Delamination of the lower crust and lithospheric mantle has occurred in several convergent orogens, most notably the Alps and Pyrenees. Some workers suggest that the process is mechanically similar to tectonic wedging and triangle‐zone development, and dependent on the pattern of mechanical layering. A search of over 35 orogens that have been explored by geophysical techniques showed that no correlation exists between crustal composition and delamination. Delamination of passive subducting plate margins is more common than that of tectonically and/or volcanically active overriding margins. Estimates show that the lithospheric mantle of cool passive margins may contain greater net negatively buoyant mass than warmer active margins. The top of the lower lithospheric layer containing the greatest net negatively buoyant mass is aligned with a weak zone near the Moho. Passive margin lithosphere thus has a greater tendency to delaminate during a collisional event than active margin lithosphere. For delamination to initiate above the Moho, the lower crust must be subducted or depressed to allow for exposure to eclogite grade conditions. Transformation of the mafic lower crust to mafic eclogite also creates a likely delamination horizon above a lower lithospheric layer containing net negatively buoyant mass aligned with a weak zone in the lithosphere. In contrast to the stratigraphic delamination that is key to the development of small‐scale wedge structures, syncollisional delamination is likely to occur in response to an increase in the lateral tectonic stress on a weak horizon already stressed by net negatively buoyant mass in the lower lithosphere.

Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. REPORT DATE FEB 20062 U.S. Army Engineer Research and Development Center Vicksburg, MS 391808. PERFORMING ORGANIZATION REPORT NUMBER SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release, distribution unlimited SUPPLEMENTARY NOTESThe original document contains color images. The chemicals were evaluated on their ability to control dust and prevent foreign object damage. Each evaluation consisted of dust particle collection and soil property measurements. Pertinent conclusions from the testing conducted are noted, and recommendations for selecting dust abatement methods and materials are provided. DISCLAIMER:The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. List of Tables PrefaceThe purpose of this report is to present results from a field experiment conducted for the evaluation of chemical dust palliatives for use on helipads. Dust abatement materials selected for use on helipads should effectively reduce dust concentrations during takeoff and landings and should pose little risk for foreign object damage to the aircraft. This report provides data for the following:a. Evaluation of commercially available dust palliatives for mitigating dust on helipads.b. Evaluation of commercially available hydroseeders for distributing dust palliatives.c. Evaluation of the effect of palliative application rates on product performance.Users of this report include the U.S. Marine Corps Systems Command (USMCSC) units charged with expedient helipad construction, and agencies assigned operations planning responsibilities.The project described in this report is part of the Dust Abatement Program currently sponsored by Headquarters, USMCSC, 2200 Lester Street, Quantico, VA 22134-6050. Executive SummaryThe U.S. Army Engineer Research and Development Center was tasked by the U.S. Marine Corps Systems Command to develop dust control systems for ...

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The U.S. Army Engineer Research and Development Center was tasked by the U.S. Marine Corps Systems Command to develop dust control systems for sustainment use on roads and other large-area applications in temperate climates as part of a comprehensive dust abatement program. The project consisted of evaluating various dust palliatives and application procedures during field tests. The products of this effort include equipment recommendations, palliative recommendations, and complete application guidance. This report addresses testing performed to evaluate commercial palliatives and application processes for constructing and maintaining lines-of-communication. Twenty-five test sections were constructed at Fort Leonard Wood, MO, using commercial palliatives for dust abatement. Several application procedures were evaluated in the process, including topical applications and admixture applications with alternate application rates. Each test section was evaluated at 0, 30, 80, and 220 days after construction. The evaluation consisted of dust particle collection and soil property measurements. Pertinent conclusions from the testing conducted are noted, and recommendations for selecting dust abatement methods and materials are provided.

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