Gravity variations along the Southeast Bohol Ophiolite Complex (SEBOC), Central Philippines: Implications on Ophiolite Emplacement

Abstract The basement complex of Bohol Island consists of the Southeast Bohol Ophiolite Complex (SEBOC), Cansiwang Melange and Alicia Schist. The SEBOC is a complete, but dismembered ophiolite with outcrops generally trending northeast– southwest and dipping north-west. The harzburgite units of the SEBOC are almost always observed to be thrusted onto the Cansiwang Melange, which in turn is thrusted onto the Alicia Schist. Bouguer gravity values on Bohol range from about +60 mGal in the west to +120 mGal in the east, in the region to the north-east of the SEBOC outcrops. Based on the present distribution of the SEBOC units and their thrust fault relationship with the Cansiwang Melange and Alicia Schist, it is proposed that the SEBOC was emplaced by onramping towards the south-eastward direction. However, the orientation of the Bouguer highs suggests that the thrusting direction of the ophiolite units is towards the south-west and not towards the south-east.     

Contrasting morphological trends of islands in Central Philippines: Speculation on their origin

Abstract The Palawan microcontinental block collided with the Philippine Mobile Belt in the Central Philippine region resulting in the counterclockwise rotation of Mindoro– Marinduque and clockwise rotation of Panay. The collision also brought about the clockwise rotation of north-east Negros, Cebu, north-west Masbate and Bohol (collectively called the Western Visayan block), resulting into their present-day northeast–southwest trend. This suggests a far more dramatic role of the collision than was previously recognized. Furthermore, the south-east Sulu Sea sub-basin is inferred to have also undergone collision-related clockwise rotation which can account for the observed east-west trending magnetic lineations in the basin. Aside from explaining the contrasting morphological trends of the different islands in Central Philippines, the rotation can also explain, albeit in a different way, how the belts of sedimentary basins, ophiolites and arcs in Panay and Negros can extend to Northern Luzon. Published paleomagnetic data suggest that the collision-related rotation commenced during the early to middle Miocene and had ceased by the late Miocene.     

Greenhouse gas emission associated with sugar production in southern Brazil

Background  

Since sugarcane areas have increased rapidly in Brazil, the contribution of the sugarcane production, and, especially, of the sugarcane harvest system to the greenhouse gas emissions of the country is an issue of national concern. Here we analyze some data characterizing various activities of two sugarcane mills during the harvest period of 2006-2007 and quantify the carbon footprint of sugar production.