Linking sill morphology to emplacement mechanisms
by
Nick Schofield
A thesis submitted to The University of Birmingham For the degree of DOCTOR OF PHILOSOPHY
Department of Earth Sciences School of Geography, Earth And environmental sciences The University of Birmingham May 2009
University of Birmingham Research Archive
e-theses repository
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation.
Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
37 40 43 46 49 52
MAP1 Composite aerial photograph ofTrotternish Peninsula NG grid square
N
75
72
69
66
63
4km 60 37 40 43 46 49 52
MAP2 Rubha Hun ish Slope Shaded DTM (bare earth) NG grid square
N
75
Galta Mor
Flodigarry ~ 72 '
69
Staffin Harbour
Kilt Rock 66
Lough Mealt
Sm DTM NexU'\''Iapternin data from NEOOC (NERC Eanh Obsen.oatbns Data Centre)
Rubha nam Brathairean 63
4km 60 49 37 40 43 46 52
Composite aerial photograph ofTrotternish peninsula rendered with slope shaded DTM to highlight changes in slope MAP3 NG grid square
N
75 •
72
69
66
63
4km 60 37 40 43 46 49 52
______.,. ____ _ MAP4 NG grid square
Meall Tuath N
75
Cam as Galta Mor
7 1
Al •~\ ,:·:;,,;,., 1 , \ ':::.:1111''\' Sb '• C!ill~• ~ft --+--10--1-- ' '' \ '•
\
\ ' \ \ '• ' ' '
Kilt Rock
Lough Mealt
' '\ ' Map data. from Ed ina Dg imap (1 :SO:OO OS raster & 1: 9DOO BGS Geo bgy Bed rock rastel)
= Uttla Minch Trottamish Sill Complex Palaeogene '\. =Dip ...... ~ ...... I 63 I I Slaffin Shala Formation (prQVious formation mambers; KimarDgaCBy,CoraiiBn and Oxford CICI}1 = I
=BE!Iemnita Sands I I = UpperOst~a boos I I f = Skud i~urgh Format on (fvbttled Clay~ I I f = Kilmalucg Formatbn·(Ostra:cd Umas10nE!) 53 Jurassi c (Great Estuarine Series) = Duntulm Formation (LowarOsti"E!a Bads) 4km 60 l'i,,, YI,l(l =Valtos Formation ((oncratbnary Sandstone) lnvertote Quarry
=l.Qalt Shala Formatioo 37 40 43 46 49 52
MAPS BG S sol id rock g f£ R;r.o..:;',(l overla non aerial photograph NG grid square t N
74
L ilb an 73 L
72 >, . 72 "" <>, .L
71
51 52
I n n a v
66
P/Bp data from Edina Digimap (1 :9JODOS raster & 1:9JOD BGSG:obgy Bedrock raitel) I I I =Faults ~tk on downth IOW) I I = Little Minch Trotternish Sill Ccrn plex Palaeogene ' =Dip :'.'\. 63
= Staffin Shala Formatbn (praviousformatbn mambers;Kimaridga CBy.Corallian and Oxford ClaY.!
= BalemnitE! Sands
= UpperOstO!a beds
= Skudiburgh Formation (Mettle:! Clay~
=Kilmaluag Formation (Ostla:cd Lima stone) 53
Jurassic (Great Estuarine Series) = Duntulm Formatbn (lowarOstrE!a BEds) 4km ------111060
=Valtos Formatbn (Concnationary Sandstone)
=lea~ Shale Formatbn 37 40 43 46 49 52
NG grid square MAP6 BGS solid rock geology & slope shaded DTM N
75 !• 1"1>1" fruuillar '11 1. ~'"j. ,, ....b, =·~I
\ ht r";l;. ,,,, ~!!tl
72
69
66
·.
1\o'Bpdata from 6:1ina Dgimap (1 :9:10:0 OS raster& 1:500:0 9:3SGeobgy Bedrock raster)
= Lktle M inch Trottamish Sill Complex Palaeogene ' =Dip r.'\. 63
= Stafti n Shala Formation (p I"QViou s format ion members; Kime ridge CBy, Cora 11 ia n and Oxfold Claf,l
= BeiE!mnitE! Sands
= UpperOst"'a bEds
= Skudibug h Formatbn OVIottiEd Clay~
= Kilmalucg Formatbn (Ostra::cd limestone)
= Duntulm Formation (lowEuOstraa BEds) Jurassic (Great Estuarine series) 4km 60
=Valtos Format ion (Cone rQt ionary Sands tone)
=!.salt Shale Formation 10111...... 1 37 40 43 46 49 52
Map:7 IHJBW\ HlHJISII BGS solid rock geology NG grid square ••• 11. & slope shaded DTM N ., . iti'lla.£•ffs!et· clr.. tcJpo•gr jl"'l!l .!' sheet along inferred fault trace I' ""'&lu et..:• Ml l.iJ;r,j 72 69 66 \ ' '' Clear topographic manifestation ' ' along inferred faulttraces 1\<'Q p date! f10 m 6::1 i m Og ima p (I :500:0 OS raster & I :50:00 BGS Glolcgy Bed rock raster) I I I =Faults (tick on dovmthro.v) I I = little M inch TlottE~rnish Sill Complex Palaeogene ' =Dip = Skye la\la field ~ 63 = Staffin Shala Formatbn (pr01bus formation mambers; KimarOga Clay.Corallian and Oxfold Clay) = Belam nita Sands = UpperOst"a bOOs = Skudiburgh Formation (1\'bttled Clays) = Kilmaluag Formation (Ostra:cd limastona) Jurassic (Great Estuarine series) = Duntu lm Formatbn (~JarOstrE!a BOOs) 4km 60 =Valtos Formation (Concretbnary Sands10na) = leak Shale Fonnation w ~ ,~- - , 0. 0. - .. s: " " )> "tJ r ' ~ ~ 00 , , ~ -• 0. 0. -• , -•0 •0 •0 - 0. a. ,,.,,. " ~,"·' ... ~,·-·· ... < ••••••• + ...• • + ~;:,"·''"·''.;:.;:,..-;, + . + .. + + "·''"·''' + ...+ + + ~-'·""-''·"'" ' "'g w -:T " Q m ., ,-· c ~ n ," '· ~ ~ ,• ,• -0 0 - -· 0 ~ -• • ~ - -• - ~ c Ill 0 ... -0 ~-~ ., ~ 0 iil 0 0 --· "'0 :D ~ ... -•"' "'a- - ~ ,. §i ,. 0 ;;: ;;: 0 ' - "~ IQ-· .g ~ ~ or ro ;;; • 0 0 "' iJ' ~ ;o:il' ,. §i , " ~ iil " 0 3 0 " 3 "0. ~ ,." ~ ~ -• -o " ~ 3 0~"' iJ • 3 ~- ::::r ,. 0 a- 3 ,. ~ 0 a- " 3 '- 0 -• '< a- ~ 3 ' ~ 0 0 •~- 3 a- ' " "' a- 0 n Ill ' 0 z ~ ,• ' • :I 3 ' 3 Vl -" c. ro ,, " ii .... "T'' ... .. ' ·' - 0 !lJ...... >' l.Q-· ...... ,~ .... ; . z' " ~ "m m 1-:;:: - ~ z z ~ z ~ ' m 0 Cl m c ~ z ~ l.Q "m ;: ....- · • a_ - Vl "'0 .n -,•" c "' !lJ.... -0. ro ~... "'0 w "' "' "' "' " ""' 37 40 43 46 49 52 MAP9 Inferred flow directions of Trotternish/little Minch Sill Complex NG grid square N 75 72 \ y 'I I ~ \I '~ \ • ' \ :\. \ \ \'(,, ., \ '( ' ' I ' ' X i ' < ' \ ' \ ~- 69 \ ·~ \ 'Y" ,\. f. :I ' \ ' ' ' ' ~ ( I ' ' ... ' \ \ "' ' \ ' ' ' I I I I I ,. ( 66 I I ,. ''// 1 • Stratigraphy South Eastern Dolerites Northern & Central Dolerites Timing Timing Lithology Proposed Stratigraphic Name Lithology Proposed Stratigraphic Name llllain Pulse Sub Pulse 2nd/3rd Staffin Member Relative 63 2nd/3rd Va/tos Member Crinanite timing Rubh' a' Chaim Leith sub-unit 3'd Picrite unkown D 2nd Va ltos sub-member • + >+ ' + ' + ' + >+ ' ••' ' Lough Mea/t Member '" + ' + ' + .+ ' > ' ' ' 2nd 2nd/3rd? 2nd? D Rubha Nam Brathairean F/odigarry Member Member 2nd Picrite 2nd 2nd? Crinanite D 1st? 1st Trottemish Picrite Member Staffin Island member 4km 60 '" Picrite South Eastern Picrite Member '" Crinanite Northern Crinanite Member Pullout 1 lnvertote and Rub nam Brathairean SW Fig.4.1 & D = Crinanite and Pulse) = Picrite (1st Pulse soom Fig.P1.2- Cliff section and interpretation of lnvertoteto Rum nam Brathairean Fig. P1.1- Cliff section at lnvertote showing crinanite and picrite units (crinanite post dates pi cri te) Dun Dearg, Lough Mealt and Kilt Rock IUIW Kilt Dun Dearg Lough R'ock Maalt = Fig.P1.S Fig.P1.7 ----I Fig.PI h ------F-... ---- 4.24 I I Dun Dearg I"- - Kilt I .... -- I I ______.J ------J Rg. PI .7 .J Rg. Pl.S Fg.P1.6 ------Fig.------P1 A· Sketch cross-section showing structure of Dun Dearg to Kilt Rock. Notethe first main pulse of crinaniteforming the lower tier of sillswhich is Fig. P1.3- Dun Dearg, Lough mealt and Kilt rock coastal section showing general sill form. Note the general open syndinal nature of the dolerite in the upper tier of the cliff face, and occurence of a large sea le broken bridge structure in the diff cross-cut bythe 2nd main pulse of crinanite in the region of Lough Mealt. face. Locations of other figures are marked. A) SOOtb SE ls t Pu ls:e Crir•an ite - -· - ~ ------.- 2nd PulseCrinanite 2nd/3d PulseCrinan~ = lh~r~d o.:isof fbw (innd 150 m 50 m Fig. P1 s . Dun Dearg cliff section showing sill intrusions into cltf and occurrence of steps un-broken and broken bridges. Fig. P1.6. Broken bridge structure at Lough Mea~ OJ caused by the inflation of two separate offset sill segments. The lowertier ofdolerite appears to have inflated by a series of sub-pulses.lhe chronology of the sub-pulses can be deduced from one another by the presence of internal chills within the sheet OiJ. South North step-up structure Lough Fig. Mealt Kilt Rock broken bridges (s.., Fig. 4.24) 250m Fig. P1.7- Sill structu"' ronhoflough Meak sl'owingtho uppertierdolents cross- Inland exprQssbn of sill suatigraphyas seen on Galta Morcoastal se::tioo North ii. i. B) SSE NNW .375m C) Decrc¥c inoolumnwidthceuscd by ooo ling it~ to 0\'o! rly irg C rii'IO nite ...:- ...... , .... = PicriteBrd Puis~ ,. -· . --·-~· - ·-· I ------,, .. I"' ... I ".-•o:l< =Picrit" (3rd Puis") = Picrite (2nd Pulse) I I .. I ... ,., '·;.; I ...... '' =Picrit" (2nd PulsQ) I ...... = Crinanite (1st Pulse) I ··········· , ... <' • • • I ·"' ...... 1.5 kdl ~---~----·------·---·--· ---~·:>· ·' .· ····· '• .,. ... ' ' .... =Crinanit" (1st PuiSQ) Fig. P2.2 -Sill stratigraphy seen on ooasral se cri on traClOd by changes in slope inland. Points i. ····· ~ .:' and ii. represent the same features in diagram A and B. , ' ······"' ::. . Fig. P2.1 -(a) Galra mor coasral secrionand (b) interpreration. (c) Overall sill structure from Flodigarry t'O B:!lmaqueen, showing crinanite overlying picrite (picrite pos·t-dates crinanil'e). Figure C redrawn and modified from Hurton & Owens (unpublished report). Rubha'a'chairn Leith (RCL) Rubha•'Ch•imw~h l RIJ>ha "Chitirn Lalh 1 &1st West Ea'it N N t t 500 1'1'1 Fig. P2.3- Coasral secrion of Rubh' a' chairn Le~h (RCL), showing internal conracrs between different picrite units visiblewithin the diff face. Photo courtesy of Donny Hutton Detached Block 500 m R Fig, P2.5 - Flow units of Rubha a' chai rn Leith mapped inland from coastal section by changes in slope. Fig. P2.4- A) Internal contact between two picrite sheets. B) Inland expression of the contact between sheets as traced by change in slope. Note points i. and ii on figure A correspond Northern Section to points i. and ii. on figure B. ~~ Go.lumnar jointirg conti.nuous be~n w~• Cooling joints orientated Columnar jointirg ootcontinuousthrough units both unitssug;;~est~heyempbce:l sug;;~~ing diffient.toolirg regimes ~Cri1e post: datirg cr)nailite) approximatly perpendicular to sill top Woast con1emporaneouslywith oneaoother East suggesting sill top is close to original geometry irr€gu la r joi nti rg SUQ:I~ing unstable cooling conditO ns Fig. P2.7- Paultzonecuttirg M&~~IITuath.TI'P- fault post·dates the intrusbn of the sills. Point LrmrkEd for or ~rrt:atbnonMap Somecurvirg and pinching ofoolumns visible. pulbut's. sug;;~estirg pbitecooling int.ocrinanit.e SOOm Fig. P2.6- Sill structure of the northern dolerite sheet exposed in the northern most part of the Trottern ish Peninsula. Note the peva sive nature of cooling joints through East both crinanite and picrite units. iv. soom =pie rite f ig. P2.8- Exp!e$Sbnofsillstratgrop~ s.:en on coastalcliffsection(~p) mapped intard by charges in.sbpe . Solid black I ines rep reg:nt pro mim nt = crinanite lardformfeatufeS. Points i. • ;.. tepre:sent featu~e:Son cliff se:tOnseasilj trace:! in l~nd by~ pogra phi: e( pres:sbn. Point LV. deti nes tirgEll like fe-atures"" 25 • 30m in wdth wh i:h can te ttace:l in land.