The Experts below are selected from a list of 1794 Experts worldwide ranked by ideXlab platform
Yuanxiu Hui - One of the best experts on this subject based on the ideXlab platform.
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A novel approach for extraction of Ripple Mark parameters based on SfM
Sedimentary Geology, 2019Co-Authors: Ran Wang, Jingyu Lin, Zhouxuan Xiao, Yuanxiu HuiAbstract:Abstract Ripple Marks, formed by non-cohesive materials under the action of water, waves or wind, have been regarded as a diagnostic indicator in sedimentology, especially for the identification of current orientation and paleo-sedimentary environment reconstruction. However, it is difficult to obtain the different parameters of Ripple Marks in the field. Scientists still hitherto rely on compass and ruler to measure the Ripples. In this paper, a method based on Structure from Motion to obtain the parameters of Ripples is proposed. The whole workflow can be divided into seven steps: 1) Designing a Structure from Motion survey; 2) Taking photographs of high quality; 3) Generating a low-density point cloud; 4) Creating a high-density point cloud; 5) Building a georeferenced mesh model; 6) Establishing a digital surface model and a digital outcrop model; and 7) Extracting and calculating parameters of Ripple Marks. Through this approach, 253 attitudes (strike, dip-direction and dip angle) of Ripples, 50 Ripple wavelengths and 50 Ripple heights are extracted. In addition, 50 Ripple indexes, 50 Ripple symmetry indexes and 50 Ripple curvatures are calculated. Compared with traditional field observations, this method could be more efficient, lower-cost, more quantitative and more precise (millimeter scale), and could provide an alternative and competitive manner to extract the surface morphology parameters of consolidated or loose deposits with up to millimeter spatial resolution.
Ran Wang - One of the best experts on this subject based on the ideXlab platform.
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A novel approach for extraction of Ripple Mark parameters based on SfM
Sedimentary Geology, 2019Co-Authors: Ran Wang, Jingyu Lin, Zhouxuan Xiao, Yuanxiu HuiAbstract:Abstract Ripple Marks, formed by non-cohesive materials under the action of water, waves or wind, have been regarded as a diagnostic indicator in sedimentology, especially for the identification of current orientation and paleo-sedimentary environment reconstruction. However, it is difficult to obtain the different parameters of Ripple Marks in the field. Scientists still hitherto rely on compass and ruler to measure the Ripples. In this paper, a method based on Structure from Motion to obtain the parameters of Ripples is proposed. The whole workflow can be divided into seven steps: 1) Designing a Structure from Motion survey; 2) Taking photographs of high quality; 3) Generating a low-density point cloud; 4) Creating a high-density point cloud; 5) Building a georeferenced mesh model; 6) Establishing a digital surface model and a digital outcrop model; and 7) Extracting and calculating parameters of Ripple Marks. Through this approach, 253 attitudes (strike, dip-direction and dip angle) of Ripples, 50 Ripple wavelengths and 50 Ripple heights are extracted. In addition, 50 Ripple indexes, 50 Ripple symmetry indexes and 50 Ripple curvatures are calculated. Compared with traditional field observations, this method could be more efficient, lower-cost, more quantitative and more precise (millimeter scale), and could provide an alternative and competitive manner to extract the surface morphology parameters of consolidated or loose deposits with up to millimeter spatial resolution.
Lee R. High - One of the best experts on this subject based on the ideXlab platform.
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SHALLOW MARINE CURRENTS ON THE EARLY (?) TR IASS IC WYOMING SHEL l m
2016Co-Authors: Dane M. Picard, Lee R. HighAbstract:Analysis of 690 asymmetric Ripple Mark and 40 cross-stratification paleocurrent directions from 37 localities in the Red Peak Formation of Wyoming indicates three major current directions: northeast, southwest, and northwest. These are interpreted to respectively represent wave drift, rip, and longshore currents moving on, off, and along a northwest-southeast oriented coast that bordered the shallow, open marine, Wyoming shelf embayment during the Early (?) Triassic. Commonly used interpretive techniques based on calculated vector means of paleocurrent directions are inadequate for the polymodal distributions in the Red Peak. Instead, the major directions at each locality are determined and the resulting pattern interpreted visually. The use of vector means and moving averages would not deline and could possibly mask the complex current patterns to be expected in the shallow, open marine environment. Ripple Marks have been used infrequently as paleocurrent direction indicators. The long standing misconcep-tion equating external shape with mode of formation has inhibited their use. Evidence from the Red Peak supports other studies which have suggested that "symmetric " and "asymmetric " Ripple Marks are not wave-and current-formed respectively. Rather, niost Ripple Marks possess ome degree of asymmetry, either in shape or internal structure, and are formed bv currents (including most waves in shallow-water). Truly symmetric Ripple Marks formed by standing oscillatory waves are probably rare. Being current-formed, asymmetric Ripple Marks should prove increasingly important in reconstructing paleocurrent systems and paleogeography
Rani A Ramsof - One of the best experts on this subject based on the ideXlab platform.
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coastal deposit characteristic influenced by terrestrial organic matter and its sedimentary structure at jangkang beach bengkalis district riau province indonesia
2018Co-Authors: Yuniarti Yuskar, Tiggi Choanji, Adi Suryadi, Rani A RamsofAbstract:Jangkang Beach is located in the Deluk village, Bengkalis District, Riau Province, Indonesia. This beach is overgrown by mangrove plants and peat. Its presence resulting varying thickness amount of terrestrial organic material deposited to the shore. Purpose of this research is to determine the characteristics of coastal sediments that influenced by the distribution of terrestrial organic materials and its sedimentary structures. The method is used for field survey that consists of drilling core at five locations, lateral measured section, and granulometric analysis at laboratory. This research resulted in that coastal sediments consist of medium to fine sand, silt, clay, and organic material. The terrestrial organic material (TOM) deposited at Jangkang Beach has size ±35 cm which is wooden to finely sized (less than 2 mm) with thickness 5–15 cm. Distribution of this material located on littoral zone (intertidal) and number of TOM decreased seaward with increasingly more fine wood. This TOM was deposited above Ripple Mark sedimentary structure. Ripple Mark has slope 100–480 with symmetrical shape. Other sedimentary structures found are bioturbation structure (burrow, track, trail), lenses of TOM, cross lamination, and parallel lamination.
Philippe Claeys - One of the best experts on this subject based on the ideXlab platform.
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Ripple Marks indicate Mid-Devonian paleo-wind directions in the Orcadian Basin (Orkney Isles, Scotland)
Palaeogeography Palaeoclimatology Palaeoecology, 2015Co-Authors: David De Vleeschouwer, David Leather, Philippe ClaeysAbstract:Abstract Few climate proxies provide information on paleo-wind directions. However, fossilized bedform elements can provide insight into the direction of flow that formed them. Wave-formed Ripple Marks, for example, which developed in shallow waters, extend transversely to the wind direction. In this study, Middle Devonian paleo-wind directions are reconstructed by measuring the orientation of 511 fossilized wave Ripple Marks in the Rousay Flagstone Formation on the island of Westray, Orkney, Scotland. The orientation of Ripple Marks was measured in four different localities on the island. A chi-squared test demonstrates that these four Ripple-Mark subsets show the same distribution of Ripple Mark orientation and thus indicates that the studied Ripple Marks display the same distribution of paleo-winds. Two dominant Ripple Mark orientations were observed at all studied localities. The most abundant Ripple Mark orientation suggests paleo-winds from the present-day North or South. Second most abundant are Ripple Marks that suggest paleo-winds from the present-day ENE or WSW (70° or 250°). When a 40° clockwise rotation of Orkney since the Middle Devonian is taken into account, the Ripple Marks suggest that the dominant wind directions were south-southeast (SSE) and north-northeast (NNE) in the tropical setting of the Orcadian basin. The SSE wind-direction is represented by the abundant Ripple Marks, with a present-day near N–S orientation of the line perpendicular to the crests. These Ripple Marks are also characterized by the largest wavelengths. The abundance of the latter Ripple Marks with long wavelengths is the result of a lower water level and thus a larger wave-exposed surface during the dry winter season, from April to July, which was mainly characterized by SSE paleo-trade winds.
