The role of rifting in the formation of the recent structure of the Mongolia-Okhotsk orogen is extremely high, but it is still underestimated with regard to flanks of the Dzhagda segment of this orogen. Current researches refer to a combination of physical and chemical processes in the depth of the lithosphere, as well as interactions between the Izanagi, Eurasian and Pacific plates as explanations of repeated rifting events in East Asia. Upwelling of the asthenosphere due to significant differences in the lithosphere thickness (150-200 km under cratons, and only 100 km under orogenic belts) was viewed as a cause of rifting. It was assumed that rifting was controlled by mantle plumes, volcanism and heat regime. Structures bordering the Mongolia-Okhotsk orogen from north and south were considered as superimposed or marginal troughs. Recent studies have revealed numerous riftogenic Late Mesozoic structures in the Central Asian orogenic belt, which resulted from the collision of the Siberian and North Chinese cratons. New geological survey and geochemical data on volcanites confirmed the riftogenic origin of the Zeya-Uda (or Uda) and Nora-Selemdzha troughs bordering the Mongolia-Okhotsk orogen from north and south, respectively ( Fig. 1, and 2). Geology and geophysics of those troughs has been described. It is noted that riftogenic volcanites formed later in the east than those in the west. The Late Mesozoic rifting is widely manifested in North Eastern Asia across the area exceeding two million square kilometers, from Lake Baikal to the Sikhote-Alin region (west to east) and from the Southern Yakutia basins to North China (north to south). It is evidenced by intra-continental rifts of various trends, volcanic provinces and extension structures along large strike-slip faults [Ren et al., 2002]. The Uda and Nora-Selemdzha marginal troughs located along the Dzhagda segment of the Mongolia-Okhotsk orogen give evidence that compression was replaced by extension in the study area. Rifting structures may be due to physical and chemical processes, the development of plumes [Yarmolyuk et al., 2000], as well as the interaction between the Pacific and Eurasian lithospheric plates. Volcanic activity took place earlier in the west and then propagated to the east due to the shifting of the subduction zone in this direction. This paper analyzes regional and global geological events on the basis of new drilling data and the geochronological dating of volcanites. It describes the Late Mesozoic stage of rifting at the flanks of the Dzhagda segment of the Mongolia-Okhotsk collisional orogen. P a l e o g e o d y n a m i c s RESEARCH ARTICLEДля цитирования: Кириллова Г.Л. Позднемезозойский рифтогенез на флангах Джагдинского звена Монголо-Охотского коллизионного орогена: глобальные и региональные аспекты // Геодинамика и тектонофизика.

G r a v i t y a n d p o t e n t i a l f i e l d s 892 The Leading Edge August 2013 SPECIAL SECTION: G r a v i t y a n d p o t e n t i a l f i e l d s Toward 1-mGal accuracy in global marine gravity from CryoSat-2, Envisat, and Jason-1 M ore than 60% of the Earth's land and shallow marine areas are covered by > 2 km of sediments and sedimentary rocks, with the thickest accumulations on rifted continental margins (Figure 1). Free-air marine gravity anomalies derived from Geosat and ERS-1 satellite altimetry (Fairhead et al., 2001; Sandwell and Smith, 2009; Andersen et al., 2009) outline most of these major basins with remarkable precision. Moreover, gravity and bathymetry data derived from altimetry are used to identify current and paleo-submarine canyons, faults, and local recent uplifts. These geomorphic features provide clues to where to look for large deposits of sediments. While current altimeter data delineate large offshore basins and major structures, they do not resolve some of the smaller geomorphic features and basins (Yale et al., 1998; Fairhead et al., 2001). Improved accuracy and resolution is desirable: to facilitate comparisons between continental margins; as an exploration tool and to permit extrapolation of known structures from well-surveyed areas; to follow fracture zones out of the deep-ocean basin into antecedent continental structures, to define and compare segmentation of margins along strike and identify the position of the continent-ocean boundary; and to study mass anomalies (e.g., sediment type and distribution) and isostatic compensation at continental margins. In this article, we assess the accuracy of a new global marine gravity model based on a wealth of new radar altimetry data and demonstrate that these gravity data are superior in quality to the majority of publicly available academic and government ship gravity data. New radar altimeter data Gravity field accuracy depends on four factors: spatial track density, altimeter range precision, diverse track orientation, and the accuracy of the coastal tide models. Recently three new nonrepeat altimeter data sets have become available: 1) CryoSat-2 was successfully launched in February 2010 and has routinely collected altimetry data over ice, land, and ocean since July 2010 (Wingham et al., 2006). The satellite has a long 369-day repeat cycle resulting in an average ground track spacing of 3.5 km at the equator. 2) The Envisat satellite, which has been in continuous operation since 2002, was running low on the fuel needed for maintaining a repeating ground track. In October 2010, Envisat was placed in a new partly drifting-phase orbit (~30 day repeat) to conserve fuel. Although the spacecraft failed in April 2012, it was able to collect 1.5 years of data along this new ground track. These data combined with 97 repeat cycles in the 35-day ground track make a significant

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Oceanic fracture zone traces are widely used in studies of seafloor morphology and plate kinematics. Satellite altimetry missions have resulted in high-resolution gravity maps in which all major fracture zones and other tectonic fabric can be identified, and numerous scientists have digitized such lineaments. We have initiated a community effort to maintain low-cost infrastructure that allows seafloor fabric lineaments to be stored, accessed, and updated. A key improvement over past efforts is our processing software (released as a GMT5 supplement) that allows for semiautomatic corrections to previously digitized fracture zone traces given improved gridded data sets. Here we report on our seafloor fabric processing tools, which complement our database of seafloor fabric lineations, magnetic anomaly identifications, and plate kinematic models.

[1] We have examined 4918 track line geophysics cruises archived at the U.S. National Geophysical Data Center (NGDC) using comprehensive error checking methods. Each cruise was checked for observation outliers, excessive gradients, metadata consistency, and general agreement with satellite altimetry-derived gravity and predicted bathymetry grids. Thresholds for error checking were determined empirically through inspection of histograms for all geophysical values, gradients, and differences with gridded data sampled along ship tracks. Robust regression was used to detect systematic scale and offset errors found by comparing ship bathymetry and free-air anomalies to the corresponding values from global grids. We found many recurring error types in the NGDC archive, including poor navigation, inappropriately scaled or offset data, excessive gradients, and extended offsets in depth and gravity when compared to global grids. While $5-10% of bathymetry and free-air gravity records fail our conservative tests, residual magnetic errors may exceed twice this proportion. These errors hinder the effective use of the data and may lead to mistakes in interpretation. To enable the removal of gross errors without over-writing original cruise data, we developed an errata system that concisely reports all errors encountered in a cruise. With such errata files, scientists may share cruise corrections, thereby preventing redundant processing. We have implemented these quality control methods in the modified MGD77 supplement to the Generic Mapping Tools software suite.Citation: Chandler, M. T., and P. Wessel (2008), Improving the quality of marine geophysical track line data: Along-track analysis,