Importance of active tectonics during karat formation. A Middle Eocene to Pleistocene example of the Lina Moutains (Irian Jaya, Indonesia)

The Lina Mountains show a typical example of karst formation associated to recent and active tectonics. The limestone samples were collected from gian t potholes present beneath the heavy rainforest, during speleological exped itions to the Bird's Head of Irian-Jaya. Micropalaeontological data allow u s to give a Middle Pleistocene age for the most recent karst formation. A d etailed stratigraphy between the Upper Lutetian and the Middle Pleistocene was recorded, with tectonic events during the Oligocene and Pleistocene. Th e edge of the resurgence layer was also dated. We also conclude the probabl e existence of a subterraneous network downhill of the karst within the mos t recent levels of the Kais Limestone formation. We replace this formation within the tectonic evolution of this area between the Eocene and the Middl e Pleistocene, in conjunction with the oblique convergence of the Pacific p late carrying volcanic are fragments and the Australian margin, which resul ted in folding, normal faulting associated with local extension, and wrench motion, which are settings capable of creating uplift of the carbonated pl atform. (C) Elsevier, Paris.