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The stratigraphy of marine Plio-Pleistocene sediments from northeast Rhodes (Dodecanese islands, Greece) is revised in the light of facies mapping and the recognition of three major transgression–regression cycles. Before late Pliocene submergence, metamorphosed Mesozoic limestones formed a high-relief karstic landscape. During subsequent transgressions, subsiding basins with spectacular cliffed and bioeroded margins were infilled by a mosaic of carbonate-dominated sediments, sourced by high rates of carbonate productivity on narrow shelves rimming the basins and their drowning islands. Periods of relative sea-level fall superimposed a complex series of ‘fossil’ coastal geomorphological features such as cliffs, abrasion platforms, surf caves, notches, boulder beaches and palaeokarsts. These created the rugged present day topography of the island's northeast coast. Three main lithostratigraphic units, the Kritika, Rhodes and Lindos Acropolis Formations, are defined. The Rhodes and Lindos Acropolis Formations are subdivided into mappable facies groups rather than members, as the lithofacies are strongly diachronous. The Kritika and Rhodes Formations were each subaerially exposed and partly eroded before re-transgression. Although there is a general pattern of lithological succession, details vary across the study area and some facies groups are restricted in development, indicating differences in tectonic behaviour and palaeo-geomorphology between neighbouring basins. A preliminary process-response model is presented for the sedimentation history of the Rhodes and Lindos Acropolis Formations, using sedimentological, palaeontological, palaeoecological and ichnological data. © 1996 John Wiley & Sons, Ltd. 相似文献
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The 18 ichnospecies of the vertically oriented, helical marine to marginal marine trace fossil Gyrolithes Saporta, 1884 known so far are revised. A new ichnospecies, G. lorcaensis isp. n. (Miocene, SE Spain), is introduced, and Conispiron Vialov, 1969 and Spirocircus Mikulá? and Pek, 1994 are included in Gyrolithes. The ichnotaxobases of the Gyrolithes ichnospecies are based on the character of the burrow margin (presence or absence of a wall or ornamentation) and/or on morphometric parameters (burrow width versus radius of the whorls). As a result of synonymization, 13 ichnospecies are recommended. The morphometric parameters of Gyrolithes show two distinct lineages (large ratio of whorl radius to burrow width and medium ratio of whorl radius to burrow width; 10–12 and 1–1.6, respectively). The third lineage (small ratio of whorl radius to burrow width; up to 1) is less distinct. 相似文献
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