113 Geo-Eco-Marina 19/2013 1. INTRODUCTION The Bucegi Conglomerate Formation is the lithostrati- graphic term referring to thick conglomerate deposits accu- mulated at the end of the Lower Cretaceous, cropping out in the Bucegi Massif area, at the southern extremity of the Eastern Carpathians. Recent observations pointed out to a succession of sever- al distinct Albian conglomerate units genetically related, but with unclear stratigraphic signifcance. In order to proceed to upcoming sedimentology interpretations, it was essential to built up an up-to-date model of the geologic architecture in the northern Bucegi study area. This became the goal of a de- tailed stratigraphy and tectonics study that is herein present- ed. Our investigation was focused at the level of the upper member of the Albian Bucegi Formation, namely the Babele Sandstone Member. The present study was carried out in the Obârşia Moun- tain zone, between Şugărilor and Obârşiei Rivers (Fig. 1). This area is located in the northern part of the Bucegi Massif, where the map published by Patrulius (1969) shows multiple olistoliths (Fig. 2). Geographically, the study area is situated in the Prahova County, in the spring area of the Ialomiţa River. The Obârşia Mountain has two topography summits, which will be frequently referred to in this paper: the Colţii Obârşiei Peak (2488 m) to the north, and a nameless summit with 2380 m elevation to the south (Fig. 1). Geologic mapping was the main approach to accomplish the study objective. The map previously made by Patrulius (1969) served as a starting point, the new cartographic activ- ity looking for more detailed geologic features. Besides the classical rock-outcrop examination, special consideration was paid to the relief morphology, capable to reveal the trend of some geological boundaries, mainly in the areas with poor quality outcrop coverage. The satellite image examination, STRATIGRAPHY AND TECTONICS OF THE UPPERMOST BUCEGI CONGLOMERATE FORMATION (ALBIAN, EASTERN CARPATHIANS, ROMANIA) DAN CONSTATIN JIPA, CONSTANTIN UNGUREANU AND GABRIEL ION National Institute of Marine Geology and Geo-ecology, 23-25 Dimitrie Onciul Street, RO-024053 Bucharest, Romania, e-mail: jipa@geoecomar.ro, costinungureanu@geoecomar.ro, gion@geoecomar.ro Abstract. This paper presents a detailed lithostratigraphic investigation carried out in the Bucegi Massif, a mountainous zone from the southern part of the Eastern Carpathians. The study focused on the 50 - 70 m thick succession of four conglomerate units associated with olistoliths, intercalated in the upper part of the Babele Sandstone Member (the uppermost lithostratigraphic unit of the Albian Bucegi Conglomerate Formation). The conglomerate beds suc- cession stands for the uppermost strata of the thick Bucegi conglomeratic accumulation. All the four conglomerate bodies are stratiform and continuous for almost two kilometers, and show mainly constant lithofacies features on wide areas. The study emphasizes two large-scale trends of high implication on depositional interpretation. The reduced areal extension of the basal conglomerate unit, compared with the larger extension area of the overlying units 2, 3 and 4, is one of the features with genetic signifcance. Another remarkable characteristic is the lateral passage from the single thick conglomerate units 2, 3 and 4, to conglomerate units alternating with sandstones beds. Another remarkable characteristic is the northwards amalgamation of the conglomerate units 1, 2, 3 and 4 into a single body, named in this paper the Conglomerates with Olistoliths. Key words: Bucegi Massif, Albian, lithostratigraphy, conglomerate unit, olistoliths, fning upward trend.