Utwory cechsztyńskie a problem uzyskiwania głębokich granic sejsmicznych metodą refleksyjną

Abstract

Przedstawiono pogląd na temat powstawania fal odbitych na granicach utworów podcechsztyńskich w nawiązaniu do sprężystych parametrów ośrodka, wyników sejsmogramów syntetycznych oraz pionowych profilowań sejsmicznych. Fale odbite mogą być rejestrowane pod warunkiem zastosowania optymalnej metodyki badań refleksyjnych.ZECHSTEIN DEPOSITS AND THE QUESTION OF SURVEYING DEEP SEISMIC BOUNDARIES WITH THE USE OF REFLECTION METHODThe studies on geological structure of sub-Zechstein rocks with the use of reflection seismic method appear difficult. It is widely held that unsatisfactory results of seismic surveys of that complex are due to screening of energy of elastic waves by Zechstein cover. The paper presents characteristics of waves reflected from Zechstein boundaries and analysis of values of reflection coefficients for Paleozoic rocks. The results of vertical seismic profilling and synthetic seismograms are discussed and a special attention is paid to wave image obtained for Zechstein and deeperseated rocks. The analysis of that wave image showed that Zechstein rocks may not act as a screen precluding any record of waves reflected from sub-Zechstein complex. The effectiveness of reflection seismic surveys may be increased by weakening of disturbing surface waves. Such waves may be effectively kept down by appropriate distribution of boreholes and geophones along elongate bases, also in directions ·perpendicular to the profile.