Calcareous plankton bio-chronostratigraphy of the Maltese Lower Globigerina Limestone member

Abstract

ABSTRACT:Baldassini, N., Mazzei, R., Foresi L.M., Riforgiato, F. and Salvatorini, G. 2012. Calcareous plankton bio-chronostratigraphy of the Maltese Lower Globigerina Limestone member. Acta Geologica Polonica, 63 (1), 105-135. Warszawa.The planktonic foraminifera and calcareous nannofossil biostratigraphy of the Maltese Lower Globigerina Limestone member has been investigated. The member was dated to early planktonic foraminiferal P22 Zone and nannofossil NP25 Zone (upper Chattian). A climate-stratigraphic approach, based on the quantitative analyses of calcareous nannofossils, was used additionally to achieve a more precise chronology. The species Coccolithus pelagicus (diameter ⩽11 µm) and the genus Umbilicosphaera were selected for the recognition of cold and warm surface waters intervals respectively. The ratio of their percentages enabled the construction of a Climatic Factor (CLF) curve. The CLF values were consistent with a warm climatic phase, which is probably represented by the portion of the oxygen stable isotope curve of Miller et al. above the Oi2c event and below the beginning of the cooling trend that culminates in the Mi1 event. Considering these two climatic events and the upper boundary of the NP25 Zone, it can be inferred that the deposition of the Lower Globigerina Limestone member took place between 25.1 and 24.3 Ma. members (Giannelli and Salvatorini 1972, 1975;Bennett 1979;Challis 1979; Rose et al. 1992), or at the base and at the top of the Middle Globigerina Limestone member (Kienel et al. 1995; Rehfeld and Janssen 1995).Despite the fact that the first chronostratigraphic data on the Globigerina Limestone formation were published in the late nineteenth century (e.g., Wright 1855); Gregory (1890-91); and Cooke (1896a, b), the first reliable reports date from the 1970s and 1980s century, when Giannelli and Salvatorini (1972) and Mazzei (1980Mazzei ( , 1986 recognised the Aquitanian and Burdigalian age of the Middle Globigerina Limestone member and the Langhian age of the Upper Globigerina Limestone member. Moreover, these authors identified sedimentary hiatuses associated with the two phosphatic beds. Their chronostratigraphic conclusions were substantially confirmed by Felix (1973). The researches concerning the Lower Globigerina Limestone member enabled Giannelli and Salvatorini (1972) to suggest a Chattian (Late Oligocene) age for the member, and Felix (1973) to refer it to the Aquitanian (Early Miocene). Subsequently, even though the Chattian age of the member was confirmed by several Sr-isotope analyses (Pratt 1990, unpublished Ph.D. thesis; Rose et al. 1992; Jacobs et al. 1996; Follmi et al. 2008), the attribution of the member to the Aquitanian was quoted in a number of reports (e.g., Rose 1974; Pedley et al. 1976;Challis 1979; Menesini 1979a, b;Theodoridis 1984; Pedley 1993; Kienel et al. 1995; Rehfeld and Janssen 1995).The aim of this study is to clarify the age of the Lower Globigerina Limestone member by quantitative and semiquantitative analyses of the planktonic fora...

Proposal for the nomination of Lower Globigerina Limestone of the Maltese Islands as a “Global Heritage Stone Resource”

“…Aquitanian (Early Miocene, 23.03-20.44 Ma) in age (Felix, 1973;Pedley et al, 1976); Oil Exploration Directorate (1993); (Foresi et al, 2007;Baldassini et al, 2013) Petrographic Name and Characteristics…”

Architectural Ruins: Geoculture of the anatomy of buildings as illustrated by Casa Ippolito, Malta

“…LGL is characterized by calcareous plankton [27]. The dominant mineralogy is calcite with minor inclusions of quartz, feldspar, muscovite, kaolinite, illite, smectite and glauconite.…”

Architectural Ruins: A Geoheritage Essay on the Anatomy of Buildings

“…Beds of LGL and MM occur in the immediate vicinity, south of the site, and their diagnostic properties and uses in the building industry are given in Table 2. LGL is pale cream to yellow in colour and is composed of planktonic foraminiferal packstones rapidly becoming wackestones above the base, whilst MM is composed of tabular beds of pale-cream to pale-grey carbonate mudstones, wackestones and packstones. The LGL is characterized by calcareous plankton [20]. The dominant mineralogy is calcite with minor inclusions of quartz, feldspar, muscovite, kaolinite, illite, smectite and glauconite.…”