Spectral Pattern Classification in Lidar Data for Rock Identification in Outcrops

The present study aimed to develop and implement a method for detection and classification of spectral signatures in point clouds obtained from terrestrial laser scanner in order to identify the presence of different rocks in outcrops and to generate a digital outcrop model. To achieve this objective, a software based on cluster analysis was created, named K-Clouds. This software was developed through a partnership between UNISINOS and the company V3D. This tool was designed to begin with an analysis and interpretation of a histogram from a point cloud of the outcrop and subsequently indication of a number of classes provided by the user, to process the intensity return values. This classified information can then be interpreted by geologists, to provide a better understanding and identification from the existing rocks in the outcrop. Beyond the detection of different rocks, this work was able to detect small changes in the physical-chemical characteristics of the rocks, as they were caused by weathering or compositional changes

High-resolution spectroscopy for detecting stratigraphic surfaces and stacking patterns in sedimentary basins

In this research was evaluated the potential of using scores derived from spectral data to detect surfaces and stacking patterns in the sedimentary record, and propose a new method for analyzing spectral data. Spectral field surveys with wavelengths ranging between 2.0 and 2.5 μm were acquired from three well-exposed outcrops in the Neuquén Basin, Argentina. The sedimentary succession surveyed in this area presents a continuous exposure up to 600 m thick and comprises both pure and hybrid siliciclastic, carbonate and evaporitic rocks. Reflectance data obtained from this area were processed by multivariate analysis, which demonstrates that almost all of the data variance is represented by the first principal component. Inflections of the scores' derivatives can be used to identify stratigraphic surfaces and as an indicator of stacking patterns. Overall, these results demonstrate that fast, inexpensive and non-destructive spectral data are useful tools in the fields of sedimentology and stratigraphy, which have the potential to eventually support more complex and detailed hyperspectral stratigraphy research

Late Cenozoic evolution of the Nicobar Fan - Insights from U-Pb-Hf in Zircon

International audienceLate Cenozoic deep-sea deposits of the Bengal – Nicobar Fan recorded the events of Himalayan accretion during the India – Asia collision. IODP Expedition 362 – The Sumatra Subduction Zone – recovered a sedimentary section at the Nicobar Fan that comprises Early Miocene to Holocene strata. This work aims to identified potential sources and the evolution of the fluvial system that fed into the Nicobar Fan during that interval. For this, we analyzed zircon U-Pb-Hf in seven samples from sandy and silty turbidite deposits of U1480 and U1481 Sites. U-Pb zircon ages range from 22 to 3358 Ma and εHf −33.7 to +15, originated from Central and Eastern Himalayan, Lhasa Block, peninsular India and Indo Burma Ranges, the Ganges – Brahmaputra rivers drained areas. Our data suggest a significant reorganization of source areas since the Late Miocene. Rapid uplift of the Himalayan syntaxis in the Late Miocene to Pleistocene exposed distinct source rocks, altering the provenance signature and enhancing sediment delivery towards the sink. This is evidenced by gradually switched in first cycle zircons in the Nicobar Fan from the Lhasa Block and Gangdese Batholith to the Bomi-Chayu and Lohit Batholiths. Sediment provenance shifted since the Pliocene, with an increase in Ganges-derived Archean peninsular India, Cambro-Ordovician granites and Greater Himalaya orthogneisses at the Nicobar Fan. We attribute this shift to the rise of the Shillong Plateau, which projected the Brahmaputra delta to the west towards the Ganges river. This rise of the Shillong Plateau and the sea level fall at the Plio-Pleistocene enabled the merge of the Brahmaputra and Ganges deltas for the first time. Our data suggest that the Nicobar Fan was majorly supplied by the Brahmaputra River during the Tortonian, with an only minor contribution from the Ganges river. Following that, an increase in sediment contribution from the Ganges River is observed

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)