Overprinted strike-slip deformation in the southern Valley and Ridge in Pennsylvania

Two major faults, over 32 km long and 6.4 km apart, truncate or overprint most previous folds and faults as they trend more northerly than the previous N25°E to N40°E fold trends. The faults were imposed as the last event in a region undergoing sequential counter-clockwise generation of tectonic structures. The western Big Cove anticline has an early NW verging thrust fault that emplaces resistant rocks on its NW limb. A 16 km overprint by the Cove Fault is manifested as 30 small northeast striking right-lateral strike-slip faults. This suggests major left-lateral strike-slip separation on the Cove Fault, but steep, dip-slip separation also occurs. From south to north the Cove Fault passes from SE dipping beds within the Big Cove anticline, to the vertical beds of the NW limb. Then it crosses four extended, separated, Tuscarora blocks along the ridge, brings Cambro-Ordovician carbonates against Devonian beds, and initiates the zone of overprinted right-lateral faults. Finally, it deflects the Lat 40°N fault zone as it crosses to the next major anticline to the northwest. To the east, the major Path Valley Fault rotates and overprints the earlier Carrick Valley thrust. The Path Valley Fault and Cove Fault may be Mesozoic in age, based upon fault fabrics and overprinting on the east–west Lat 40°N faults.     

采用偏心割刀处理小口径钻孔掉钻事故实践

偏心割刀切割钻杆、钻具,多应用在大口径工程施工钻中,在地质钻探施工中,偏心割刀可以用来切割套管、岩心管。在贵州省普安县青山镇泥堡二矿的钻探施工中,使用偏心割刀从钻杆的外面将钻杆切割掉,成功处理了一次复杂的钻孔事故。介绍了采用偏心割刀处理钻孔事故的技术措施及注意事项。     

Intermediate-mass black holes and ultraluminous X-ray sources in the Cartwheel ring galaxy

Chandra and XMM–Newton observations of the Cartwheel galaxy show ∼17 bright X-ray sources  (≳5 × 10³⁸ erg s⁻¹)  , all within the gas-rich outer ring. We explore the hypothesis that these X-ray sources are powered by intermediate-mass black holes (IMBHs) accreting gas or undergoing mass transfer from a stellar companion. To this purpose, we run N -body/smoothed particle hydrodynamics simulations of the galaxy interaction which might have led to the formation of Cartwheel, tracking the dynamical evolution of two different IMBH populations: halo and disc IMBHs. Halo IMBHs cannot account for the observed X-ray sources, as only a few of them cross the outer ring. Instead, more than half of the disc IMBHs are pulled in the outer ring as a consequence of the galaxy collision. However, also in the case of disc IMBHs, accretion from surrounding gas clouds cannot account for the high luminosities of the observed sources. Finally, more than 500 disc IMBHs are required to produce ≲15 X-ray sources via mass transfer from very young stellar companions. Such number of IMBHs is very large and implies extreme assumptions. Thus, the hypothesis that all the observed X-ray sources in Cartwheel are associated with IMBHs is hardly consistent with our simulations, even if it is still possible that IMBHs account for the few (≲1–5) brightest ultraluminous X-ray sources.     

Measuring the accretion rate and kinetic luminosity functions of supermassive black holes

We derive accretion rate functions (ARFs) and kinetic luminosity functions (KLFs) for jet-launching supermassive black holes. The accretion rate as well as the kinetic power of an active galaxy is estimated from the radio emission of the jet. For compact low-power jets, we use the core radio emission while the jet power of high-power radio-loud quasars is estimated using the extended low-frequency emission to avoid beaming effects. We find that at low luminosities the ARF derived from the radio emission is in agreement with the measured bolometric luminosity function (BLF) of active galactic nucleus (AGN), i.e. all low-luminosity AGN launch strong jets. We present a simple model, inspired by the analogy between X-ray binaries (XRBs) and AGN, that can reproduce both the measured ARF of jet-emitting sources as well as the BLF. The model suggests that the break in power-law slope of the BLF is due to the inefficient accretion of strongly sub-Eddington sources. As our accretion measure is based on the jet power it also allows us to calculate the KLF and therefore the total kinetic power injected by jets into the ambient medium. We compare this with the kinetic power output from supernova remnants (SNRs) and XRBs, and determine its cosmological evolution.