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La Grotta sottomarina lu Lampiune: novità esplorative e prime indagini ecologiche


Abstract


It
Scoperta nel 1989, la Grotta sottomarina de lu Lampiùne, è una delle più complesse della costa orientale salentina. Una serie di ispezioni ha condotto alla scoperta di una galleria ed un camino non descritti nel rilievo realizzato nel 1989, ed ha aggiunto informazioni alla interpretazione dell’intero sistema di grotte di Punta Facì. Nel presente lavoro viene proposto il nuovo rilievo topografico de lu Lampiùne, la descrizione speleologica della nuova galleria rinvenuta e di nuove cavità limitrofe (grotte gemelle del Tau-Manhattan),nonchè i risultati delle prime indagini sulle biocenosi benthoniche sessili. Viene inoltre discussa la genesi di due delle concrezioni stalattitiche eccentriche presenti un po’ ovunque nella grotta. Per la prima volta in ambiente marino sommerso mediterraneo è stata appurata l’esistenza di stalattiti inequivocabilmente organogene.
En
The submarine cave lu Lampiùne, Pu 1318, was discovered in 1989 (ONORATO and PALMISANO, 1990), and immediately appeared as one of the most complex and largest caves of the Salento coast (South East Italy). In the last two years, the cave has been repeatedly visited by the speleodivers of the CSS “Apogon” Association, and those of the Marine Biology Station of the University of Lecce (see BELMONTE et al., 2001). A new passage which was not described in 1989, and another cave, the Tau-Manhattan grotto, Pu 1610, have been discovered which could belong, even being connected, to the same karstic complex (Fig. 4). A new topographic map of lu Lampiùne is presented here (Fig. 1), together with the morphological description of two anomalous stalactite structures (Tav. I, II). These structures hang abundant from the roof and lateral walls of the cave where they show an oblique position which does not agree with the gravity force (Tav. I). The study undoubtedly revealed the organic origin of such structures (up to 2 m long) which have been compared with the pseudostalactites of Belize (MACINTYRE et al., 1982), with the abiotic trays of New Mexico caves (CALAFORRA and FORTI, 1994), and with palm trunk stalagmites (HILL and FORTI, 1997). The biogenic stalactites of lu Lampiùne have different composition in different portions of the cave. They are typically coralligenous structures (built up by calcareous algae, and bored by endolithic organisms) at the cave entrance (Tav. I d, e, f), but they are monotonous aggregation of serpulid tubes in the inner portion of the cave (Tav. II a, c, d, e, f). At intermediate position, biogenic stalactites were composed by oister grapes (Tav. II b), this revealing the heterogeneous composition of this not well known structure. The underwater biogenic stalactites here ascertained, are discussed in consideration of their possible inclusion in the Sciafilic Biogenic Concretions (sensu PERES and PICARD, 1964) to which the more diffused coralligenous biocoenose belongs.

DOI Code: 10.1285/i15910725v26supp55

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