguru Beds, only nine samples contained spore-pollen and dinoflagellate cyst assemblages. Similar observations were made further south in the Rovuma Basin in northern Mozambique, where the terrestrial deposits of the Rio Mecole
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Formation yielded very poor assemblages of palynomorphs (Smelror et al., 2008). However, more specific palynological sampling may provide better recoveries, as documented by Schrank (2010). In the present material, the fluvial and fluvio-deltatic sediments of the Kipatimu Formation and the Tendaguru Formation yielded only a few pollen and spores, together with some freshwater algae (Appendix A). Further, the shallow marine (subtidal) sample from the Mitole Formation contained only a few palynomorphs, of which none are of specific value for any detailed age-determinations. However, the marine microfloras found in the deeper marine part of the Mitole Formation offer good means for correlation to the Tithonian Berriasian. The two samples from the Makonde Formation were almost completely barren, yielding only a few specimens of pollen. The nonmarine sample from the sandstone member of the Nalwehe Formation yielded only one specimen of Cyathidites minor, while the sample from the limestone in the same formation contained a somewhat richer assemblage of pollen and spores, along with the marine algae Tasmanites sp. Sample TDP40A-20/2 from the Nalwehe Formation yielded a relatively rich assemblage of dinoflagellate cysts, with foraminifera linings and scolecodonts also present. The marine Kihuluhulu Formation contains moderately rich and diverse assemblages of both terrestrial and marine palynomorphs. These provide good means for the stratigraphic correlations as discussed further. A list of palynomorphs from the Upper Jurassic and Lower Cretaceous of the Mandawa Basin, sample-by-sample within formations is shown in Appendix A. Selected terrestrial palynomorphs and marine
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microplankton taxa recovered in the studied formations are illustrated in Plate I. 4.1. Kipatimu formation The eight samples from the Kipatimu Formation contained a few pollen and spores, together with some fungal remains and rare freshwater (Ovoidites sp.) and marine algae (Tasmanites). The presence of Cyathidites minor in samples K25/5-5-14 and WP92-3-14 points towards a Middle Jurassic or younger Mesozoic age. Araucariacites australis found in several samples from the Kipatimu Formation has a very long stratigraphic range from the Early Jurassic (Sinemurian) to the Miocene. The presence of Contignisporites cooksonii WP92-8-14 limit the age of this sample from Middle Jurassic to Albian (Srivastava, 1987). A presence of cf. Chasmatosporites cf. hians in sample WP92-8-14 may indicate reworking from older Jurassic or Rhaetian strata, as this pteridophytic monolete spore appears to be restricted to the Rhaeto-Jurassic (Srivastava, 1987). The single record of the prasinophycean algae Tasmanites sp. in sample WP92-8-14 may indicate a somewhat restricted circulation marine depositional environment. The present palynostratigraphic records from the Kipatimu Formation are not well-constrained, but the regular occurrence of Araucariacites australis and the common Classopollis spp. in sample WP92-8-14 allow a rough correlation to the mid- Oxfordian Tithonian Classopollis Araucariacites Shanbeipollenits Assemblage Zones as defined by Schrank (2010) in southeast Tanzania.
Plate I.. Marine and terrestrial palynomorphs from the Mandawa Basin. Sample number and England Finder coordinates (in brackets) are given for the illustrated species. 1. Cribroperidinium sp., TDP40A-26/1 (W43/0), 2. Florentinia sp., TDP40A-20/2 (O34/2), 3. Callaiosphaeridum asymmetricum, TDP40A-20/2 (R42/1), 4. Indet., TDP40A-11/3 (029/2), 5. Systematophora sp., TDP40A-20/2 (N40/1), 6. Kaiwaradinium scrutillinum, TDP40A-32/2 (T42/2), 7. Classopollis sp., TDP40A-11/3 (U41/0), 8. Ephedripites jansonii, TDP40–6/2 (S44/0), 9. Canningopsis sp., WP232 (S53/O).
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4.2. Mitole formation Sample NG1-3-13 from subtidal siltstone yielded only one single grain of Araucariacites australis. This species has a very long stratigraphic range from the Early Jurassic (Sinemurian) to the Miocene. In contrast, sample WP232-5-14 consisting of marine siltstone with reworked oolites, yielded a moderately rich and diverse assemblage of terrestrial and marine palynomorphs. Pollen and spores include Araucariacites autralis, Baculatisporites comaumensis, Callialasporites dampieri, Classopollis spp. and Perinopollenites elatoides. The gymnosperm pollen Callialasporites dampieri has a worldwide Middle Jurassic (Bajocian) to Early Cretaceous occurrence (Srivastava, 1987). In his study of the Upper Jurassic Lower Cretaceous Tendaguru Beds in southeastern Tanzania, Schrank (2005) found that all productive samples are dominated by pollen grains from conifers, mainly Classopollis, and to a lesser degree Araucariacites. The marine microflora in WP232-5-14 include Canningopsis sp., common Cribroperidinium spp., Circulodinium distinctum, Dingodinium jurassicum, Scriniodinium cf. inritibile and Systematophora areolata. This dinoflagellate cyst assemblage bears similarities to the Dingodinium jurassicum–Kilwacysta assemblage as described from the Tithonian Trigonia smeei Bed of the Tendaguru Hill in southeast Tanzania by Schrank (2005). Comparable Tithonian dinoflagellate cyst assemblages to the one found in WP232-5-14 are recorded in the lower Pemba Formation in the northern Mozambique Rovuma Basin (Smelror et al., 2008). The two lowermost samples from well TDP40A are here tentatively assigned to the Mitole Formation. Sample TDP40A-32/2 contains a fairly diverse assemblage of dinoflagellate cysts, including Canningia reticulata, Circulodinium distinctum, Kaiwaradinium scrutillinum, Surculosphaeridium sp. and Systematophora spp.. The presence of Systematophora areolata suggests a general Late Jurassic age (Riding & Thomas, 1992), while the recovery of common Canningia reticulata indicates an Early Cretaceous age (Helby et al., 1987). Kaiwaradinium scrutillinum was originally described from the Early Valanginian in the Perth Basin, Western Australia (Backhouse, 1987), but the total stratigraphic range of this species is poorly documented. The presence of Kilwacysta sp. and common Systematophora spp. may suggest a correlation to the Tithonian Dingodinium jurassicum Kilwacysta Assemblage Zone of Schrank (2005). Sample TDP40A-26/1, which is tentatively assigned to the Motole Formation, contains common Classopollis spp. and Cicatricosisporites spp. These findings suggest a rough correlation to the Late Valanginian Hauterivian Classopollis Cicatricosisporites Ruffordiaspora Assemblage Zone as defined by Schrank 2010). However, both taxa have a rather wide stratigraphic range within the latest Jurassic and Early Cretaceous. Sample TDP40A-26/1 also contains Circulodinium disctintum and common Cribroperidinium spp., including Cribroperidinium cf. edwardsii and Cribroperidinum aparsium. The latter species is known from the Berriasian Cassiculosphaeridia delicate Zone on the Exmouth Plateau in Western Australia (Stevens, 1987). 4.3. Tendaguru formation The single sample from the Tendaguru Formation included in the present study (sample TGU 6-14) yielded only Cyathidites minor and freshwater algae Botryococcus. Cyathidites minor has wide stratigraphic range through the Middle Jurassic and Cretaceous. The present palynostratigraphic information does not allow a correlation to the assemblage zones defined in the dinosaur-bearing Tendaguru Beds in southeast Tanzania by Schrank (2005, 2010). 4.4. Nalwehe formation Two of the samples from the Nalwehe Formation yielded sparse palynomorphs, with no specific age-diagnostic species. Sample
WP126-2-14 contained only one single specimen of Cyathidites minor. Sample NQ2-2-14 yielded Classopollis spp., Cyathidites minor, Deltoidospora minor, together with Tasmanites sp. The presence of Classopollis spp. and Cyathidites minor give no further stratigraphic breakdown than indicating a general Middle Jurassic to Cretaceous age, which is in agreement with the Hauterivian Barremian age previously suggested for the formation (Hudson, 2011). The common Florentinia spp. in TDP40A-20/2 may indicate a correlation to the Albian ( Cenomanian) dinoflagellate cyst assemblages recovered in the Luhoi and Kizimbani boreholes in southern Tanzania (Srivastava and Msaky, 1999). Kleithriasphaeridium eoinodes is typically found in the Early Valanginian to Early Albian, but is also known from the Berriasian (Savelieva et al., 2017). Callaiosphaeridium asymmetricum found in TDP40A-20/2 is known from the Hauterivian to the Campanian (Costa and Davey, 1992). The presence of Exochosphaeridium phragmites in this sample further suggests a Hauterivian or younger Cretaceous age (Costa and Davey, 1992). 4.5. Makonde formation The two analyzed samples from the Makonde Formation (MB1-0-13 and MB1-1-13) only yielded single specimens of Inaperturopollenites sp. and Cyathidites minor, respectively. These are in agreement with an Aptian–Albian age of the formation (Hudson, 2011). The Makonde Formation correlates with the Macomia Formation in the northern Mozambique Rovuma Basin. The Aptian Albian Macomia Formation comprises mainly continental conglomerates and sandstones, and passes laterally into the coeval middle and upper parts of the Pemba Formation (Key et al., 2008; Smelror et al., 2008). In the Mandawa Basin, we find a similar depositional setting, with the continental Makonde Formation passing laterally into the marine Kiturika and Kihuluhulu formations (Fig. 2). 4.6. Kihuluhulu formation Productive assemblages of terrestrial and marine palynomorphs were recovered from several of the analyzed samples from the Kihuluhulu Formation. Lowest abundance and diversity were found in the mudstone samples from locations WP92, WP222 and WP232 (Fig. 1), interpreted to represent marine, somewhat restricted depositional environments. The samples from exploration well TDP40A yielded richer and more diverse assemblages of pollen, spores and dinoflagellate cysts. The presence of common Classopollis spp. and Cicatricosisporites spp. in samples TDP40A-11/3 could suggest correlation to the Late Valanginian-Hauterivian Classopollis-Cicatricosisporites-Ruffordiaspora Assemblage Zone (Schrank, 2010), but both taxa have a wide stratigraphic range within the latest Jurassic and Early Cretaceous. Among the palynomorphs recovered in sample WP92-17-14, Callialasporites trilobatus is evidence of an age range between the Middle Jurassic and Early Cretaceous, while Cyathidites minor suggests an age not older than Callovian. The presence of Leiosphaeridia sp. and Tasmanites sp. in WP92-14-17, and Tasmanites sp. in WP222-1-14, may indicate a somewhat restricted marine depositional environment, with reduced bottom water circulation and low toxic conditions. The recovery of the freshwater algae Botryococcus sp. in sample WP92-20-14, a sample which yielded no marine palynomorphs, is also noteworthy. A biostratigraphic breakdown of the Aptian-Cenomanian strata in the wells TDP40A and -40B based on foraminiferal assemblages was established by Mweneinda (2014). She further provided a tentative correlation of the carbon isotope stratigraphy to the isotope records from Ocean Drilling Program Site 1049 in the subtropical Western North Atlantic and Vocontian Basin, southeast France. Her investigations showed that lowermost part of the Albian is missing in TDP Holes 40A and 40B,
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and she argued that this may explain why no organic carbon-rich shales relating to Oceanic Anoxic Event 1b were encountered. More expanded and organic rich successions may exist in the northern part of Tanzania and offshore where the succession thickens (Mweneinda, 2014). Upwards in TDP40A, the recovery of Batioladinium micropodum in sample TDP40A-11/3 suggests an Aptian Albian age at this level in the well. Sample TDP40A-11/3 also contains small amounts of the freshwater algae Botryococcus spp., indicating influx from nearby river systems into the offshore depositional sites. Similar freshwater algae are also found in the Upper Jurassic Lower Cretaceous Pemba Formation in the Rovuma Basin, northern Mozambique (Smelror et al., 2008) (Fig. 2). Sample TDP40A-6/2 from the Kihuluhulu Formation contains relatively abundant and diverse assemblages of marine and freshwater algae, and terrestrial palynomorphs. The recovery of Callialasporites trilobatus restrict the age to not younger than Early Cretaceous, and the presences of Oligosphaeridium cf. asterigerum and Oligosphaeridium complex in the sample support an Early Cretaceous age. The records of the ginkgoopsida Ephedripites jansonii and the fern Crybelosporites pannuceus in TDP40A-6/2 sample points to an age not older than Aptian, although the genus Ephedripites jansonii may first appear in the Barremian (Huges and McDougall, 1987). Comparable ginkoopsida microfloras have been described from the top most core sample in well Kiranjeranje-1 (depth 198–206 ft) by Srivastava (1994), and from the Aptian in the Bahrein-1 well in the Western Desert, Egypt (Lashin, 2007). 5. Discussion The fluvial to shallow marine, nearshore, deposits of the Kipatimu, Mitole, Tendaguru and Makonde formations contain mainly poor sporomorph assemblages, while some of the samples from the offshore, more open marine deposits of the Mitole, Nalwehe and Kihuluhulu formations contain more abundant assemblages of both terrestrial and marine palynomorphs. Even though the palynological record is rather limited, the present data still provide additional insight into the depositional history in the Mandawa Basin. The deposition of the sedimentary formation in southern Tanzania was controlled by regional rifting and local faulting which occurred sporadically along what is now the east coast of Africa during the initial breakup of Gondwana. The local faulting controlled the ingress of seawater into the developing fracture system with marine sedimentation infilling local fault-controlled basins as they opened to the sea. The oldest sedimentary rocks in Coastal Tanzania are Upper Paleozoic to Lower Mesozoic continental Karoo deposits (Kapilima, 2003). The Karoo sequence was succeeded by a marine transgression in the Middle Jurassic, that eventually covered the entire Costal Basin and led to the formation of a carbonate continental shelf in Bajocian times (i.e. the Mtumbei Formation) (Fig. 2). From Middle Jurassic to Early Cretaceous times, a mixed siliciclastic and carbonate depositional environment persisted in the Mandawa Basin leading to deposition of the Mandawa and Mavuij groups (Fig. 2). The data herein confirm the presence of sediments related to profound marine transgressions and subsequent sea-level high-stands in the Late Jurassic and in the late Early Cretaceous. The Late Jurassic transgression appears to have covered most of the Mandwana Basin. While shallow marine sediments of the Tendaguru Formation were deposited to the west and north, fine-grained mudstones accumulated in the low-energy, offshore depositional environments in the central part of the basin. The open marine environment is evident from the relatively diverse marine microfloras found in the lower Mitole Formation. Open marine conditions appear to have prevailed through the Berriasian. During the Valanginian-Middle Aptian, a regression cycle started, followed by deposition of fluvial sediments along the shore-line (Kapilima, 2003; Said et al., 2015), documented by the absence of
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marine palynomorphs in the present samples from the Tendaguru Formation, proximal part of Nalwehe Formation and the overlying Makonde Formation. Subsequent faulting from Early Cretaceous times onwards accompanied continental crust extension, associated with active sea-floor spreading. Hauterivian–Albian ages are confirmed for the marine facies of the Nalwehe and Kihuluhulu formations and for the continental sediments of the Makonde Formation. The data herein indicate both a lateral and a time-transgressive transition from the continental to deltaic and shallow marine Makonde Formation to the distal marine, offshore settings of the Kihuluhulu Formation. These were sourced from a highland area that today is capped by proximal strata on the Makonde Plateau. The highland divided the region into two sub-basins, with deposition of the Makonde, Kiturika and Kikhuluhulu formations in southern Tanzania, and the Macomia Formation and upper Pemba Formation in northern Mozambique (Smelror et al., 2008). A new transgressive cycle in the Aptian Albian (Said et al., 2015) is confined by the dinoflagellate cyst assemblages appearing in the upper Kihuluhulu Formation. This marine transgression is further well-documented by the incoming extensive marine microfloras in the upper Pemba Formation of the Rovuma Basin, northern Mozambique (Hancox et al., 2002; Key et al. 2008; Smelror et al., 2008). 6. Conclusions New palynostratigraphic data are presented for Upper Jurassic and Lower Cretaceous formations in the Mandawa Basin, southeastern Tanzania. The preservation of palynomorphs is generally good, but the abundance and diversity of taxa vary considerably. The fluvial to shallow marine, nearshore, deposits of the Kipatimu, Mitole, Tendaguru and Makonde formations and the sandstone member of the Nalwehe Formation, contain mainly poor assemblages of sporomorphs. The samples from the offshore, open marine, deposits of the Mitole, Nalwehe and Kihuluhulu formations contain more abundant assemblages of terrestrial and marine palynomorphs. A Late Jurassic age (Kimmeridgian-Tithonian age) is confirmed for the Kipatimu Formation, from which the sporomorphs allow a rough correlation to the mid Oxfordian-Tithonian Classopollis-AraucariacitesShanbeipollenits Assemblage Zones as defined by Schrank (2010) in the southeast Tanzania. The dinoflagellate cyst assemblage recorded in the distal part of the Mitole Formation (including samples TDP40A-32/2 and TDP40A-26/1, which tentatively are assigned to this formation) bears similarities to the Dingodinium jurassicum–Kilwacysta assemblage as described from the Tithonian Trigonia smeei Bed of the Tendaguru Hill in southeast Tanzania by Schrank (2005) and to assemblages recorded from the lower Pemba Formation in the northern Mozambique Rovuma Basin (Smelror et al., 2008). Sample TDP40A-26/1, which is tentatively assigned to the Nalwehe Formation, contains terrestrial palynofloras which suggest a rough correlation to the Late Valanginian Hauterivian Classopollis Cicatricosisporites Ruffordiaspora Assemblage Zone as defined by Schrank 2010). Marine microfloras recovered from the more distal, marine part of the Nalwehe Formation confirm Hauterivian to Barremian ages. Marine microfloras recovered in the Kihuluhuhu Formation support previous Aptian Albian age-determinations based on foraminifera (Mweneinda, 2014). Terrestrial floras (i.e. ginkgoopsida Ephedripites jansonii and the fern Crybelosporites pannuceus) in sample TDP40A-6/ 2, further point to an age not older than Aptian. The deposition of the sedimentary formation in southern Tanzania was controlled by regional rifting and local faulting during the breakup of Gondwana. The local faulting controlled the ingress of seawater into the developing fracture system with marine sedimentation infilling local fault-controlled basins as they opened to the sea. The palynological records confirm the presence of sediments related to profound marine
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transgressions and subsequent sea-level high-stands in the Late Jurassic (Kimmeridgian-Tihonian) and in the late Early Cretaceous (Aptian Albian). Acknowledgements Thanks are due to Tanzania Petroleum Development Corporation and Statoil (Tanzania) for supporting the Mandawa Basin Project, the many team members of the Mandawa Basin project, and to Mufak Said Naoroz (UiO) for preparing the palynological slides. Constructive comments on the manuscript by Przemysław Gedl and an anonymous reviewer greatly improved the final paper. Appendix A. List of palynomorphs from the Upper Jurassic and Lower Cretceous of the Mandawa Basin, sample-by-sample within formations Kipatimu formation (Kimmeridgian Tithonian): Sample K25/5–5-14 (Silty mudstone) – Terrestrial palynomorphs: Alisporites similis, Alisporites cf. thomasii, Cyathidites minor. Sample K25/6-1-14 (Mudstone) – Terrestrial palynomorphs: Araucariacites autralis, Cibatiumspora juncta, Todisporites minor. Sample K25/6-4-14 (Mudstone) – Terrestrial palynomorphs: Araucariacites autralis, Araucariacites autralis. Freshwater algae: Botryococcus sp. Sample MN1-1-13 (Mudstone) – Terrestrial palynomorphs: Alisporites similis. Freshwater algae: Ovoidites sp. Sample WP92-3-14 (Mudstone) – Terrestrial palynomorphs: Clavatipollenties sp., Cyathidites minor, fungal remains. Freshwater algae: Ovoidites sp. Sample WP92-8-14 (Mudstone) – Terrestrial palynomorphs: Araucariacites autralis, Baculatisporites sp., Chasmatosporites cf. hians, Classopollis spp., Contignisporites cookonii, Cyathidites minor, Deltoidospora sp., Laevigatisporites mesozoicus. Marine palynomorphs: Tasmanites sp. Sample WP92-9-14 (Silty mudstone) – Terrestrial palynomorphs: Araucariacites autralis. Mitole formation (Kimmeridgian Berriasian): Sample WP232-5-14 (Siltstone with reworked oolites) – Terrestrial palynomorphs: Alisporites spp., Araucariacites autralis, Baculatisporites comaumensis, Callialasporites dampieri, Classopollis spp., Perinopollenites elatoides. Marine palynomorphs: Canningopsis sp., Cleistosphaeridium sp., Cribroperidinium spp., Circulodinium distinctum, Dingodinium jurassicum, Dissilidinium sp., Sentusidinium spp., Scriniodinium cf. inritibile, Systematophora areolata. Sample NG1-3-13 (Siltstone) – Terrestrial palynomorphs: Araucariacites autralis. Tendaguru formation (Tithonian): Sample WP126–2-14 (Muddy siltstone) – Terrestrial palynomorphs: Cyathidites minor. Freshwater algae: Botryococcus sp. Nalwehe formation (Hauterivian Barremian): Sample WP126-2-14 (Very fine sandstone) – Terrestrial palynomorphs: Cyathidites minor. Sample NQ2-2-14 (Silty mudstone with shell fragments) – Terrestrial palynomorphs: Classopollis spp., Cyathidites minor, Deltoidospora minor. Marine palynomorphs: Tasmanites sp. Sample TDP40A-20/2 (Siltstone) – Terrestrial palynomorphs: Cicatricosisporites sp., Classopollis spp., Cyathidites australis, Spheripollenites sp.. Marine palynomorphs: Apteodinium maculatum, Apteodinium sp. A, Callaiosphaeridium asymmetricum, Cassiculosphaeridia reticulata, Circulodinium distinctum, Cleistosphaeridium polypes, Cleistosphaeridium spp., Cribroperidinium cooksoniae, Cribroperidinium? tenuiceras, Cribroperidinium spp., Exochosphaeridium phragmites, Florentinia clavigera, Florentinia mantellii, Florentinia sp., Hapsocysta sp., Kleithriasphaeridium eoinodes, Micrhystridium spp., Surculosphaeridium longifurcatum, Systematophora sp., scolecodonts, foraminiferal linings.
Makonde formation (Aptian Albian): Sample MB1-0-13 (Silty mudstone) – Terrestrial palynomorphs: Inaperturopollenites sp. Sample MB1-1-13 (Very fine silty sandstone) – Terrestrial palynomorphs: Cyathidites australis. Kihuluhulu formation (Aptian Albian): Sample WP222-1-14 (Silty claystone) – Terrestrial palynomorphs: Araucariacites sp.. Marine palynomorphs: Tasmanites sp. Sample WP92-14-14 (Silty mudstone) – Terrestrial palynomorphs: Cyathidites minor. Marine palynomorphs: Leiosphaeridia sp., Tasmanites sp. Sample WP92-17-14 (Silty mudstone) – Terrestrial palynomorphs: Baculatisporites sp., Callialasporites trilobatus, Cyathidites minor. Marine palynomorphs: Indet. species. Sample WP92-20-14 (Silty mudstone with clay clasts) – Terrestrial palynomorphs: Araucariacites autralis. Freshwater algae: Botryococcus spp.. Sample TDP40A-11/3 (Siltstone) – Terrestrial palynomorphs: Alisporites sp., Cicatricosisporites orbiculatus, Classopollis spp., Dictyophyllidites impensus, Ephedripites jansonii, Ephedripites multicostatus, Rugulatisporites sp., Spheripollenites sp., Triporoletes radiatus. Marine palynomorphs: Batioladinium micropodum, Circulodinium distinctum, Micrhystridium sp., Pterospermopsis sp., Spiniferites spp., Tasmanites sp., sp. indet. Sample TDP40A-6/2 (Siltstone) – Terrestrial palynomorphs: Araucariacites australis, Baculatisporites sp., Callialasporites trilobatus, Citricosisporites avnimelechi, Classopollis spp., Contignisporites cooksonii, Crybelosporites pannuceus, Cyathidites minor, Ephedripites jansonii, Ephedripites multicostatus, Perinopollenites elatoides. Freshwater algae: Botryococcus spp.. Marine palynomorphs: Impletosphaeridium sp., Oligosphaeridium cf. asterigerum, Oligosphaeridium complex, Sentusidinium spp., Spiniferites spp., dinocyst indet, foraminiferal linings. Unknown, here assigned to the Mitole Formation (Oxfordian Berriasian): Sample TDP40A-32/2 (Sandy siltstone) – Terrestrial palynomorphs: Araucariacites autralis, Baculatisporites sp., Callialasporites dampieri, Classopollis spp., Inaperturopollenites sp., Verrucosisporites sp.. Marine palynomorphs: Canningia reticulata, Circulodinium disctintum, Cyclonephelium sp., Kaiwaradinium scrutillinum, Kilwacysta sp., Surculosphaeridium sp. I, Systematophora areolata, Systematophora sp. Sample TDP40A-26/1 (Sandy siltstone) – Terrestrial palynomorphs: Alisporites sp., Araucariacites autralis, Baculatisporites sp., Callialasporites trilobatus, Classopollis spp., Verrucosisporites sp. Marine palynomorphs: Circulodinium disctintum, Cleistosphaeridium sp., Cribroperidinium cf. edwardsii, Cribroperidinum cf. aparsium, Cribroperidinium spp., Tasmanites sp. References Backhouse, J., 1987. Microplankton zonation of the lower CretaceousWarnbro Group, Perth Basin, Western Australia. Mem. Ass. Australas. Palaeontol. 4, 205–226. Balduzzi, A., Msaky, E., Trincianti, E., Manum, S.B., 1992. Mesozoic Karoo and post-Karoo Formations in the Kilwa area, southeastern Tanzania – a stratigraphic study based on palynology, micropalaeontology and well log data from the Kizimbani Well. J. Afr. Earth Sci. 15, 405–427. Barss, M.S., Williams, G.L., 1973. Palynology and Nannofossil processing techniques. Geol. Surv. Canada 73, 22 Paper. Costa, L.I., Davey, R.J., 1992. Dinoflagellate cysts of the Cretaceous System. In: Powell, A.J. (Ed.), A Stratigraphic Index of Dinoflagellate Cysts. Chapmann & Hall, London, pp. 99–153. Dypvik, H., Einvik-Heitmann, V., Hudson, W., Fossum, K., Karega, A., Gundersveen, E., Nerbaten, K., Mahmic, O., Hou, G.M.V.D., Andresen, A., Rwechungura, R., Boniface, N., Kaaya, C., Holtar, E., Schomacker, E., 2015a. The Mandawa Basin Project – an interdisciplinary, educational-based research project in costal Tanzania. Abstract, East African Petroleum Conference and Exhibition, 4–6 March, 2015, Kigali, Rwanda. Dypvik, H., Einvik-Heitmann, V., Hudson, W., Fossum, K., Karega, A., Gundersveen, E., Nerbaten, K., Mahmic, O., Hou, G.M.V.D., Andresen, A., Rwechungura, R., Boniface, N., Kaaya, C., Holtar, E., Schomacker, E., 2015b. The Mandawa Basin of Coatal Tanzania and its Reservoir Potential. Abstract, First EAGE Eastern Africa Petroleum Geoscience Forum, 17–19 November 2015, Dar Es Salaam, Tanzania.
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