The Control Factors Of Color Changes And Its Paleoclimatic Significances On Zhangye Color Hilly

Cretaceous is the last period of Mesozoic Cretaceous,in 145.5Ma,at the end of 65.5Ma,after about 80Ma,is a Mesozoic period lasted for the longest time,some important events occurred during this period(oceanic anoxic events,ocean red event,dinosaur extinction events etc.)typical geological history is also recognized in the the extreme greenhouse climate,has been regarded as the earth system science research paradigm of international earth science community,known as "the world",is undoubtedly a detailed study of the Cretaceous is unique geological era,providing a possible explanation for the cause of the Cretaceous climate can produce many geological events,and predict the future change of greenhouse effect in the remodeling of climate history and also has important significance.For the study of the Cretaceous climate is more focused on marine sediments,terrestrial sediments due to scattered distribution of existing sedimentation intervals of relatively less reason of continental deposits with marine sediments also contains important climate information is an indispensable part of a comprehensive study of the Cretaceous climate.Zhangye color Hilly Formation color cycle obviously,as the early Cretaceous continental sedimentary during the whole deposition sequence has good continuity,the deposition thickness reaches about 1000m,the formation of good exposure,is the study of the Cretaceous climate change rare material.This paper selects Zhangye Nantaizi color Hilly Village section as the research object,the detailed rock magnetic measurements at room temperature(magnetic parameters,hysteresis and thermal magnetic curve color(red);parameter measurement,yellowness,brightness);grain size measurement;carbonate content measurement;X-ray diffraction analysis and wavelet analysis,the following conclusions:(1)Zhangye Nantaizi Village section of color hilly red sediment with SD particles of hematite as the main magnetic minerals in the sediments of yellow;magnetic minerals include hematite and goethite and goethite;grey sediments contain more paramagnetic minerals and magnetic minerals are mainly of iron sulfide.(2)The climate characteristics of representative samples of Zhangye Nantaizi village red color Hilly section in hot dry,grey samples represent a humid climate and the climate where the Yellow sample belongs to a transition stage from humid to arid.The gray green to yellow to red sample sample sample,the climate is cold wet gradually become a hot and dry process.(3)Color hilly in red and yellow sediment surface oxidation environment belongs to dust accumulation products,perhaps as a Cretaceous soil type has not been identified.The grey sample has no grain size characteristics of aeolian deposits,should belong to the reduction under the environment of the lake sediments.(4)During the Cretaceous climate is not change continued warm steady state,a rough analysis of extraction of satellite images of the indicator shows that the early Cretaceous are six changes of wet and dry cycles;the whole section of the magnetic susceptibility value analysis showed that the Xiagou Formation in the early Cretaceous sedimentary formation period of the climate there are a number of alternate to change;ditch group part(section 0-85m)wavelet stratigraphic magnetic susceptibility index analysis showed the presence of 4 Changes of wet and dry cycles,all kinds of analysis results of multiple indicators showed changes of climate fluctuations are frequent.Based on the early Cretaceous...