WILSON AND HEAD: FISSURE ERUPTION OF IO JGR-E 1323, IN PRESS, 2/11/01 Lava fountains from the 1999 Tvashtar Catena fissure eruption on Io: Implications for dike emplacement mechanisms, eruption rates and crustal structure
نویسندگان
چکیده
The first direct evidence that patterns of basaltic eruptive activity may be very similar on Io and Earth was seen on 26 November 1999, when the Solid State Imaging System on board the Galileo spacecraft obtained high-resolution images of a fissure eruption taking place in one of the calderas of the Tvashtar Catena complex. We analyzed the dynamics of the fissure eruption from the morphology of the lava fountains and pyroclastic deposits and derived an estimate of the eruption rate; our best estimate of the volume eruption rate per unit length of fissure lies in the range 0.7 to 7 m s -1 m , and multiplying this rate by the fissure length of ~ 25 km yields a total volume eruption rate of magma of ~2 x 10 to 2 x 10 m s . The upper end of the inferred eruption rate is very close to the upper end of the range of eruption rates observed or inferred for fissure eruptions on Earth. Theoretical models of the possible dike systems feeding the fissure show that, for eruptions of positively buoyant magma, the elastic properties of rocks are such that a magma flux of 6 to 7 m s -1 m -1 is the largest value that can ever be realized in such eruptions, this limiting value being independent of planetary gravity and thus the same on all silicate bodies. The eruption rate inferred for Tvashtar can also be achieved by a negatively buoyant magma, but in that case the source depth cannot be much greater than a few tens of km. We find that some eruptive events are consistent with the effusion of magmas which are buoyant relative to the crust, whereas others appear to involve magmas which are not. This implies that the distribution of crustal volatiles is laterally very inhomogeneous. Our analyses suggest that the depths from which magmas make their final ascent to the surface of Io are generally of order tens, rather than hundreds, of kilometers.
منابع مشابه
Eruption of magmatic foams on the Moon: Formation in the waning stages of dike emplacement events as an explanation of “irregular mare patches”
Article history: Received 23 September 2016 Received in revised form 31 January 2017 Accepted 7 February 2017 Available online 9 February 2017 Volcanic eruptions on theMoon take place in conditions of low gravity and negligible atmospheric pressure, very different from those on Earth. These differences lead to characteristic lunar versions of hawaiian and strombolian explosive activity, and to ...
متن کاملLunar Regional Pyroclastic Deposits: Evidence for Eruption from Dikes Emplaced into the Near-surface Crust
Introduction: Lunar pyroclastic deposits can be subdivided into several modes of occurrence [1], suggesting different modes of emplacement. For example, some smaller pyroclastic deposits have been interpreted to have erupted during strombolian/hawaiian activity [2], while others are linked to vulcanian activity related to dike and sill emplacement below crater floors [3,4]. The largest pyroclas...
متن کاملGeneration, ascent and eruption of magma on the Moon: New insights into source depths, magma supply, intrusions and effusive/explosive eruptions (Part 2: Predicted emplacement processes and observations)
We utilize a theoretical analysis of the generation, ascent, intrusion and eruption of basaltic magma on the Moon to develop new insights into magma source depths, supply processes, transport and emplacement mechanisms via dike intrusions, and effusive and explosive eruptions. We make predictions about the intrusion and eruption processes and compare these with the range of observed styles of m...
متن کاملPost-glacial Dike Emplacement Event at Arsia Mons, Mars: Eruptive Spatter Cones, Tephra Cones and Flows along a Dike-related Fissure
متن کامل
Volcanism on Mercury: A new model for the history of magma ascent and eruption
[1] We use the identification of volcanism on Mercury, together with lobate, flow-front like topography, crustal composition information and data on the stress state and history of the lithosphere, to derive a new model for the ascent and eruption of magma on Mercury. We find that extrusion is likely to be dominated by high-effusion rate events. Initial emplacement of dikes in the crust and ext...
متن کامل